WO2022155861A1 - 正极活性材料、锂离子二次电池、电池模块、电池包和用电装置 - Google Patents
正极活性材料、锂离子二次电池、电池模块、电池包和用电装置 Download PDFInfo
- Publication number
- WO2022155861A1 WO2022155861A1 PCT/CN2021/073158 CN2021073158W WO2022155861A1 WO 2022155861 A1 WO2022155861 A1 WO 2022155861A1 CN 2021073158 W CN2021073158 W CN 2021073158W WO 2022155861 A1 WO2022155861 A1 WO 2022155861A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- positive electrode
- active material
- electrode active
- lithium
- battery
- Prior art date
Links
Images
Classifications
-
- 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
- H01M4/362—Composites
- H01M4/366—Composites as layered products
-
- 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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
-
- 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
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2220/00—Batteries for particular applications
- H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
-
- 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
-
- 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 belongs to the field of electrochemical technology. More specifically, the present application relates to positive electrode active materials, lithium ion secondary batteries, battery modules, battery packs, and electrical devices.
- secondary batteries especially lithium-ion secondary batteries
- Lithium iron phosphate is one of the most widely used cathode active materials for lithium-ion batteries. Compared with ternary cathode active materials, it has significant advantages in safety performance, cycle performance and cost, and is widely used in commercial vehicles, passenger vehicles and large-scale energy storage fields.
- lithium-ion secondary batteries prepared from traditional lithium iron phosphate materials often have low energy density and cannot meet the needs of some large-scale electrical devices. higher requirements.
- the present application develops a positive electrode active material with high gram capacity and high powder compaction density, and a lithium ion secondary battery with high energy density.
- the present application provides a positive electrode active material with high gram capacity and high powder compaction density.
- the lithium ion secondary battery prepared from the positive electrode active material of the present application has improved energy density It also has excellent cycle performance under the premise of density.
- An object of the present application is to provide a positive electrode active material with high gram capacity.
- An object of the present application is to provide a positive electrode active material with improved powder compaction density.
- An object of the present application is to provide a lithium ion secondary battery with high energy density.
- a first aspect of the present application provides a positive electrode active material comprising a substrate and a coating layer, the coating layer wraps the substrate, and the coating layer includes a fast ion conductor layer and a carbon coating layer,
- the matrix includes one or more of the compounds of formula (I):
- M1 is one or more selected from Cu, Mn, Cr, Zn, Pb, Ca, Co, Ni, Sr, Nb and Ti, 0 ⁇ a ⁇ 0.01,
- the fast ion conductor layer comprises a fast ion conductor with a NASICON structure as shown in formula (II),
- M2 is one or more selected from Ti, Zr, Hf, Ge, and Sn with a valence of +4, and 0 ⁇ b ⁇ 1.
- the positive electrode active material of the first aspect of the present application fully utilizes the advantages of low cost, high safety performance and good cycle stability of lithium iron phosphate, and at the same time utilizes the coating layer (fast ion conductor layer with NASICON structure fast ion conductor and Carbon coating layer), which solves the disadvantages of poor electronic conductivity and ionic conductivity of lithium iron phosphate, thereby improving the gram capacity and powder compaction density of lithium iron phosphate.
- the lithium ion secondary battery prepared from the positive electrode active material of the first aspect of the present application has a significantly improved energy density on the premise of excellent cycle performance.
- the LiFe 1- a M1 a PO 4 and the Li 3-b Fe 2-b M2 b (PO 4 ) 3 The molar ratio is (1-x):x, and 0 ⁇ x ⁇ 0.005.
- the positive electrode active material of the present application when the molar weight x of the fast ion conductor of the NASICON structure is 0 ⁇ x ⁇ 0.005, the positive electrode active material has an excellent gram capacity. Introducing an appropriate amount of fast ion conductors with NASICON structure into lithium iron phosphate can effectively solve the problem of poor ionic conductivity, improve the gram capacity of lithium iron phosphate, and improve the energy density of corresponding lithium ion secondary batteries.
- the mass percentage content C% of carbon in the positive electrode active material is 1%-1.5%, and the specific surface area S of the positive electrode active material is 10-15 m 2 /g , the ratio of the specific surface area S of the positive electrode active material to the carbon content C% satisfies 9 ⁇ S/C ⁇ 12.
- the carbon coating layer is an important component to improve the overall electronic conductivity of the positive electrode active material of the present application.
