WO2025112796A1 - 电池单体、二次电池和用电装置 - Google Patents

电池单体、二次电池和用电装置 Download PDF

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Publication number
WO2025112796A1
WO2025112796A1 PCT/CN2024/118339 CN2024118339W WO2025112796A1 WO 2025112796 A1 WO2025112796 A1 WO 2025112796A1 CN 2024118339 W CN2024118339 W CN 2024118339W WO 2025112796 A1 WO2025112796 A1 WO 2025112796A1
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Prior art keywords
positive electrode
active material
electrode active
optionally
further optionally
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English (en)
French (fr)
Inventor
吴凯
尚义博
刘鹤
郭锁刚
何建福
付成华
叶永煌
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Contemporary Amperex Technology Co Ltd
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Contemporary Amperex Technology Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/204—Racks, modules or packs for multiple batteries or multiple cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/249—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders specially adapted for aircraft or vehicles, e.g. cars or trains
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the technical field of secondary batteries, and in particular to a battery cell, a secondary battery and an electrical device.
  • secondary batteries represented by lithium-ion batteries are widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, and are also widely used in smart phones, tablet computers, smart wearables, power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.
  • energy storage power systems such as hydropower, thermal power, wind power and solar power stations
  • smart phones tablet computers, smart wearables, power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.
  • risks such as thermal runaway may be brought about, resulting in poor thermal stability of batteries.
  • the present application provides a battery cell, a secondary battery and an electric device.
  • the battery cell has good electrical performance, good thermal stability and low risk of thermal runaway.
  • a battery cell which includes a positive electrode plate and an electrolyte; in the positive electrode active material layer of the positive electrode plate, the mass ratio of the Co element in the first positive electrode active material to the Fe element in the second positive electrode active material is A; the first cationic salt in the electrolyte includes a first cation having an ion radius greater than that of a lithium ion; the mass percentage of the first cationic salt in the electrolyte salt is B; 0.47 ⁇ A/B ⁇ 202.
  • a battery cell which includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, wherein the separator is disposed between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet includes a positive electrode active material layer, the positive electrode active material layer includes a first positive electrode active material and a second positive electrode active material, the electrolyte includes an electrolyte salt, and the electrolyte salt includes a first cation salt and an electrolyte lithium salt;
  • the first positive electrode active material is a lithium oxide containing Co and M1 elements
  • the second positive electrode active material is a lithium oxide containing Fe and Mn elements, wherein the M1 element in the first positive electrode active material includes one or both of Mn and Al elements;
  • the mass ratio of the Co element in the first positive electrode active material to the Fe element in the second positive electrode active material is denoted as A;
  • the first cationic salt includes a first cation, the ionic radius of the first cation is greater than the ionic radius of the lithium ion; the mass percentage of the first cationic salt in the electrolyte salt is denoted as B;
  • a and B satisfy 0.47 ⁇ A/B ⁇ 202.
  • the active ions in the battery cell include lithium ions.
  • the positive electrode sheet in the battery cell is a composite positive electrode sheet, in which different positive active materials are arranged, and the composite positive electrode sheet includes a first positive active material containing cobalt (Co) element and M1 element, M1 element includes one or two of manganese (Mn) element and aluminum (Al) element, and also includes a second positive active material containing iron (Fe) element and Mn element.
  • the composite positive electrode sheet design can make different positive active materials complement each other, it is hoped that the comprehensive electrical performance in aspects such as material structure stability, battery safety, rate performance, cycle performance, etc. can be improved, and the voltage platform and manufacturing cost can be taken into account.
  • the lithium oxide containing Co and M1 elements and the lithium oxide containing Fe and Mn elements are different positive electrode active materials, and have different activities and ionic conductivities, resulting in different degrees of utilization during the charge and discharge cycle.
  • the lithium oxide containing Co and M1 elements is easily over-utilized, causing damage to the surface structure of the first positive electrode active material and releasing oxygen, and may even cause the material structure to collapse, posing a risk of thermal runaway of the battery; in addition, the released oxygen may also trigger side reactions in the electrolyte.
  • the active ion diffusion in the composite positive electrode plate design is presumed to be one-dimensional channel diffusion.
  • a first cation with an ion radius larger than that of lithium (Li) ions is introduced.
  • the first cation can replace part of the active ions and embed into the first positive electrode active material, blocking the active ion diffusion channel in the first positive electrode active material, reducing the utilization of the first positive electrode active material, and reducing the release of oxygen.
  • the first cation can also play a role in supporting the surface structure of the first positive electrode active material, which can hinder the removal of active ions during discharge, further increase the stability of oxygen on the surface of the positive electrode active material, and reduce the release of oxygen.
  • the first cation can improve the thermal stability of the composite positive electrode plate and the battery cell, and reduce the risk of thermal runaway.
  • the mass ratio A of the Co element in the first positive electrode active material to the Fe element in the second positive electrode active material also recorded as the I Co /II Fe ratio
  • the content ratio between the first positive electrode active material and the second positive electrode active material can be adjusted, and the A/B value can be further used to coordinately adjust the first positive electrode active material in the electrolyte.
  • the mass percentage B of a cationic salt relative to the electrolyte salt can make the concentration of the first cation in the electrolyte better match the demand of the first positive electrode active material for appropriately reducing the utilization rate, thereby achieving better overall comprehensive electrical performance, significantly improving the thermal stability of the composite positive electrode plate and the battery cell, reducing the risk of thermal runaway, and also helping the composite positive electrode plate to have good active ion transport performance as a whole. It can be seen that the battery cell has better overall performance, good thermal stability, and low risk of thermal runaway.
  • the ratio of the ionic conductivity of the first positive electrode active material to the ionic conductivity of the second positive electrode active material is recorded as X ⁇ , then X ⁇ 10 4 ;
  • X ⁇ 10 6 further optionally X ⁇ 10 10 ;
  • the ionic conductivity of the first positive electrode active material at 25° C. is ⁇ 1 , which satisfies ⁇ 1 ⁇ 3.2 ⁇ 10 -6 S/cm, and further optionally ⁇ 1 ⁇ 1.7 ⁇ 10 -3 S/cm;
  • the ionic conductivity of the second positive electrode active material at 25° C. is ⁇ 2 , satisfying ⁇ 2 ⁇ 10 ⁇ 9 S/cm, and further optionally ⁇ 2 ⁇ 10 ⁇ 12 S/cm.
  • the probability of the first positive electrode active material being over-utilized increases significantly.
  • the A/B value to balance the demand for the first positive electrode active material to appropriately reduce the utilization rate and the comprehensive demand for good transmission of active ions in the composite positive electrode sheet, the improvement effect on the thermal stability of the positive electrode sheet and the overall comprehensive performance of the battery cell is more significant.
  • the ionic conductivity of the first positive electrode active material can be adjusted by adjusting the nickel (Ni) content in the first positive electrode active material. Generally, the higher the Ni content, the higher the ionic conductivity of the first positive electrode active material.
  • the ionic conductivity of the second positive electrode active material can be adjusted by adjusting the manganese (Mn) element content. Generally, the higher the Mn element content, the lower the ionic conductivity of the second positive electrode active material.
  • the content ratio between the first positive electrode active material and the second positive electrode active material can be adjusted by adjusting the A value.
  • the A value By adjusting the A value within the above range, it is more conducive to giving full play to the comprehensive advantages of the first positive electrode active material and the second positive electrode active material, and achieving better electrical performance.
  • the mass percentage of the first cationic salt relative to the electrolyte salt can be adjusted by adjusting the B value.
  • the concentration of the first cation in the electrolyte can be better matched with the demand of the first positive electrode active material for appropriately reducing the utilization, thereby achieving better overall battery performance.
  • the first positive electrode active material satisfies one or more of the following characteristics:
  • R c The atomic molar ratio of the Co element to the Li element is denoted as R c , and R c satisfies 0.05 ⁇ R c ⁇ 0.5, optionally, 0.05 ⁇ R c ⁇ 0.3, optionally, 0.05 ⁇ R c ⁇ 0.2;
  • R d The atomic molar ratio of the M1 element to the Li element is denoted as R d , and R d satisfies 0.05 ⁇ R d ⁇ 0.5, and optionally, 0.05 ⁇ R d ⁇ 0.3;
  • the M1 element includes a Mn element, and the atomic molar ratio of the Mn element to the Li element is recorded as R d-Mn , and R d-Mn satisfies 0.05 ⁇ R d-Mn ⁇ 0.4, and further optionally, 0.05 ⁇ R d-Mn ⁇ 0.3;
  • R c+d The ratio of the sum of the atomic molar equivalents of the Co element and the M1 element to the atomic molar equivalent of the Li element is recorded as R c+d , and R c+d satisfies 0.1 ⁇ R c+d ⁇ 0.5, further optionally, 0.1 ⁇ R c+d ⁇ 0.3, and further optionally, 0.1 ⁇ R c+d ⁇ 0.2.
  • the presence of the Co element is beneficial to improving the structural stability of the material.
  • the thermal stability of the first positive electrode active material can be adjusted.
  • the Mn element is beneficial to improving the thermal stability of the first positive electrode active material
  • the M1 element includes the Al element is beneficial to improving the capacity and thermal stability of the material, and is beneficial to reducing the internal resistance and improving the rate performance and cycle performance.
  • the content ratio of the Co element and the M1 element can be adjusted as needed to balance the comprehensive effects of the Co element and the M1 element on the battery performance.
  • the first positive electrode active material further comprises a Ni element; in the first positive electrode active material, the atomic molar ratio of the Ni element to the Li element is denoted as R b , and R b satisfies 0.5 ⁇ R b ⁇ 1;
  • the first positive electrode active material contains the Ni element
  • the higher the nickel (Ni) content the higher the energy density of the composite positive electrode sheet, and the more beneficial it is to improve the ionic conductivity; however, when the first positive electrode active material is highly utilized, the risk of damage to the surface structure of the first positive electrode active material or even structural collapse is greater.
  • the thermal stability of the composite positive electrode sheet is improved more significantly.
  • the concentration of the first cation in the electrolyte can better match the demand of the first positive electrode active material for appropriately reducing the utilization rate, so as to achieve a better match of the comprehensive performance of the battery as a whole and achieve a higher energy density. It can significantly improve the thermal stability of the composite positive electrode plate and the battery cell, reduce the risk of thermal runaway, and is also beneficial for the composite positive electrode plate to have good active ion transport performance as a whole.
  • the atomic molar equivalent Qa of the Li element is 0.75 to 1.2, optionally 0.8 to 1.1, further optionally 0.9 to 1.05, and further optionally 1, and the first positive electrode active material satisfies one or more of the following characteristics:
  • the atomic molar equivalent of the Co element is Q c ⁇ 0.4, optionally, Q c ⁇ 0.3, further optionally, Q c ⁇ 0.2;
  • the atomic molar equivalent of the M1 element is Q d ⁇ 0.5, optionally, Q d ⁇ 0.4, further optionally, Q d ⁇ 0.3;
  • the M1 element includes a Mn element, and the atomic molar equivalent of the Mn element is ⁇ 0.4, and optionally, the atomic molar equivalent of the Mn element is ⁇ 0.3;
  • the sum of the atomic molar equivalents of the Co element and the M1 element is Q c+d ⁇ 0.5, optionally, Q c+d ⁇ 0.4, Q c+d ⁇ 0.3, Q c+d ⁇ 0.2.
  • the atomic molar equivalent Q a of the Li element is 0.75 to 1.2, optionally 0.8 to 1.1, further optionally 0.9 to 1.05, and further optionally 1, and the first positive electrode active material contains the Ni element, and the atomic molar equivalent Q b of the Ni element satisfies 0.5 ⁇ Q b ⁇ 1, optionally, 0.6 ⁇ Q b ⁇ 1, and further optionally, 0.65 ⁇ Q b ⁇ 1.
  • the content of the corresponding elements can be adjusted by adjusting the atomic molar equivalents of the Co element, the M1 element and the Ni element.
  • 0.8 ⁇ a ⁇ 1.2 further optionally, 0.9 ⁇ a ⁇ 1.1, further optionally, 0.95 ⁇ a ⁇ 1.05;
  • 0.5 ⁇ b ⁇ 1 further optionally, 0.5 ⁇ b ⁇ 0.9, further optionally, 0.6 ⁇ b ⁇ 0.9;
  • 0.05 ⁇ c ⁇ 1 further optionally, 0.05 ⁇ c ⁇ 0.5, further optionally, 0.05 ⁇ c ⁇ 0.3;
  • 0.05 ⁇ d ⁇ 1 further optionally, 0.05 ⁇ d ⁇ 0.5, further optionally, 0.05 ⁇ d ⁇ 0.3;
  • 0 ⁇ e ⁇ 0.1 further optionally, 0 ⁇ e ⁇ 0.05, further optionally, 0 ⁇ e ⁇ 0.03;
  • 0 ⁇ g ⁇ 0.5 further optionally, 0 ⁇ g ⁇ 0.1, further optionally, 0 ⁇ g ⁇ 0.05.
  • the second positive electrode active material satisfies one or more of the following characteristics:
  • the atomic molar ratio of the Mn element to the Fe element is 0.42 to 9, and optionally, the atomic molar ratio of the Mn element to the Fe element is 0.66 to 4;
  • the atomic molar equivalent of the Li element is 0.9 to 1.1, optionally 0.9 to 1.05, and further optionally 1, and the atomic molar equivalent of the Mn element is 0.5 to 0.999, and optionally 0.5 to 0.6;
  • the atomic molar equivalent of the Li element is 0.9 to 1.1, optionally 0.9 to 1.05, and further optionally 1, and the atomic molar equivalent of the Fe element is 0.001 to 0.5, and optionally 0.4 to 0.5.
  • Increasing the Mn content in the second positive electrode active material is beneficial to improving the energy density, voltage platform and material cost of the second positive electrode active material.
  • By controlling the Mn element within the above range it is beneficial to form a uniform solid solution while exerting the effect of the Mn element, and it can also minimize or avoid defects and pores, thereby reducing or avoiding defects and pores that extend the insertion and migration path of active ions.
  • the Mn element by controlling the Mn element within the above range, it is beneficial to make the second active material have good ion
  • the ion migration rate is increased, and the difference in the active ion conductivity between the second positive electrode active material and the first positive electrode active material is shortened, thereby reducing the probability of over-utilization and lithium de-lithiation of the first positive electrode active material, which is beneficial to further improve the thermal stability of the composite positive electrode sheet.
  • the introduction of Fe element is conducive to achieving better ion transport and higher ion conductivity, and is also conducive to promoting the embedding and extraction of active ions, thereby improving the battery charging and discharging efficiency and energy density.
  • the content of the corresponding elements can be adjusted by adjusting the atomic molar equivalents of the Fe element and the Mn element.
  • the second active material includes a second body, and further includes or does not include a second coating layer located on at least a portion of the surface of the second body; wherein the chemical formula of the second body is Li 1+x Mn 1-yw Fe w M3 y P 1-z Q z O 4 , wherein -0.1 ⁇ x ⁇ 0.1, 0.1 ⁇ w ⁇ 0.5, 0.001 ⁇ y ⁇ 0.5, 0.001 ⁇ z ⁇ 0.1, the M3 element in the second active material includes one or more elements of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Ni, Co, Ga, Sn, Sb, Nb and Ge, and the Q element in the second active material includes one or more elements of B, Si, N, S, F, Cl and Br;
  • 0.1 ⁇ y ⁇ 0.5 further optionally, 0.2 ⁇ y ⁇ 0.5, further optionally, 0.3 ⁇ y ⁇ 0.5;
  • 0.2 ⁇ w ⁇ 0.5 further optionally, 0.3 ⁇ w ⁇ 0.5, further optionally, 0.4 ⁇ w ⁇ 0.5;
  • the M3 element in the second active material includes one or more elements selected from Ti, V, Ni, Co and Mg;
  • the Q element in the second active material includes one of B, Si, N and S;
  • the second coating layer comprises one or more of pyrophosphate, phosphate and carbon;
  • the second coating layer is a single-layer structure or a multi-layer structure.
  • the total mass proportion of the first positive electrode active material and the second positive electrode active material in the positive electrode active material layer is R I+II ⁇ 85%;
  • the first cation includes cations of one or more elements of alkali metal elements and alkaline earth metal elements;
  • the first cation includes one or more of sodium ions, potassium ions, calcium ions and magnesium ions;
  • the anion in the first cationic salt includes one or more of hexafluorophosphate ion, perchlorate ion, tetrafluoroborate ion, bis(trifluoromethylsulfonyl)imide ion, trifluoromethanesulfonate ion, bis(fluorosulfonyl)imide ion and tris(trifluoromethylsulfonyl)methyl ion;
  • the first cationic salt includes one or more of sodium hexafluorophosphate, sodium perchlorate, sodium tetrafluoroborate, sodium bistrifluoromethylsulfonyl imide, sodium trifluoromethanesulfonate, sodium bisfluorosulfonyl imide, sodium tris(trifluoromethylsulfonyl)methyl, potassium hexafluorophosphate, potassium perchlorate, potassium tetrafluoroborate, potassium bistrifluoromethylsulfonyl imide, potassium trifluoromethanesulfonate, potassium bisfluorosulfonyl imide and potassium tris(trifluoromethylsulfonyl)methyl;
  • the first cationic salt includes one or two of sodium hexafluorophosphate, sodium tetrafluoroborate and sodium perchlorate.
  • the type of the first cation and the corresponding anion can have a flexible range of selection.
  • sodium hexafluorophosphate is low in cost and can be used on a large scale; the difference in radius between sodium ions and lithium ions is small, which is more conducive to embedding active materials.
  • the negative electrode plate includes a negative electrode active material layer, the negative electrode active material layer includes a negative electrode active substance, and the negative electrode active substance includes a silicon-based material; the mass percentage of the silicon-based material in the negative electrode active substance is recorded as X1,
  • X1 ⁇ 3% further optionally 3% ⁇ X1 ⁇ 50%;
  • the silicon-based material includes one or more of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, silicon alloy, silicon-graphene composite, silicon-carbon nanotube and silicon-containing conductive polymer.
  • the negative electrode active material layer of the negative electrode plate includes a silicon-based material, it is beneficial to further improve the energy density of the battery cell.
  • a secondary battery which includes the battery cell described in the first aspect of the present application.
  • the secondary battery is a lithium ion secondary battery.
  • an electrical device which includes at least one of the battery cell described in the first aspect of the present application and the secondary battery described in the second aspect of the present application.
  • FIG. 1 is a schematic diagram of a battery cell according to an embodiment of the present application.
  • FIG. 2 is an exploded view of the battery cell according to an embodiment of the present application shown in FIG. 1 .
  • FIG. 3 is a schematic diagram of a battery module according to an embodiment of the present application.
  • FIG. 4 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application.
  • FIG. 6 is a schematic diagram of an electrical device using a secondary battery as a power source according to an embodiment of the present application.
  • Scope disclosed in the present application can be limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range.
  • the scope limited in this way can be including end value or excluding end value, and any end value can be included or not included independently, and can be combined arbitrarily, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected.
  • the numerical range "a-b" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers.
  • the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations.
  • a parameter is expressed as an integer ⁇ 2 it is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
  • a parameter is expressed as an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9 and 10.
  • multiple means one or greater than or equal to ( ⁇ , greater than or equal to) two.
  • each step does not mean a strict execution order and constitutes any limitation to the implementation process, and the detailed execution order of each step should be determined by its function and possible internal logic. If there is no special explanation, all steps of the present application can be performed in sequence, or can be performed randomly, and can preferably be performed in sequence.
  • method M includes steps (a) and (b), indicating that method M may include steps (a) and (b) performed in sequence, or steps (b) and (a) performed in sequence.
  • method M may also include step (c), indicating that step (c) can be added to method M in any order, for example, method M may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.
  • A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.
  • the features or solutions corresponding to "and/or” include any one of two or more related listed items, and also include any and all combinations of the related listed items, wherein the arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items.
  • “A and/or B” means a group consisting of A, B, and “a combination of A and B”.
  • “comprising A and/or B” can mean “comprising A, comprising B, and comprising A and B”, and can also mean “comprising A, comprising B, or comprising A and B", which can be properly understood according to the sentence in which it is located.
  • first”, “second”, “third”, etc. in “the first aspect”, “the second aspect”, “the third aspect”, etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features.
  • first”, “second”, “third”, etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.
  • room temperature generally refers to 4°C to 35°C, and may refer to 20°C ⁇ 5°C. In some embodiments of the present application, room temperature refers to 20°C to 30°C.
  • “approximate number” includes the number itself and its approximate value within a reasonable fluctuation range based on the number.
  • the reasonable fluctuation range may vary depending on the type and value of the number.
  • the weight of the relevant components mentioned in the embodiments or examples of the present application can not only refer to the content of each component, but also represent the proportional relationship of the weight between the components. Therefore, as long as the content of the relevant components of the embodiments or examples of the present application is proportionally enlarged or reduced, it is within the scope described in the present application.
  • the mass involved in the embodiments or examples of the present application can be a mass unit known in the chemical industry such as microgram ( ⁇ g), milligram (mg), gram (g), kilogram (kg).
  • the mass ratio is equal to the corresponding weight ratio, such as the mass of substance A is m1, the weight is W1, the mass of substance B is m2, and the weight is W2, then the mass ratio m1/m2 of the two is numerically equal to the corresponding weight ratio W1/W2.
  • wt% represents weight percentage by weight, which is numerically equal to the corresponding mass percentage by mass.
  • the temperature unit °C means “degrees Celsius”
  • the time unit min means “minute”
  • the length unit ⁇ m means “micrometer”
  • the viscosity unit mPa ⁇ S means “milliPascal ⁇ second”
  • the surface density unit mg/cm 2 means “milligram per square centimeter”
  • the volume density unit g/cm 3 means “gram per cubic centimeter”
  • the amount of substance unit mol means “mole”
  • the molar concentration unit mol/L means “mole per liter”
  • the conductivity unit S/cm means "Siemens per centimeter”.
  • the positive active materials in the positive active material layer of the positive electrode sheet.
  • at least two positive active materials can be set in the hope of achieving complementary advantages of different positive active materials; non-restrictive, for example, when a positive active material with high energy density is used in combination with a positive active material with a better voltage platform and lower manufacturing cost, it is expected that the corresponding positive electrode sheet can have both high energy density, better voltage platform and lower manufacturing cost.
  • positive active materials with different properties often have different activities and ionic conductivities, which leads to different utilization levels of different positive active materials under charge and discharge cycles.
  • the ionic conductivities of different positive active materials differ too much, one of the positive active materials will be over-utilized, which can easily cause the surface structure of the positive active material to be damaged and release oxygen, and may even cause the material structure to collapse, and there is a risk of thermal runaway of the battery; in addition, the released oxygen may also trigger electrolyte side reactions.
  • the present application at least provides a battery cell, a secondary battery and an electrical device.
  • the battery cell includes a positive electrode plate, a negative electrode plate, a separator and an electrolyte
  • the positive electrode active material layer in the positive electrode plate includes a first positive electrode active material and a second positive electrode active material
  • the electrolyte salt in the electrolyte includes a first cationic salt
  • the first positive electrode active material is a lithium oxide containing Co element and M1 element, wherein the M1 element includes one or two of Mn element and Al element
  • the second positive electrode active material is a lithium oxide containing Fe element and Mn element
  • the mass ratio of the Co element in the first positive electrode active material to the Fe element in the second positive electrode active material is A
  • the first cationic salt includes a first cation having an ionic radius greater than a lithium ion
  • the mass percentage of the first cationic salt in the electrolyte salt is B; 0.47 ⁇ A/B ⁇ 202.
  • the battery cell has better electrical performance and good thermal stability, and has a low risk of thermal runaway.
  • battery cell refers to a basic unit that can realize the mutual conversion of chemical energy and electrical energy.
  • a battery cell includes a positive electrode plate, a negative electrode plate, an electrolyte and a separator.
  • active ions are embedded and released back and forth between the positive electrode plate and the negative electrode plate.
  • the electrolyte plays the role of conducting ions between the positive electrode plate and the negative electrode plate.
  • the separator is arranged between the positive electrode plate and the negative electrode plate, which mainly prevents the positive and negative electrodes from short-circuiting, while allowing ions to pass through.
  • the electrode plate can be a positive electrode plate or a negative electrode plate
  • the "active material” in the electrode plate refers to a substance that can reversibly embed and release active ions.
  • negative electrode active material refers to a substance used for negative electrode plates that can reversibly embed and release active ions
  • positive electrode active material refers to a substance used for positive electrode plates that can reversibly release and embed active ions.
  • electrode active material In this application, “electrode active material”, “electrode active substance”, “active material” and “active substance” have the same meaning and can be used interchangeably; “positive electrode active substance” and “positive electrode active material” have the same meaning and can be used interchangeably; “negative electrode active substance” and “negative electrode active material” have the same meaning and can be used interchangeably. “Positive electrode active substance” and “positive electrode active material” have the same meaning and can be used interchangeably; “negative electrode active substance” and “negative electrode active material” have the same meaning and can be used interchangeably.
  • the “electrode active material layer” includes at least one of the positive electrode active material layer of the positive electrode sheet and the negative electrode active material layer of the negative electrode sheet.
  • the electrode active material layer may refer to the positive electrode active material layer or the negative electrode active material layer. It is understood that the positive electrode active material layer contains positive electrode active substances, and the negative electrode active material layer contains negative electrode active substances.
  • the “electrode active material layer” may also be abbreviated as the "active material layer”.
  • a battery cell which includes a positive electrode plate and an electrolyte; in the positive electrode active material layer of the positive electrode plate, the mass ratio of the Co element in the first positive electrode active material to the Fe element in the second positive electrode active material is A; the first cationic salt in the electrolyte includes a first cation having an ion radius greater than that of a lithium ion; the mass percentage of the first cationic salt in the electrolyte salt is B; 0.47 ⁇ A/B ⁇ 202.
  • the first positive electrode active material is a lithium oxide containing Co and M1 elements
  • the second positive electrode active material is a lithium oxide containing Fe and Mn elements, wherein the M1 element in the first positive electrode active material includes one or both of Mn and Al elements;
  • the mass ratio of the Co element in the first positive electrode active material to the Fe element in the second positive electrode active material is denoted as A;
  • the first cationic salt includes a first cation, the ionic radius of the first cation is greater than the ionic radius of the lithium ion; the mass percentage of the first cationic salt in the electrolyte salt is denoted as B;
  • the first positive electrode active material and the second positive electrode active material are two different positive electrode active materials in the positive electrode active material layer.
  • the active ions in the battery cell include lithium ions.
  • the electrolyte salt includes a first cation salt and an electrolyte lithium salt.
  • the electrolyte lithium salt facilitates the conduction of active lithium ions.
  • a battery cell which includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, wherein the separator is disposed between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet includes a positive electrode active material layer, the positive electrode active material layer includes a first positive electrode active material and a second positive electrode active material, the electrolyte includes an electrolyte salt, and the electrolyte salt includes a first cation salt and an electrolyte lithium salt;
  • the first positive electrode active material is a lithium oxide containing Co and M1 elements
  • the second positive electrode active material is a lithium oxide containing Fe and Mn elements, wherein the M1 element in the first positive electrode active material includes one or both of Mn and Al elements;
  • the mass ratio of the Co element in the first positive electrode active material to the Fe element in the second positive electrode active material is denoted as A;
  • the first cationic salt includes a first cation, the ionic radius of the first cation is greater than the ionic radius of the lithium ion; the mass percentage of the first cationic salt in the electrolyte salt is denoted as B;
  • a and B satisfy 0.47 ⁇ A/B ⁇ 202.
  • the positive electrode sheet in the battery cell is a composite positive electrode sheet, in which different positive active materials are arranged, and the composite positive electrode sheet includes a first positive active material containing cobalt (Co) element and M1 element, M1 element includes one or two of manganese (Mn) element and aluminum (Al) element, and also includes a second positive active material containing iron (Fe) element and Mn element.
  • the composite positive electrode sheet design can make different positive active materials complement each other, it is hoped that the comprehensive electrical performance in aspects such as material structure stability, battery safety, rate performance, cycle performance, etc. can be improved, and the voltage platform and manufacturing cost can be taken into account.
  • the lithium oxide containing Co and M1 elements and the lithium oxide containing Fe and Mn elements are different positive electrode active materials, and have different activities and ionic conductivities, resulting in different degrees of utilization during the charge and discharge cycle.
  • the lithium oxide containing Co and M1 elements is easily over-utilized, causing damage to the surface structure of the first positive electrode active material and releasing oxygen, and may even cause the material structure to collapse, posing a risk of thermal runaway of the battery; in addition, the released oxygen may also trigger side reactions in the electrolyte.
  • the active ion diffusion in the design of the composite positive electrode plate is presumed to be one-dimensional channel diffusion.
  • the first cation with an ion radius larger than that of lithium (Li) ions is introduced by introducing a first cationic salt.
  • the first cation can replace part of the active ions and be embedded in the first positive electrode active material, blocking the active ion diffusion channel in the first positive electrode active material, reducing the utilization of the first positive electrode active material, and reducing oxygen release.
  • the first cation can also play a role in supporting the surface structure of the first positive electrode active material, which can hinder the removal of active ions during discharge, further increase the stability of oxygen on the surface of the positive electrode active material, and reduce oxygen release.
  • the first cation can improve the thermal stability of the composite positive electrode plate and the battery cell, and reduce the risk of thermal runaway.
  • the content ratio between the first positive electrode active material and the second positive electrode active material can be adjusted, and the A/B value is further used to coordinately adjust the mass percentage B of the first cationic salt relative to the electrolyte salt in the electrolyte, so that the concentration of the first cation in the electrolyte can be better matched with the demand of the first positive electrode active material for appropriately reducing the utilization, thereby achieving better overall comprehensive electrical performance, significantly improving the thermal stability of the composite positive electrode plate and the battery cell, reducing the risk of thermal runaway, and also facilitating the composite positive electrode plate to have good active ion transport performance as a whole. It can be seen that the battery cell has better overall performance, good thermal stability, and low risk of thermal runaway.
  • ICP inductively coupled plasma
  • EDS energy dispersive spectrometer
  • ICP inductively coupled plasma
  • other methods can be used for testing and analysis.
  • EDS can be used to identify different types of active materials
  • ICP can be used to perform quantitative testing and analysis of component content.
  • the active material sample can be extracted from the electrode sheet, and the solid particles can be collected by methods including but not limited to solvent washing, ultrasonic dispersion, etc., and then the elemental composition of the solid particles can be analyzed by inductively coupled plasma optical emission spectrometer (ICP-OES).
  • ICP-OES inductively coupled plasma optical emission spectrometer
  • EDS testing can be used to obtain a two-dimensional image with different color markings for different components, and different particles corresponding to different active materials can be distinguished according to the type of components and aggregation methods.
  • a reagent such as nitric acid, perchloric acid, etc.
  • the chemical composition of the positive electrode active material can be tested by an inductively coupled plasma optical emission spectrometer.
  • it can be The negative electrode active material layer is digested using a reagent (such as aqua regia, reverse aqua regia, a combination of aqua regia and hydrogen fluoride, etc.), and the chemical composition of the negative electrode active material is tested by inductively coupled plasma emission spectrometry.
  • the content of each element in the first positive electrode active material and the second active material can be identified, the total mass proportion of the first positive electrode active material and the second positive electrode active material in the positive electrode active material layer can be calculated, and the mass ratio (A) of the Co element in the first positive electrode active material to the Fe element in the second positive electrode active material can also be calculated.
  • the element content relationship described in the context can also be tested, such as Rc , Rd , Rd -Mn , Rc +d , Rb , Qc / Qa , Qd/ Qa , Qc +d / Qa , Qb , etc.
  • the composition of the negative electrode active material in the negative electrode active material layer can be determined, and whether it contains silicon-based materials can be determined. If contained, the type and composition of the silicon-based materials and their mass percentage in the negative electrode active material (which can be recorded as X1) can also be determined.
  • the electrolyte salt in the electrolyte can be quantitatively tested based on GB/T36240-2018 and an ion chromatograph. According to the identified cation types in the electrolyte, combined with the atomic number of the element, it can be determined whether there is a first cation with an ionic radius greater than that of lithium ions in the electrolyte. If so, it can also be determined what types of first cations are present. According to the quantitative test analysis results of the electrolyte salt, the composition of the electrolyte salt in the electrolyte and the content of different electrolyte salts can be determined.
  • the mass percentage of the first cation salt in the electrolyte salt (denoted as B) is calculated according to "the mass of the first cation in the electrolyte relative to the sum of the mass of all cations in the electrolyte".
  • the B value can be numerically equal to "the mass of the first cation in the electrolyte relative to the mass of the metal cation in the electrolyte".
  • the B value may be numerically equal to "the percentage of the mass of the first cations in the electrolyte relative to the total mass of the first cations and lithium ions”.
  • the cations in the electrolyte salt are metal cations.
  • a battery cell which includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, wherein the separator is disposed between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet includes a positive electrode active material layer, the positive electrode active material layer includes a first positive electrode active material and a second positive electrode active material, the electrolyte includes an electrolyte salt, the electrolyte salt includes a first cationic salt and an electrolyte lithium salt; the electrolyte salt is composed of cations and anions, and the cations in the electrolyte salt are metal cations;
  • the first positive electrode active material is a lithium oxide containing Co and M1 elements
  • the second positive electrode active material is a lithium oxide containing Fe and Mn elements, wherein the M1 element in the first positive electrode active material includes one or both of Mn and Al elements;
  • the mass ratio of the Co element in the first positive electrode active material to the Fe element in the second positive electrode active material is denoted as A;
  • the first cationic salt includes a first cation, the ionic radius of the first cation is greater than the ionic radius of the lithium ion; the percentage of the mass of the first cation relative to the total mass of each cation in the electrolyte salt can also be recorded as B;
  • a and B satisfy 0.47 ⁇ A/B ⁇ 202.
  • the battery cell includes a positive electrode plate, a negative electrode plate, a separator and an electrolyte
  • the positive electrode active material layer in the positive electrode plate includes a first positive electrode active material and a second positive electrode active material
  • the electrolyte salt in the electrolyte includes a metal cation
  • the metal cation includes a first cation
  • the first positive electrode active material is a lithium oxide containing Co element and M1 element, wherein the M1 element includes one or two of Mn element and Al element
  • the second positive electrode active material is a lithium oxide containing Fe element and Mn element
  • the mass ratio of the Co element in the first positive electrode active material to the Fe element in the second positive electrode active material is A
  • the ionic radius of the first cation is greater than the ionic radius of the lithium ion
  • the mass percentage of the first cation relative to the metal cation in the electrolyte salt is recorded as B'; 0.47 ⁇ A/B' ⁇ 202.
  • the battery cell has better
  • a battery cell which includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, wherein the separator is disposed between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet includes a positive electrode active material layer, the positive electrode active material layer includes a first positive electrode active material and a second positive electrode active material, the electrolyte includes an electrolyte salt, the electrolyte salt includes a metal cation and an anion; the metal cation includes a first cation and a lithium ion;
  • the first positive electrode active material is a lithium oxide containing Co and M1 elements
  • the second positive electrode active material is a lithium oxide containing Fe and Mn elements, wherein the M1 element in the first positive electrode active material includes one or both of Mn and Al elements;
  • the mass ratio of the Co element in the first positive electrode active material to the Fe element in the second positive electrode active material is denoted as A;
  • the ionic radius of the first cation is greater than the ionic radius of the lithium ion
  • the mass percentage of the first cation relative to the metal cation in the electrolyte salt is recorded as B';
  • a and B satisfy 0.47 ⁇ A/B’ ⁇ 202.
  • the value of B' and its value range and the value of A/B' and its value range can refer to the value of B and its value range and the value of A/B and its value range, respectively.
  • B and B' are numerically the same.
  • the definition of the value and value range of B in the context of the present application can be applied to B', and the definition of the value and value range of A/B in the context of the present application can be applied to A/B'.
  • the ratio of the ionic conductivity of the first positive electrode active material to the ionic conductivity of the second positive electrode active material is recorded as X ⁇ , then X ⁇ 10 4 ; optionally, X ⁇ 10 6 , further optionally X ⁇ 10 10 .
  • X ⁇ may also be any of the following values, or greater than or equal to ( ⁇ ) any of the following values, or greater than (>) any of the following values, or an interval consisting of any two of the following values (which may be expressed in scientific notation): 1 ⁇ 10 4 (equivalent to 1E4), 2 ⁇ 10 4 , 4 ⁇ 10 4 , 5 ⁇ 10 4 , 6 ⁇ 10 4 , 8 ⁇ 10 4 , 1 ⁇ 10 5 , 2 ⁇ 10 5 , 4 ⁇ 10 5 , 5 ⁇ 10 5 , 6 ⁇ 10 5 , 8 ⁇ 10 5 , 1 ⁇ 10 6 , 2 ⁇ 10 6 , 4 ⁇ 10 6 , 5 ⁇ 10 6 , 6 ⁇ 10 6 , 8 ⁇ 10 6 , 1 ⁇ 10 7 , 2 ⁇ 10 7 , 4 ⁇ 10 7 , 5 ⁇ 10 7 , 6 ⁇ 10 7 9 , 6 ⁇ 10 9 , 8 ⁇ 10 9 , 1 ⁇ 10 10 , 2 ⁇ 10 10 , etc.
  • aEb described in scientific notation is equivalent to a ⁇ 10 b .
  • 1 ⁇ 10 4 can be expressed as 1E4.
  • the ionic conductivity of the first positive electrode active material at 25° C. is ⁇ 1 , which satisfies ⁇ 1 ⁇ 3.2 ⁇ 10 ⁇ 6 S/cm, and further optionally ⁇ 1 ⁇ 1.7 ⁇ 10 ⁇ 3 S/cm.
  • any of the following values can also be any of the following values, or greater than or equal to ( ⁇ ) any of the following values, or greater than (>) any of the following values, or selected from an interval consisting of any two of the following values (which can be expressed in scientific notation): 3.2 ⁇ 10 -6 S/cm, 3.5 ⁇ 10 -6 S/cm, 4 ⁇ 10 -6 S/cm, 5 ⁇ 10 -6 S/cm, 6 ⁇ 10 -6 S/cm, 8 ⁇ 10 -6 S/cm, 1 ⁇ 10 -5 S/cm, 2 ⁇ 10 -5 S/cm, 4 ⁇ 10 -5 S/cm, 5 ⁇ 10 -5 S/cm, 6 ⁇ 10 -5 S/cm, 8 ⁇ 10 -5 S/cm, 1 ⁇ 10 -4 S/cm, 2 ⁇ 10 -4 S/cm, 4 ⁇ 10 -4 S/cm, 5 ⁇ 10 -4 S/cm, 6 ⁇ 10 -4 S/cm, 8 ⁇ 10 -4 S/cm, 1 ⁇ 10 -3 S
  • ⁇ 1 can also be selected from any of the following ranges: 1 ⁇ 10 -3 S/cm to 3 ⁇ 10 -3 S/cm, 3 ⁇ 10 -3 S/cm to 5 ⁇ 10 -3 S/cm, 5 ⁇ 10 -3 S/cm to 7 ⁇ 10 -3 S/cm, 7 ⁇ 10 -3 S/cm to 9 ⁇ 10 -3 S/cm, 3.2 ⁇ 10 -6 S/cm to 1 ⁇ 10 -3 S/cm, 1 ⁇ 10 -3 S/cm ⁇ 1 ⁇ 3 ⁇ 10 -3 S/cm, 3 ⁇ 10 -3 S/cm ⁇ 1 ⁇ 5 ⁇ 10 -3 S/cm, 5 ⁇ 10 -3 S/cm ⁇ 1 ⁇ 7 ⁇ 10 -3 S/cm, 7 ⁇ 10 -3 S/cm ⁇ 1 ⁇ 9 ⁇ 10 -3 S/cm, 3.2 ⁇ 10 -6 S/cm ⁇ 1 ⁇ 1 ⁇ 10 -3 S/cm, etc.
  • the ionic conductivity of the second positive electrode active material at 25° C. is ⁇ 2 , which satisfies ⁇ 2 ⁇ 10 ⁇ 9 S/cm, and further optionally ⁇ 2 ⁇ 10 ⁇ 12 S/cm.
  • any of the following values can also be any of the following values, or less than or equal to ( ⁇ ) any of the following values, or less than any of the following values, or selected from an interval consisting of any two of the following values (which can be expressed in scientific notation): 1 ⁇ 10 -9 S/cm, 8 ⁇ 10 -10 S/cm, 6 ⁇ 10 -10 S/cm, 5 ⁇ 10 -10 S/cm, 4 ⁇ 10 -10 S/cm, 2 ⁇ 10 -10 S/cm, 1 ⁇ 10 -10 S/cm, 8 ⁇ 10 -11 S/cm, 6 ⁇ 10 -11 S/cm, 5 ⁇ 10 -11 S/cm, 4 ⁇ 10 -11 S/cm, 2 ⁇ 10 -11 S/cm, 1 ⁇ 10 -11 S/cm, 8 ⁇ 10 -12 S/cm, 6 ⁇ 10 -12 S/cm, 5 ⁇ 10 -12 S/cm, 4 ⁇ 10 -12 S/cm -12 S/cm, 2 ⁇ 10 -12 S/cm, 1 ⁇ 10 -12
  • ionic conductivity refers to the ionic conductivity when the active ions are lithium ions.
  • ⁇ 2 can also be selected from any of the following ranges: 3 ⁇ 10 -13 S/cm to 9 ⁇ 10 -13 S/cm, 1 ⁇ 10 -13 S/cm to 3 ⁇ 10 -13 S/cm, 3 ⁇ 10 -13 S/cm ⁇ 2 ⁇ 9 ⁇ 10 -13 S/cm, 1 ⁇ 10 -13 S/cm ⁇ 2 ⁇ 3 ⁇ 10 -13 S/cm, etc.
  • ionic conductivity refers to the ionic conductivity at 25°C.
  • the following method can be used to test the ionic conductivity of different positive active materials in the positive active material layer:
  • the positive electrode active material to be tested is made into a positive electrode plate for testing, and the lithium plate is used as the negative electrode plate, and assembled into a button battery for testing; the battery is discharged to 3.0V at 1C and then an AC impedance spectrum test is performed.
  • the test parameters are selected as follows: the test temperature is room temperature (such as 25°C), the scanning frequency is 0.1Hz ⁇ 10 5 Hz, and the voltage amplitude is 5mV.
  • the test results are fitted using Zview software to obtain the ionic conductivity.
  • the positive current collector is aluminum foil
  • the mass percentage of the positive active material in the positive active material layer is controlled at 95% ⁇ 1%
  • the binder is polyvinylidene fluoride (PVDF)
  • the conductive agent is conductive carbon
  • the compaction density is 3.0 g/cm 3 to 3.6 g/cm 3 .
  • the positive active material in the electrode plate, battery cell or secondary battery the positive active material with the same chemical composition can be prepared according to the component analysis results as the positive active material to be tested, and its ion conductivity can be tested by the above method.
  • the probability of the first positive electrode active material being overutilized becomes significantly greater.
  • the A/B value to balance the first positive electrode active material to appropriately reduce the utilization
  • the ionic conductivity of the first positive electrode active material can be adjusted by adjusting the nickel (Ni) content in the first positive electrode active material. Generally, the higher the Ni content, the higher the ionic conductivity of the first positive electrode active material.
  • the ionic conductivity of the second positive electrode active material can be adjusted by adjusting the manganese (Mn) element content. Generally, the higher the Mn element content, the lower the ionic conductivity of the second positive electrode active material.
  • A/B may also be any of the following values, or an interval consisting of any two of the following values: 0.47, 0.5, 0.6, 2/3, 0.7, 0.75, 0.8, 0.9, 1, 1.2, 1.25, 1.5, 1.6, 1.75, 1.8, 2, 2.5, 3, 3.5, 4, 5, 6, 7, 8, 9, 9.9, 10, 12, 12.5, 1 5, 16, 18, 20, 25, 30, 35, 40, 45, 50, 55, 60, 70, 75, 80, 90, 95, 96, 98, 99, 100, 110, 120, 125, 130, 140, 150, 160, 175, 180, 190, 192, 194, 195, 196, 198, 199, 200, 201, 202, etc.
  • A can also be any of the following values, or an interval consisting of any two of the following values: 0.19, 0.2, 0.22, 0.24, 0.25, 0.26, 0.28, 0.3, 0.32, 0.34, 0.35, 0.36, 0.38, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.0 .95, 1, 1.1, 1.2, 1.25, 1.3, 1.4, 1.5, 1.6, 1.7, 1.75, 1.8, 2, 2.1, 2.2, 2.25, 2.3, 2.4, 2.5, 2.6, 2.8, 3, 3.5, 3.6, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 9.6, 9.8, 9.9, 10, 10.1, etc.
  • the content ratio between the first positive electrode active material and the second positive electrode active material can be adjusted by adjusting the A value.
  • the A value By adjusting the A value within the above range, it is more conducive to giving full play to the comprehensive advantages of the first positive electrode active material and the second positive electrode active material, and achieving better electrical performance.
  • B can also be any of the following percentages, or an interval consisting of any two of the following percentages: 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 12.5%, 13%, 14%, 15%, 16%, 18%, 20%, 22%, 22.5%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, etc.
  • the mass percentage of the first cationic salt relative to the electrolyte salt can be adjusted by adjusting the B value.
  • the concentration of the first cation in the electrolyte can be better matched with the demand of the first positive electrode active material for appropriately reducing the utilization, thereby achieving better overall battery performance.
  • the atomic molar ratio of the Co element to the Li element can be recorded as R c , and R c satisfies 0.05 ⁇ R c ⁇ 0.5, optionally, 0.05 ⁇ R c ⁇ 0.3, optionally, 0.05 ⁇ R c ⁇ 0.2.
  • R c can also be any of the following values, or an interval consisting of any two of the following values: 0.05, 0.06, 0.08, 0.09, 0.1, 0.11, 0.12, 0.125, 0.14, 0.15, 0.16, 0.175, 0.18, 0.2, 0.22, 0.225, 0.24, 0.25, 0.26, 0.275, 0.28, 0.3, 0.32, 0.34, 0.35, 0.36, 0.38, 0.4, 0.42, 0.44, 0.45, 0.46, 0.48, 0.5, etc.
  • the atomic molar ratio of the Co element to the oxygen (O) element can be recorded as R Co/O , and R Co/O satisfies 0.025 ⁇ R Co/O ⁇ 0.25, optionally, 0.025 ⁇ R Co/O ⁇ 0.15, optionally, 0.025 ⁇ R Co/O ⁇ 0.1.
  • R Co/O can also be any of the following values, or an interval consisting of any two of the following values: 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.06, 0.08, 0.09, 0.1, 0.11, 0.12, 0.125, 0.14, 0.15, 0.16, 0.175, 0.18, 0.2, 0.22, 0.225, 0.24, 0.25, etc.
  • the ratio of the sum of the atomic molar ratios of the Co element to the non-lithium metal elements can be recorded as R Co/all , and R Co/all satisfies 0.05 ⁇ R Co/all ⁇ 0.5, optionally, 0.05 ⁇ R Co/all ⁇ 0.3, optionally, 0.05 ⁇ R Co/all ⁇ 0.2.
  • R Co/all can also be any of the following values, or an interval consisting of any two of the following values: 0.05, 0.06, 0.08, 0.09, 0.1, 0.11, 0.12, 0.125, 0.14, 0.15, 0.16, 0.175, 0.18, 0.2, 0.22, 0.225, 0.24, 0.25, 0.26, 0.275, 0.28, 0.3, 0.32, 0.34, 0.35, 0.36, 0.38, 0.4, 0.42, 0.44, 0.45, 0.46, 0.48, 0.5, etc.
  • non-lithium metal elements refer to metal elements other than lithium.
  • the types of elements in the positive electrode active material to be tested can be obtained by elemental analysis, and then the atomic molar ratio between different elements can be calculated in combination with the relative atomic masses of different elements.
  • the presence of the Co element is beneficial to improving the structural stability of the material.
  • the atomic molar ratio of the M1 element to the Li element can be recorded as R d , and R d satisfies 0.05 ⁇ R d ⁇ 0.5, and optionally, 0.05 ⁇ R d ⁇ 0.3.
  • R d can also be any of the following values, or an interval consisting of any two of the following values: 0.05, 0.06, 0.08, 0.09, 0.1, 0.11, 0.12, 0.125, 0.14, 0.15, 0.16, 0.175, 0.18, 0.2, 0.22, 0.225, 0.24, 0.25, 0.26, 0.275, 0.28, 0.3, 0.32, 0.34, 0.35, 0.36, 0.38, 0.4, 0.42, 0.44, 0.45, 0.46, 0.48, 0.5, etc.
  • R d can also be any of the following ranges: R d ⁇ 0.2, 0.05 ⁇ R d ⁇ 0.2, etc.
  • the atomic molar ratio of the M1 element to the O element can be recorded as RM1/O , RM1/O satisfies 0.025 ⁇ RM1 /O ⁇ 0.25 , optionally, 0.025 ⁇ RM1 /O ⁇ 0.15 .
  • RM1/O can also be any of the following values, or an interval consisting of any two of the following values: 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.06, 0.08, 0.09, 0.1, 0.11, 0.12, 0.125, 0.14, 0.15, 0.16, 0.175, 0.18, 0.2, 0.22, 0.225, 0.24, 0.25, etc.
  • R M1/O may also be any of the following ranges: R M1/O ⁇ 0.1, 0.025 ⁇ R M1/O ⁇ 0.1, etc.
  • the atomic molar ratio of the M1 element to the non-lithium metal element can be recorded as RM1 /all , RM1 /all satisfies 0.05 ⁇ RM1 / all ⁇ 0.5, optionally, 0.05 ⁇ RM1 /all ⁇ 0.3 .
  • R M1/all can also be any of the following values, or an interval consisting of any two of the following values: 0.05, 0.06, 0.08, 0.09, 0.1, 0.11, 0.12, 0.125, 0.14, 0.15, 0.16, 0.175, 0.18, 0.2, 0.22, 0.225, 0.24, 0.25, 0.26, 0.275, 0.28, 0.3, 0.32, 0.34, 0.35, 0.36, 0.38, 0.4, 0.42, 0.44, 0.45, 0.46, 0.48, 0.5, etc.
  • R M1/all can also be any of the following ranges: R M1/all ⁇ 0.2, 0.05 ⁇ R M1/all ⁇ 0.2, etc.
  • the M1 element in the first positive electrode active material, includes the Mn element.
  • the atomic molar ratio of the Mn element to the Li element is recorded as R d-Mn , and optionally, R d-Mn satisfies 0.05 ⁇ R d-Mn ⁇ 0.4, and further optionally, 0.05 ⁇ R d-Mn ⁇ 0.3.
  • R d-Mn can also be any of the following values, or an interval consisting of any two of the following values: 0.05, 0.06, 0.08, 0.09, 0.1, 0.11, 0.12, 0.125, 0.14, 0.15, 0.16, 0.175, 0.18, 0.2, 0.22, 0.225, 0.24, 0.25, 0.26, 0.275, 0.28, 0.3, 0.32, 0.34, 0.35, 0.36, 0.38, 0.4, etc.
  • RMn/O the atomic molar ratio of the Mn element to the O element is recorded as RMn/O .
  • RMn/O satisfies 0.025 ⁇ RMn /O ⁇ 0.2 , and further optionally, 0.025 ⁇ RMn /O ⁇ 0.15 .
  • RMn/O can also be any of the following values, or an interval consisting of any two of the following values: 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.06, 0.08, 0.09, 0.1, 0.11, 0.12, 0.125, 0.14, 0.15, 0.16, 0.175, 0.18, 0.19, 0.2, etc.
  • the atomic molar ratio of the Mn element to the non-lithium metal element is recorded as R Mn/all , optionally, R Mn/all satisfies 0.05 ⁇ R Mn/all ⁇ 0.4, further optionally, 0.05 ⁇ R Mn/all ⁇ 0.3.
  • R Mn/all can also be any of the following values, or an interval consisting of any two of the following values: 0.05, 0.06, 0.08, 0.09, 0.1, 0.11, 0.12, 0.125, 0.14, 0.15, 0.16, 0.175, 0.18, 0.2, 0.22, 0.225, 0.24, 0.25, 0.26, 0.275, 0.28, 0.3, 0.32, 0.34, 0.35, 0.36, 0.38, 0.4, etc.
  • the thermal stability of the first positive electrode active material can be adjusted.
  • the Mn element is beneficial to improving the thermal stability of the first positive electrode active material
  • the M1 element includes the Al element is beneficial to improving the capacity and thermal stability of the material, and is beneficial to reducing the internal resistance and improving the rate performance and cycle performance.
  • the ratio of the sum of the atomic molar equivalents of the Co element and the M1 element to the atomic molar equivalent of the Li element is recorded as R c+d , and R c+d satisfies 0.1 ⁇ R c+d ⁇ 0.5, further optionally, 0.1 ⁇ R c+d ⁇ 0.3, and further optionally, 0.1 ⁇ R c+d ⁇ 0.2.
  • the ratio of the sum of the atomic molar equivalents of the Co element and the M1 element to the atomic molar equivalent of the O element is recorded as R (Co+M1)/O , and R (Co+M1)/O satisfies 0.05 ⁇ R (Co+M1)/O ⁇ 0.25, further optionally, 0.05 ⁇ R (Co+M1)/O ⁇ 0.15, and further optionally, 0.05 ⁇ R (Co+M1)/O ⁇ 0.1.
  • R (Co + M1) / O can also be any of the following values, or an interval consisting of any two of the following values: 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.125, 0.14, 0.15, 0.16, 0.175, 0.18, 0.2, 0.22, 0.225, 0.24, 0.25, etc.
  • the ratio of the sum of the atomic molar equivalents of the Co element and the M1 element to the atomic molar equivalent of the non-lithium metal element is recorded as R (Co+M1)/all , and R (Co+M1)/all satisfies 0.1 ⁇ R (Co+M1)/all ⁇ 0.5, further optionally, 0.1 ⁇ R (Co+M1)/all ⁇ 0.3, and further optionally, 0.1 ⁇ R (Co+M1)/all ⁇ 0.2.
  • R (Co + M1) / all can also be any of the following values, or an interval consisting of any two of the following values: 0.1, 0.11, 0.12, 0.125, 0.14, 0.15, 0.16, 0.175, 0.18, 0.2, 0.22, 0.225, 0.24, 0.25, 0.26, 0.275, 0.28, 0.3, 0.32, 0.34, 0.35, 0.36, 0.38, 0.4, 0.42, 0.44, 0.45, 0.46, 0.48, 0.5, etc.
  • the content ratio of the Co element and the M1 element can be adjusted as needed to balance the comprehensive effects of the Co element and the M1 element on the battery performance.
  • the first positive electrode active material satisfies one or more of the following characteristics:
  • R c The atomic molar ratio of the Co element to the Li element is denoted as R c , and R c satisfies 0.05 ⁇ R c ⁇ 0.5, optionally, 0.05 ⁇ R c ⁇ 0.3, optionally, 0.05 ⁇ R c ⁇ 0.2 (R c can also be selected from the numerical value or range in any suitable embodiment of the present application);
  • R d The atomic molar ratio of the M1 element to the Li element is denoted as R d , and R d satisfies 0.05 ⁇ R d ⁇ 0.5, and optionally, 0.05 ⁇ R d ⁇ 0.3 (R d may also be selected from a numerical value or range in any suitable embodiment of the present application);
  • the M1 element includes the Mn element, and the atomic molar ratio of the Mn element to the Li element is recorded as R d-Mn , then R d-Mn satisfies 0.05 ⁇ R d-Mn ⁇ 0.4, and further optionally, 0.05 ⁇ R d-Mn ⁇ 0.3 (R d-Mn can also be selected from the numerical value or range in any suitable embodiment of the present application);
  • R c+d The ratio of the sum of the atomic molar equivalents of the Co element and the M1 element to the atomic molar equivalent of the Li element is recorded as R c+d , then R c+d satisfies 0.1 ⁇ R c+d ⁇ 0.5, further optionally, 0.1 ⁇ R c+d ⁇ 0.3, and further optionally, 0.1 ⁇ R c+d ⁇ 0.2 (R c+d can also be selected from the numerical value or range in any appropriate embodiment of the present application).
  • the first positive electrode active material satisfies one or more of the following characteristics:
  • R c The atomic molar ratio of the Co element to the Li element is denoted as R c , and R c satisfies 0.05 ⁇ R c ⁇ 0.5, optionally, 0.05 ⁇ R c ⁇ 0.3, optionally, 0.05 ⁇ R c ⁇ 0.2 (R c can also be selected from the numerical value or range in any suitable embodiment of the present application);
  • R Co/O The atomic molar ratio of the Co element to the O element is denoted as R Co/O , then R Co/O satisfies 0.025 ⁇ R Co/O ⁇ 0.25, optionally, 0.025 ⁇ R Co/O ⁇ 0.15, optionally, 0.025 ⁇ R Co/O ⁇ 0.1 (R Co/O may also be selected from a numerical value or range in any suitable embodiment of the present application);
  • the ratio of the sum of the atomic molar ratios of the Co element to the non-lithium metal element can be recorded as R Co/all , satisfying 0.05 ⁇ R Co/all ⁇ 0.5, optionally, 0.05 ⁇ R Co/all ⁇ 0.3, optionally, 0.05 ⁇ R Co/all ⁇ 0.2 (R Co/all can also be selected from the numerical value or range in any suitable embodiment of the present application);
  • R d The atomic molar ratio of the M1 element to the Li element is denoted as R d , and R d satisfies 0.05 ⁇ R d ⁇ 0.5, and optionally, 0.05 ⁇ R d ⁇ 0.3 (R d may also be selected from a numerical value or range in any suitable embodiment of the present application);
  • RM1/O The atomic molar ratio of the M1 element to the O element is denoted as RM1/O , then RM1/O satisfies 0.025 ⁇ RM1 /O ⁇ 0.25 , optionally, 0.025 ⁇ RM1 /O ⁇ 0.15 ( RM1/O may also be selected from a numerical value or range in any suitable embodiment of the present application);
  • the atomic molar ratio of the M1 element to the non-lithium metal element can be recorded as R M1/all , R M1/all satisfies 0.05 ⁇ R M1/all ⁇ 0.5, optionally, 0.05 ⁇ R M1/all ⁇ 0.3 (R M1/all can also be selected from any value or range in any suitable embodiment of the present application);
  • the M1 element includes the Mn element, and the atomic molar ratio of the Mn element to the Li element is recorded as R d-Mn , then R d-Mn satisfies 0.05 ⁇ R d-Mn ⁇ 0.4, and further optionally, 0.05 ⁇ R d-Mn ⁇ 0.3 (R d-Mn can also be selected from the numerical value or range in any suitable embodiment of the present application);
  • the M1 element includes the Mn element, and the atomic molar ratio of the Mn element to the O element is recorded as R Mn/O , then R Mn/O satisfies 0.025 ⁇ R Mn/O ⁇ 0.2, and further optionally, 0.025 ⁇ R Mn/O ⁇ 0.15 (R Mn/O can also be selected from the numerical value or range in any suitable embodiment of the present application);
  • the M1 element includes the Mn element, and the atomic molar ratio of the Mn element to the non-lithium metal element is recorded as R Mn/all , and optionally, R Mn /all satisfies 0.05 ⁇ R Mn/all ⁇ 0.4, and further optionally, 0.05 ⁇ R Mn/all ⁇ 0.3 (R Mn/all can also be selected from the numerical value or range in any suitable embodiment of the present application);
  • R c+d The ratio of the sum of the atomic molar equivalents of the Co element and the M1 element to the atomic molar equivalent of the Li element is recorded as R c+d , and R c+d satisfies 0.1 ⁇ R c+d ⁇ 0.5, further optionally, 0.1 ⁇ R c+d ⁇ 0.3, and further optionally, 0.1 ⁇ R c+d ⁇ 0.2 (R c+d can also be selected from the numerical value or range in any suitable embodiment of the present application);
  • R (Co+M1)/O The ratio of the sum of the atomic molar equivalents of the Co element and the M1 element to the atomic molar equivalent of the Li element is recorded as R (Co+M1)/O , then R (Co+M1)/O satisfies 0.05 ⁇ R (Co+M1)/O ⁇ 0.25, further optionally, 0.05 ⁇ R (Co+M1)/O ⁇ 0.15, and further optionally, 0.05 ⁇ R (Co+M1)/O ⁇ 0.1 (R (Co+M1)/O can also be selected from the numerical value or range in any suitable embodiment of the present application);
  • the ratio of the sum of the atomic molar equivalents of the Co element and the M1 element to the atomic molar equivalent of the non-lithium metal element is recorded as R (Co+M1)/all , and R (Co+M1)/all satisfies 0.1 ⁇ R (Co+M1)/all ⁇ 0.5, further optionally, 0.1 ⁇ R (Co+M1)/all ⁇ 0.3, and further optionally, 0.1 ⁇ R (Co+M1)/all ⁇ 0.2 (R (Co+M1)/all can also be selected from the numerical value or range in any suitable embodiment of the present application).