- the carbon coating layer is loose and porous, which can make the electrolyte and the lithium iron phosphate matrix fully and effectively contact, ensure the transport of lithium ions at the phase interface, and improve the energy density of lithium ion secondary batteries.
- a suitable carbon content (1% to 1.5%) can significantly improve the active electron conductivity of the positive electrode, thereby increasing the energy density of the lithium ion secondary battery.
- carbon is an inactive material. When the amount of carbon coating is too large, the proportion of active material decreases, which reduces the overall gram capacity of the positive active material.
- the main contributor to its specific surface area is the loose and porous carbon coating.
- the specific surface area (10-15m 2 /g) of the positive electrode active material in a suitable range helps to increase the contact area between the electrolyte and the positive electrode active material, improves the reaction kinetics of the battery, and is beneficial to the improvement of the energy density of the battery.
- the ratio of carbon content and specific surface area of the positive electrode active material of the present application, S/C has a great influence on the gram capacity of the positive electrode active material and the cycle performance of the lithium ion secondary battery. Under the condition that the powder compaction density is basically the same, when the ratio S/C of the mass percentage of carbon in the positive electrode active material and the specific surface area of the positive electrode active material is within a reasonable range, the positive electrode active material has a high gram capacity, and the corresponding lithium ion The secondary battery also has excellent cycle performance.
- free lithium is present in the positive electrode active material.
- the free lithium in this application is inactive free lithium that cannot be inserted into/extracted from the positive electrode active material, which is unavoidable in the process of synthesizing lithium iron phosphate positive electrode active materials, and generally exists in the form of lithium iron phosphate in the form of lithium iron phosphate matrix. Outside the phase structure, it is different from the active lithium located in the bulk phase structure of the lithium iron phosphate matrix.
- the pH of the positive electrode active material is not less than 9.
- the existence of the ion conductor layer of the fast ion conductor with the NASICON structure accelerates the dissolution of the active lithium in the lithium iron phosphate matrix phase structure of the present application, so that the positive electrode active material of the present application has a higher energy content than only carbon-coated but no fast-acting lithium.
- the pH of the lithium iron phosphate of the ion conductor layer is the pH of the lithium iron phosphate of the ion conductor layer.
- free lithium exists in the positive electrode active material, and the pH of the positive electrode active material and the mass percentage content of the free lithium N Li+ % satisfy 0.15 ⁇ pH-(36N Li+ +8) ⁇ 1.1.
- pH-(36N Li+ +8) is positively correlated with the dissolution of active lithium in the bulk phase structure of lithium iron phosphate matrix.
- the active lithium in the iron-lithium matrix bulk structure is easier to dissolve.
- the value of pH-(36N Li+ +8) is within a reasonable range, the corresponding positive active material has excellent gram capacity and excellent cycle performance.
- the volume average particle size of the positive electrode active material satisfies 1 ⁇ m ⁇ Dv50 ⁇ 2 ⁇ m, and 0.4 ⁇ m ⁇ Dv10 ⁇ 0.7 ⁇ m.
- the overall particle size distribution of the positive electrode active material is reasonable, which is beneficial to improve the powder compaction density of the positive electrode active material of the present application , which is beneficial to improve the compaction density of the positive pole piece, thereby improving the energy density of the lithium ion secondary battery.
- the powder compaction density of the positive electrode active material of the present application is related to the particle size distribution of the positive electrode active material and the particle size of the primary particles. A reasonable particle size distribution of the positive electrode active material and a larger primary particle size are beneficial to the positive electrode active material powder. An increase in the compaction density of the body.
- the positive electrode active material is primary particles or quasi-single crystals.
- Increasing the particle size of the primary particles of the positive electrode active material is another way to increase the powder compaction density of the positive electrode active material.
- the larger the primary particle size of the positive electrode active material the larger the powder compaction density, which is beneficial to improve the energy density of the corresponding lithium ion secondary battery.
- the powder compaction density ⁇ of the positive electrode active material is greater than or equal to 2.5 g/cm 3 .
- the powder of the positive electrode active material has high compaction density
- the positive electrode piece prepared therefrom has high compaction density
- the corresponding lithium ion secondary battery has high energy density.
- the powder resistivity R of the positive electrode active material is less than or equal to 11 ⁇ cm.
- the positive electrode active material of the present application has a significantly lower powder resistivity, indicating that the arrangement of the carbon coating layer can significantly reduce the resistance of the positive electrode active material.