  • the first positive electrode active material may be a lithium oxide containing Co, M1 and Ni elements.
  • the first positive electrode active material may have a layered structure, and a higher ionic conductivity is achieved in the first positive electrode active material.
  • the first positive electrode active material further includes a Ni element.
  • the atomic molar ratio of the Ni element to the Li element can be recorded as R b .
  • R b satisfies 0.5 ⁇ R b ⁇ 1, optionally, 0.5 ⁇ R b ⁇ 0.9; further optionally, 0.6 ⁇ R b ⁇ 0.9; further optionally, 0.65 ⁇ R b ⁇ 0.9; further optionally, 0.8 ⁇ R b ⁇ 0.9.
  • Rb can also be any of the following values, or greater than or equal to any of the following values and less than 1, or selected from an interval consisting of any two of the following values: 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.83, 0.833, 0.85, 0.86, 0.88, 0.9, 0.91, 0.92, 0.94, 0.95, etc.
  • the atomic molar ratio of the Ni element to the O element can be recorded as R Ni/O .
  • R Ni/O satisfies 0.25 ⁇ R Ni/O ⁇ 0.5, optionally, 0.25 ⁇ R Ni/O ⁇ 0.45; further optionally, 0.3 ⁇ R Ni/O ⁇ 0.45; further optionally, 0.325 ⁇ R b ⁇ 0.45; further optionally, 0.4 ⁇ R Ni /O ⁇ 0.45.
  • R b can also be any of the following values, or greater than or equal to any of the following values and less than 0.5, or selected from the interval consisting of any two of the following values: 0.25, 0.3, 0.325, 0.35, 0.4, 0.45, 0.46, 0.47, 0.475, 0.48, 0.49, 0.495, etc.
  • the atomic molar ratio of the Ni element to the non-lithium metal element can be recorded as R Ni/all .
  • R Ni/all satisfies 0.5 ⁇ R Ni/all ⁇ 1, optionally, 0.5 ⁇ R Ni/all ⁇ 0.9; further optionally, 0.6 ⁇ R Ni/all ⁇ 0.9; further optionally, 0.65 ⁇ R Ni/all ⁇ 0.9; further optionally, 0.8 ⁇ R Ni/all ⁇ 0.9.
  • R Ni/all can also be any of the following values, or greater than or equal to any of the following values and less than 1, or selected from an interval consisting of any two of the following values: 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.83, 0.833, 0.85, 0.86, 0.88, 0.9, 0.91, 0.92, 0.94, 0.95, etc.
  • the first positive electrode active material contains the Ni element
  • the higher the nickel (Ni) content the higher the energy density of the composite positive electrode sheet, and the more beneficial it is to improve the ionic conductivity; however, when the first positive electrode active material is highly utilized, the risk of damage to the surface structure of the first positive electrode active material or even structural collapse is greater.
  • the thermal stability of the composite positive electrode sheet is improved more significantly.
  • the concentration of the first cation in the electrolyte can better match the demand of the first positive electrode active material for appropriately reducing the utilization rate, so as to achieve a better match of the comprehensive performance of the battery as a whole and achieve a higher energy density. It can significantly improve the thermal stability of the composite positive electrode plate and the battery cell, reduce the risk of thermal runaway, and is also beneficial for the composite positive electrode plate to have good active ion transport performance as a whole.
  • the battery is accompanied by lithium (Li) deintercalation and consumption during the charging and discharging process, and the Li content in the positive electrode plate is different when the battery is discharged to different states.
  • the Li content can be the initial state of the material or the non-initial state after charge and discharge cycles.
  • the positive electrode active material is applied to the positive electrode plate in the battery system. After charge and discharge cycles, the content of Li in the positive electrode active material contained in the positive electrode plate usually changes. Among them, the content of Li can be measured by atomic molar content, but is not limited to this.
  • the content of Li is the initial state of the material
  • the initial state of the material refers to the state before the material is added to the positive electrode slurry. It can be understood that new materials or new substances obtained by appropriate modification on the basis of the listed positive electrode active materials are also within the scope of positive electrode active materials.
  • the aforementioned appropriate modification refers to acceptable modification methods for positive electrode active materials, and non-limiting examples include coating modification.
  • the battery when testing parameters such as R c , R d , R d-Mn , R c+d , R b , etc. relative to the Li element measurement, before extracting the test sample of the positive electrode active material in the positive electrode plate from the battery, the battery can be fully discharged first, and then the battery can be disassembled and the positive electrode plate can be taken to obtain the test sample of the positive electrode active material.
  • the content of oxygen (O) is only a theoretical state value.
  • the release of oxygen from the lattice will cause the atomic molar content of oxygen to change, and the actual content of O will fluctuate.
  • the content of O can be measured by atomic molar content, but is not limited to this.
  • the definition of atomic ratios such as Q a , a, and x in this context may include the atomic molar content of Li under different charge and discharge states of the battery (usually the battery voltage is between 2V and 5V).
  • Q a in the first positive electrode active material, with respect to "atomic molar equivalent of Li element Q a ,” Q a may be 0.9 to 1.1, optionally 0.9 to 1.05, and further optionally 1.
  • Q a in the first positive electrode active material may also be any of the following values, or an interval consisting of any two of the following values: 0.9, 0.92, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.08, 1.1, and the like.
  • Qa in the first positive electrode active material can also be any of the following values, or an interval consisting of any two of the following values: 0.75, 0.8, 0.85, 0.9, 0.92, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.08, 1.1, etc.
  • Non-limiting examples of Qa are also 0.9-1, 0.85-1, 0.8-1, 0.75-1, etc.
  • the atomic molar equivalent Qa of the Li element is 0.75 to 1.2, optionally 0.8 to 1.1, further optionally 0.9 to 1.05, and further optionally 1, and the atomic molar equivalent Qc of the Co element is ⁇ 0.4, optionally Qc ⁇ 0.3, and further optionally Qc ⁇ 0.2.
  • Qc can also be any of the following values, or less than or equal to any of the following values, or selected from the interval consisting of any two of the following values: 0.4, 0.38, 0.36, 0.35, 0.34 , 0.32, 0.3, 0.28, 0.26, 0.25, 0.24, 0.22, 0.20, etc.
  • the atomic molar equivalent Qa of the Li element is 0.75 to 1.2, optionally 0.8 to 1.1, further optionally 0.9 to 1.05, and further optionally 1, and the atomic molar equivalent Qd of the M1 element is ⁇ 0.5, optionally Qd ⁇ 0.4, and further optionally Qd ⁇ 0.3.
  • Qd can also be any of the following values, or less than or equal to any of the following values, or selected from the interval consisting of any two of the following values: 0.5, 0.48 , 0.46, 0.45, 0.44, 0.42, 0.4, 0.38, 0.36, 0.35, 0.34, 0.32, 0.3, etc.
  • the atomic molar equivalent Qa of the Li element is 0.75 to 1.2, optionally 0.8 to 1.1, further optionally 0.9 to 1.05, and further optionally 1, and the M1 element includes the Mn element.
  • the atomic molar equivalent of the Mn element (which can be recorded as Q1 Mn ) can satisfy ⁇ 0.4, and optionally, the atomic molar equivalent of the Mn element is ⁇ 0.3.
  • the atomic molar equivalent of the Mn element can also be any of the following values, or less than or equal to any of the following values, or selected from the interval consisting of any two of the following values: 0.4, 0.38, 0.36, 0.35, 0.34, 0.32, 0.3, etc.
  • Q1 Mn can also be any of the following ranges: Q1 Mn ⁇ 0.2, 0.05 ⁇ Q1 Mn ⁇ 0.2, etc.
  • the atomic molar equivalent Qa of the Li element is 0.75 to 1.2, optionally 0.8 to 1.1, further optionally 0.9 to 1.05, and further optionally 1, and the sum of the atomic molar equivalents of the Co element and the M1 element is Qc + d ⁇ 0.5, optionally, Qc +d ⁇ 0.4 , Qc + d ⁇ 0.3, Qc + d ⁇ 0.2.
  • Qc +d can also be any of the following values, or less than or equal to any of the following values, or selected from an interval consisting of any two of the following values: 0.5, 0.48, 0.46, 0.45, 0.44, 0.42, 0.4, 0.38, 0.36, 0.35, 0.34, 0.32, 0.3, 0.28, 0.26, 0.25, 0.24, 0.22, 0.2, etc.
  • the atomic molar equivalent Qa of the Li element is 0.75 to 1.2, optionally 0.8 to 1.1, further optionally 0.9 to 1.05, and further optionally 1, and the first positive electrode active material satisfies one or more of the following characteristics:
  • the atomic molar equivalent of the Co element is Q c ⁇ 0.4, optionally, Q c ⁇ 0.3, further optionally, Q c ⁇ 0.2 (Q c can also be selected from a numerical value or range in any suitable embodiment of the present application);
  • the atomic molar equivalent of the M1 element is Q d ⁇ 0.5, optionally, Q d ⁇ 0.4, further optionally, Q d ⁇ 0.3 (Q d may also be selected from a numerical value or range in any suitable embodiment of the present application);
  • the M1 element includes the Mn element, and the atomic molar equivalent of the Mn element is ⁇ 0.4.
  • the atomic molar equivalent of the Mn element is ⁇ 0.3 (the atomic molar equivalent of the Mn element can be recorded as Q1 Mn , and can also be selected from a value or range in any suitable embodiment of the present application);
  • the sum of the atomic molar equivalents of the Co element and the M1 element is Q c+d ⁇ 0.5, optionally, Q c+d ⁇ 0.4, Q c+d ⁇ 0.3, Q c+d ⁇ 0.2 (Q c+d can also be selected from a numerical value or range in any appropriate embodiment of the present application).
  • the atomic molar equivalent Q a of the Li element is 0.75 to 1.2, optionally 0.8 to 1.1, further optionally 0.9 to 1.05, and further optionally 1, the first positive electrode active material includes the Ni element, and the atomic molar equivalent Q b of the Ni element satisfies 0.5 ⁇ Q b ⁇ 1, optionally 0.6 ⁇ Q b ⁇ 1, and further optionally 0.65 ⁇ Q b ⁇ 1.
  • Q b can also be any of the following values, or greater than or equal to any of the following values and less than 1, or selected from the interval consisting of any two of the following values: 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8 , 0.85, 0.83, 0.833, 0.85, 0.86, 0.88, 0.9, 0.91, 0.92, 0.94, 0.95, etc.
  • the content of the corresponding elements can be adjusted by adjusting the atomic molar equivalents of the Co element, the M1 element and the Ni element.
  • the M2 element in the first positive electrode active material may be selected from, but not limited to, one or more of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, and Nb.
  • the R element in the first positive active material may be selected from, but not limited to, one or more of N, F, S, and Cl.
  • a can also be any of the following values, or an interval consisting of any two of the following values: 0.8, 0.85, 0.83, 0.833, 0.85, 0.86, 0.88, 0.9, 0.91, 0.92, 0.94, 0.95, 0.96, 0.98, 0.99, 1, 1.01, 1.02, 1.04, 1.05, 1.06, 1.08, 1.09, 1.1, 1.12, 1.24, 1.15, 1.16, 1.18, 1.2, etc.
  • b can also be any of the following values, or greater than or equal to any of the following values and less than 1, or selected from an interval consisting of any two of the following values: 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.83, 0.833, 0.85, 0.86, 0.88, 0.9, 0.91, 0.92, 0.94, 0.95, etc.
  • c can also be any of the following values, or an interval consisting of any two of the following values: 0.05, 0.06, 0.08, 0.09, 0.1, 0.11, 0.12, 0.125, 0.14, 0.15, 0.16, 0.175, 0.18, 0.2, 0.22, 0.225, 0.24, 0.25, 0.26, 0.275, 0.28, 0.3, 0.32, 0.34, 0.35, 0.36, 0.38, 0.4, 0.42, 0.44, 0.45, 0.46, 0.48, 0.5, etc.
  • d can also be any of the following values, or an interval consisting of any two of the following values: 0.05, 0.06, 0.08, 0.09, 0.1, 0.11, 0.12, 0.125, 0.14, 0.15, 0.16, 0.175, 0.18, 0.2, 0.22, 0.225, 0.24, 0.25, 0.26, 0.275, 0.28, 0.3, 0.32, 0.34, 0.35, 0.36, 0.38, 0.4, 0.42, 0.44, 0.45, 0.46, 0.48, 0.5, etc.
  • e can also be any of the following values, or an interval consisting of any two of the following values: 0.03, 0.035, 0.04, 0.045, 0.05, etc.
  • f can also be any of the following values, or an interval consisting of any two of the following values: 1, 1.1, 1.2, 1.25, 1.3, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.8, 1.85, 1.9, 1.95, 2, 2.05, 2.1, etc.
  • g can also be any of the following values, or an interval consisting of any two of the following values: 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.46, 0.48, etc.
  • the first positive electrode active material includes one or more of lithium nickel cobalt manganese oxide (also referred to as lithium nickel cobalt manganese oxide), lithium nickel cobalt aluminum oxide, and modified compounds thereof.
  • lithium nickel cobalt manganese oxide may include LiNi 0.5 Co 0.2 Mn 0.3 O 2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), etc.
  • Non-limiting examples of lithium nickel cobalt aluminum oxide may include LiNi 0.80 Co 0.15 Al 0.05 O 2 .
  • the atomic molar equivalent of Li element in the second positive electrode active material, can be 0.9 to 1.1, optionally 0.9 to 1.05, and further optionally 1.
  • the atomic molar equivalent of Li element in the second positive electrode active material, can also be any of the following values, or an interval consisting of any two of the following values: 0.9, 0.92, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.08, 1.1, etc.
  • the atomic molar equivalent of the Li element in the second positive electrode active material, can also be any of the following values, or an interval consisting of any two of the following values: 0.75, 0.8, 0.85, 0.9, 0.92, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.08, 1.1, etc.
  • non-limiting examples of the atomic molar equivalent of the Li element are also such as 0.9-1, 0.85-1, 0.8-1, 0.75-1, etc.
  • the atomic molar ratio of the Mn element to the Fe element (which can be recorded as R2 Mn/Fe ) is 0.42 to 9, and optionally, the atomic molar ratio of the Mn element to the Fe element is 0.66 to 4.
  • R2 Mn/Fe can also be any of the following values, or an interval consisting of any two of the following values: 0.42, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 6.5, 7, 7.5, 8, 8.5, 9, etc.
  • the atomic mole equivalent of the Li element is 0.9 to 1.1, optionally 0.9 to 1.05, and further optionally 1, and the atomic mole equivalent of the Mn element is
  • the equivalent weight (which can be recorded as Q2 Mn ) is 0.5 to 0.999, and optionally, Q2 Mn is 0.5 to 0.6.
  • Q2 Mn can also be any of the following values, or an interval consisting of any two of the following values: 0.5, 0.55, 0.6, 0.65, 0.7, 0.8, 0.9, 0.92, 0.94, 0.95, 0.96, 0.98, 0.99, 0.995, 0.999, etc.
  • the atomic molar equivalent of the Li element is 0.9 to 1.1, optionally 0.9 to 1.05, and further optionally 1, and the atomic molar equivalent of the Fe element (which can be recorded as Q2 Fe ) is 0.001 to 0.5, and optionally, Q2 Fe is 0.4 to 0.5.
  • Q2 Fe can also be any of the following values, or an interval consisting of any two of the following values: 0.001, 0.002, 0.004, 0.005, 0.006, 0.008, 0.01, 0.02, 0.04, 0.05, 0.06, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, etc.
  • the second positive electrode active material satisfies one or more of the following characteristics:
  • the atomic molar ratio of the Mn element to the Fe element (which can be recorded as R2 Mn/Fe ) is 0.42 to 9, and optionally, R2 Mn/Fe is 0.66 to 4 (R2 Mn/Fe can also be selected from a numerical value or range in any suitable embodiment of the present application);
  • the atomic molar equivalent of the Li element is 0.9 to 1.1, optionally 0.9 to 1.05, and further optionally 1, and the atomic molar equivalent of the Mn element (which can be recorded as Q2 Mn ) is 0.5 to 0.999, and optionally, Q2 Mn is 0.5 to 0.6 (Q2 Mn can also be selected from the numerical value or range in any suitable embodiment of the present application);
  • the atomic molar equivalent of Li element is 0.9 to 1.1, optionally 0.9 to 1.05, and further optionally 1, and the atomic molar equivalent of Fe element (which can be expressed as Q2 Fe ) is 0.001 to 0.5, optionally, Q2 Fe is 0.4 to 0.5 (Q2 Fe can also be selected from the numerical value or range in any suitable embodiment of the present application).
  • Increasing the Mn element content in the second positive electrode active material is beneficial to improving the energy density, voltage platform and material cost of the second positive electrode active material.
  • By controlling the Mn element within the above range it is beneficial to form a uniform solid solution while exerting the effect of the Mn element, and it can also minimize or avoid defects and pores, thereby reducing or avoiding defects and pores to extend the insertion and migration path of active ions.
  • the second active material has a good ion migration rate, shorten the gap between the active ion conductivity of the second positive electrode active material and the first positive electrode active material, thereby reducing the probability of the first positive electrode active material being over-utilized and de-lithiumed, which is beneficial to further improve the thermal stability of the composite positive electrode sheet.
  • the introduction of Fe element is conducive to achieving better ion transport and higher ion conductivity, and is also conducive to promoting the embedding and extraction of active ions, thereby improving the battery charging and discharging efficiency and energy density.
  • the content of the corresponding elements can be adjusted by adjusting the atomic molar equivalents of the Fe element and the Mn element.
  • the second active material includes a second body, and also includes or does not include a second coating layer located on at least a portion of the surface of the second body; wherein the chemical formula of the second body is Li 1+x Mn 1-yw Fe w M3 y P 1-z Q z O 4 , wherein -0.1 ⁇ x ⁇ 0.1, 0.1 ⁇ w ⁇ 0.5, 0.001 ⁇ y ⁇ 0.5, 0.001 ⁇ z ⁇ 0.1, the M3 element in the second active material may include one or more elements of zinc (Zn), aluminum (Al), sodium (Na), potassium (K), magnesium (Mg), molybdenum (Mo), tungsten (W), titanium (Ti), vanadium (V), zirconium (Zr), nickel (Ni), cobalt (Co), gallium (Ga), tin (Sn), antimony (Sb), niobium (Nb) and germanium (Ge), and the Q element in the second active material may include one or more
  • the M3 element in the second active material can be selected from but not limited to one or more elements of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Ni, Co, Ga, Sn, Sb, Nb and Ge.
  • the Q element in the second active material may be selected from, but not limited to, one or more elements including B, Si, N, S, F, Cl, and Br.
  • y can also be any of the following values, or an interval consisting of any two of the following values: 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, etc.
  • w can also be any of the following values, or an interval consisting of any two of the following values: 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, etc.
  • 0.001 ⁇ z ⁇ 0.1 further optionally, 0.001 ⁇ z ⁇ 0.05, and further optionally, 0.001 ⁇ z ⁇ 0.002.
  • z can also be any of the following values, or an interval consisting of any two of the following values: 0.001, 0.002, 0.004, 0.005, 0.006, 0.008, 0.01, 0.02, 0.04, 0.05, 0.06, 0.08, 0.1, etc.
  • the M3 element in the second active material includes one or more elements of titanium (Ti), vanadium (V), nickel (Ni), cobalt (Co) and magnesium (Mg). Further, the M3 element in the second active material can be selected from but not limited to one or more elements of Ti, V, Ni, Co and Mg.
  • the Q element in the second active material includes one of boron (B), silicon (Si), nitrogen (N) and sulfur (S). Further, the Q element in the second active material can be selected from but not limited to one of B, Si, N and S.
  • the second coating layer includes one or more of pyrophosphate, phosphate, and carbon.
  • the second coating layer may be a single-layer structure or a multi-layer structure.
  • the total mass proportion of the first positive electrode active material and the second positive electrode active material in the positive electrode active material layer is RI +II ⁇ 85%; alternatively, RI +II ⁇ 90%; further alternatively, RI +II ⁇ 95%.
  • RI+II can also be any of the following percentages, or greater than or equal to any of the following percentages, or selected from the interval consisting of any two of the following percentages: 85%, 86%, 88%, 90%, 92%, 94%, 95%, 96%, 98%, etc.
  • the first cation includes cations of one or more elements of alkali metal elements and alkaline earth metal elements.
  • the first cation may include one or more of sodium ions, potassium ions, calcium ions, and magnesium ions.
  • the anion in the first cationic salt may include one or more of hexafluorophosphate ion, perchlorate ion, tetrafluoroborate ion, bistrifluoromethylsulfonyl imide ion, trifluoromethanesulfonate ion, bisfluorosulfonyl imide ion, and tris(trifluoromethylsulfonyl)methyl ion.
  • the anions in the electrolyte salt may include one or more of hexafluorophosphate ion, perchlorate ion, tetrafluoroborate ion, bistrifluoromethylsulfonyl imide ion, trifluoromethanesulfonate ion, bisfluorosulfonyl imide ion, and tris(trifluoromethylsulfonyl)methyl ion.
  • the first cationic salt may include one or more of sodium hexafluorophosphate, sodium perchlorate, sodium tetrafluoroborate, sodium bistrifluoromethylsulfonyl imide, sodium trifluoromethanesulfonate, sodium bisfluorosulfonyl imide, sodium tris(trifluoromethylsulfonyl)methyl, potassium hexafluorophosphate, potassium perchlorate, potassium tetrafluoroborate, potassium bistrifluoromethylsulfonyl imide, potassium trifluoromethanesulfonate, potassium bisfluorosulfonyl imide, and potassium tris(trifluoromethylsulfonyl)methyl.
  • the first cationic salt includes one or both of sodium hexafluorophosphate, sodium tetrafluoroborate, and sodium perchlorate.
  • the first cationic salt comprises sodium hexafluorophosphate.
  • the type of the first cation and the corresponding anion can have a flexible range of selection.
  • sodium hexafluorophosphate is low in cost and can be used on a large scale; the difference in radius between sodium ions and lithium ions is small, which is more conducive to embedding active materials.
  • the negative electrode plate includes a negative electrode active material layer, the negative electrode active material layer includes a negative electrode active substance, and the negative electrode active substance includes a silicon-based material; the mass percentage of the silicon-based material in the negative electrode active substance is recorded as X1.
  • X1 can also be any of the following percentages, or an interval consisting of any two of the following percentages: 3%, 4%, 5%, 6%, 8%, 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 5%, 36%, 38%, 40%, 42%, 44%, 45%, 46%, etc.
  • the silicon-based material may include one or more of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, silicon alloy, silicon-graphene composite, silicon-carbon nanotube, and silicon-containing conductive polymer.
  • the negative electrode active material layer of the negative electrode plate includes a silicon-based material, it is beneficial to further improve the energy density of the battery cell.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active substance.
  • the definition of the positive electrode active substance can be found in the above text.
  • the positive electrode active substance includes at least the first positive electrode active substance and the second positive electrode active substance mentioned above.
  • the mass percentage of the positive electrode active material in the positive electrode active material layer may be ⁇ 85%, further may be ⁇ 90%, and further may be ⁇ 95%.
  • the sum of the mass of the first positive electrode active material and the second positive electrode active material in the total mass of the positive electrode active material in the positive electrode active material layer may satisfy ⁇ 85%, optionally ⁇ 95%, further optionally ⁇ 96%, etc., and further optionally 100%, etc.
  • the percentage of the first positive electrode active material and the second positive electrode active material in the total mass of the positive electrode active material in the positive electrode active material layer may also be any of the following percentages, or greater than or equal to any of the following percentages and less than or equal to 100%, or selected from the interval consisting of any two of the following percentages: 85%, 86%, 88%, 95%, 96%, 98%, 100%, etc.
  • the positive electrode active material in the positive electrode active material layer consists of a first positive electrode active material and a second positive electrode active material.
  • the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is disposed on any one or both of the two surfaces facing each other of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • aluminum foil may be used as the metal foil.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.
  • the composite current collector may be obtained by forming a metal material on a polymer material substrate.
  • the metal material may include but is not limited to one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy.
  • the polymer material substrate may include but is not limited to one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode active material layer may also optionally include a binder.
  • the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer
  • the positive electrode active material layer may further optionally include a conductive agent.
  • the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the mass percentage of the conductive agent in the positive electrode active material layer may be 0 to 8%, and further may be 0 to 5%.
  • the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive active material, the conductive agent, the binder and any other components, are dispersed in a solvent to form a positive electrode slurry. Further, the positive electrode slurry is coated on at least one side of the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained. Cold pressing can be performed by a cold rolling mill.
  • the type of solvent may include but is not limited to any of the aforementioned embodiments, for example, it may include N-methylpyrrolidone (NMP), and further may be NMP.
  • the surface of the positive electrode collector coated with the positive electrode slurry may be on a single surface of the positive electrode collector, or on both surfaces of the positive electrode collector.
  • the solid content of the positive electrode slurry may be 40wt% to 80wt%.
  • the viscosity of the positive electrode slurry at room temperature may be adjusted to 3000mPa ⁇ s to 25000mPa ⁇ s, and may be optionally 3000mPa ⁇ s to 10000mPa ⁇ s.
  • the coating unit area density based on dry weight (excluding solvent) may be 15 mg/cm 2 to 35 mg/cm 2 .
  • the compaction density of the positive electrode sheet may be 3.0 g/cm 3 to 3.6 g/cm 3 , and may be 3.3 g/cm 3 to 3.5 g/cm 3 .
  • the electrode sheet area does not change much before and after cold pressing, and the corresponding compaction density is calculated as follows:
  • Compacted density coating surface density/(thickness of the electrode after cold pressing - thickness of the current collector).
  • Coating surface density slurry dry weight / electrode area before cold pressing.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material.
  • the definition of the negative electrode active material can be found in the above text.
  • the mass percentage of the negative electrode active material in the negative electrode active material layer may be ⁇ 85%, further may be ⁇ 90%, and further may be ⁇ 95%.
  • the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material layer may be disposed on any one or both of the two facing surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • a metal foil a copper foil may be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate.
  • the composite current collector may be formed by forming a metal material on a polymer material substrate.
  • the metal material may include, but is not limited to, one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy.
  • the polymer material substrate may include, but is not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative electrode active material can adopt the negative electrode active material for batteries known in the art.
  • the negative electrode active material may include one or more of the following substances or materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc.
  • Silicon-based materials may include one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • Tin-based materials may include one or more of elemental tin, tin oxide compounds, and tin alloys.
  • the present application is not limited to these materials or substances, and other traditional materials or substances that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the negative electrode active material includes one or more of carbon-based materials, silicon-based materials, tin-based materials, lithium titanate, and modified forms of any of the foregoing materials, wherein the modified forms include one or more of doping modification and coating modification.
  • Both the doping modification method and the coating modification method can adopt or refer to the existing modification methods in the art, including but not limited to the element type and Selection of doping amount.
  • the carbon-based material may include, but is not limited to, one or more of graphite material, soft carbon, hard carbon, etc.
  • the graphite material may include one or more of artificial graphite and natural graphite.
  • the negative electrode active material includes a carbon-based material and a silicon-based material.
  • the sum of the mass of the carbon-based material and the silicon-based material in the total mass of the negative electrode active material can be ⁇ 85%, optionally ⁇ 90%, further optionally ⁇ 95%, further optionally ⁇ 96%, etc., and further optionally 100%, etc.
  • the sum of the mass of the graphite material and the silicon-based material in the total mass of the negative electrode active material can also be any of the following percentages, or greater than or equal to any of the following percentages and less than or equal to 100%, or selected from the interval consisting of any two of the following percentages: 85%, 86%, 88%, 90%, 92%, 94%, 95%, 96%, 98%, etc.
  • the definitions of carbon-based materials and silicon-based materials can be found in the foregoing, for example, the carbon-based material can be a graphite material.
  • the content of the carbon-based material and the silicon-based material can also be found in any suitable embodiment in the context.
  • the negative electrode active material includes a carbon-based material.
  • the mass percentage of the carbon-based material in the negative electrode active material can be ⁇ 85%, optionally ⁇ 90%, further optionally ⁇ 95%, further optionally ⁇ 96%, etc., further optionally 100%, etc.
  • the mass percentage of the carbon-based material in the negative electrode active material can also be any of the following percentages, or greater than or equal to any of the following percentages and less than or equal to 100%, or selected from the interval consisting of any two of the following percentages: 85%, 86%, 88%, 90%, 92%, 94%, 95%, 96%, 98%, etc.
  • the definition of carbon-based materials can be found in the above text, for example, the carbon-based material can be a graphite material.
  • the negative electrode active material layer may further include a binder.
  • the binder may include, but is not limited to, one or more of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).
  • SBR styrene-butadiene rubber
  • PAA polyacrylic acid
  • PAAS sodium polyacrylate
  • PAM polyacrylamide
  • PVA polyvinyl alcohol
  • SA sodium alginate
  • PMAA polymethacrylic acid
  • CMCS carboxymethyl chitosan
  • the mass percentage of the binder in the negative electrode active material layer may be 0 to 10%, further 0 to 5%, further 1% to 5%, and further optionally 1% to 3%.
  • the negative electrode active material layer may further include a conductive agent.
  • the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the mass percentage of the conductive agent may be 0 to 15%, further optionally 0 to 10%, and further optionally 0 to 5%.
  • the negative electrode active material layer may further include other additives, such as a thickener (such as sodium carboxymethyl cellulose (CMC-Na)).
  • a thickener such as sodium carboxymethyl cellulose (CMC-Na)
  • the mass percentage of other additives in the negative electrode active material layer may be 0 to 15%, further 0 to 10%, further 0 to 5%, further 0 to 3%, further 0 to 2%.
  • the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (a non-limiting example of the solvent is deionized water) to form a negative electrode slurry. Further, the negative electrode slurry is coated on at least one side of the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained. The surface of the negative electrode collector coated with the negative electrode slurry can be on a single surface of the negative electrode collector or on both surfaces of the negative electrode collector.
  • a solvent a non-limiting example of the solvent is deionized water
  • the solid content of the negative electrode slurry can be 30wt% to 70wt%, and can be optionally 40wt% to 60wt%.
  • the viscosity of the negative electrode slurry at room temperature can be adjusted to 2000mPa ⁇ s to 10000mPa ⁇ s, and can be optionally 3000mPa ⁇ s to 10000mPa ⁇ s.
  • the compaction density of the negative electrode sheet may be 1.2 g/cm 3 to 2.0 g/cm 3 , and may be optionally 1.2 g/cm 3 to 1.8 g/cm 3 .
  • the electrolyte will be described below.
  • the electrolyte has the function of conducting ions between the positive electrode plate and the negative electrode plate.
  • the electrolyte includes a liquid electrolyte.
  • the liquid electrolyte can also be called an electrolyte, that is, the electrolyte includes an electrolyte.
  • the electrolyte includes an electrolyte salt.
  • the electrolyte is an electrolyte solution.
  • the electrolyte is a non-aqueous electrolyte.
  • the non-aqueous electrolyte includes an electrolyte salt and a solvent.
  • the definition of the electrolyte salt can be referred to above, and at least includes a first electrolyte salt.
  • the electrolyte salt also includes an electrolyte lithium salt.
  • the concentration of the electrolyte salt can generally be 0.5 mol/L to 5 mol/L.
  • the electrolyte lithium salt may include one or more of lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium bisoxalatoborate (LiBOB), lithium difluorophosphate (LiPO 2 F 2 ), lithium difluorobisoxalatophosphate (LiDFOP), and lithium tetrafluorooxalatophosphate (LiTFOP).
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium perchlorate
  • the solvent in the non-aqueous electrolyte may include fluoroethylene carbonate (FEC), ethylene carbonate (EC, ), propylene carbonate (PC, ), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate Ester (BC, ), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), cyclopentane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (MSM),
  • the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • additives such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • the additives in the electrolyte may include, but are not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethylethylene carbonate (TFPC), and the like.
  • FEC fluoroethylene carbonate
  • DFEC difluoroethylene carbonate
  • TFPC trifluoromethylethylene carbonate
  • the separator will be described below.
  • the secondary battery further includes a separator.
  • the present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.
  • the material of the isolation membrane may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation membrane may be a single-layer film or a multi-layer composite film, without particular limitation.
  • the materials of each layer may be the same or different, without particular limitation.
  • the thickness of the isolation film is 6 ⁇ m to 40 ⁇ m, and may be 12 ⁇ m to 20 ⁇ m.
  • the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.
  • a secondary battery which includes the battery cell described in the first aspect of the present application.
  • battery cell refers to a basic unit that can realize the mutual conversion of chemical energy and electrical energy, and further, generally speaking, at least includes a positive electrode sheet, a negative electrode sheet and an electrolyte. During the battery charging and discharging process, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting active ions between the positive electrode sheet and the negative electrode sheet.
  • the definition of battery cell can be found in the context, for example, the first aspect of this application can be found.
  • a secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator.
  • active ions are embedded and extracted back and forth between the positive electrode sheet and the negative electrode sheet.
  • the electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet.
  • the separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.
  • the secondary battery is a lithium ion secondary battery.
  • the secondary battery is a lithium ion secondary battery
  • the electrolyte salt may include an electrolyte lithium salt
  • the secondary battery may include an outer package, which may be used to encapsulate the electrode assembly and the electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft package, such as a bag-type soft package.
  • the material of the soft package may be plastic, and further, non-limiting examples of plastic may include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.
  • the secondary battery includes at least one battery cell.
  • the secondary battery may include one or more battery cells.
  • FIG1 is a battery cell 5 of a square structure as an example.
  • the outer package may include a shell 51 and a cover plate 53.
  • the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity.
  • the shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity.
  • the positive electrode sheet, the negative electrode sheet and the isolation film can form an electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is encapsulated in the receiving cavity.
  • the electrolyte is infiltrated in the electrode assembly 52.
  • the number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to actual needs.
  • the secondary battery may be a battery module 4 or a battery pack 1 .
  • the battery module includes at least one battery cell.
  • the number of battery cells contained in the battery module can be one or more, and those skilled in the art can select a suitable number according to the application and capacity of the battery module.
  • FIG3 is a battery module 4 as an example.
  • a plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.
  • the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.
  • the battery modules may be assembled into a battery pack.
  • the battery pack may contain one or more battery modules. Those skilled in the art may select a suitable number according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a device.
  • a plurality of battery modules 4 are placed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3.
  • the upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4.
  • the plurality of battery modules 4 can be arranged in the battery box in any manner.
  • an electrical device which includes at least one of the battery cell described in the first aspect of the present application and the secondary battery described in the second aspect of the present application.
  • the present application also provides an electrical device, which includes a secondary battery of any embodiment provided in the present application.
  • the secondary battery can be used as a power source for the electrical device, or as an energy storage unit for the electrical device.
  • the electrical device may include mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.
  • mobile devices may be, for example, mobile phones, laptop computers, etc.; electric vehicles may be, for example, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, electric motorcycles, electric tools, etc., but are not limited thereto.
  • the electrical device can also be used in the fields of military equipment, aerospace, etc., and can also be used in energy storage power supply systems such as hydropower, thermal power, wind power and solar power stations.
  • a secondary battery can be selected according to its usage requirements.
  • Fig. 6 is an example of an electric device 6.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.
  • a battery pack or a battery module may be used.
  • a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be thin and light, and a secondary battery may be used as a power source.
  • room temperature refers to 20°C to 30°C.
  • the following embodiments take a soft-pack laminated battery as an example, and it is understood that the outer packaging of the secondary battery is not limited thereto. Similarly, the material selection and assembly method of the tabs may also adopt other methods in the art.
  • the positive electrode active material to be tested was made into a positive electrode plate for testing, and the lithium plate was used as the negative electrode plate, and assembled into a button battery for testing; the battery was discharged to 3.0V at 1C and then an AC impedance spectrum test was performed.
  • the test parameters were selected as follows: the test temperature was 25°C, the scanning frequency was 0.1Hz ⁇ 10 5 Hz, and the voltage amplitude was 5mV.
  • the test results were fitted using Zview software to obtain the ionic conductivity.
  • the positive current collector is aluminum foil
  • the mass percentage of the positive active material in the positive active material layer is controlled at 95% ⁇ 1%
  • the binder is polyvinylidene fluoride (PVDF)
  • the conductive agent is conductive carbon
  • the compaction density is 3.0 g/cm 3 to 3.6 g/cm 3 .
  • raw materials with the same chemical formula have the same source or are prepared by the same method. Therefore, the ion conductivities of the raw materials with the same chemical formula are substantially the same.
  • the first positive electrode active material and the second positive electrode active material, the binder polyvinylidene fluoride (PVDF) and the conductive carbon are added to the solvent N-methylpyrrolidone (NMP), the mass ratio of the positive electrode active material: the binder: the conductive agent is 95:2.5:2.5, and stirred in a drying room to form a uniform positive electrode slurry, and the viscosity of the positive electrode slurry is controlled to be 3000mPa ⁇ S ⁇ 10000mPa ⁇ S, and the above positive electrode slurry is coated on the double-side surface of the aluminum foil, and the positive electrode sheet is made after drying and cold pressing.
  • the compaction density is 3.4g/ cm3 .
  • the first positive electrode active material is a lithium nickel cobalt manganese oxide (a NCM material), and the second positive electrode active material is a lithium manganese iron phosphate oxide.
  • the types and content ratios of the first positive electrode active material and the second positive electrode active material (the usage ratio of the two is determined by the A value) can be found in Table 1 and Table 2.
  • the value A is the mass ratio of the Co element in the first positive electrode active material to the Fe element in the second positive electrode active material.
  • Graphite material artificial graphite
  • sodium carboxymethyl cellulose sodium carboxymethyl cellulose
  • SBR styrene butadiene rubber
  • conductive carbon conductive carbon
  • the mass ratio of graphite material: sodium carboxymethyl cellulose: styrene butadiene rubber: conductive agent being 95:1:2.5:1.5
  • the viscosity of the negative electrode slurry was controlled to be 3000mPa ⁇ S ⁇ 10000mPa ⁇ S, and the above negative electrode slurry was coated on one side of the copper foil, and the negative electrode sheet was formed after drying and cold pressing.
  • the compaction density was 1.55g/ cm3 .
  • the electrolyte solution is composed of electrolyte salt, solvent and additives: the electrolyte salt is sodium hexafluorophosphate (NaPF 6 , the first cation salt) and lithium hexafluorophosphate (LiPF 6 ), wherein the mass of the sodium element in the electrolyte is the relative percentage of the sum of the mass of the sodium element and the lithium element.
  • the electrolyte salt is sodium hexafluorophosphate (NaPF 6 , the first cation salt) and lithium hexafluorophosphate (LiPF 6 ), wherein the mass of the sodium element in the electrolyte is the relative percentage of the sum of the mass of the sodium element and the lithium element.
  • the ratio is 5wt% (corresponding to the target value of B is 5%), the concentration of lithium hexafluorophosphate (electrolyte lithium salt) in the electrolyte is 1 mol/L; the solvent is ethylene carbonate (EC), diethyl carbonate (DEC) and dimethyl carbonate (DMC) in a volume ratio of 1:1:1; the additive is fluoroethylene carbonate (FEC), and the mass percentage in the electrolyte is 5wt%.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • DMC dimethyl carbonate
  • FEC fluoroethylene carbonate
  • the first cationic salt is sodium hexafluorophosphate
  • the first cation is sodium ion
  • the electrolyte lithium salt is lithium hexafluorophosphate
  • the electrolyte salt in the electrolyte is composed of metal cations and anions
  • the metal cations are a combination of sodium ions and lithium ions
  • the anions are hexafluorophosphate ions.
  • the type and dosage ratio of the first cationic salt in the electrolyte can also be found in Table 1.
  • the B value is the mass percentage of the first cation salt in the electrolyte salt of the electrolyte solution, and is numerically calculated as "the ratio of the mass of the first cation to the total mass of the metal cations in the electrolyte salt".
  • a polyethylene (PE) porous polymer film is used as the isolation membrane.
  • the prepared positive electrode sheet, negative electrode sheet and separator are made into corresponding electrode assemblies (i.e. bare cells) according to the Z-shaped stacking structure, and the bare cells are vacuum dried at 90°C for 12h, followed by ultrasonic welding of the positive and negative electrode tabs, the positive electrode using aluminum tabs, the negative electrode using nickel tabs, the positive and negative tabs are located on the same side of the cell, the cell after the tabs are welded is placed in an aluminum-plastic film for top-side sealing, the electrolyte is injected, the cell is left to stand, formed, aged, exhausted, and packaged for the second time to obtain a secondary battery with a preset capacity (0.1Ah), which is an exemplary soft-pack stacking battery.
  • a hard shell method can be used.
  • Examples 2 to 21 use a method basically the same as Example 1 to prepare secondary batteries, with the following differences: the type of the first positive electrode active material, the type of the second positive electrode active material, the usage ratio A value of the first positive electrode active material and the second positive electrode active material, the type of the first cationic salt in the electrolyte, the usage (B value) of the first cationic salt, the A/B value, and the type and usage of the negative electrode active material, which can be found in Tables 1, 2 and 3.
  • Comparative Example 1 uses a method substantially the same as that of Example 1 to prepare a secondary battery, except that the A value and the A/B value are different.
  • Comparative Example 2 uses a method substantially the same as that of Example 1 to prepare a secondary battery, except that the B value and the A/B value are different.
  • Comparative Example 3 uses a method substantially the same as that of Example 1 to prepare a secondary battery, except that the second positive electrode active material is omitted from the positive electrode active material, and only the first positive electrode active material is used, and the A value and A/B value are different.
  • Comparative Example 4 uses a method substantially the same as that of Example 1 to prepare a secondary battery, except that the first positive electrode active material is omitted from the positive electrode active material, and only the second positive electrode active material is used, and the A value and A/B value are different.
  • Comparative Example 5 uses a method substantially the same as that of Example 1 to prepare a secondary battery, except that the first cationic salt is not added, and the B value and the A/B value are different.
  • Comparative Example 6 uses a method substantially the same as that of Example 8 to prepare a secondary battery, except that the A value, B value and A/B value are different.
  • Comparative Example 7 uses a method substantially the same as that of Example 12 to prepare a secondary battery, except that the A value, B value and A/B value are different.
  • Comparative Example 8 uses a method substantially the same as that of Example 16 to prepare a secondary battery, except that the B value and the A/B value are different.
  • Comparative Example 9 uses a secondary battery prepared by a method substantially the same as that of Comparative Example 2, except that the ratio of the atomic molar equivalents of the Mn element and the Fe element in the second positive electrode active material (R2 Mn/Fe ) is different.
  • the A value and B value in Table 1 are design values (corresponding to their respective target values) calculated based on the raw material composition and dosage ratio.
  • the Ni content, Mn content and R2 Mn/Fe are atomic ratios obtained based on the chemical composition of the raw materials, measured in terms of atomic number ratio or atomic molar ratio.
  • the cations in the electrolyte salt of the electrolyte are a combination of lithium ions and first cations.
  • the type and dosage ratio of the first cationic salt in the electrolyte can be found in Table 1, and the dosage of the first cationic salt is determined based on the target value of B; when the anions of the electrolyte salt are different, the dosage of the first cationic salt and the target value of B are determined by "the ratio of the mass of the first cation to the total mass of the metal cations in the electrolyte salt".
  • the A value is the target value of the mass ratio (A) of the Co element in the first positive electrode active material to the Fe element in the second positive electrode active material; the first cation is the sodium ion, and the B value is the target value of the mass percentage (B) of the first cation salt in the electrolyte salt of the electrolyte, which is numerically equal to the percentage of the mass of the first cation in the electrolyte relative to the mass of the metal cation in the electrolyte.
  • the “nickel (Ni) content” in the first positive electrode active material is the ratio of the atomic molar equivalents of the Ni element to the lithium (Li) element, which is also numerically equal to the atomic ratio of the Ni element to the Li element;
  • the “manganese (Mn) content” in the first positive electrode active material is the ratio of the atomic molar equivalents of the Mn element to the lithium (Li) element, which is also numerically equal to the atomic ratio of the Mn element to the Li element;
  • R2 Mn/Fe refers to the ratio of the atomic molar equivalents of the Mn element and the Fe element in the second positive electrode active material.
  • mass percentage of silicon-based material represents the mass percentage of silicon-based material in the negative electrode active material.
  • the electrolyte lithium salt and the first cationic salt in the electrolyte are quantitatively tested.
  • the mass of lithium ions in the electrolyte lithium salt is recorded as m1
  • the mass of the first cation in the first cationic salt is recorded as m2.
  • Test the content of Ni, Co and Mn in the first positive electrode active material test the content of Mn and Fe in the second positive electrode active material, and test and analyze the ratio of elements such as A value.
  • the chemical formula of the first positive electrode active material and the content of Mn in the first positive electrode active material can be obtained based on the molar mass and mass percentage of Ni and Co elements; after removing the content of Mn in the first positive electrode active material, the mass percentage of Mn in the second positive electrode active material can be obtained, and the chemical formula of the second active material can be obtained based on the molar mass and mass percentage of Mn and Fe in the second positive electrode active material.
  • the mass ratio (A value) of Co in the first positive electrode active material and Fe in the second positive electrode active material and other ratios with atomic molar ratios of different elements can be calculated, for example, the mass ratio of Mn and Fe in the second positive electrode active material (R2 Mn/Fe ).
  • the test analysis result of the A/B value can be calculated.
  • Test battery capacity leave the battery for 3 minutes; discharge at 0.33C to the lower cut-off voltage (such as 2.5V); leave for 3 minutes; charge at 0.33C constant current and constant voltage to the upper cut-off voltage (such as 4.4V), and cut off the current at 0.05C; leave for 3 minutes; discharge at 0.33C to the cut-off voltage (this step gets the battery capacity); leave for 3 minutes; calculate the energy value released by the first discharge of the battery. Divide the energy value released by the first discharge of the battery by the mass of the battery to be tested to get the mass energy density of the battery, in watt-hours per kilogram (W ⁇ h/kg).
  • the ionic conductivity of the first positive electrode active material used in Examples 1 to 12, 17 to 21 and Comparative Examples 1-3, 5-7 and 9 is in the range of 1 ⁇ 10 -3 S/cm to 3 ⁇ 10 -3 S/cm
  • the ionic conductivity of the first positive electrode active material used in Example 13 is in the range of 3 ⁇ 10 -3 S/cm to 5 ⁇ 10 -3 S/cm
  • the ionic conductivity of the first positive electrode active material used in Example 14 is in the range of 5 ⁇ 10 -3 S/cm to 7 ⁇ 10 -3 S/cm
  • the ionic conductivity of the first positive electrode active material used in Example 15 is in the range of 7 ⁇ 10 -3 S/cm to 9 ⁇ 10 -3 S/cm
  • the ionic conductivity of the first positive electrode active material used in Example 16 and Comparative Example 8 is in the range of 3.2 ⁇ 10 -6 S/cm to 1 ⁇ 10
  • the ionic conductivity of the second positive electrode active material used in Examples 1-17, 20-21 and Comparative Examples 1-2 and 4-9 is in the range of 3 ⁇ 10 -13 S/cm to 9 ⁇ 10 -13 S/cm
  • the ionic conductivity of the second positive electrode active material used in Examples 18-19 is in the range of 1 ⁇ 10 -13 S/cm to 3 ⁇ 10 -13 S/cm.
  • the ⁇ 2 of Examples 1-17 and 20-21 are greater than the ⁇ 2 of Examples 18-19.
  • the ionic conductivity ( ⁇ 1 ) of the first positive electrode active material at 25° C. all satisfies ⁇ 1 ⁇ 3.2 ⁇ 10 -6 S/cm. Most of them satisfy ⁇ 1 ⁇ 1.7 ⁇ 10 -3 S/cm.
  • the ionic conductivity ( ⁇ 2 ) of the second positive electrode active material at 25°C satisfies ⁇ 2 ⁇ 10 -9 S/cm, and also satisfies ⁇ 2 ⁇ 10 -12 S/cm, and most of them satisfy ⁇ 2 ⁇ 8 ⁇ 10 -13 S/cm.
  • the ratio (X ⁇ ) of the ionic conductivity of the first positive electrode active material at 25°C to the ionic conductivity of the second positive electrode active material at 25°C satisfies X ⁇ 10 4 , and also satisfies X ⁇ 10 6 , and some of them satisfy X ⁇ 10 10 .
  • the A value calculated based on the test analysis results of the B value and the element analysis results of the positive electrode active material in the positive electrode plate is basically consistent with the target values of A and B in Table 1.
  • the battery mass energy densities of Examples 1-4, 9-12, 17, 20-21 and Comparative Examples 1, 2, 5, 7, and 9 are all in the range of 235W ⁇ h/kg to 255W ⁇ h/kg
  • the battery mass energy densities of Examples 13-15 are all in the range of 240W ⁇ h/kg to 270W ⁇ h/kg
  • the battery energy densities of Examples 5 to 8 are between the battery energy densities of Examples 1-4 and the battery energy densities of Examples 13 to 16
  • the battery mass energy densities of Example 16 and Comparative Examples 3, 6, and 8 are all in the range of 235W ⁇ h/kg to 265W ⁇ h/kg
  • the battery mass energy densities of Examples 18-19 are all in the range of 220W ⁇ h/kg to 245W ⁇ h/kg
  • the battery mass energy density of Comparative Example 4 is in the range of 220W ⁇ h/kg to 230W ⁇ h/kg.
  • the secondary batteries prepared in Examples 1 to 21 all have good thermal stability, high thermal runaway temperature, good energy density, and good comprehensive electrical performance.
  • the comprehensive performance of Comparative Documents 1 to 9 is significantly worse: the thermal runaway temperature of some comparative examples is significantly reduced, and the battery energy density does not change much or even decreases, such as Comparative Examples 1, 2, 5, 7 and 9 relative to Example 1, and Comparative Example 6 relative to Example 8, and Comparative Example 8 relative to Example 16; some comparative examples (such as Comparative Example 3) have improved battery energy density relative to some embodiments, but the thermal runaway temperature is significantly reduced, and the comprehensive performance is not good; some comparative examples (such as Comparative Example 4) achieve some improvement in thermal stability at the expense of significantly sacrificing battery energy density, and the comprehensive performance is not good.
  • Comparative Examples 1, 2, 7 and 9 are between 0.47 and 202, the thermal runaway temperatures of Comparative Examples 1, 2, 7 and 9 are significantly reduced relative to the embodiments (such as Embodiments 1-4, etc.) having A/B values within the range of 0.47 to 202.
  • Comparative Example 3 uses only a single type of first positive electrode active material. Compared with Examples 1-4, although the battery energy density of Comparative Example 3 is improved, its thermal runaway temperature is significantly reduced, and the overall performance is inferior to that of Examples 1-4.
  • Comparative Example 4 uses only a single type of second positive electrode active material. Although the thermal runaway temperature is relatively high, the battery energy density is very low (220W ⁇ h/kg ⁇ 230W ⁇ h/kg), which is significantly lower than the battery energy density of Examples 1-4 (235W ⁇ h/kg ⁇ 255W ⁇ h/kg), and the overall performance is inferior to that of Examples 1-4.
  • Comparative Example 5 does not add the first cation, and the thermal runaway temperature is significantly worse than that of each embodiment (such as Embodiment 1) in which the first cation is added.
  • the A/B values of Comparative Examples 6 and 8 are outside the range of 0.47 to 202, and the thermal runaway temperature is relatively low. Specifically, the thermal runaway temperature of Comparative Example 6 is significantly lower than that of Example 8 using the same negative electrode active material; and the thermal runaway temperature of Comparative Example 8 is significantly lower than that of Example 16 using the same negative electrode active material.