- a second aspect of the present application provides a lithium ion secondary battery, including the positive electrode material of the first aspect of the present application.
- the lithium ion secondary battery provided by the second aspect of the present application has an improved energy density because it includes a positive electrode active material having an improved gram capacity and an improved powder compaction density.
- the lithium ion secondary battery is a coin-type battery, and in the 0.1C charge-discharge curve of the coin-type battery, there is a charge-discharge curve in the voltage range of 2.5-2.9Vvs Li + discharge platform.
- This platform can prove the existence of NASICON fast ion conductor contained in the positive electrode active material of the present application.
- a third aspect of the present application provides a battery module including the lithium ion secondary battery of the second aspect of the present application.
- a fourth aspect of the present application provides a battery pack including one or more of the lithium ion secondary battery of the second aspect of the present application or the battery module of the third aspect of the present application.
- a fifth aspect of the present application provides an electrical device, comprising more than one of the lithium ion secondary battery of the second aspect of the present application, the battery module of the third aspect of the present application, or the battery pack of the fourth aspect of the present application;
- the lithium ion secondary battery or battery module or battery pack can be used as a power source for an electrical device or as an energy storage unit for an electrical device.
- the application provides a positive electrode active material.
- a positive electrode active material By modifying lithium iron phosphate, a positive electrode active material with both a fast ion conductor layer and a carbon coating layer of NASICON structure is synthesized.
- the relationship between specific surface area and carbon content, pH, free lithium content, and the relationship between limited pH and free lithium content can improve the ionic and electronic conductivity of lithium ions at the phase interface, thereby improving the gram capacity of lithium iron phosphate.
- the present application also obtains a positive electrode active material with high powder compaction density and high electrode sheet compaction by improving the particle size distribution of primary particles and increasing the primary particle size of lithium iron phosphate.
- the ion secondary battery has improved energy density and excellent cycle performance.
- FIG. 1 is a schematic structural diagram of a positive electrode active material according to an embodiment of the present application.
- FIG. 2 is a schematic diagram illustrating the influence of different primary particle sizes on powder compaction according to an embodiment of the present application.
- Example 3 is a 0.1C charge-discharge curve diagram of the coin cell corresponding to the positive electrode active materials of Example 1 and Comparative Example 1 of the present application.
- FIG. 4 is a charge-discharge curve diagram of the coin cell corresponding to the positive electrode active material of Example 1 and Comparative Example 1 of the present application in the voltage range of 2.5-2.9 Vvs Li + .
- FIG. 5 is a schematic diagram of a lithium ion secondary battery according to an embodiment of the present application.
- FIG. 6 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 5 .
- FIG. 7 is a schematic diagram of a battery module according to an embodiment of the present application.
- FIG. 8 is a schematic diagram of a battery pack according to an embodiment of the present application.
- FIG. 9 is an exploded view of the battery pack according to the embodiment of the present application shown in FIG. 8 .
- FIG. 10 is a schematic diagram of an electrical device according to an embodiment of the present application.
- any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with any other lower limit to form an unspecified range, and similarly any upper limit can be combined with any other upper limit to form an unspecified range.
- each individually disclosed point or single value can itself serve as a lower or upper limit in combination with any other point or single value or with other lower or upper limits to form a range not expressly recited.
- Lithium iron phosphate is currently the most widely used cathode active material for lithium-ion batteries. Compared with ternary materials, it has significant advantages in safety performance, cycle performance and cost, and is widely used in commercial vehicles, passenger vehicles and large-scale energy storage. However, lithium-ion secondary batteries prepared from traditional lithium iron phosphate often have low energy density and cannot meet the needs of some large-scale electrical devices. put forward higher requirements.
- lithium iron phosphate limits its gram capacity. Compared with ternary materials, lithium iron phosphate has poor ionic conductivity and electronic conductivity of about 10 -9 S/cm, which is five orders of magnitude lower than ternary materials with two-dimensional diffusion channels.
- the nanosized lithium iron phosphate makes the compaction density of the pole piece low.
- it is currently alleviated by nanometerization of lithium iron phosphate.
- the nanosized lithium iron phosphate determines its low spatial density, which in turn leads to low powder and electrode compaction, and ultimately to low volumetric energy density of the secondary battery.
- the pole piece compaction density is typically 2.4 g/cm 3 .
- the inventors of the present application have synthesized a positive electrode active material with a NASICON structure of a fast ion conductor layer and a carbon coating layer by modifying lithium iron phosphate through a lot of research and experiments.