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Abstract

本申请提供了一种电池单体。该电池单体包括正极极片和电解液；在正极极片的正极活性材料层中，第一正极活性物质中的Co元素与第二正极活性物质中的Fe元素的质量比为A；电解液中的第一阳离子盐包括离子半径大于锂离子的第一阳离子；第一阳离子盐在电解质盐中的质量百分比为B；0.47≤A/B≤202。

Description

电池单体、二次电池和用电装置
相关申请
本申请要求于2023年11月30日提交的、申请号为CN2023116403270、名称为“电池单体、二次电池和用电装置”的中国专利申请的优先权，在此将其全文引入作为参考。
技术领域
本申请涉及二次电池技术领域，特别涉及一种电池单体、二次电池和用电装置。
背景技术
这里的陈述仅提供与本申请有关的背景信息，而不必然构成现有技术。
随着二次电池的应用范围越来越广泛，以锂离子电池为代表的二次电池被广泛应用于水力、火力、风力和太阳能电站等储能电源系统，还被广泛应用于智能手机、平板电脑、智能穿戴、电动工具、电动自行车、电动摩托车、电动汽车、军事装备、航空航天等多个领域。随着应用的拓宽与发展，对电池的电性能提出了更高要求，但与此同时，可能带来热失控等风险，导致电池的热稳定性不佳。
基于此，有必要开发电性能好且热稳定性好的二次电池新技术。
发明内容
根据本申请的各种实施方式和各种实施例，本申请提供了一种电池单体、二次电池和用电装置。该电池单体具有较佳的电性能，且热稳定性好，热失控风险低。
在本申请的第一方面，提供了一种电池单体，其包括正极极片和电解液；在正极极片的正极活性材料层中，第一正极活性物质中的Co元素与第二正极活性物质中的Fe元素的质量比为A；电解液中的第一阳离子盐包括离子半径大于锂离子的第一阳离子；第一阳离子盐在电解质盐中的质量百分比为B；0.47≤A/B≤202。
在一些实施方式中，提供了一种电池单体，其包括正极极片、负极极片、隔离膜和电解液，所述隔离膜设置于所述正极极片和所述负极极片之间，所述正极极片包括正极活性材料层，所述正极活性材料层包括第一正极活性物质和第二正极活性物质，所述电解液包括电解质盐，所述电解质盐包括第一阳离子盐和电解质锂盐；
其中，所述第一正极活性物质为包含Co元素和M1元素的锂氧化物，所述第二正极活性物质为包含Fe元素和Mn元素的锂氧化物，其中，所述第一正极活性物质中的M1元素包括Mn元素和Al元素中的一种或两种；
所述第一正极活性物质中的Co元素与所述第二正极活性物质中的Fe元素的质量比记为A；
所述第一阳离子盐包括第一阳离子，所述第一阳离子的离子半径大于锂离子的离子半径；所述第一阳离子盐在所述电解质盐中的质量百分比记为B；
则A和B满足0.47≤A/B≤202。
可以理解，在正极极片包括第一正极活性物质和第二正极活性物质的情况下，该电池单体中的活性离子包括锂离子。
该电池单体中的正极极片是复合正极极片，其中设置有不同的正极活性物质，该复合正极极片包括含钴(Co)元素和M1元素的第一正极活性物质，M1元素包括锰(Mn)元素和铝(Al)元素中的一种或两种，还包括含铁(Fe)元素和Mn元素的第二正极活性物质。虽然理论上利用该复合正极极片设计可以使不同的正极活性物质优势互补，希望能够在例如材料结构稳定性、电池安全性、倍率性能、循环性能等方面的综合电性能获得提升，并可兼顾电压平台和制造成本。然而，包含Co元素和M1元素的锂氧化物与包含Fe元素和Mn元素的锂氧化物是不同的正极活性物质，会具有不同的活性及离子电导率，从而导致在充放电循环过程中的被利用程度不同，其中，包含Co元素和M1元素的锂氧化物容易被过度利用，引发第一正极活性物质的表层结构损坏而释放氧气，甚至可能导致材料结构坍塌，存在电池热失控风险；此外，释放的氧气还可能引发电解液副反应。该复合正极极片设计中的活性离子扩散推测是一维通道扩散，通过引入第一阳离子盐而引入离子半径大于锂(Li)离子的第一阳离子，该第一阳离子可以代替部分活性离子嵌入到第一正极活性物质中，阻挡第一正极活性物质中的活性离子扩散通道，降低第一正极活性物质的被利用度，可减少氧气释放，第一阳离子还可起到支撑第一正极活性物质的表层结构的作用，可阻碍活性离子在放电过程中脱除，进一步增加正极活性物质表层氧的稳定性，减少氧气的释放，第一阳离子可提高复合正极极片及电池单体的热稳定性，降低热失控风险。进一步地，通过调节第一正极活性物质中的Co元素与第二正极活性物质中的Fe元素的质量比A(也可记为ICo/IIFe比)，可以调节第一正极活性物质与第二正极活性物质之间的含量比例，进一步利用A/B值协同调节电解液中第 一阳离子盐相对于电解质盐的质量百分比B，可以使第一阳离子在电解液中的浓度能够较佳地匹配第一正极活性物质对适当降低被利用度的需求，从而整体上实现较佳的综合电性能，可以显著提升复合正极极片与电池单体的热稳定性，降低热失控风险，还有利于复合正极极片整体上具有良好的活性离子传输性能。可见，该电池单体具有较佳的综合性能，热稳定性好，热失控风险低。
基于本申请中任意合适的实施方式，在一些实施方式中，在25℃条件下，所述第一正极活性物质的离子电导率与所述第二正极活性物质的离子电导率的比值记为Xσ，则Xσ≥104；
可选地，Xσ≥106，进一步可选地Xσ≥1010；
可选地，所述第一正极活性物质在25℃时的离子电导率为σ1，满足σ1≥3.2×10-6S/cm，进一步可选地σ1≥1.7×10-3S/cm；
可选地，所述第二正极活性物质在25℃时的离子电导率为σ2，满足σ2≤10-9S/cm，进一步可选地σ2≤10-12S/cm。
当第一正极活性物质与第二正极活性物质的离子电导率相差较大时，第一正极活性物质被过度利用度的几率显著变大，此时，通过调节A/B值平衡第一正极活性物质对适当降低被利用度的需求与活性离子在复合正极极片中的良好传输等方面的综合需求时，对正极极片热稳定性以及电池单体整体综合性能的提升作用更为显著。
可以通过调节第一正极活性物质中的镍(Ni)元素含量来调节第一正极活性物质(包含Co元素和M1元素的锂氧化物)的离子电导率。通常地，Ni含量越高，则第一正极活性物质的离子电导率越高。
可以通过调节锰(Mn)元素含量来调节第二正极活性物质(包含Fe元素和Mn元素的锂氧化物)的离子电导率。通常地，Mn元素含量越高，则第二正极活性物质的离子电导率越低。
基于本申请中任意合适的实施方式，在一些实施方式中，1.3≤A/B≤25.4。
通过将A/B值调节在更为合适的范围内，更有利于在有效地改善电池综合性能的同时实现较佳的热稳定性。
基于本申请中任意合适的实施方式，在一些实施方式中，0.19≤A≤10.1；可选地，0.28≤A≤2.53。
通过调节A值可以调节第一正极活性物质与第二正极活性物质之间的含量比例。通过将A值调控在上述范围内，更有利于发挥第一正极活性物质与第二正极活性物质的综合优势，实现更佳的电性能。
基于本申请中任意合适的实施方式，在一些实施方式中，5％≤B≤40％；可选地，10％≤B≤20％。
通过调节B值可以调节第一阳离子盐相对于电解质盐的质量百分比。通过将B值调控在上述范围内，可以使第一阳离子在电解液中的浓度更佳地匹配第一正极活性物质对适当降低被利用度的需求，从而整体上实现更佳的电池综合性能。
基于本申请中任意合适的实施方式，在一些实施方式中，所述第一正极活性物质满足如下特征中的一项或多项：
Co元素相对于Li元素的原子摩尔比记为Rc，则Rc满足0.05≤Rc≤0.5，可选地，0.05≤Rc≤0.3，可选地，0.05≤Rc≤0.2；
所述M1元素相对于Li元素的原子摩尔比记为Rd，则Rd满足0.05≤Rd≤0.5，可选地，0.05≤Rd≤0.3；
所述M1元素包括Mn元素，Mn元素相对于Li元素的原子摩尔比记为Rd-Mn，则Rd-Mn满足0.05≤Rd-Mn≤0.4，进一步可选地，0.05≤Rd-Mn≤0.3；
Co元素与所述M1元素的原子摩尔当量之和相对于Li元素的原子摩尔当量的比值记为Rc+d，则Rc+d满足0.1≤Rc+d≤0.5，进一步可选地，0.1≤Rc+d≤0.3，更进一步可选地，0.1≤Rc+d≤0.2。
Co元素的存在有利于提升材料的结构稳定性，通过调节第一正极活性物质中的Co元素含量在更为合适的范围内，更有利于提升电池的充放电倍率性能和循环性能。
通过调节第一正极活性物质中M1元素的含量，可以调节第一正极活性物质的热稳定性。例如，当M1元素包括Mn元素时，Mn元素有利于提高第一正极活性物质的热稳定性；当M1元素包括Al元素时，Al元素有利于提升容量和材料热稳定性，有利于降低内阻而改善倍率性能和循环性能。
可以根据需要调节Co元素与M1元素的含量比例，平衡Co元素与M1元素对电池性能的综合影响。
基于本申请中任意合适的实施方式，在一些实施方式中，所述第一正极活性物质还包含Ni元素；在所述第一正极活性物质中，Ni元素相对于Li元素的原子摩尔比记为Rb，则Rb满足0.5≤Rb<1；
可选地，0.5≤Rb≤0.9；
进一步可选地，0.6≤Rb≤0.9；
更进一步可选地，0.65≤Rb≤0.9；
更进一步可选地，0.8≤Rb≤0.9。
当第一正极活性物质包含Ni元素时，有利于赋予第一正极活性物质较高的能量密度和较高的离子电导率。镍(Ni)含量越高，复合正极极片的能量密度越高，也越有利提高离子电导率；不过，在第一正极活性物质被高度利用的情况下，第一正极活性物质的表层结构发生损坏甚至结构坍塌的风险越大。此时，通过引入第一阳离子并调控A/B值，对复合正极极片的热稳定性提升作用越显著。
在第一正极活性物质含有Ni元素的情况下，通过引入第一阳离子并调控A/B值，可以使第一阳离子在电解液中的浓度能够较佳地匹配第一正极活性物质对适当降低被利用度的需求，可以在整体上实现电池综合性能的较佳匹配，实现较高的能量密度，可以显著提升复合正极极片与电池单体的热稳定性，降低热失控风险，还有利于复合正极极片整体上具有良好的活性离子传输性能。
基于本申请中任意合适的实施方式，在一些实施方式中，以Li元素的原子摩尔当量Qa为0.75～1.2计，可选地以0.8～1.1计，进一步可选地以0.9～1.05计，更进一步可选地以1计，所述第一正极活性物质满足如下特征中的一项或多项：
Co元素的原子摩尔当量Qc≤0.4，可选地，Qc≤0.3，进一步可选地，Qc≤0.2；
所述M1元素的原子摩尔当量Qd≤0.5，可选地，Qd≤0.4，进一步可选地，Qd≤0.3；
所述M1元素包括Mn元素，Mn元素的原子摩尔当量≤0.4，可选地，Mn元素的原子摩尔当量≤0.3；
Co元素和所述M1元素的原子摩尔当量之和Qc+d≤0.5，可选地，Qc+d≤0.4，Qc+d≤0.3，Qc+d≤0.2。
基于本申请中任意合适的实施方式，在一些实施方式中，以Li元素的原子摩尔当量Qa为0.75～1.2计，可选地以0.8～1.1计，进一步可选地以0.9～1.05计，更进一步可选地以1计，所述第一正极活性物质包含Ni元素，Ni元素的原子摩尔当量Qb满足0.5≤Qb<1，可选地，0.6≤Qb<1，进一步可选地，0.65≤Qb<1。
在第一正极活性物质中的Li元素具有一定的原子摩尔当量的情况下，可以通过调节Co元素、M1元素及Ni元素的原子摩尔当量实现对相应元素含量的调节。
基于本申请中任意合适的实施方式，在一些实施方式中，所述第一正极活性物质包括第一本体，还包括或不包括位于所述第一本体的至少一部分表面的第一包覆层；其中，所述第一本体的化学组成为LiaNibCocM1dM2eOfRg，其中，0.75≤a≤1.2，0<b<1，0<c<1，0<d<1，0≤e≤0.2，b+c+d+e＝1，1≤f≤2.5，0≤g≤1，f+g≤3，所述第一正极活性物质中的M2元素包括Zr、Zn、Cu、Cr、Mg、Fe、V、Ti、Sr、Sb、Y、W和Nb中的一种或多种，所述第一正极活性物质中的R元素包括N、F、S和Cl中的一种或多种；
可选地，0.8≤a≤1.2，进一步可选地，0.9≤a≤1.1，进一步可选地，0.95≤a≤1.05；
可选地，0.5≤b<1，进一步可选地，0.5≤b≤0.9，更进一步可选地，0.6≤b≤0.9；
可选地，0.05≤c<1，进一步可选地，0.05≤c≤0.5，更进一步可选地，0.05≤c≤0.3；
可选地，0.05≤d<1，进一步可选地，0.05≤d≤0.5，更进一步可选地，0.05≤d≤0.3；
可选地，0≤e<0.1，进一步可选地，0≤e≤0.05，更进一步可选地，0≤e≤0.03；
可选地，1≤f≤2.1，进一步可选地，1.8≤f≤2.05，更进一步可选地，1.95≤f≤2.05；
可选地，0≤g<0.5，进一步可选地，0≤g≤0.1，更进一步可选地，0≤g≤0.05。
基于本申请中任意合适的实施方式，在一些实施方式中，所述第二正极活性物质满足如下特征中的一项或多项：
Mn元素和Fe元素的原子摩尔比为0.42～9，可选地，Mn元素和Fe元素的原子摩尔比为0.66～4；
以Li元素的原子摩尔当量为0.9～1.1计，可选地以0.9～1.05计，进一步可选地以1计，Mn元素的原子摩尔当量为0.5～0.999，可选地，Mn元素的原子摩尔当量为0.5～0.6；
以Li元素的原子摩尔当量为0.9～1.1计，可选地以0.9～1.05计，进一步可选地以1计，Fe元素的原子摩尔当量为0.001～0.5，可选地，Fe元素的原子摩尔当量为0.4～0.5。
提高第二正极活性物质中的Mn元素含量有利于改善第二正极活性物质的能量密度、电压平台及材料成本。通过将Mn元素控制在上述范围内，有利于在发挥Mn元素作用的同时有利于形成均一的固溶体，还可尽量减少或避免缺陷和孔隙，从而减少或避免缺陷和孔隙延长活性离子的嵌入迁出路径，因此，通过将Mn元素控制在上述范围内，有利于使第二活性物质具有良好的离 子迁移速率，缩短第二正极活性物质与第一正极活性物质中活性离子电导率的差距，从而降低第一正极活性物质被过度利用及脱锂的几率，有利于进一步提高复合正极极片的热稳定性。
在第二正极活性物质中，Fe元素的引入有利于实现更好的离子传输性和更高的离子电导率，还有利促进活性离子的嵌入和脱出，提高电池充放电效率和能量密度。
在第二正极活性物质中的Li元素具有一定的原子摩尔当量的情况下，通过调节Fe元素、Mn元素的原子摩尔当量可以实现对相应元素含量的调节。
基于本申请中任意合适的实施方式，在一些实施方式中，所述第二活性物质包括第二本体，还包括或不包括位于所述第二本体表面至少一部分的第二包覆层；其中，所述第二本体的化学式为Li1+xMn1-y-wFewM3yP1-zQzO4，其中，-0.1≤x≤0.1，0.1≤w≤0.5，0.001≤y≤0.5，0.001≤z≤0.1，所述第二活性物质中的M3元素包括Zn、Al、Na、K、Mg、Mo、W、Ti、V、Zr、Ni、Co、Ga、Sn、Sb、Nb和Ge中的一种或多种元素，所述第二活性物质中的Q元素包括B、Si、N、S、F、Cl和Br中的一种或多种元素；
可选地，0.1≤y≤0.5，进一步可选地，0.2≤y<0.5，更进一步可选地，0.3≤y<0.5；
可选地，0.2≤w≤0.5，进一步可选地，0.3≤w<0.5，更进一步可选地，0.4≤w<0.5；
可选地，0.001≤z≤0.1，进一步可选地，0.001≤z<0.05，更进一步可选地，0.001≤z<0.002；
可选地，所述第二活性物质中的M3元素包括Ti、V、Ni、Co和Mg中一种或多种元素；
可选地，所述第二活性物质中的Q元素包括B、Si、N和S中的一种元素；
可选地，所述第二包覆层包括焦磷酸盐、磷酸盐和碳中的一种或多种；
可选地，所述第二包覆层为单层结构或多层结构。
基于本申请中任意合适的实施方式，在一些实施方式中，所述第一正极活性物质和所述第二正极活性物质在所述正极活性材料层中的总质量占比RI+II≥85％；
可选地，RI+II≥90％；进一步可选地，RI+II≥95％。
通过调节第一正极活性物质和第二正极活性物质在正极活性材料层中的总质量占比RI+II在上述范围内，更有利于促进两种正极活性物质综合优势的发挥。
基于本申请中任意合适的实施方式，在一些实施方式中，所述第一阳离子包括碱金属元素和碱土金属元素中的一种或多种元素的阳离子；
可选地，所述第一阳离子包括钠离子、钾离子、钙离子和镁离子中的一种或多种；
可选地，所述第一阳离子盐中的阴离子包括六氟磷酸根离子、高氯酸根离子、四氟硼酸根离子、双三氟甲基磺酰亚胺根离子、三氟甲磺酸根离子、双氟磺酰基酰亚胺根离子和三(三氟甲基磺酰)甲基离子中的一种或多种；
进一步可选地，所述第一阳离子盐包括六氟磷酸钠、高氯酸钠、四氟硼酸钠、双三氟甲基磺酰亚胺钠、三氟甲磺酸钠、双氟磺酰基酰亚胺钠、三(三氟甲基磺酰)甲基钠、六氟磷酸钾、高氯酸钾、四氟硼酸钾、双三氟甲基磺酰亚胺钾、三氟甲磺酸钾、双氟磺酰基酰亚胺钾和三(三氟甲基磺酰)甲基钾中的一种或多种；
更进一步可选地，所述第一阳离子盐包括六氟磷酸钠、四氟硼酸钠和高氯酸钠中的一种或两种。
在第一阳离子的离子半径大于锂离子的情况下，第一阳离子的种类及相应的阴离子可以具有灵活的选择范围。作为非限制性示例，例如六氟磷酸钠成本低，可大规模使用；钠离子与锂离子半径差异较小，更有利于嵌入活性物质。
基于本申请中任意合适的实施方式，在一些实施方式中，所述负极极片包括负极活性材料层，所述负极活性材料层包括负极活性物质，所述负极活性物质包括硅基材料；所述硅基材料在所述负极活性物质中所占的质量百分比记为X1，
可选地，X1≥3％，进一步可选为3％≤X1≤50％；
可选地，所述硅基材料包括单质硅、硅氧化物、硅碳复合物、硅氮复合物、硅合金、硅石墨烯复合材料、硅碳纳米管和含硅导电聚合物中的一种或多种。
当负极极片的负极活性材料层包括硅基材料时，有利于进一步提升电池单体的能量密度。
在本申请的第二方面，提供一种二次电池，其包括本申请第一方面所述电池单体。
在一些实施方式中，所述二次电池为锂离子二次电池。
在本申请的第三方面，提供一种用电装置，其包括本申请第一方面所述电池单体和本申请第二方面所述二次电池中的至少一种。
本申请的一个或多个实施方式的细节在下面的附图和描述中提出。本申请的其他特征、目的和优点将从说明书、附图以及权利要求书变得明显。
附图说明
为了更好地描述和说明这里公开的那些申请的实施方式、实施例或示例，可以参考一幅或多幅附图。用于描述附图的附加细节或示例不应当被认为是对所公开的申请、目前描述的实施方式、实施例或示例以及目前理解的这些申请的最佳模式中的任何一者的范围的限制。而且在全部附图中，用相同的附图标号表示相同的部件。在附图中：
图1为本申请一实施方式的电池单体的示意图。
图2为图1所示的本申请一实施方式的电池单体的分解图。
图3为本申请一实施方式的电池模块的示意图。
图4为本申请一实施方式的电池包的示意图。
图5为图4所示的本申请一实施方式的电池包的分解图。
图6为本申请一实施方式的二次电池用作电源的用电装置的示意图。
附图标记说明：
1为电池包；2为上箱体；3为下箱体；4为电池模块；5为电池单体；51为壳体；52为电极组件；53为盖板；6为用电装置。
具体实施方式
以下，适当地参照附图详细描述了本申请的电池单体、二次电池和用电装置的一些实施方式和一些实施例。但是会有省略非必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”可以采用下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，任一个端值可以独立地被包括或不被包括，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出了最小范围值1和2，且如果还列出了最大范围值3、4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。比如，当表述某个参数为选自“2-10”的整数，相当于列出了整数2、3、4、5、6、7、8、9和10。
在本申请中，涉及“多个”、“多种”、“多项”、“若干”等，如无特别限定，指在数量上大于2或等于2。例如，“一种或多种”表示一种或大于等于(≥，大于或等于)两种。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
在本文中提及“实施例”意味着，结合实施例描述的特定特征、结构或特性可以包含在本申请的至少一个实施例或实施方式中。在说明书中的各个位置出现该短语并不一定均是指相同的实施例，也不是与其它实施例互斥的独立的或备选的实施例。本领域技术人员显式地和隐式地理解的是，本文所描述的实施例可以与其它实施例相结合。在本文中提及的“实施方式”具有类似理解。
本领域技术人员可以理解，在各实施方式或实施例的方法中，各步骤的撰写顺序并不意味着严格的执行顺序而对实施过程构成任何限定，各步骤的详细执行顺序应当以其功能和可能的内在逻辑确定。如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，可以优选是顺序进行的。例如，方法M包括步骤(a)和(b)，表示方法M可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，方法M还可包括步骤(c)，表示步骤(c)可以任意顺序加入到方法M，例如，方法M可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
在本申请中，以“含有”、“包含”、“包括”等词语描述的开放式技术特征或技术方案中，如无其他说明，不排除所列成员之外的额外成员，可视为既提供了由所列成员构成的封闭式特征或方案，还提供了在所列成员之外还包括额外成员的开放式特征或方案。例如，A包括a1、a2和a3，如无其他说明，可以还包括其他成员，也可以不包括额外成员，可视为既提供了“A由a1、a2和a3组成”或“A选自a1、a2和a3”的特征或方案，还提供了“A不仅包括a1、a2和a3， 还包括其他成员”的特征或方案。
在本申请中，如无其他说明，A(如B)，表示B为A中的一种非限制性示例，可以理解A不限于为B。
在本申请中，“可选地”、“可选的”、“可选”，指可有可无，也即指选自“有”或“无”两种并列方案中的任一种。如果一个技术方案中出现多处“可选”，如无特别说明，且无矛盾之处或相互制约关系，则每项“可选”各自独立。如无其他说明，本申请中“可选地包括”、“可选地包含”等描述，以“可选地包括”为例，表示“可以包括或不包括”。
在本申请中，如无其他说明，“和/或”对应的特征或方案包括两个或两个以上相关所列项目中任一个项目，也包括相关所列项目的任意的和所有的组合，所述任意的和所有的组合包括任意的两个相关所列项目、任意的更多个相关所列项目、或者全部相关所列项目的组合。例如，“A和/或B”表示A、B以及“A与B的组合”构成的组。其中，“包含A和/或B”可以表示“包含A，包含B，以及包含A与B”，还可以表示“包含A，包含B，或者包含A与B”，可根据所在语句恰当理解。
本文中所使用的“其组合”、“其任意组合”、“其任意组合方式”等中包括所列项目中任两个或任两个以上项目的所有合适的组合方式。
本文中，“合适的组合方式”、“合适的方式”、“任意合适的方式”等中所述“合适”，以能够实施本申请的技术方案为准。
本文中，“优选”、“更好”、“更佳”、“为宜”、“较好”、“较佳”仅为描述效果更好的实施方式或实施例，应当理解，并不构成对本申请保护范围的限制。如果一个技术方案中出现多处“优选”，如无特别说明，且无矛盾之处或相互制约关系，则每项“优选”各自独立。
本申请中，“进一步”、“更进一步”、“特别”、“例如”、“如”、“示例”、“举例”等用于描述目的，表示内容上的差异，但并不应理解为对本申请保护范围的限制。
本申请中，“第一方面”、“第二方面”、“第三方面”等中，术语“第一”、“第二”、“第三”等仅用于描述目的，不能理解为指示或暗示相对重要性或数量，也不能理解为隐含指明所指示的技术特征的重要性或数量。而且“第一”、“第二”、“第三”等仅起到非穷举式的列举描述目的，应当理解并不构成对数量的封闭式限定。
本申请中，术语“室温”一般指4℃～35℃，可以指20℃±5℃。在本申请的一些实施例中，室温是指20℃～30℃。
在本申请中，涉及数据范围的单位，如果仅在右端点后带有单位，则表示左端点和右端点的单位是相同的。比如，3～5h或3-5h均表示左端点“3”和右端点“5”的单位都是h(小时)，均与3h～5h具有相同含义。此外，温度、尺寸等其他参数的类似描述也进行相同方式的理解。
在本申请中，如无特别限定，涉及“约数”，涵盖本数及基于本数的合理波动范围内的近似值，合理波动范围可因本数的类型和数值大小有所差异。
本申请实施方式或实施例中所提到的相关成分的重量不仅可以指代各组分的含量，也可以表示各组分间重量的比例关系，因此，只要是按照本申请实施方式或实施例相关组分的含量按比例放大或缩小均在本申请所描述的范围之内。进一步地，本申请实施方式或实施例中涉及的质量可以是微克(μg)、毫克(mg)、克(g)、千克(kg)等化工领域公知的质量单位。如无其他说明，质量比等于相应的重量比，比如物质A的质量为m1，重量为W1，物质B的质量为m2，重量为W2，则二者的质量比m1/m2在数值上等于相应的重量比W1/W2。
在本申请中，如无其他说明，wt％表示以重量计的重量百分比，在数值上与以质量计的相应的质量百分比相等。
在本申请中，“大于等于”、“大于或等于”和“≥”具有相同含义，可互换使用；“小于等于”、“小于或等于”和“≤”具有相同含义，可互换使用；“大于”可等价地表示为“>”，“小于”可等价地表示为“<”。在本申请中，如无其他说明，“大于或等于”与“≥”可视为还提供了“大于”与“等于”两种方案。在本申请中，如无其他说明，“小于或等于”与“≤”可视为还提供了“小于”与“等于”两种方案。
在本申请中，涉及参数单位，如无其他说明，温度单位℃表示“摄氏度”，时间单位min表示“分钟”，长度单位μm表示“微米”，粘度单位mPa·S表示“毫帕·秒”，面密度单位mg/cm2表示“毫克每平方厘米”，体积密度单位g/cm3均表示“克每立方厘米”，物质的量单位mol表示“摩尔”，摩尔浓度单位mol/L均表示“摩尔每升”，电导率单位S/cm表示“西门子每厘米”。
在本申请中，涉及“在一些实施方式(或实施例)中”、“在一个实施方式(或实施例)中”等示例性描述，可以涵盖但不限于如下含义：这些方案可以与其他方案以合适的方式相互组合形 成新的技术方案。
在本申请中，涉及“基于本申请中任意合适的实施方式，在一些实施方式中，”或与其类似的示例性描述，可以涵盖但不限于如下含义：这些方案可以以合适的方式相互组合形成新的技术方案。
为了提高电池的综合电性能，可以考虑在正极极片的正极活性材料层中设置不同的正极活性物质，比如，理论上可以设置至少两种正极活性物质以期望实现不同正极活性物质的优势互补；非限制性地，例如，将具有高能量密度的正极活性物质与具有较佳电压平台及较低制造成本的正极活性物质组合使用时，会期望相应的正极极片可以兼具较高的能量密度、较佳的电压平台和较低的制造成本。然而，性质不同的正极活性物质往往具有不同的活性及离子电导率，这就导致在充放电循环情况下，不同的正极活性物质的利用程度不同。如果不同的正极活性物质的离子电导率相差过大，就会导致其中一种正极活性物质被过度利用，容易引发该正极活性物质的表层结构损坏而释放氧气，甚至可能导致材料结构坍塌，存在电池热失控风险；此外，释放的氧气还可能引发电解液副反应。
本申请至少提供了一种电池单体、二次电池和用电装置。
在一些实施方式中，该电池单体包括正极极片、负极极片、隔离膜和电解液，正极极片中的正极活性材料层包括第一正极活性物质和第二正极活性物质，电解液中的电解质盐包括第一阳离子盐；第一正极活性物质为包含Co元素和M1元素的锂氧化物，其中的M1元素包括Mn元素和Al元素中的一种或两种；第二正极活性物质为包含Fe元素和Mn元素的锂氧化物；第一正极活性物质中的Co元素与第二正极活性物质中的Fe元素的质量比为A；第一阳离子盐包括离子半径大于锂离子的第一阳离子；第一阳离子盐在电解质盐中的质量百分比为B；0.47≤A/B≤202。该电池单体具有较佳的电性能且热稳定性好，热失控风险低。
在本申请中，如无其他说明，“电池单体”指能够实现化学能和电能相互转化的基本单元。通常情况下，电池单体包括正极极片、负极极片、电解质和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
在本申请中，如无其他说明，电极极片可以为正极极片或负极极片，电极极片中的“活性物质”指能够可逆地嵌入与脱出活性离子能力的物质。如无其他说明，“负极活性物质”指用于负极极片的、能够可逆地嵌入与脱出活性离子能力的物质；“正极活性物质”指用于正极极片的、能够可逆地脱出与嵌入活性离子能力的物质。二次电池充电时，活性离子从正极脱出，经过电解质嵌入负极；而二次电池放电时，活性离子则从负极脱出，嵌入正极。活性离子没有特别限定，非限制性，活性离子可以为锂离子，此时对应锂离子二次电池。
在本申请中，“电极活性材料”、“电极活性物质”、“活性材料”和“活性物质”，具有相同含义，可以互换使用；“正极活性物质”与“正极活性材料”具有相同含义，可以互换使用；“负极活性物质”与“负极活性材料”具有相同含义，可以互换使用。“正极活性物质”与“正极活性材料”具有相同含义，可以互换使用；“负极活性物质”与“负极活性材料”具有相同含义，可以互换使用。
在本申请中，如无特别说明，“电极活性材料层”包括正极极片的正极活性材料层以及负极极片的负极活性材料层中的至少一者，根据详细的情形，电极活性材料层可以指正极活性材料层或负极活性材料层。可以理解，正极活性材料层含有正极活性物质，负极活性材料层含有负极活性物质。在本申请中，“电极活性材料层”也可简记为“活性材料层”。
在本申请的第一方面，提供了一种电池单体，其包括正极极片和电解液；在正极极片的正极活性材料层中，第一正极活性物质中的Co元素与第二正极活性物质中的Fe元素的质量比为A；电解液中的第一阳离子盐包括离子半径大于锂离子的第一阳离子；第一阳离子盐在电解质盐中的质量百分比为B；0.47≤A/B≤202。
在一些实施方式中，提供了一种电池单体，该电池单体包括正极极片和电解液，正极极片包括正极活性材料层，正极活性材料层包括第一正极活性物质和第二正极活性物质，电解液包括电解质盐，电解质盐包括第一阳离子盐；
其中，第一正极活性物质为包含Co元素和M1元素的锂氧化物，第二正极活性物质为包含Fe元素和Mn元素的锂氧化物，其中，第一正极活性物质中的M1元素包括Mn元素和Al元素中的一种或两种；
第一正极活性物质中的Co元素与第二正极活性物质中的Fe元素的质量比记为A；
第一阳离子盐包括第一阳离子，第一阳离子的离子半径大于锂离子的离子半径；第一阳离子盐在电解质盐中的质量百分比记为B；
可选地，0.47≤A/B≤202。
在本申请中，第一正极活性物质和第二正极活性物质为正极活性材料层中的两种不同的正极活性物质。
可以理解，在正极极片包括第一正极活性物质和第二正极活性物质的情况下，该电池单体中的活性离子包括锂离子。
在一些实施方式中，电解质盐包括第一阳离子盐和电解质锂盐。电解质锂盐有利于活性锂离子的传导。
在一些实施方式中，提供了一种电池单体，其包括正极极片、负极极片、隔离膜和电解液，隔离膜设置于正极极片和负极极片之间，正极极片包括正极活性材料层，正极活性材料层包括第一正极活性物质和第二正极活性物质，电解液包括电解质盐，电解质盐包括第一阳离子盐和电解质锂盐；
其中，第一正极活性物质为包含Co元素和M1元素的锂氧化物，第二正极活性物质为包含Fe元素和Mn元素的锂氧化物，其中，第一正极活性物质中的M1元素包括Mn元素和Al元素中的一种或两种；
第一正极活性物质中的Co元素与第二正极活性物质中的Fe元素的质量比记为A；
第一阳离子盐包括第一阳离子，第一阳离子的离子半径大于锂离子的离子半径；第一阳离子盐在电解质盐中的质量百分比记为B；
则A和B满足0.47≤A/B≤202。
该电池单体中的正极极片是复合正极极片，其中设置有不同的正极活性物质，该复合正极极片包括含钴(Co)元素和M1元素的第一正极活性物质，M1元素包括锰(Mn)元素和铝(Al)元素中的一种或两种，还包括含铁(Fe)元素和Mn元素的第二正极活性物质。虽然理论上利用该复合正极极片设计可以使不同的正极活性物质优势互补，希望能够在例如材料结构稳定性、电池安全性、倍率性能、循环性能等方面的综合电性能获得提升，并可兼顾电压平台和制造成本。然而，包含Co元素和M1元素的锂氧化物与包含Fe元素和Mn元素的锂氧化物是不同的正极活性物质，会具有不同的活性及离子电导率，从而导致在充放电循环过程中的被利用程度不同，其中，包含Co元素和M1元素的锂氧化物容易被过度利用，引发第一正极活性物质的表层结构损坏而释放氧气，甚至可能导致材料结构坍塌，存在电池热失控风险；此外，释放的氧气还可能引发电解液副反应。该复合正极极片设计中的活性离子扩散推测是一维通道扩散，通过引入第一阳离子盐而引入离子半径大于锂(Li)离子的第一阳离子，该第一阳离子可以代替部分活性离子嵌入到第一正极活性物质中，阻挡第一正极活性物质中的活性离子扩散通道，降低第一正极活性物质的被利用度，可减少氧气释放，第一阳离子还可起到支撑第一正极活性物质的表层结构的作用，可阻碍活性离子在放电过程中脱除，进一步增加正极活性物质表层氧的稳定性，减少氧气的释放，第一阳离子可提高复合正极极片及电池单体的热稳定性，降低热失控风险。进一步地，通过调节第一正极活性物质中的Co元素与第二正极活性物质中的Fe元素的质量比A(也可记为ICo/IIFe比)，可以调节第一正极活性物质与第二正极活性物质之间的含量比例，进一步利用A/B值协同调节电解液中第一阳离子盐相对于电解质盐的质量百分比B，可以使第一阳离子在电解液中的浓度能够较佳地匹配第一正极活性物质对适当降低被利用度的需求，从而整体上实现较佳的综合电性能，可以显著提升复合正极极片与电池单体的热稳定性，降低热失控风险，还有利于复合正极极片整体上具有良好的活性离子传输性能。可见，该电池单体具有较佳的综合性能，热稳定性好，热失控风险低。
在本申请中，如无其他说明，可以采用本领域已有技术测试电池单体及二次电池中正极极片、负极极片及电解液的元素组成和化学组成，包括但不限于电感耦合等离子体(inductively coupled plasma，ICP)方法。
非限制性地，对于正极极片中的正极活性物质，或负极极片中的负极活性物质，可以采用能谱仪(EDS,Energy Dispersive Spectrometer)、电感耦合等离子体(inductively coupled plasma，ICP)法等方法进行测试分析，可以利用EDS识别不同种类的活性物质，利用ICP进行成分含量的定量测试分析。可以从电极极片中提取活性物质样品，利用包括但不限于溶剂洗涤、超声分散等的方法收集固体颗粒，进而采用电感耦合等离子体发射光谱仪(ICP-OES)对固体颗粒的元素组成进行分析。可以利用EDS测试获得对不同成分进行不同颜色标记的二维图像，根据成分种类及聚集方式可区分出不同的活性物质对应的不同颗粒。例如，可以使用试剂(如硝酸、高氯酸等)消解正极活性材料层，通过电感耦合等离子发射光谱仪测试正极活性物质的化学组成。还例如，可以 使用试剂(如王水、逆王水、王水与氟化氢的组合等)消解负极活性材料层，通过电感耦合等离子发射光谱仪测试负极活性物质的化学组成。
根据正极极片中正极活性物质的化学组成及元素分析结果，可以识别出第一正极活性物质与第二活性物质中各元素的含量，可以计算出第一正极活性物质和第二正极活性物质在正极活性材料层中的总质量占比，还可计算出第一正极活性物质中的Co元素与第二正极活性物质中的Fe元素的质量比(A)，还可以测试出上下文中描述的元素含量关系，如，第一正极活性物质中的Rc、Rd、Rd-Mn、Rc+d、Rb、Qc/Qa、Qd/Qa、Qc+d/Qa、Qb等，还如LiaNibCocM1dM2eOfRg中M1元素和M2元素的组成及各元素下标的数值，还如第二正极活性物质中的Mn元素和Fe元素的原子摩尔当量的比值(可记为R2Mn/Fe)，Li1+xMn1-y-wFewM3yP1-zQzO4中M3元素的组成及各元素下标的数值等等。