- Carbon content, specific surface area, the relationship between limited specific surface area and carbon content, pH, free lithium content, limited pH and the relationship between free lithium content improve the ionic conductivity and electronic conductivity of lithium ions at the phase interface, and then improve iron phosphate
- the gram capacity of lithium is a positive electrode active material with a NASICON structure of a fast ion conductor layer and a carbon coating layer by modifying lithium iron phosphate through a lot of research and experiments.
- the positive electrode active material of the present application includes a matrix and a coating layer, the coating layer covers the matrix, and the coating layer includes a fast ion conductor layer and a carbon coating layer,
- the matrix includes one or more of the compounds of formula (I):
- M1 is one or more selected from Cu, Mn, Cr, Zn, Pb, Ca, Co, Ni, Sr, Nb and Ti, 0 ⁇ a ⁇ 0.01,
- the fast ion conductor layer comprises a fast ion conductor with a NASICON structure as shown in formula (II),
- M2 is one or more selected from Ti, Zr, Hf, Ge, and Sn with a valence of +4, and 0 ⁇ b ⁇ 1.
- the positive active material is the raw material for providing lithium ions.
- the properties of the material itself and the properties of the phase interface in contact with the electrolyte directly affect the extraction and insertion of lithium ions, which in turn affects lithium ions. Energy density of secondary batteries.
- Lithium iron phosphate is a positive active material for lithium ion secondary batteries with high safety performance, good structural stability and low cost, but the biggest drawback is that the corresponding lithium ion secondary battery has a low energy density, which is significantly lower than that of ternary materials. .
- this application develops and designs a positive electrode active material with high gram capacity and high powder compaction density by modifying lithium iron phosphate, and the lithium ion secondary battery prepared therefrom has significantly improved energy density.
- the positive electrode active material of the present application is a coating structure in which a coating layer coats a substrate, and the coating layer coats the substrate.
- the matrix includes LiFe 1-a M1 a PO 4 , optionally, M1 is selected from one or more of Cu, Mn, Cr, Zn, Pb, Ca, Co, Ni, Sr, Nb and Ti, optionally, 0 ⁇ a ⁇ 0.01.
- LiFe 1-a M1 a PO 4 is selected as the matrix, for example, LiFePO 4 , which can make full use of the advantages of lithium iron phosphate relative to ternary materials, improve the safety performance and structural performance of lithium ion secondary batteries prepared from it, and improve the performance of lithium ion secondary batteries. Reduce the synthesis cost of lithium-ion secondary batteries.
- the coating layer is set up to make up for the poor ion conductivity and electronic conductivity of lithium iron phosphate, which can significantly improve the ionic conductivity and electronic conductivity of lithium iron phosphate, thereby increasing the gram capacity of lithium iron phosphate, thereby increasing the corresponding lithium ion The energy density of the secondary battery.
- the coating layer includes a fast ion conductor layer. Specifically, the arrangement of the fast ion conductor layer enables the positive electrode active material of the present application to have the following advantages:
- the introduction of a fast ion conductor layer can improve the transport rate of lithium ions at the positive end for multiple de/intercalation.
- the fast ion conductor layer includes a fast ion conductor Li 3-b Fe 2-b M2 b (PO 4 ) 3 with a NASICON structure, optionally, M2 is selected from +4 valence Ti, Zr, Hf, Ge and Sn more than one of, optionally, 0 ⁇ b ⁇ 1.
- the fast ion conductor Li 3-b Fe 2-b M2 b (PO 4 ) 3 with NASICON structure is a material with ultrafast ion conductivity, rich in three-dimensional lithium ion diffusion and transport channels, and can be used in multiple de/intercalation.
- the lithium process has the advantages of high ion conduction efficiency and strong structural stability.
- coating a fast ion conductor layer containing a NASICON structure fast ion conductor on the surface of the lithium iron phosphate substrate can significantly improve the transfer rate of lithium ions at the positive end for multiple desorption/intercalation, and improve the ionic conductivity of the positive electrode active material. , thereby increasing the gram capacity, and further increasing the energy density of the corresponding lithium-ion secondary battery.
- the fast ion conductor with NASICON structure can be Li 2 FeTi(PO 4 ) 3 , Li 2 FeZr(PO 4 ) 3 , Li 2 FeSn(PO 4 ) 3 , or any two or three of the above combination.