根据负极极片中负极活性物质的化学组成及元素分析结果，可以确定负极活性材料层中负极活性物质的组成，可确定是否包含硅基材料，如包含，还可确定硅基材料的种类、组成及其在负极活性物质中所占的质量百分比(可记为X1)。
可以基于GB/T36240-2018和离子色谱仪对电解液中的电解质盐进行定量测试。根据识别出的电解液中的阳离子种类，结合元素的原子序数，可以判断出电解液中是否存在离子半径大于锂离子的第一阳离子，如存在，还可确定存在哪些种类的第一阳离子。根据电解质盐的定量测试分析结果，可以确定电解液中的电解质盐的组成及不同电解质盐的含量。由于电解液中的阳离子和阴离子为游离态，可以迁移，并不局限于电解质盐投料时的阳离子和阴离子配合方式，但电解液体系整体上保持电荷平衡，因此，在本申请中，如无其他说明，第一阳离子盐在电解质盐中的质量百分比(记为B)按照“电解液中第一阳离子的质量相对于电解液中所有阳离子的质量总和的百分比”计。例如，当电解液中的电解质盐所含阳离子为金属阳离子时，则B值数值上可等于“电解液中第一阳离子的质量相对于电解液中金属阳离子的质量的百分比”。再例如，当电解液中的电解质盐所含阳离子由锂离子和第一阳离子组成时，则B值数值上可等于“电解液中第一阳离子的质量相对于第一阳离子和锂离子的质量总和的百分比”。
如无其他说明，通常地，电解质盐中的阳离子为金属阳离子。
在一些实施方式中，提供了一种电池单体，其包括正极极片、负极极片、隔离膜和电解液，隔离膜设置于正极极片和负极极片之间，正极极片包括正极活性材料层，正极活性材料层包括第一正极活性物质和第二正极活性物质，电解液包括电解质盐，电解质盐包括第一阳离子盐和电解质锂盐；电解质盐由阳离子和阴离子组成，电解质盐中的阳离子为金属阳离子；
其中，第一正极活性物质为包含Co元素和M1元素的锂氧化物，第二正极活性物质为包含Fe元素和Mn元素的锂氧化物，其中，第一正极活性物质中的M1元素包括Mn元素和Al元素中的一种或两种；
第一正极活性物质中的Co元素与第二正极活性物质中的Fe元素的质量比记为A；
第一阳离子盐包括第一阳离子，第一阳离子的离子半径大于锂离子的离子半径；第一阳离子的质量相对于电解质盐中各阳离子的质量总和的百分比也可记为B；
此时，A和B满足0.47≤A/B≤202。
在一些实施方式中，该电池单体包括正极极片、负极极片、隔离膜和电解液，正极极片中的正极活性材料层包括第一正极活性物质和第二正极活性物质，电解液中的电解质盐包括金属阳离子，金属阳离子包括第一阳离子；第一正极活性物质为包含Co元素和M1元素的锂氧化物，其中的M1元素包括Mn元素和Al元素中的一种或两种；第二正极活性物质为包含Fe元素和Mn元素的锂氧化物；第一正极活性物质中的Co元素与第二正极活性物质中的Fe元素的质量比为A；第一阳离子的离子半径大于锂离子的离子半径；第一阳离子相对于电解质盐中金属阳离子的质量百分比记为B’；0.47≤A/B’≤202。该电池单体具有较佳的电性能且热稳定性好，热失控风险低。
在一些实施方式中，提供了一种电池单体，其包括正极极片、负极极片、隔离膜和电解液，隔离膜设置于正极极片和负极极片之间，正极极片包括正极活性材料层，正极活性材料层包括第一正极活性物质和第二正极活性物质，电解液包括电解质盐，电解质盐包括金属阳离子和阴离子；金属阳离子包括第一阳离子和锂离子；
其中，第一正极活性物质为包含Co元素和M1元素的锂氧化物，第二正极活性物质为包含Fe元素和Mn元素的锂氧化物，其中，第一正极活性物质中的M1元素包括Mn元素和Al元素中的一种或两种；
第一正极活性物质中的Co元素与第二正极活性物质中的Fe元素的质量比记为A；
第一阳离子的离子半径大于锂离子的离子半径；
第一阳离子相对于电解质盐中金属阳离子的质量百分比记为B’；
则A和B满足0.47≤A/B’≤202。
在本申请中，B’的取值及其取值范围和A/B’取值及其取值范围可分别参考B的取值及其取值范围及A/B取值及其取值范围。当电解质盐中的阳离子均为金属阳离子时，B与B’在数值上相同。在一些实施方式中，本申请上下文中对B的取值及取值范围的定义均可适用于B’，本申请上下文中对A/B的取值及取值范围的定义均可适用于A/B’。
基于本申请中任意合适的实施方式，在一些实施方式中，在25℃条件下，第一正极活性物质的离子电导率与第二正极活性物质的离子电导率的比值记为Xσ，则Xσ≥104；可选地，Xσ≥106，进一步可选地Xσ≥1010。非限制性地，Xσ还可以为下述任一种数值、或者大于或等于(≥)下述任一种数值、或者大于(>)下述任一种数值、或者选自下述任两种数值构成的区间(可以采用科学计数法表示)：1×104(相当于1E4)、2×104、4×104、5×104、6×104、8×104、1×105、2×105、4×105、5×105、6×105、8×105、1×106、2×106、4×106、5×106、6×106、8×106、1×107、2×107、4×107、5×107、6×107、8×107、1×108、2×108、4×108、5×108、6×108、8×108、1×109、2×109、4×109、5×109、6×109、8×109、1×1010、2×1010等。
在本申请中，以科学计数法方式描述的数值aEb等价于a×10b。例如，1×104可记为1E4。
在一些实施方式中，第一正极活性物质在25℃时的离子电导率为σ1，满足σ1≥3.2×10-6S/cm，进一步可选地σ1≥1.7×10-3S/cm。非限制性地，第一正极活性物质在25℃时的离子电导率σ1还可以为下述任一种数值、或者大于或等于(≥)下述任一种数值、或者大于(>)下述任一种数值、或者选自下述任两种数值构成的区间(可以采用科学计数法表示)：3.2×10-6S/cm、3.5×10-6S/cm、4×10-6S/cm、5×10-6S/cm、6×10-6S/cm、8×10-6S/cm、1×10-5S/cm、2×10-5S/cm、4×10-5S/cm、5×10-5S/cm、6×10-5S/cm、8×10-5S/cm、1×10-4S/cm、2×10-4S/cm、4×10-4S/cm、5×10-4S/cm、6×10-4S/cm、8×10-4S/cm、1×10-3S/cm、1.5×10-3S/cm、1.7×10-3S/cm、2×10-3S/cm、3×10-3S/cm、3.5×10-3S/cm、4×10-3S/cm、5×10-3S/cm、6×10-3S/cm、7×10-3S/cm、8×10-3S/cm、9×10-3S/cm等。非限制性地，σ1还可以选自下述任一范围：1×10-3S/cm～3×10-3S/cm、3×10-3S/cm～5×10-3S/cm、5×10-3S/cm～7×10-3S/cm、7×10-3S/cm～9×10-3S/cm、3.2×10-6S/cm～1×10-3S/cm、1×10-3S/cm<σ1<3×10-3S/cm、3×10-3S/cm<σ1<5×10-3S/cm、5×10-3S/cm<σ1<7×10-3S/cm、7×10-3S/cm<σ1<9×10-3S/cm、3.2×10-6S/cm<σ1<1×10-3S/cm等。
在一些实施方式中，第二正极活性物质在25℃时的离子电导率为σ2，满足σ2≤10-9S/cm，进一步可选地σ2≤10-12S/cm。非限制性地，第二正极活性物质在25℃时的离子电导率σ2还可以为下述任一种数值、或者小于或等于(≤)下述任一种数值、或者小于下述任一种数值、或者选自下述任两种数值构成的区间(可以采用科学计数法表示)：1×10-9S/cm、8×10-10S/cm、6×10-10S/cm、5×10-10S/cm、4×10-10S/cm、2×10-10S/cm、1×10-10S/cm、8×10-11S/cm、6×10-11S/cm、5×10-11S/cm、4×10-11S/cm、2×10-11S/cm、1×10-11S/cm、8×10-12S/cm、6×10-12S/cm、5×10-12S/cm、4×10-12S/cm、2×10-12S/cm、1×10-12S/cm、9×10-13S/cm、8×10-13S/cm、7×10-13S/cm、6×10-13S/cm、5×10-13S/cm、4×10-13S/cm、3×10-13S/cm、2×10-13S/cm、1×10-13S/cm等。
在本申请中，如无其他说明，“离子电导率”指活性离子为锂离子时的离子电导率。非限制性地，σ2还可以选自下述任一范围：3×10-13S/cm～9×10-13S/cm、1×10-13S/cm～3×10-13S/cm、3×10-13S/cm<σ2<9×10-13S/cm、1×10-13S/cm<σ2<3×10-13S/cm等。
在本申请中，如无其他说明，“离子电导率”指在25℃时的离子电导率。在本申请中，如无其他说明，可以采用如下方法测试正极活性材料层中不同正极活性物质的离子电导率：
将待测正极活性物质制成测试用正极极片，锂片作为负极极片，组装成纽扣电池进行测试；将电池以1C放电至3.0V后进行交流阻抗谱测试，测试参数选取：测试温度为室温(如25℃)，扫描频率为0.1Hz～105Hz，电压振幅为5mV，利用Zview软件对测试结果进行拟合即得到离子电导率。
如无其他说明，测试用正极极片中，正极集流体选取铝箔，正极活性材料层中正极活性物质的质量百分比控制在95％±1％，粘结剂选用聚偏二氟乙烯(PVDF)，导电剂选用导电碳，压实密度为3.0g/cm3～3.6g/cm3。
对于电极极片、电池单体或二次电池中的正极活性物质，可根据成分分析结果制备相同化学组成的正极活性物质，作为待测正极活性物质，以上述方法测试其离子电导率。
当第一正极活性物质与第二正极活性物质的离子电导率相差较大时，第一正极活性物质被过度利用度的几率显著变大，此时，通过调节A/B值平衡第一正极活性物质对适当降低被利用度的 需求与活性离子在复合正极极片中的良好传输等方面的综合需求时，对正极极片热稳定性以及电池单体整体综合性能的提升作用更为显著。
可以通过调节第一正极活性物质中的镍(Ni)元素含量来调节第一正极活性物质(包含Co元素和M1元素的锂氧化物)的离子电导率。通常地，Ni含量越高，则第一正极活性物质的离子电导率越高。
可以通过调节锰(Mn)元素含量来调节第二正极活性物质(包含Fe元素和Mn元素的锂氧化物)的离子电导率。通常地，Mn元素含量越高，则第二正极活性物质的离子电导率越低。
在一些实施方式中，0.47≤A/B≤202。非限制性地，A/B还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.47、0.5、0.6、2/3、0.7、0.75、0.8、0.9、1、1.2、1.25、1.5、1.6、1.75、1.8、2、2.5、3、3.5、4、5、6、7、8、9、9.9、10、12、12.5、15、16、18、20、25、30、35、40、45、50、55、60、70、75、80、90、95、96、98、99、100、110、120、125、130、140、150、160、175、180、190、192、194、195、196、198、199、200、201、202等。
基于本申请中任意合适的实施方式，在一些实施方式中，1.3≤A/B≤25.4。
通过将A/B值调节在更为合适的范围内，更有利于在有效地改善电池综合性能的同时实现较佳的热稳定性。
基于本申请中任意合适的实施方式，在一些实施方式中，0.19≤A≤10.1；可选地，0.28≤A≤2.53。非限制性地，A还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.19、0.2、0.22、0.24、0.25、0.26、0.28、0.3、0.32、0.34、0.35、0.36、0.38、0.4、0.45、0.5、0.55、0.6、0.65、0.7、0.75、0.8、0.85、0.9、0.95、1、1.1、1.2、1.25、1.3、1.4、1.5、1.6、1.7、1.75、1.8、2、2.1、2.2、2.25、2.3、2.4、2.5、2.6、2.8、3、3.5、3.6、4、4.5、5、5.5、6、6.5、7、7.5、8、8.5、9、9.5、9.6、9.8、9.9、10、10.1等。
通过调节A值可以调节第一正极活性物质与第二正极活性物质之间的含量比例。通过将A值调控在上述范围内，更有利于发挥第一正极活性物质与第二正极活性物质的综合优势，实现更佳的电性能。
基于本申请中任意合适的实施方式，在一些实施方式中，5％≤B≤40％；可选地，10％≤B≤20％。非限制性地，B还可以为下述任一种百分数、或者选自下述任两种百分数构成的区间：5％、6％、7％、8％、9％、10％、11％、12％、12.5％、13％、14％、15％、16％、18％、20％、22％、22.5％、24％、25％、26％、28％、30％、32％、34％、35％、36％、38％、40％等。
通过调节B值可以调节第一阳离子盐相对于电解质盐的质量百分比。通过将B值调控在上述范围内，可以使第一阳离子在电解液中的浓度更佳地匹配第一正极活性物质对适当降低被利用度的需求，从而整体上实现更佳的电池综合性能。
基于本申请中任意合适的实施方式，在一些实施方式中，在第一正极活性物质中，Co元素相对于Li元素的原子摩尔比可记为Rc，Rc满足0.05≤Rc≤0.5，可选地，0.05≤Rc≤0.3，可选地，0.05≤Rc≤0.2。非限制性地，Rc还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.05、0.06、0.08、0.09、0.1、0.11、0.12、0.125、0.14、0.15、0.16、0.175、0.18、0.2、0.22、0.225、0.24、0.25、0.26、0.275、0.28、0.3、0.32、0.34、0.35、0.36、0.38、0.4、0.42、0.44、0.45、0.46、0.48、0.5等。
基于本申请中任意合适的实施方式，在一些实施方式中，在第一正极活性物质中，Co元素相对于氧(O)元素的原子摩尔比可记为RCo/O，RCo/O满足0.025≤RCo/O≤0.25，可选地，0.025≤RCo/O≤0.15，可选地，0.025≤RCo/O≤0.1。非限制性地，RCo/O还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.025、0.03、0.035、0.04、0.045、0.05、0.06、0.08、0.09、0.1、0.11、0.12、0.125、0.14、0.15、0.16、0.175、0.18、0.2、0.22、0.225、0.24、0.25等。
基于本申请中任意合适的实施方式，在一些实施方式中，在第一正极活性物质中，Co元素相对于非锂金属元素的原子摩尔比之和的比值可记为RCo/all，RCo/all满足0.05≤RCo/all≤0.5，可选地，0.05≤RCo/all≤0.3，可选地，0.05≤RCo/all≤0.2。非限制性地，RCo/all还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.05、0.06、0.08、0.09、0.1、0.11、0.12、0.125、0.14、0.15、0.16、0.175、0.18、0.2、0.22、0.225、0.24、0.25、0.26、0.275、0.28、0.3、0.32、0.34、0.35、0.36、0.38、0.4、0.42、0.44、0.45、0.46、0.48、0.5等。
在本申请中，如无其他说明，“非锂金属元素”是指除锂以外的金属元素。
可以根据元素分析法获得待测正极活性物质中各元素的种类，进而结合不同元素的相对原子质量计算出不同种元素之间的原子摩尔比。
Co元素的存在有利于提升材料的结构稳定性，通过调节第一正极活性物质中的Co元素含量在更为合适的范围内，更有利于提升电池的充放电倍率性能和循环性能。
基于本申请中任意合适的实施方式，在一些实施方式中，在第一正极活性物质中，M1元素相对于Li元素的原子摩尔比可记为Rd，Rd满足0.05≤Rd≤0.5，可选地，0.05≤Rd≤0.3。非限制性地，Rd还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.05、0.06、0.08、0.09、0.1、0.11、0.12、0.125、0.14、0.15、0.16、0.175、0.18、0.2、0.22、0.225、0.24、0.25、0.26、0.275、0.28、0.3、0.32、0.34、0.35、0.36、0.38、0.4、0.42、0.44、0.45、0.46、0.48、0.5等。Rd还可以为下述任一种范围：Rd≤0.2、0.05≤Rd≤0.2等。
在本申请中，如无其他说明，在第一正极活性物质中，M1元素相对于O元素的原子摩尔比可记为RM1/O，RM1/O满足0.025≤RM1/O≤0.25，可选地，0.025≤RM1/O≤0.15。非限制性地，RM1/O还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.025、0.03、0.035、0.04、0.045、0.05、0.06、0.08、0.09、0.1、0.11、0.12、0.125、0.14、0.15、0.16、0.175、0.18、0.2、0.22、0.225、0.24、0.25等。RM1/O还可以为下述任一种范围：RM1/O≤0.1、0.025≤RM1/O≤0.1等。
基于本申请中任意合适的实施方式，在一些实施方式中，在第一正极活性物质中，M1元素相对于非锂金属元素的原子摩尔比可记为RM1/all，RM1/all满足0.05≤RM1/all≤0.5，可选地，0.05≤RM1/all≤0.3。非限制性地，RM1/all还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.05、0.06、0.08、0.09、0.1、0.11、0.12、0.125、0.14、0.15、0.16、0.175、0.18、0.2、0.22、0.225、0.24、0.25、0.26、0.275、0.28、0.3、0.32、0.34、0.35、0.36、0.38、0.4、0.42、0.44、0.45、0.46、0.48、0.5等。RM1/all还可以为下述任一种范围：RM1/all≤0.2、0.05≤RM1/all≤0.2等。
基于本申请中任意合适的实施方式，在一些实施方式中，在第一正极活性物质中，M1元素包括Mn元素。Mn元素相对于Li元素的原子摩尔比记为Rd-Mn，可选地，Rd-Mn满足0.05≤Rd-Mn≤0.4，进一步可选地，0.05≤Rd-Mn≤0.3。非限制性地，Rd-Mn还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.05、0.06、0.08、0.09、0.1、0.11、0.12、0.125、0.14、0.15、0.16、0.175、0.18、0.2、0.22、0.225、0.24、0.25、0.26、0.275、0.28、0.3、0.32、0.34、0.35、0.36、0.38、0.4等。
在本申请中，如无其他说明，在第一正极活性物质中，Mn元素相对于O元素的原子摩尔比记为RMn/O，可选地，RMn/O满足0.025≤RMn/O≤0.2，进一步可选地，0.025≤RMn/O≤0.15。非限制性地，RMn/O还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.025、0.03、0.035、0.04、0.045、0.05、0.06、0.08、0.09、0.1、0.11、0.12、0.125、0.14、0.15、0.16、0.175、0.18、0.19、0.2等。
基于本申请中任意合适的实施方式，在一些实施方式中，Mn元素相对于非锂金属元素的原子摩尔比记为RMn/all，可选地，RMn/all满足0.05≤RMn/all≤0.4，进一步可选地，0.05≤RMn/all≤0.3。非限制性地，RMn/all还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.05、0.06、0.08、0.09、0.1、0.11、0.12、0.125、0.14、0.15、0.16、0.175、0.18、0.2、0.22、0.225、0.24、0.25、0.26、0.275、0.28、0.3、0.32、0.34、0.35、0.36、0.38、0.4等。
通过调节第一正极活性物质中M1元素的含量，可以调节第一正极活性物质的热稳定性。例如，当M1元素包括Mn元素时，Mn元素有利于提高第一正极活性物质的热稳定性；当M1元素包括Al元素时，Al元素有利于提升容量和材料热稳定性，有利于降低内阻而改善倍率性能和循环性能。
基于本申请中任意合适的实施方式，在一些实施方式中，在第一正极活性物质中，Co元素与M1元素的原子摩尔当量之和相对于Li元素的原子摩尔当量的比值记为Rc+d，Rc+d满足0.1≤Rc+d≤0.5，进一步可选地，0.1≤Rc+d≤0.3，更进一步可选地，0.1≤Rc+d≤0.2。非限制性地，Rc+d还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.1、0.11、0.12、0.125、0.14、0.15、0.16、0.175、0.18、0.2、0.22、0.225、0.24、0.25、0.26、0.275、0.28、0.3、0.32、0.34、0.35、0.36、0.38、0.4、0.42、0.44、0.45、0.46、0.48、0.5等。
基于本申请中任意合适的实施方式，在一些实施方式中，在第一正极活性物质中，Co元素与M1元素的原子摩尔当量之和相对于O元素的原子摩尔当量的比值记为R(Co+M1)/O，R(Co+M1)/O满足0.05≤R(Co+M1)/O≤0.25，进一步可选地，0.05≤R(Co+M1)/O≤0.15，更进一步可选地，0.05≤R(Co+M1)/O≤0.1。非限制性地，R(Co+M1)/O还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.05、0.06、0.07、0.08、0.09、0.1、0.11、0.12、0.125、0.14、0.15、0.16、0.175、0.18、0.2、0.22、0.225、0.24、0.25等。
基于本申请中任意合适的实施方式，在一些实施方式中，在第一正极活性物质中，Co元素与M1元素的原子摩尔当量之和相对于非锂金属元素的原子摩尔当量的比值记为R(Co+M1)/all，R(Co+M1)/all满足0.1≤R(Co+M1)/all≤0.5，进一步可选地，0.1≤R(Co+M1)/all≤0.3，更进一步可选地，0.1≤R(Co+M1)/all≤0.2。非限制性地，R(Co+M1)/all还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.1、0.11、0.12、0.125、0.14、0.15、0.16、0.175、0.18、0.2、0.22、0.225、0.24、0.25、0.26、0.275、0.28、0.3、0.32、0.34、0.35、0.36、0.38、0.4、0.42、0.44、0.45、0.46、0.48、0.5等。
可以根据需要调节Co元素与M1元素的含量比例，平衡Co元素与M1元素对电池性能的综合影响。
基于本申请中任意合适的实施方式，在一些实施方式中，第一正极活性物质满足如下特征中的一项或多项：
Co元素相对于Li元素的原子摩尔比记为Rc，则Rc满足0.05≤Rc≤0.5，可选地，0.05≤Rc≤0.3，可选地，0.05≤Rc≤0.2(Rc还可以选自本申请任一合适的实施方式中的数值或范围)；
M1元素相对于Li元素的原子摩尔比记为Rd，则Rd满足0.05≤Rd≤0.5，可选地，0.05≤Rd≤0.3(Rd还可以选自本申请任一合适的实施方式中的数值或范围)；
M1元素包括Mn元素，Mn元素相对于Li元素的原子摩尔比记为Rd-Mn，则Rd-Mn满足0.05≤Rd-Mn≤0.4，进一步可选地，0.05≤Rd-Mn≤0.3(Rd-Mn还可以选自本申请任一合适的实施方式中的数值或范围)；
Co元素与M1元素的原子摩尔当量之和相对于Li元素的原子摩尔当量的比值记为Rc+d，则Rc+d满足0.1≤Rc+d≤0.5，进一步可选地，0.1≤Rc+d≤0.3，更进一步可选地，0.1≤Rc+d≤0.2(Rc+d还可以选自本申请任一合适的实施方式中的数值或范围)。
基于本申请中任意合适的实施方式，在一些实施方式中，第一正极活性物质满足如下特征中的一项或多项：
Co元素相对于Li元素的原子摩尔比记为Rc，则Rc满足0.05≤Rc≤0.5，可选地，0.05≤Rc≤0.3，可选地，0.05≤Rc≤0.2(Rc还可以选自本申请任一合适的实施方式中的数值或范围)；
Co元素相对于O元素的原子摩尔比记为RCo/O，则RCo/O满足0.025≤RCo/O≤0.25，可选地，0.025≤RCo/O≤0.15，可选地，0.025≤RCo/O≤0.1(RCo/O还可以选自本申请任一合适的实施方式中的数值或范围)；
Co元素相对于非锂金属元素的原子摩尔比之和的比值可记为RCo/all，满足0.05≤RCo/all≤0.5，可选地，0.05≤RCo/all≤0.3，可选地，0.05≤RCo/all≤0.2(RCo/all还可以选自本申请任一合适的实施方式中的数值或范围)；
M1元素相对于Li元素的原子摩尔比记为Rd，则Rd满足0.05≤Rd≤0.5，可选地，0.05≤Rd≤0.3(Rd还可以选自本申请任一合适的实施方式中的数值或范围)；
M1元素相对于O元素的原子摩尔比记为RM1/O，则RM1/O满足0.025≤RM1/O≤0.25，可选地，0.025≤RM1/O≤0.15(RM1/O还可以选自本申请任一合适的实施方式中的数值或范围)；
M1元素相对于非锂金属元素的原子摩尔比可记为RM1/all，RM1/all满足0.05≤RM1/all≤0.5，可选地，0.05≤RM1/all≤0.3(RM1/all还可以选自本申请任一合适的实施方式中的数值或范围)；
M1元素包括Mn元素，Mn元素相对于Li元素的原子摩尔比记为Rd-Mn，则Rd-Mn满足0.05≤Rd-Mn≤0.4，进一步可选地，0.05≤Rd-Mn≤0.3(Rd-Mn还可以选自本申请任一合适的实施方式中的数值或范围)；
M1元素包括Mn元素，Mn元素相对于O元素的原子摩尔比记为RMn/O，则RMn/O满足0.025≤RMn/O≤0.2，进一步可选地，0.025≤RMn/O≤0.15(RMn/O还可以选自本申请任一合适的实施方式中的数值或范围)；
M1元素包括Mn元素，Mn元素相对于非锂金属元素的原子摩尔比记为RMn/all，可选地，RMn/all满足0.05≤RMn/all≤0.4，进一步可选地，0.05≤RMn/all≤0.3(RMn/all还可以选自本申请任一合适的实施方式中的数值或范围)；
Co元素与M1元素的原子摩尔当量之和相对于Li元素的原子摩尔当量的比值记为Rc+d，则Rc+d满足0.1≤Rc+d≤0.5，进一步可选地，0.1≤Rc+d≤0.3，更进一步可选地，0.1≤Rc+d≤0.2(Rc+d还可以选自本申请任一合适的实施方式中的数值或范围)；
Co元素与M1元素的原子摩尔当量之和相对于Li元素的原子摩尔当量的比值记为R(Co+M1)/O，则R(Co+M1)/O满足0.05≤R(Co+M1)/O≤0.25，进一步可选地，0.05≤R(Co+M1)/O≤0.15，更进一步可选地，0.05≤R(Co+M1)/O≤0.1(R(Co+M1)/O还可以选自本申请任一合适的实施方式中的数值或范围)；
Co元素与M1元素的原子摩尔当量之和相对于非锂金属元素的原子摩尔当量的比值记为R(Co+M1)/all，R(Co+M1)/all满足0.1≤R(Co+M1)/all≤0.5，进一步可选地，0.1≤R(Co+M1)/all≤0.3，更进一步可选地，0.1≤R(Co+M1)/all≤0.2(R(Co+M1)/all还可以选自本申请任一合适的实施方式中的数值或范围)。
在一些实施方式中，第一正极活性物质可以为包含Co元素、M1元素和Ni元素的锂氧化物。此时，第一正极活性物质可具有层状结构，在第一正极活性物质内实现较高的离子电导率。作为非限制性示例，如锂镍钴锰氧化物及其改性形式，其中，改性形式可以包括掺杂改性和包覆改性中的一种或多种。
基于本申请中任意合适的实施方式，在一些实施方式中，第一正极活性物质还包含Ni元素。在第一正极活性物质中，Ni元素相对于Li元素的原子摩尔比可记为Rb。在其中的一些实施方式中，Rb满足0.5≤Rb<1，可选地，0.5≤Rb≤0.9；进一步可选地，0.6≤Rb≤0.9；更进一步可选地，0.65≤Rb≤0.9；更进一步可选地，0.8≤Rb≤0.9。非限制性地，Rb还可以为下述任一种数值、或者大于或等于下述任一种数值且小于1、或者选自下述任两种数值构成的区间：0.5、0.55、0.6、0.65、0.7、0.75、0.8、0.85、0.83、0.833、0.85、0.86、0.88、0.9、0.91、0.92、0.94、0.95等。
在本申请中，在第一正极活性物质中，Ni元素相对于O元素的原子摩尔比可记为RNi/O。在其中的一些实施方式中，RNi/O满足0.25≤RNi/O<0.5，可选地，0.25≤RNi/O≤0.45；进一步可选地，0.3≤RNi/O≤0.45；更进一步可选地，0.325≤Rb≤0.45；更进一步可选地，0.4≤RNi/O≤0.45。非限制性地，Rb还可以为下述任一种数值、或者大于或等于下述任一种数值且小于0.5、或者选自下述任两种数值构成的区间：0.25、0.3、0.325、0.35、0.4、0.45、0.46、0.47、0.475、0.48、0.49、0.495等。
基于本申请中任意合适的实施方式，在一些实施方式中，在第一正极活性物质中，Ni元素相对于非锂金属元素的原子摩尔比可记为RNi/all。在其中的一些实施方式中，RNi/all满足0.5≤RNi/all<1，可选地，0.5≤RNi/all≤0.9；进一步可选地，0.6≤RNi/all≤0.9；更进一步可选地，0.65≤RNi/all≤0.9；更进一步可选地，0.8≤RNi/all≤0.9。非限制性地，RNi/all还可以为下述任一种数值、或者大于或等于下述任一种数值且小于1、或者选自下述任两种数值构成的区间：0.5、0.55、0.6、0.65、0.7、0.75、0.8、0.85、0.83、0.833、0.85、0.86、0.88、0.9、0.91、0.92、0.94、0.95等。
当第一正极活性物质包含Ni元素时，有利于赋予第一正极活性物质较高的能量密度和较高的离子电导率。镍(Ni)含量越高，复合正极极片的能量密度越高，也越有利提高离子电导率；不过，在第一正极活性物质被高度利用的情况下，第一正极活性物质的表层结构发生损坏甚至结构坍塌的风险越大。此时，通过引入第一阳离子并调控A/B值，对复合正极极片的热稳定性提升作用越显著。
在第一正极活性物质含有Ni元素的情况下，通过引入第一阳离子并调控A/B值，可以使第一阳离子在电解液中的浓度能够较佳地匹配第一正极活性物质对适当降低被利用度的需求，可以在整体上实现电池综合性能的较佳匹配，实现较高的能量密度，可以显著提升复合正极极片与电池单体的热稳定性，降低热失控风险，还有利于复合正极极片整体上具有良好的活性离子传输性能。
可以理解地，电池在充放电过程中会伴随锂(Li)的脱嵌及消耗，电池在放电到不同状态时正极极片中Li的含量不同。
本申请中关于正极活性物质的示例性描述中，如无其他说明，Li的含量可以为材料初始状态，也可以为经充放电循环后的非初始状态。将正极活性物质应用于电池体系中的正极极片，经过充放电循环，正极极片所含正极活性物质中Li的含量通常会发生变化。其中，Li的含量可以采用原子摩尔含量进行计量，但不限于此。关于“Li的含量为材料初始状态”，材料初始状态指投料于正极浆料之前的状态。可以理解，在所列举正极活性物质基础上进行适当改性而获得的新材料或新物质也在正极活性物质范畴之内，前述适当改性指针对正极活性物质可接受的改性方式，非限制性示例如包覆改性。
可以理解，测试Rc、Rd、Rd-Mn、Rc+d、Rb等相对于Li元素计量的参数时，从电池中提取正极极片中的正极活性物质的待测样品之前，可以先对电池进行满放处理，再拆除电池，取正极极片以获得正极活性物质的待测样品。
本申请中关于正极活性物质的示例性描述中，氧(O)的含量仅为理论状态值，晶格释氧会导致氧的原子摩尔含量发生变化，实际O的含量会出现浮动。其中，O的含量可以采用原子摩尔含量进行计量，但不限于此。
对于活性离子包括锂离子的电池单体及二次电池，上下文中对Qa、a、x等原子比的限定可以包括电池不同充放电状态下Li的原子摩尔含量(通常电池电压在2V～5V之间)。
基于本申请中任意合适的实施方式，在一些实施方式中，在第一正极活性物质中，涉及“Li元素的原子摩尔当量Qa”，Qa可以为0.9～1.1，可选为0.9～1.05，进一步可选为1。非限制性地，在第一正极活性物质中的Qa还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.9、0.92、0.94、0.95、0.96、0.97、0.98、0.99、1、1.01、1.02、1.03、1.04、1.05、1.06、1.08、1.1等。非限制性地，在第一正极活性物质中的Qa还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.75、0.8、0.85、0.9、0.92、0.94、0.95、0.96、0.97、0.98、0.99、1、1.01、1.02、1.03、1.04、1.05、1.06、1.08、1.1等。Qa的非限制性示例还如0.9～1、0.85～1、0.8～1、0.75～1等。
基于本申请中任意合适的实施方式，在一些实施方式中，以Li元素的原子摩尔当量Qa为0.75～1.2计，可选地以0.8～1.1计，进一步可选地以0.9～1.05计，更进一步可选地以1计，Co元素的原子摩尔当量Qc≤0.4，可选地，Qc≤0.3，进一步可选地，Qc≤0.2。非限制性地，Qc还可以为下述任一种数值、或者小于或等于下述任一种数值、或者选自下述任两种数值构成的区间：0.4、0.38、0.36、0.35、0.34、0.32、0.3、0.28、0.26、0.25、0.24、0.22、0.20等。
基于本申请中任意合适的实施方式，在一些实施方式中，以Li元素的原子摩尔当量Qa为0.75～1.2计，可选地以0.8～1.1计，进一步可选地以0.9～1.05计，更进一步可选地以1计，M1元素的原子摩尔当量Qd≤0.5，可选地，Qd≤0.4，进一步可选地，Qd≤0.3。非限制性地，Qd还可以为下述任一种数值、或者小于或等于下述任一种数值、或者选自下述任两种数值构成的区间：0.5、0.48、0.46、0.45、0.44、0.42、0.4、0.38、0.36、0.35、0.34、0.32、0.3等。
基于本申请中任意合适的实施方式，在一些实施方式中，以Li元素的原子摩尔当量Qa为0.75～1.2计，可选地以0.8～1.1计，进一步可选地以0.9～1.05计，更进一步可选地以1计，M1元素包括Mn元素，进一步地，Mn元素的原子摩尔当量(可记为Q1Mn)可以满足≤0.4，可选地，Mn元素的原子摩尔当量≤0.3。非限制性地，Mn元素的原子摩尔当量还可以为下述任一种数值、或者小于或等于下述任一种数值、或者选自下述任两种数值构成的区间：0.4、0.38、0.36、0.35、0.34、0.32、0.3等。Q1Mn还可以为下述任一种范围：Q1Mn≤0.2、0.05≤Q1Mn≤0.2等。
基于本申请中任意合适的实施方式，在一些实施方式中，以Li元素的原子摩尔当量Qa为0.75～1.2计，可选地以0.8～1.1计，进一步可选地以0.9～1.05计，更进一步可选地以1计，Co元素和M1元素的原子摩尔当量之和Qc+d≤0.5，可选地，Qc+d≤0.4，Qc+d≤0.3，Qc+d≤0.2。非限制性地，Qc+d还可以为下述任一种数值、或者小于或等于下述任一种数值、或者选自下述任两种数值构成的区间：0.5、0.48、0.46、0.45、0.44、0.42、0.4、0.38、0.36、0.35、0.34、0.32、0.3、0.28、0.26、0.25、0.24、0.22、0.2等。
基于本申请中任意合适的实施方式，在一些实施方式中，以Li元素的原子摩尔当量Qa为0.75～1.2计，可选地以0.8～1.1计，进一步可选地以0.9～1.05计，更进一步可选地以1计，第一正极活性物质满足如下特征中的一项或多项：
Co元素的原子摩尔当量Qc≤0.4，可选地，Qc≤0.3，进一步可选地，Qc≤0.2(Qc还可以选自本申请任一合适的实施方式中的数值或范围)；
M1元素的原子摩尔当量Qd≤0.5，可选地，Qd≤0.4，进一步可选地，Qd≤0.3(Qd还可以选自本申请任一合适的实施方式中的数值或范围)；
M1元素包括Mn元素，Mn元素的原子摩尔当量≤0.4，可选地，Mn元素的原子摩尔当量≤0.3(Mn元素的原子摩尔当量，可记为Q1Mn，还可以选自本申请任一合适的实施方式中的数值或范围)；
Co元素和M1元素的原子摩尔当量之和Qc+d≤0.5，可选地，Qc+d≤0.4，Qc+d≤0.3，Qc+d≤0.2(Qc+d还可以选自本申请任一合适的实施方式中的数值或范围)。
基于本申请中任意合适的实施方式，在一些实施方式中，以Li元素的原子摩尔当量Qa为0.75～1.2计，可选地以0.8～1.1计，进一步可选地以0.9～1.05计，更进一步可选地以1计，第一正极活性物质包含Ni元素，Ni元素的原子摩尔当量Qb满足0.5≤Qb<1，可选地，0.6≤Qb<1，进一步可选地，0.65≤Qb<1。非限制性地，Qb还可以为下述任一种数值、或者大于或等于下述任一种数值且小于1、或者选自下述任两种数值构成的区间：0.5、0.55、0.6、0.65、0.7、0.75、0.8、0.85、0.83、0.833、0.85、0.86、0.88、0.9、0.91、0.92、0.94、0.95等。
在第一正极活性物质中的Li元素具有一定的原子摩尔当量的情况下，可以通过调节Co元素、M1元素及Ni元素的原子摩尔当量实现对相应元素含量的调节。
基于本申请中任意合适的实施方式，在一些实施方式中，第一正极活性物质包括第一本体，还包括或不包括位于第一本体的至少一部分表面的第一包覆层；其中，第一本体的化学组成为LiaNibCocM1dM2eOfRg，其中，0.75≤a≤1.2，0<b<1，0<c<1，0<d<1，0≤e≤0.2，b+c+d+e＝1，1≤f≤2.5， 0≤g≤1，f+g≤3，第一正极活性物质中的M2元素可以包括锆(Zr)、锌(Zn)、铜(Cu)、铬(Cr)、镁(Mg)、铁(Fe)、钒(V)、钛(Ti)、锶(Sr)、锑(Sb)、钇(Y)、钨(W)和铌(Nb)中的一种或多种，第一正极活性物质中的R元素可以包括N、F、S和Cl中的一种或多种。
在一些实施方式中，第一正极活性物质中的M2元素可以选自但不限于Zr、Zn、Cu、Cr、Mg、Fe、V、Ti、Sr、Sb、Y、W和Nb中的一种或多种。
在一些实施方式中，第一正极活性物质中的R元素可以选自但不限于N、F、S和Cl中的一种或多种。
在一些实施方式中，0.8≤a≤1.2，进一步可选地，0.9≤a≤1.1，进一步可选地，0.95≤a≤1.05。a还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.8、0.85、0.83、0.833、0.85、0.86、0.88、0.9、0.91、0.92、0.94、0.95、0.96、0.98、0.99、1、1.01、1.02、1.04、1.05、1.06、1.08、1.09、1.1、1.12、1.24、1.15、1.16、1.18、1.2等。
在一些实施方式中，0.5≤b<1，进一步可选地，0.5≤b≤0.9，更进一步可选地，0.6≤b≤0.9。b还可以为下述任一种数值、或者大于或等于下述任一种数值且小于1、或者选自下述任两种数值构成的区间：0.5、0.55、0.6、0.65、0.7、0.75、0.8、0.85、0.83、0.833、0.85、0.86、0.88、0.9、0.91、0.92、0.94、0.95等。
在一些实施方式中，0.05≤c<1，进一步可选地，0.05≤c≤0.5，更进一步可选地，0.05≤c≤0.3。c还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.05、0.06、0.08、0.09、0.1、0.11、0.12、0.125、0.14、0.15、0.16、0.175、0.18、0.2、0.22、0.225、0.24、0.25、0.26、0.275、0.28、0.3、0.32、0.34、0.35、0.36、0.38、0.4、0.42、0.44、0.45、0.46、0.48、0.5等。
在一些实施方式中，0.05≤d<1，进一步可选地，0.05≤d≤0.5，更进一步可选地，0.05≤d≤0.3。d还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.05、0.06、0.08、0.09、0.1、0.11、0.12、0.125、0.14、0.15、0.16、0.175、0.18、0.2、0.22、0.225、0.24、0.25、0.26、0.275、0.28、0.3、0.32、0.34、0.35、0.36、0.38、0.4、0.42、0.44、0.45、0.46、0.48、0.5等。
在一些实施方式中，0≤e<0.1，进一步可选地，0≤e≤0.05，更进一步可选地，0≤e≤0.03。e还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.03、0.035、0.04、0.045、0.05等。
在一些实施方式中，1≤f≤2.1，进一步可选地，1.8≤f≤2.05，更进一步可选地，1.95≤f≤2.05。f还可以为下述任一种数值、或者选自下述任两种数值构成的区间：1、1.1、1.2、1.25、1.3、1.4、1.45、1.5、1.55、1.6、1.65、1.7、1.8、1.85、1.9、1.95、2、2.05、2.1等。
在一些实施方式中，0≤g<0.5，进一步可选地，0≤g≤0.1，更进一步可选地，0≤g≤0.05。g还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0、0.01、0.02、0.03、0.04、0.05、0.06、0.08、0.1、0.15、0.2、0.25、0.3、0.35、0.4、0.45、0.46、0.48等。
在一些实施方式中，第一正极活性物质包括锂镍钴锰氧化物(也可称为镍钴锰酸锂)、锂镍钴铝氧化物及其改性化合物等中的一种或多种。锂镍钴锰氧化物的非限制性示例可以包括LiNi0.5Co0.2Mn0.3O2(也可以简称为NCM523)、LiNi0.5Co0.25Mn0.25O2(也可以简称为NCM211)、LiNi0.6Co0.2Mn0.2O2(也可以简称为NCM622)、LiNi0.8Co0.1Mn0.1O2(也可以简称为NCM811)等。锂镍钴铝氧化物的非限制性示例可以包括LiNi0.80Co0.15Al0.05O2。
基于本申请中任意合适的实施方式，在一些实施方式中，在第二正极活性物质中，涉及“Li元素的原子摩尔当量”，Li元素的原子摩尔当量可以为0.9～1.1，可选为0.9～1.05，进一步可选为1。非限制性地，在第二正极活性物质中，Li元素的原子摩尔当量还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.9、0.92、0.94、0.95、0.96、0.97、0.98、0.99、1、1.01、1.02、1.03、1.04、1.05、1.06、1.08、1.1等。非限制性地，在第二正极活性物质中，Li元素的原子摩尔当量还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.75、0.8、0.85、0.9、0.92、0.94、0.95、0.96、0.97、0.98、0.99、1、1.01、1.02、1.03、1.04、1.05、1.06、1.08、1.1等。在第二正极活性物质中，Li元素的原子摩尔当量的非限制性示例还如0.9～1、0.85～1、0.8～1、0.75～1等。
基于本申请中任意合适的实施方式，在一些实施方式中，在第二正极活性物质中，Mn元素和Fe元素的原子摩尔比(可记为R2Mn/Fe)为0.42～9，可选地，Mn元素和Fe元素的原子摩尔比为0.66～4。非限制性地，R2Mn/Fe还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.42、0.45、0.5、0.55、0.6、0.65、0.7、0.8、0.9、1、1.5、2、2.5、3、3.5、4、4.5、5、6、6.5、7、7.5、8、8.5、9等。
基于本申请中任意合适的实施方式，在一些实施方式中，在第二正极活性物质中，以Li元素的原子摩尔当量为0.9～1.1计，可选地以0.9～1.05计，进一步可选地以1计，Mn元素的原子摩尔 当量(可记为Q2Mn)为0.5～0.999，可选地，Q2Mn为0.5～0.6。Q2Mn还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.5、0.55、0.6、0.65、0.7、0.8、0.9、0.92、0.94、0.95、0.96、0.98、0.99、0.995、0.999等。
基于本申请中任意合适的实施方式，在一些实施方式中，在第二正极活性物中，以Li元素的原子摩尔当量为0.9～1.1计，可选地以0.9～1.05计，进一步可选地以1计，Fe元素的原子摩尔当量(可记为Q2Fe)为0.001～0.5，可选地，Q2Fe为0.4～0.5。非限制性地，Q2Fe还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.001、0.002、0.004、0.005、0.006、0.008、0.01、0.02、0.04、0.05、0.06、0.08、0.1、0.15、0.2、0.25、0.3、0.35、0.4、0.45、0.5等。
基于本申请中任意合适的实施方式，在一些实施方式中，第二正极活性物质满足如下特征中的一项或多项：
Mn元素和Fe元素的原子摩尔比(可记为R2Mn/Fe)为0.42～9，可选地，R2Mn/Fe为0.66～4(R2Mn/Fe还可以选自本申请任一合适的实施方式中的数值或范围)；
以Li元素的原子摩尔当量为0.9～1.1计，可选地以0.9～1.05计，进一步可选地以1计，Mn元素的原子摩尔当量(可记为Q2Mn)为0.5～0.999，可选地，Q2Mn为0.5～0.6(Q2Mn还可以选自本申请任一合适的实施方式中的数值或范围)；
以Li元素的原子摩尔当量为0.9～1.1计，可选地以0.9～1.05计，进一步可选地以1计，Fe元素的原子摩尔当量(可记为Q2Fe)为0.001～0.5，可选地，Q2Fe为0.4～0.5(Q2Fe还可以选自本申请任一合适的实施方式中的数值或范围)。
提高第二正极活性物质中的Mn元素含量有利于改善第二正极活性物质的能量密度、电压平台及材料成本。通过将Mn元素控制在上述范围内，有利于在发挥Mn元素作用的同时有利于形成均一的固溶体，还可尽量减少或避免缺陷和孔隙，从而减少或避免缺陷和孔隙延长活性离子的嵌入迁出路径，因此，通过将Mn元素控制在上述范围内，有利于使第二活性物质具有良好的离子迁移速率，缩短第二正极活性物质与第一正极活性物质中活性离子电导率的差距，从而降低第一正极活性物质被过度利用及脱锂的几率，有利于进一步提高复合正极极片的热稳定性。
在第二正极活性物质中，Fe元素的引入有利于实现更好的离子传输性和更高的离子电导率，还有利促进活性离子的嵌入和脱出，提高电池充放电效率和能量密度。
在第二正极活性物质中的Li元素具有一定的原子摩尔当量的情况下，通过调节Fe元素、Mn元素的原子摩尔当量可以实现对相应元素含量的调节。
基于本申请中任意合适的实施方式，在一些实施方式中，第二活性物质包括第二本体，还包括或不包括位于第二本体表面至少一部分的第二包覆层；其中，第二本体的化学式为Li1+xMn1-y-wFewM3yP1-zQzO4，其中，-0.1≤x≤0.1，0.1≤w≤0.5，0.001≤y≤0.5，0.001≤z≤0.1，第二活性物质中的M3元素可以包括锌(Zn)、铝(Al)、钠(Na)、钾(K)、镁(Mg)、钼(Mo)、钨(W)、钛(Ti)、钒(V)、锆(Zr)、镍(Ni)、钴(Co)、镓(Ga)、锡(Sn)、锑(Sb)、铌(Nb)和锗(Ge)中的一种或多种元素，第二活性物质中的Q元素可以包括硼(B)、硅(Si)、氮(N)、硫(S)、氟(F)、氯(Cl)和溴(Br)中的一种或多种元素。
在一些实施方式中，第二活性物质中的M3元素可以选自但不限于Zn、Al、Na、K、Mg、Mo、W、Ti、V、Zr、Ni、Co、Ga、Sn、Sb、Nb和Ge中的一种或多种元素。
在一些实施方式中，第二活性物质中的Q元素可以选自但不限于包括B、Si、N、S、F、Cl和Br中的一种或多种元素。
在一些实施方式中，0.1≤y≤0.5，进一步可选地，0.2≤y<0.5，更进一步可选地，0.3≤y<0.5。y还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.1、0.15、0.2、0.25、0.3、0.35、0.4、0.45、0.5等。
在一些实施方式中，0.2≤w≤0.5，进一步可选地，0.3≤w<0.5，更进一步可选地，0.4≤w<0.5。w还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.2、0.25、0.3、0.35、0.4、0.45、0.5等。
在一些实施方式中，0.001≤z≤0.1，进一步可选地，0.001≤z<0.05，更进一步可选地，0.001≤z<0.002。非限制性地，z还可以为下述任一种数值、或者选自下述任两种数值构成的区间：0.001、0.002、0.004、0.005、0.006、0.008、0.01、0.02、0.04、0.05、0.06、0.08、0.1等。
在一些实施方式中，第二活性物质中的M3元素包括钛(Ti)、钒(V)、镍(Ni)、钴(Co)和镁(Mg)中一种或多种元素。进一步地，第二活性物质中的M3元素可以选自但不限于Ti、V、Ni、Co和Mg中一种或多种元素。
在一些实施方式中，第二活性物质中的Q元素包括硼(B)、硅(Si)、氮(N)和硫(S)中的一种元素。进一步地，第二活性物质中的Q元素可以选自但不限于B、Si、N和S中的一种元素。
在一些实施方式中，第二包覆层包括焦磷酸盐、磷酸盐和碳中的一种或多种。
在一些实施方式中，第二包覆层可以为单层结构或多层结构。
基于本申请中任意合适的实施方式，在一些实施方式中，第一正极活性物质和第二正极活性物质在正极活性材料层中的总质量占比RI+II≥85％；可选地，RI+II≥90％；进一步可选地，RI+II≥95％。RI+II还可以为下述任一种百分数、或者大于或等于下述任一种百分数、或者选自下述任两种百分数构成的区间：85％、86％、88％、90％、92％、94％、95％、96％、98％等。
通过调节第一正极活性物质和第二正极活性物质在正极活性材料层中的总质量占比RI+II在上述范围内，更有利于促进两种正极活性物质综合优势的发挥。
基于本申请中任意合适的实施方式，在一些实施方式中，第一阳离子包括碱金属元素和碱土金属元素中的一种或多种元素的阳离子。非限制性地，第一阳离子可以包括钠离子、钾离子、钙离子和镁离子中的一种或多种。
非限制性地，第一阳离子盐中的阴离子可以包括六氟磷酸根离子、高氯酸根离子、四氟硼酸根离子、双三氟甲基磺酰亚胺根离子、三氟甲磺酸根离子、双氟磺酰基酰亚胺根离子和三(三氟甲基磺酰)甲基离子中的一种或多种。
非限制性地，电解质盐中的阴离子可以包括六氟磷酸根离子、高氯酸根离子、四氟硼酸根离子、双三氟甲基磺酰亚胺根离子、三氟甲磺酸根离子、双氟磺酰基酰亚胺根离子和三(三氟甲基磺酰)甲基离子中的一种或多种。
非限制性地，第一阳离子盐可以包括六氟磷酸钠、高氯酸钠、四氟硼酸钠、双三氟甲基磺酰亚胺钠、三氟甲磺酸钠、双氟磺酰基酰亚胺钠、三(三氟甲基磺酰)甲基钠、六氟磷酸钾、高氯酸钾、四氟硼酸钾、双三氟甲基磺酰亚胺钾、三氟甲磺酸钾、双氟磺酰基酰亚胺钾和三(三氟甲基磺酰)甲基钾中的一种或多种。
在一些实施方式中，第一阳离子盐包括六氟磷酸钠、四氟硼酸钠和高氯酸钠中的一种或两种。
在一些实施方式中，第一阳离子盐包括六氟磷酸钠。
在第一阳离子的离子半径大于锂离子的情况下，第一阳离子的种类及相应的阴离子可以具有灵活的选择范围。作为非限制性示例，例如六氟磷酸钠成本低，可大规模使用；钠离子与锂离子半径差异较小，更有利于嵌入活性物质。
基于本申请中任意合适的实施方式，在一些实施方式中，负极极片包括负极活性材料层，负极活性材料层包括负极活性物质，负极活性物质包括硅基材料；硅基材料在负极活性物质中所占的质量百分比记为X1。
在一些实施方式中，X1≥3％，进一步可选为3％≤X1≤50％。X1还可以为下述任一种百分数、或者选自下述任两种百分数构成的区间：3％、4％、5％、6％、8％、10％、12％、14％、15％、16％、18％、20％、22％、24％、25％、26％、28％、30％、32％、34％、5％、36％、38％、40％、42％、44％、45％、46％等。
非限制性地，硅基材料可以包括单质硅、硅氧化物、硅碳复合物、硅氮复合物、硅合金、硅石墨烯复合材料、硅碳纳米管和含硅导电聚合物中的一种或多种。
当负极极片的负极活性材料层包括硅基材料时，有利于进一步提升电池单体的能量密度。
以下为关于正极极片的一些描述。
非限制性地，正极极片包括正极集流体和设置于正极集流体至少一侧的正极活性材料层，正极活性材料层中包括正极活性物质。正极活性物质的定义可参阅前文。该正极活性物质至少包括前述的第一正极活性物质和第二正极活性物质。
非限制性地，正极活性物质在正极活性材料层中的质量百分比可以≥85％，进一步可以≥90％，更进一步可以≥95％。
基于本申请中任意合适的实施方式，在一些实施方式中，第一正极活性物质和第二正极活性物质的质量之和在正极活性材料层中的正极活性物质总质量中的百分占比可以满足≥85％，可选地≥95％，进一步可选地≥96％等，更进一步可选地为100％等。非限制性地，第一正极活性物质和第二正极活性物质在正极活性材料层中的正极活性物质总质量中的百分占比还可以为下述任一种百分数、或者大于或等于下述任一种百分数且小于或等于100％、或者选自下述任两种百分数构成的区间：85％、86％、88％、95％、96％、98％、100％等。
在一些实施方式中，正极活性材料层中的正极活性物质由第一正极活性物质和第二正极活性物质组成。
作为非限制性示例，正极集流体具有在其自身厚度方向相背离的两个表面，正极活性材料层设置在正极集流体相背离的两个表面的其中任意一者或两者上。
在一些实施方式中，正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料形成在高分子材料基材上而获得。在正极集流体中，该金属材料可以包括但不限于铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等中的一种或多种。在正极集流体中，该高分子材料基材可以包括但不限于聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等中的一种或多种。
在一些实施方式中，正极活性材料层还可选地包括粘结剂。作为非限制性示例，粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的一种或多种。粘结剂在正极活性材料层中的质量百分比可以为0～10％，进一步可以为0～8％，更进一步可以为1％～5％。
在一些实施方式中，正极活性材料层还可选地包括导电剂。作为非限制性示例，导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的一种或多种。导电剂在正极活性材料层中的质量百分比可以为0～8％，进一步可以为0～5％。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性物质、导电剂、粘结剂和任意其他的组分分散于溶剂中，形成正极浆料。进一步地，将正极浆料涂覆在正极集流体的至少一侧表面上，经烘干、冷压等工序后，即可得到正极极片。冷压可以采用冷轧机进行。溶剂的种类可以包括但不限于前述实施方式中的任一种，例如可以包括N-甲基吡咯烷酮(NMP)，进一步可以为NMP。正极浆料所涂覆的正极集流体表面可以为正极集流体的单个表面上，也可以为正极集流体的两个表面上。正极浆料的固含量可以为40wt％～80wt％。正极浆料在室温下的粘度可以调整到3000mPa·s～25000mPa·s，可选为3000mPa·s～10000mPa·s。涂覆正极浆料时，以干重计(扣除溶剂)的涂布单位面密度可以为15mg/cm2～35mg/cm2。正极极片的压实密度可以为3.0g/cm3～3.6g/cm3，可选为3.3g/cm3～3.5g/cm3。
在本申请中，如无其他说明，对于正极极片和负极极片，冷压前后的极片面积变化不大，相应的压实密度的计算公式为：
压实密度＝涂布面密度/(冷压后极片厚度-集流体厚度)。
涂布面密度＝浆料干重/冷压前极片面积。
以下为关于负极极片的一些描述。
非限制性地，负极极片包括负极集流体和设置于负极集流体至少一侧的负极活性材料层，负极活性材料层中包括负极活性物质。负极活性物质的定义可参阅前文。
非限制性地，负极活性物质在负极活性材料层中的质量百分比可以≥85％，进一步可以≥90％，更进一步可以≥95％。
作为非限制性示例，负极集流体具有在其自身厚度方向相背离的两个表面，负极活性材料层可以设置在负极集流体相背离的两个表面中的任意一者或两者上。
在一些实施方式中，负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料形成在高分子材料基材上而形成。在负极集流体中，该金属材料可以包括但不限于铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等中的一种或多种。在负极集流体中，该高分子材料基材可以包括但不限于聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等中的一种或多种。
非限制性地，负极活性物质可以采用本领域公知的用于电池的负极活性物质。作为非限制性示例，负极活性物质可包括以下物质或材料中的一种或多种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。硅基材料可以包括单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的一种或多种。锡基材料可以包括单质锡、锡氧化合物以及锡合金中的一种或多种。但本申请并不限定于这些材料或物质，还可以使用其他可被用作电池负极活性物质的传统材料或物质。这些负极活性物质可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施方式中，负极活性物质包括碳基材料、硅基材料、锡基材料和钛酸锂以及前述任一种物质的改性形式中的一种或多种，其中，改性形式包括掺杂改性和包覆改性中的一种或多种。掺杂改性方式和包覆改性方式均可采用或参考本领域已有的改性方式，包括但不限于元素种类及 掺杂量的选择。碳基材料可以包括但不限于石墨材料、软炭、硬炭等中的一种或多种。石墨材料可以包括人造石墨和天然石墨中的一种或多种。
在一些实施方式中，负极活性物质包括碳基材料和硅基材料。非限制性地，碳基材料和硅基材料的质量总和在负极活性物质总质量中的百分占比可以≥85％，可选地≥90％，进一步可选地≥95％，更进一步可选地≥96％等，更进一步可选地为100％等。非限制性地，石墨材料和硅基材料的质量总和在负极活性物质总质量中的百分占比还可以为下述任一种百分数、或者大于或等于下述任一种百分数且小于或等于100％、或者选自下述任两种百分数构成的区间：85％、86％、88％、90％、92％、94％、95％、96％、98％等。碳基材料和硅基材料的定义可参阅前文，例如，碳基材料可以为石墨材料。碳基材料和硅基材料的含量还可参阅上下文中任一合适的实施方式。
在一些实施方式中，负极活性物质包括碳基材料。非限制性地，碳基材料在负极活性物质中的质量百分占比可以≥85％，可选地≥90％，进一步可选地≥95％，更进一步可选地≥96％等，更进一步可选地为100％等。非限制性地，碳基材料在负极活性物质中的质量百分占比还可以为下述任一种百分数、或者大于或等于下述任一种百分数且小于或等于100％、或者选自下述任两种百分数构成的区间：85％、86％、88％、90％、92％、94％、95％、96％、98％等。碳基材料的定义可参阅前文，例如，碳基材料可以为石墨材料。
在一些实施方式中，负极活性材料层还可选地包括粘结剂。粘结剂可以包括但不限于丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的一种或多种。非限制性地，粘结剂在负极活性材料层中的质量百分比可以为0～10％，进一步可以为0～5％，更进一步可以为1％～5％，更进一步可选为1％～3％。
在一些实施方式中，负极活性材料层还可选地包括导电剂。作为非限制性示例，导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的一种或多种。在负极活性材料层中，导电剂的质量百分比可以为0～15％，进一步可选为0～10％，更进一步可选为0～5％。
在一些实施方式中，负极活性材料层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))。其他助剂在负极活性材料层中的质量百分比可以为0～15％，进一步可选为0～10％，更进一步可选为0～5％，更进一步可选为0～3％，更进一步可选为0～2％。
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性物质、导电剂、粘结剂和任意其他组分分散于溶剂(溶剂的非限制性示例如去离子水)中，形成负极浆料。进一步地，将负极浆料涂覆在负极集流体的至少一侧表面上，经烘干、冷压等工序后，即可得到负极极片。负极浆料所涂覆的负极集流体表面可以为负极集流体的单个表面上，也可以为负极集流体的两个表面上。负极浆料固含量可以为30wt％～70wt％，可选为40wt％～60wt％。负极浆料在室温下的粘度可以调整到2000mPa·s～10000mPa·s，可选为3000mPa·s～10000mPa·s。负极极片压实密度可以为1.2g/cm3～2.0g/cm3，可选为1.2g/cm3～1.8g/cm3。
以下对电解质进行说明。
电解质具有在正极极片和负极极片之间传导离子的作用。在本申请中，电解质包括液态电解质。液态电解质也可称为电解液，也即，电解质包括电解液。电解液包括电解质盐。
在一些实施方式中，电解质为电解液。
在一些实施方式中，电解液为非水电解质。进一步地，非水电解质包括电解质盐和溶剂。电解质盐的定义可参阅前文，至少包括第一电解质盐。在一些实施方式中，电解质盐还包括电解质锂盐。电解质盐的浓度通常可以为0.5mol/L～5mol/L。
在一些实施方式中，电解质锂盐可以包括六氟磷酸锂(LiPF6)、四氟硼酸锂(LiBF4)、高氯酸锂(LiClO4)、六氟砷酸锂(LiAsF6)、双氟磺酰亚胺锂(LiFSI)、双三氟甲磺酰亚胺锂(LiTFSI)、三氟甲磺酸锂(LiTFS)、二氟草酸硼酸锂(LiDFOB)、二草酸硼酸锂(LiBOB)、二氟磷酸锂(LiPO2F2)、二氟二草酸磷酸锂(LiDFOP)及四氟草酸磷酸锂(LiTFOP)中的一种或多种。
在一些实施方式中，非水电解质中的溶剂可以包括氟代碳酸乙烯酯(FEC)、碳酸乙烯酯(EC，)、碳酸亚丙基酯(PC，)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸丁烯 酯(BC，)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)及二乙砜(ESE)中的一种或多种。
在一些实施方式中，电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
在一些实施方式中，电解液中的添加剂可以包括但不限于氟代碳酸乙烯酯(FEC)、二氟碳酸乙烯酯(DFEC)、三氟甲基碳酸乙烯酯(TFPC)等中的一种或多种。
以下对隔离膜进行说明。
在一些实施方式中，二次电池中还包括隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可以包括玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的一种或多种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施方式中，隔离膜的厚度为6μm～40μm，可选为12μm～20μm。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在本申请的第二方面，提供一种二次电池，其包括本申请第一方面所描述的电池单体。
在本申请中，如无其他说明，“电池单体”指能够实现化学能和电能相互转化的基本单元，进一步地，通常而言至少包括正极极片、负极极片和电解质。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导活性离子的作用。电池单体的定义可参阅上下文，例如，可以参阅本申请第一方面。
可以理解，通常情况下，二次电池包括正极极片、负极极片、电解质和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
在一些实施方式中，二次电池为锂离子二次电池。
在一些实施方式中，二次电池为锂离子二次电池，电解质盐可以包括电解质锂盐。
在一些实施方式中，二次电池可包括外包装。该外包装可用于封装上述电极组件及电解质。
在一些实施方式中，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，进一步地，塑料的非限制性示例可以包括聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等中的一种或多种。
二次电池中包括至少一个电池单体。二次电池可以包括1个或多个电池单体。
本申请对电池单体的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图1是作为一个示例的方形结构的电池单体5。
在其中一些实施例中，参照图2，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于开口，以封闭容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于容纳腔内。电解液浸润于电极组件52中。电池单体5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据实际需求进行选择。
二次电池可以为电池模块4或电池包1。
电池模块包括至少一个电池单体。电池模块所含电池单体的数量可以为一个或多个，本领域技术人员可根据电池模块的应用和容量选择合适的数量。
图3是作为一个示例的电池模块4。参照图3，在电池模块4中，多个电池单体5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个电池单体5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个电池单体5容纳于该容纳空间。
在其中一些实施例中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以为一个或多个，本领域技术人员可根据电池包的应用和容量选择合适的数量。
图4和图5是作为一个示例的电池包1。参照图4和图5，在电池包1中可以包括电池箱和设 置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
在本申请的第三方面，提供一种用电装置，其包括本申请第一方面所描述的电池单体和本申请第二方面所描述的二次电池中的至少一种。
在一些实施方式中，本申请还提供一种用电装置，用电装置包括本申请提供的任一实施方式的二次电池。二次电池可以用作用电装置的电源，也可以用作用电装置的能量存储单元。用电装置可以包括移动设备、电动车辆、电气列车、船舶及卫星、储能系统等，但不限于此。其中，移动设备例如可以是手机、笔记本电脑等；电动车辆例如可以是纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车、电动摩托车、电动工具等，但不限于此。该用电装置还可以应用于军事装备、航空航天等领域，还可以应用于水力、火力、风力和太阳能电站等储能电源系统。
作为用电装置，可以根据其使用需求来选择二次电池。
图6是作为一个示例的用电装置6。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用二次电池作为电源。
以下，说明本申请的一些实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明技术或条件的，按照上文中的描述进行，或者按照本领域内的文献所描述的技术或条件，或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品，或者可通过市购产品按照常规方式合成。
下面的实施例中，室温是指20℃～30℃。
以下实施例以软包叠片电池为例，可以理解，二次电池的外包装方式不限于此。类似地，极耳的材料选取和装配方式也可以采用本领域的其他方式。
以下使用的正极活性物质的离子电导率采用如下方法测试：
将待测正极活性物质制成测试用正极极片，锂片作为负极极片，组装成纽扣电池进行测试；将电池以1C放电至3.0V后进行交流阻抗谱测试，测试参数选取：测试温度为25℃，扫描频率为0.1Hz～105Hz，电压振幅为5mV，利用Zview软件对测试结果进行拟合即得到离子电导率。
如无其他说明，测试用正极极片中，正极集流体选取铝箔，正极活性材料层中正极活性物质的质量百分比控制在95％±1％，粘结剂选用聚偏二氟乙烯(PVDF)，导电剂选用导电碳，压实密度为3.0g/cm3～3.6g/cm3。
对于第一正极活性物质和第二正极活性物质，化学式相同的原料来源相同或采用相同的方法制备获得，因此，化学式相同的原料的离子电导率基本相同。
实施例1.
(1)正极极片的制备：
将第一正极活性物质和第二正极活性物质、粘结剂聚偏二氟乙烯(PVDF)和导电碳加入到溶剂N-甲基吡咯烷酮(NMP)中，正极活性物质：粘接剂：导电剂的质量比例为95：2.5：2.5，在干燥房中搅拌制成均匀的正极浆料，控制正极浆料粘度为3000mPa·S～10000mPa·S，在铝箔的双侧表面上涂覆上述正极浆料，经过烘干、冷压处理制成正极极片。压实密度为3.4g/cm3。
第一正极活性物质为镍钴锰酸锂类氧化物(一种NCM类材料)，第二正极活性物质为磷酸锰铁锂类氧化物。
第一正极活性物质和第二正极活性物质的种类和含量比例(通过A值确定二者用量比)可参阅表1和表2。
A值为第一正极活性物质中的Co元素与第二正极活性物质中的Fe元素的质量比。
(2)负极极片的制备：
将石墨材料(人造石墨)、羧甲基纤维素钠、丁苯橡胶(SBR)和导电碳加入到溶剂去离子水中，石墨材料：羧甲基纤维素钠：丁苯橡胶：导电剂的质量比例为95：1：2.5：1.5，搅拌制成均匀的负极浆料，控制负极浆料的粘度为3000mPa·S～10000mPa·S，在铜箔的单侧表面上涂覆上述负极浆料，经过烘干、冷压处理制成负极极片。压实密度为1.55g/cm3。
(3)电解液的配制
电解液由电解质盐、溶剂和添加剂组成：电解质盐为六氟磷酸钠(NaPF6，第一阳离子盐)和六氟磷酸锂(LiPF6)，其中，电解质中钠元素的质量相对于钠元素和锂元素质量之和的相对百分 比为5wt％(对应B的目标值为5％)，六氟磷酸锂(电解质锂盐)在电解液中的浓度为1mol/L；溶剂为体积比1：1：1的碳酸乙烯酯(EC)、碳酸二乙酯(DEC)和碳酸二甲酯(DMC)；添加剂是氟代碳酸乙烯酯(FEC)，在电解液中的质量百分比为5wt％。
本例中，第一阳离子盐为六氟磷酸钠，第一阳离子为钠离子，电解质锂盐为六氟磷酸锂，电解液中的电解质盐由金属阳离子和阴离子组成，金属阳离子为钠离子和锂离子的组合，阴离子为六氟磷酸根离子。电解液中第一阳离子盐的种类和用量比还可参阅表1。
B值为第一阳离子盐在电解液的电解质盐中的质量百分比，数值上按照“第一阳离子的质量相对于电解质盐中各金属阳离子的总质量之比”计。
(4)隔离膜
采用聚乙烯(PE)多孔聚合薄膜作为隔离膜。
(5)电极组件及二次电池的制备：
将制备好的正极极片、负极极片和隔离膜按照Z字型叠片结构制成相应的电极组件(也即裸电芯)，将裸电芯在90℃的环境下真空烘干12h，随后进行正极极耳和负极极耳超声焊接，正极采用铝极耳，负极采用镍极耳，正极极耳和负极极耳位于电芯同侧，将极耳焊接后的电芯装入铝塑膜中进行顶侧封封装，注入电解液，静置，化成，老化，排气，进行第二次封装，获得预设容量(0.1Ah)的二次电池，该二次电池为示例性的软包叠片电池。在其他实施例中，可以采用硬壳方式。
实施例2～21采用与实施例1基本相同的方法制备二次电池，区别在于：第一正极活性物质的种类、第二正极活性物质的种类，第一正极活性物质和第二正极活性物质的用量比例A值、电解液中第一阳离子盐的种类、第一阳离子盐的用量(B值)，A/B值，以及负极活性物质的种类和用量，可参阅表1、表2和表3。
对比例1采用与实施例1基本相同的方法制备二次电池，区别在于：A值和A/B值不同。
对比例2采用与实施例1基本相同的方法制备二次电池，区别在于：B值和A/B值不同。
对比例3采用与实施例1基本相同的方法制备二次电池，区别在于：正极活性物质省略第二正极活性物质，仅使用第一正极活性物质，A值和A/B值不同。
对比例4采用与实施例1基本相同的方法制备二次电池，区别在于：正极活性物质省略第一正极活性物质，仅使用第二正极活性物质，A值和A/B值不同。
对比例5采用与实施例1基本相同的方法制备二次电池，区别在于：未添加第一阳离子盐，B值和A/B值不同。
对比例6采用与实施例8基本相同的方法制备二次电池，区别在于：A值、B值和A/B值不同。
对比例7采用与实施例12基本相同的方法制备二次电池，区别在于：A值、B值和A/B值不同。
对比例8采用与实施例16基本相同的方法制备二次电池，区别在于：B值和A/B值不同。
对比例9采用与对比例2基本相同的方法制备二次电池，区别在于：第二正极活性物质中的Mn元素和Fe元素的原子摩尔当量的比值(R2Mn/Fe)不同。
对比例1～9的制备参数可参阅表1至表3。
表1中的A值和B值是根据原料组成及用量比计算的设计值(对应各自的目标值)。表2中，Ni含量、Mn含量以及R2Mn/Fe为根据原料的化学组成得到的原子比，以原子数量比或原子摩尔比计。各实施例中，电解液的电解质盐中的阳离子为锂离子和第一阳离子的组合。电解液中第一阳离子盐的种类和用量比可参阅表1，根据B的目标值确定第一阳离子盐的用量；当电解质盐的阴离子不同时，以“第一阳离子的质量相对于电解质盐中各金属阳离子的总质量之比”确定第一阳离子盐的用量和B的目标值。
表1.

表1中，A值为第一正极活性物质中的Co元素与第二正极活性物质中的Fe元素的质量比(A)的目标值；第一阳离子为钠离子，B值为第一阳离子盐在电解液的电解质盐中的质量百分比(B)的目标值，数值上等于电解液中第一阳离子的质量相对于电解液中金属阳离子的质量的百分比计。
表2.

表2中：
第一正极活性物质中的“镍(Ni)含量”为Ni元素与锂(Li)元素的原子摩尔当量的比值，数值上也等于Ni元素与Li元素的原子比；
第一正极活性物质中的“锰(Mn)含量”为Mn元素与锂(Li)元素的原子摩尔当量的比值，数值上也等于Mn元素与Li元素的原子比；
R2Mn/Fe指第二正极活性物质中的Mn元素和Fe元素的原子摩尔当量的比值。
表3.

表3中，“硅基材料的质量百分比”表示负极活性物质中硅基材料所占的质量百分比。
测试与分析方法
1、电解液中第一阳离子盐的质量百分占比(B值)的测试分析：
基于GB/T36240-2018和离子色谱仪对电解液中电解质锂盐和第一阳离子盐进行定量测试，一定质量电解液样品中，电解质锂盐中锂离子的质量记为m1，第一阳离子盐中的第一阳离子的质量记为m2，则，B值可以按下述公式计算得到：B＝m2/(m1+m2)×100％。
2、第一正极活性物质中Ni元素、Co元素和Mn元素的含量测试，第二正极活性物质中Mn元素和Fe元素的含量测试及A值等元素比例的测试分析。
取正极活性材料层样品约0.4g(均精确至0.0001g)于25mL烧杯中，加2mL～5mL硝酸，放置过夜，然后置于电热板上，在100℃左右加热，用调压变压器调节输入电压控温，加热至正极活性材料层消化后加入0.5mL高氯酸，在约140℃加热消解，直至白烟冒尽为止，残渣应为白色，否则应再加硝酸和高氯酸重复消解，最后用7wt％盐酸溶解提取，视待测元素含量定容至适当体积后，上ICP-OES测试仪器(511OTCP-OESVDV)上开始测试，测试元素选择Ni、Co、Mn和Fe，仪器测试结果为各元素的质量百分数，则可以根据Ni元素和Co元素的摩尔质量和质量百分数获得第一正极活性物质的化学式以及第一正极活性物质中Mn元素的含量；去除第一正极活性物质中Mn的含量后可得到第二正极活性物质中Mn的质量百分比，根据第二正极活性物质中的Mn元素和Fe元素的摩尔质量以及质量百分比可获得第二活性物质的化学式。最后即可计算出第一正极活性物质中Co元素和第二正极活性物质中Fe元素的质量比(A值)以及其他与不同元素的原子摩尔比的比值，比如，第二正极活性物质中Mn元素和Fe元素的质量比(R2Mn/Fe)。
根据测试得到的A值和B值，可计算得到A/B值的测试分析结果。
3、电池能量密度测试
测试电池容量：将待测电池搁置3min；0.33C放电到下限截止电压(如2.5V)；搁置3min；0.33C恒流恒压充电到上限截止电压(如4.4V)，0.05C电流截止；搁置3min；0.33C放电到截止电压(此步得到电池容量)；搁置3min；计算得到电池首次放电所释放的能量值。将电池首次放电所释放算的能量值除以待测电池的质量即可得到电池的质量能量密度，单位为瓦时每千克(W·h/kg)。
4、热失控温度测试：
将待测的二次电池置于25℃恒温环境，2.5V～4.4V下，按照1C充电至4.4V，然后在4.4V下恒压充电至电流≤0.05C，静置5min，然后将二次电池在正极极耳中心、负极极耳中心、大面中心、侧面中心布置感温线用于监控电芯的温度；将布置感温线后的二次电池转移至热箱内，以5℃/min升温至60℃后保温5h，之后以5℃/min升温并每升温5℃就保温30min，升温升到120℃后以2℃/min升温并每升温2℃就保温30min直至电芯失效或者直至24h；提取对应的结束温度，作为“热失控温度”的测试结果。如果测试结束时仍未发生电芯失效，则记录“测试周期内未失效”。
电芯失效判断依据：爆炸或起火。
热失控温度越高，则二次电池的热稳定性越好，热安全性越高。
测试分析结果
关于第一正极活性物质原料在25℃时的离子电导率(σ1)，实施例1～12、17～21以及对比例1-3、5-7、9中使用的第一正极活性物质的离子电导率在1×10-3S/cm～3×10-3S/cm范围内，实施例13中使用的第一正极活性物质的离子电导率在3×10-3S/cm～5×10-3S/cm范围内，实施例14中使用的第一正极活性物质的离子电导率在5×10-3S/cm～7×10-3S/cm范围内，实施例15中使用的第一正极活性物质的离子电导率在7×10-3S/cm～9×10-3S/cm范围内，实施例16和对比例8中使用的第一正极活性物质的离子电导率在3.2×10-6S/cm～1×10-3S/cm范围内(3.2×10-6S/cm<σ1<1×10-3S/cm)。其中，实施例16的σ、实施例1～12和17～21的σ1、实施例13的σ1、实施例14的σ1、以及实施例15的σ1依次递增。
关于第二正极活性物质原料在25℃时的离子电导率(σ2)，实施例1-17、20-21以及对比例1-2、4-9中使用的第二正极活性物质的离子电导率在3×10-13S/cm～9×10-13S/cm范围内，实施例18-19中使用的第二正极活性物质的离子电导率在1×10-13S/cm～3×10-13S/cm范围内。实施例1-17、20-21的σ2均大于实施例18-19的σ2。
实施例1～21中，第一正极活性物质在25℃时的离子电导率(σ1)均满足σ1≥3.2×10-6S/cm， 大部分满足σ1≥1.7×10-3S/cm。第二正极活性物质在25℃时的离子电导率(σ2)满足均满足σ2≤10-9S/cm，还均满足σ2≤10-12S/cm，且大部分满足σ2≤8×10-13S/cm。实施例1～21中，第一正极活性物质在25℃时的离子电导率与第二正极活性物质在25℃时的离子电导率的比值(Xσ)均满足Xσ≥104，还均满足Xσ≥106，其中一部分满足Xσ≥1010。
根据B值的测试分析结果以及正极极片中正极活性物质的元素分析结果计算得出的A值，与表1中A和B的目标值基本吻合。
根据电池能量密度测试结果，实施例1-4、9-12、17、20-21和对比例1、2、5、7、9的电池质量能量密度均在235W·h/kg～255W·h/kg范围内，实施例13-15的电池质量能量密度均在240W·h/kg～270W·h/kg范围内，实施例5～8的电池能量密度介于实施例1-4的电池能量密度与实施例13～16的电池能量密度之间，实施例16和对比例3、6、8的电池质量能量密度均在235W·h/kg～265W·h/kg范围内，实施例18-19的电池质量能量密度均在220W·h/kg～245W·h/kg范围内，对比例4的电池质量能量密度在220W·h/kg～230W·h/kg范围内。
实施例1～21制得的各二次电池的均具有较好的热稳定性，热失控温度高，同时还具有良高的能量密度，综合电性能好。相对而言，对比文件1～9的综合性能明显变差：一些对比例的热失控温度明显降低，而且电池能量密度变化不大甚至有所下降，如对比例1、2、5、7和9相对于实施例1等，还如对比例6相对于实施例8，对比例8相对于实施例16；有的对比例(如对比例3)虽然电池能量密度相对于一些实施例有所提高，但热失控温度显著降低，综合性能不佳；有的对比例(如对比例4)则以显著牺牲电池能量密度为代价实现热稳定性的一些提升，综合性能不佳。
对比例1、对比例2、对比例7和对比例9的A/B值在0.47～202之外，相对于A/B值在0.47～202范围内的各实施例(如实施例1-4等)，对比例1、对比例2、对比例7和对比例9的热失控温度显著下降。
对比例3仅使用单一种类的第一正极活性物质，与实施例1-4相比，尽管对比例3的电池能量密度有所提高，但其热失控温度明显降低，综合性能劣于实施例1-4。
对比例4仅使用单一种类的第二正极活性物质，虽然热失控温度较高，但是电池能量密度非常低(220W·h/kg～230W·h/kg)，明显低于实施例1-4的电池能量密度(235W·h/kg～255W·h/kg)，综合性能劣于实施例1-4。
对比例5未添加第一阳离子，相对于添加了第一阳离子的各实施例(如实施例1)，热失控温度明显变劣。
对比例6和对比例8的A/B值在0.47～202之外，热失控温度较低。其中，相对于使用相同负极活性物质的实施例8，对比例6热失控温度明显较低；相对于使用相同负极活性物质的实施例16，对比例8热失控温度明显较低。
上文对各个实施方式和实施例的描述倾向于强调各个实施方式和实施例之间的不同之处，其相同或相似之处可以相互参考，为了简洁，本文不再赘述。
以上各实施方式和实施例的各技术特征可以进行任意的组合，为使描述简洁，未对上述各实施方式和实施例中的各个技术特征所有可能的组合都进行描述，然而，只要这些技术特征的组合不存在矛盾，都应当认为是本说明书记载的范围。
需要说明的是，本申请不限定于上述实施方式和实施例。上述实施方式和实施例仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。以上描述的实施方式和实施例仅表达了本申请的几种实施方式，其描述较为详细，但并不能因此而理解为对专利范围的限制。此外，在不脱离本申请主旨的范围内，对实施方式和实施例施加本领域技术人员能够想到的各种变形、将实施方式和实施例中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。

Claims (18)

  1. 一种电池单体，其包括正极极片、负极极片、隔离膜和电解液，所述隔离膜设置于所述正极极片和所述负极极片之间，所述正极极片包括正极活性材料层，所述正极活性材料层包括第一正极活性物质和第二正极活性物质，所述电解液包括电解质盐，所述电解质盐包括第一阳离子盐和电解质锂盐；
    其中，所述第一正极活性物质为包含Co元素和M1元素的锂氧化物，所述第二正极活性物质为包含Fe元素和Mn元素的锂氧化物，其中，所述第一正极活性物质中的M1元素包括Mn元素和Al元素中的一种或两种；
    所述第一正极活性物质中的Co元素与所述第二正极活性物质中的Fe元素的质量比记为A；
    所述第一阳离子盐包括第一阳离子，所述第一阳离子的离子半径大于锂离子的离子半径；所述第一阳离子盐在所述电解质盐中的质量百分比记为B；
    则A和B满足0.47≤A/B≤202。
  2. 根据权利要求1所述的电池单体，其中，在25℃条件下，所述第一正极活性物质的离子电导率与所述第二正极活性物质的离子电导率的比值记为Xσ，则Xσ≥104；
    可选地，Xσ≥106，进一步可选地Xσ≥1010；
    可选地，所述第一正极活性物质在25℃时的离子电导率为σ1，满足σ1≥3.2×10-6S/cm，进一步可选地σ1≥1.7×10-3S/cm；
    可选地，所述第二正极活性物质在25℃时的离子电导率为σ2，满足σ2≤10-9S/cm，进一步可选地σ2≤10-12S/cm。
  3. 根据权利要求1或2所述的电池单体，其中，1.3≤A/B≤25.4。
  4. 根据权利要求1～3中任一项所述的电池单体，其中，0.19≤A≤10.1；可选地，0.28≤A≤2.53。
  5. 根据权利要求1～4中任一项所述的电池单体，其中，5％≤B≤40％；可选地，10％≤B≤20％。
  6. 根据权利要求1～5中任一项所述的电池单体，其中，所述第一正极活性物质满足如下特征中的一项或多项：
    Co元素相对于Li元素的原子摩尔比记为Rc，则Rc满足0.05≤Rc≤0.5，可选地，0.05≤Rc≤0.3，可选地，0.05≤Rc≤0.2；
    所述M1元素相对于Li元素的原子摩尔比记为Rd，则Rd满足0.05≤Rd≤0.5，可选地，0.05≤Rd≤0.3；
    所述M1元素包括Mn元素，Mn元素相对于Li元素的原子摩尔比记为Rd-Mn，则Rd-Mn满足0.05≤Rd-Mn≤0.4，进一步可选地，0.05≤Rd-Mn≤0.3；
    Co元素与所述M1元素的原子摩尔当量之和相对于Li元素的原子摩尔当量的比值记为Rc+d，则Rc+d满足0.1≤Rc+d≤0.5，进一步可选地，0.1≤Rc+d≤0.3，更进一步可选地，0.1≤Rc+d≤0.2。
  7. 根据权利要求1～6中任一项所述的电池单体，其中，所述第一正极活性物质还包含Ni元素；在所述第一正极活性物质中，Ni元素相对于Li元素的原子摩尔比记为Rb，则Rb满足0.5≤Rb<1；
    可选地，0.5≤Rb≤0.9；
    进一步可选地，0.6≤Rb≤0.9；
    更进一步可选地，0.65≤Rb≤0.9；
    更进一步可选地，0.8≤Rb≤0.9。
  8. 根据权利要求1～5中任一项所述的电池单体，其中，以Li元素的原子摩尔当量Qa为0.75～1.2计，可选地以0.8～1.1计，进一步可选地以0.9～1.05计，更进一步可选地以1计，所述第一正极活性物质满足如下特征中的一项或多项：
    Co元素的原子摩尔当量Qc≤0.4，可选地，Qc≤0.3，进一步可选地，Qc≤0.2；
    所述M1元素的原子摩尔当量Qd≤0.5，可选地，Qd≤0.4，进一步可选地，Qd≤0.3；
    所述M1元素包括Mn元素，Mn元素的原子摩尔当量≤0.4，可选地，Mn元素的原子摩尔当量≤0.3；
    Co元素和所述M1元素的原子摩尔当量之和Qc+d≤0.5，可选地，Qc+d≤0.4，Qc+d≤0.3，Qc+d≤0.2。
  9. 根据权利要求8所述的电池单体，其中，所述第一正极活性物质包含Ni元素，Ni元素的原子摩尔当量Qb满足0.5≤Qb<1，可选地，0.6≤Qb<1，进一步可选地，0.65≤Qb<1。
  10. 根据权利要求1～5中任一项所述的电池单体，其中，所述第一正极活性物质包括第一本体，还包括或不包括位于所述第一本体的至少一部分表面的第一包覆层；其中，所述第一本体的化学组成为LiaNibCocM1dM2eOfRg，其中，0.75≤a≤1.2，0<b<1，0<c<1，0<d<1，0≤e≤0.2，b+c+d+e＝1，1≤f≤2.5，0≤g≤1，f+g≤3，所述第一正极活性物质中的M2元素包括Zr、Zn、Cu、Cr、Mg、Fe、 V、Ti、Sr、Sb、Y、W和Nb中的一种或多种，所述第一正极活性物质中的R元素包括N、F、S和Cl中的一种或多种；
    可选地，0.8≤a≤1.2，进一步可选地，0.9≤a≤1.1，进一步可选地，0.95≤a≤1.05；
    可选地，0.5≤b<1，进一步可选地，0.5≤b≤0.9，更进一步可选地，0.6≤b≤0.9；
    可选地，0.05≤c<1，进一步可选地，0.05≤c≤0.5，更进一步可选地，0.05≤c≤0.3；
    可选地，0.05≤d<1，进一步可选地，0.05≤d≤0.5，更进一步可选地，0.05≤d≤0.3；
    可选地，0≤e<0.1，进一步可选地，0≤e≤0.05，更进一步可选地，0≤e≤0.03；
    可选地，1≤f≤2.1，进一步可选地，1.8≤f≤2.05，更进一步可选地，1.95≤f≤2.05；
    可选地，0≤g<0.5，进一步可选地，0≤g≤0.1，更进一步可选地，0≤g≤0.05。
  11. 根据权利要求1～10中任一项所述的电池单体，其中，所述第二正极活性物质满足如下特征中的一项或多项：
    Mn元素和Fe元素的原子摩尔比为0.42～9，可选地，Mn元素和Fe元素的原子摩尔比为0.66～4；
    以Li元素的原子摩尔当量为0.9～1.1计，可选地以0.9～1.05计，进一步可选地以1计，Mn元素的原子摩尔当量为0.5～0.999，可选地，Mn元素的原子摩尔当量为0.5～0.6；
    以Li元素的原子摩尔当量为0.9～1.1计，可选地以0.9～1.05计，进一步可选地以1计，Fe元素的原子摩尔当量为0.001～0.5，可选地，Fe元素的原子摩尔当量为0.4～0.5。
  12. 根据权利要求1～10中任一项所述的电池单体，其中，所述第二活性物质包括第二本体，还包括或不包括位于所述第二本体表面至少一部分的第二包覆层；其中，所述第二本体的化学式为Li1+xMn1-y-wFewM3yP1-zQzO4，其中，-0.1≤x≤0.1，0.1≤w≤0.5，0.001≤y≤0.5，0.001≤z≤0.1，所述第二活性物质中的M3元素包括Zn、Al、Na、K、Mg、Mo、W、Ti、V、Zr、Ni、Co、Ga、Sn、Sb、Nb和Ge中的一种或多种元素，所述第二活性物质中的Q元素包括B、Si、N、S、F、Cl和Br中的一种或多种元素；
    可选地，0.1≤y≤0.5，进一步可选地，0.2≤y<0.5，更进一步可选地，0.3≤y<0.5；
    可选地，0.2≤w≤0.5，进一步可选地，0.3≤w<0.5，更进一步可选地，0.4≤w<0.5；
    可选地，0.001≤z≤0.1，进一步可选地，0.001≤z<0.05，更进一步可选地，0.001≤z<0.002；
    可选地，所述第二活性物质中的M3元素包括Ti、V、Ni、Co和Mg中一种或多种元素；
    可选地，所述第二活性物质中的Q元素包括B、Si、N和S中的一种元素；
    可选地，所述第二包覆层包括焦磷酸盐、磷酸盐和碳中的一种或多种；
    可选地，所述第二包覆层为单层结构或多层结构。
  13. 根据权利要求1～12中任一项所述的电池单体，其中，所述第一正极活性物质和所述第二正极活性物质在所述正极活性材料层中的总质量占比RI+II≥85％；
    可选地，RI+II≥90％；
    进一步可选地，RI+II≥95％。
  14. 根据权利要求1～13中任一项所述的电池单体，其中，所述第一阳离子包括碱金属元素和碱土金属元素中的一种或多种元素的阳离子；
    可选地，所述第一阳离子包括钠离子、钾离子、钙离子和镁离子中的一种或多种；
    可选地，所述第一阳离子盐中的阴离子包括六氟磷酸根离子、高氯酸根离子、四氟硼酸根离子、双三氟甲基磺酰亚胺根离子、三氟甲磺酸根离子、双氟磺酰基酰亚胺根离子和三(三氟甲基磺酰)甲基离子中的一种或多种；
    进一步可选地，所述第一阳离子盐包括六氟磷酸钠、高氯酸钠、四氟硼酸钠、双三氟甲基磺酰亚胺钠、三氟甲磺酸钠、双氟磺酰基酰亚胺钠、三(三氟甲基磺酰)甲基钠、六氟磷酸钾、高氯酸钾、四氟硼酸钾、双三氟甲基磺酰亚胺钾、三氟甲磺酸钾、双氟磺酰基酰亚胺钾和三(三氟甲基磺酰)甲基钾中的一种或多种；
    更进一步可选地，所述第一阳离子盐包括六氟磷酸钠、四氟硼酸钠和高氯酸钠中的一种或两种。
  15. 根据权利要求1～14中任一项所述的电池单体，其中，所述负极极片包括负极活性材料层，所述负极活性材料层包括负极活性物质，所述负极活性物质包括硅基材料；所述硅基材料在所述负极活性物质中所占的质量百分比记为X1，
    可选地，X1≥3％，进一步可选为3％≤X1≤50％；
    可选地，所述硅基材料包括单质硅、硅氧化物、硅碳复合物、硅氮复合物、硅合金、硅石墨烯复合材料、硅碳纳米管和含硅导电聚合物中的一种或多种。
  16. 一种二次电池，其包括权利要求1～15任一项中所述电池单体。
  17. 根据权利要求16所述的二次电池，其中，所述二次电池为锂离子二次电池。
  18. 一种用电装置，其包括权利要求1～15任一项中所述电池单体和权利要求16或17所述二次电池中的至少一种。
PCT/CN2024/118339 2023-11-30 2024-09-11 电池单体、二次电池和用电装置 Pending WO2025112796A1 (zh)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010277958A (ja) * 2009-06-01 2010-12-09 Hitachi Chem Co Ltd リチウムイオン二次電池
CN116779980A (zh) * 2023-06-28 2023-09-19 宁德时代新能源科技股份有限公司 电池单体及其制备方法、电池及用电装置
CN116868376A (zh) * 2023-04-18 2023-10-10 宁德时代新能源科技股份有限公司 正极活性材料组合物、正极极片、电池及用电装置
CN117013054A (zh) * 2022-04-29 2023-11-07 复旦大学 一种混合锂钠电池

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010277958A (ja) * 2009-06-01 2010-12-09 Hitachi Chem Co Ltd リチウムイオン二次電池
CN117013054A (zh) * 2022-04-29 2023-11-07 复旦大学 一种混合锂钠电池
CN116868376A (zh) * 2023-04-18 2023-10-10 宁德时代新能源科技股份有限公司 正极活性材料组合物、正极极片、电池及用电装置
CN116779980A (zh) * 2023-06-28 2023-09-19 宁德时代新能源科技股份有限公司 电池单体及其制备方法、电池及用电装置

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