- the coating layer further includes a carbon coating layer.
- the carbon coating layer can be coated on the surface of the fast ion conductor layer by an organic carbon source, such as glucose, polyethylene glycol, etc., through a carbonization process.
- the carbon coating layer may partially cover the fast ion conductor layer, or may completely cover the fast ion conductor layer.
- the arrangement of the carbon coating layer can significantly improve the electronic conductivity of the lithium iron phosphate, make up for the defect of the poor electronic conductivity of the lithium iron phosphate, and improve the energy density of the lithium ion secondary battery.
- the arrangement of the carbon coating layer enables the positive electrode active material of the present application to have the following advantages:
- the carbon coating layer in the positive electrode active material of the present application provides a suitable channel for the transmission of electrons, which can significantly improve the conduction rate of electrons in the process of multiple desorption/intercalation of lithium, improve the electronic conductivity of lithium iron phosphate, and improve the corresponding lithium Energy density of ion secondary batteries.
- the carbon coating layer of the positive electrode active material of the present application is loose and porous, which enables the electrolyte to be fully and effectively contacted with the lithium iron phosphate matrix, thereby improving the transfer rate of lithium ions at the phase interface and improving the secondary lithium ion.
- the energy density of the battery is loose and porous, which enables the electrolyte to be fully and effectively contacted with the lithium iron phosphate matrix, thereby improving the transfer rate of lithium ions at the phase interface and improving the secondary lithium ion.
- Coating a carbon coating layer on the surface of the lithium iron phosphate substrate can also improve the structural stability of the positive electrode active material, and effectively prevent the iron dissolution phenomenon of the positive electrode active material during the long-term storage and recycling of the lithium ion secondary battery. The cycle life of the lithium-ion secondary battery is guaranteed.
- the positive electrode active material of the present application uses lithium iron phosphate as the base material, and fully utilizes the advantages of low cost, high safety performance and good cycle stability of lithium iron phosphate, and at the same time utilizes the coating layer (fast ion conductor layer and carbon coating layer) to solve the drawbacks of its poor electronic conductivity and ionic conductivity.
- the lithium ion secondary battery prepared from the positive electrode active material of the present application has a significantly improved energy density under the premise of excellent cycle performance.
- the molar amount of the LiFe 1-a M1 a PO 4 and the Li 3-b Fe 2-b M2 b (PO 4 ) 3 The ratio is (1-x):x, and 0 ⁇ x ⁇ 0.005.
- the inventors found that in the positive electrode active material of the present application, the molar weight x of the fast ion conductor of the NASICON structure has a great influence on the gram capacity of the positive electrode active material.
- Introducing an appropriate amount of fast ion conductors with NASICON structure into lithium iron phosphate can effectively solve the problem of poor ionic conductivity, improve the gram capacity of lithium iron phosphate, and improve the energy density of corresponding lithium ion secondary batteries.
- the theoretical gram capacity of the fast ion conductor itself is not high, and further increasing its content in a suitable range cannot further improve the gram capacity.
- x can be 0.001, 0.002, 0.003, 0.005, or its value is in the range obtained by combining any two of the above-mentioned values.
- the mass percentage content C% of carbon in the positive electrode active material is 1%-1.5%
- the specific surface area S of the positive electrode active material is 10-15 m 2 /g
- the The ratio of the specific surface area S of the positive electrode active material to the mass percentage content of carbon C% satisfies 9 ⁇ S/C ⁇ 12.
- the carbon coating layer is an important component to improve the overall electronic conductivity of the positive electrode active material of the present application.
- the carbon coating layer is loose and porous, which can make the electrolyte and the lithium iron phosphate matrix fully and effectively contact, ensure the transport of lithium ions at the phase interface, and improve the energy density of lithium ion secondary batteries.
- a suitable carbon content (1% to 1.5%) can significantly improve the active electron conductivity of the positive electrode, thereby increasing the energy density of the lithium ion secondary battery.
- carbon is an inactive material. When the amount of carbon coating is too large, the proportion of active material decreases, which reduces the overall gram capacity of the positive active material.
- the main contributor to its specific surface area is the loose and porous carbon coating.
- the specific surface area (10-15m 2 /g) of the positive electrode active material in a suitable range helps to increase the contact area between the electrolyte and the positive electrode active material, improves the reaction kinetics of the battery, and is beneficial to the improvement of the energy density of the battery.
- the active specific surface area of the positive electrode When the active specific surface area of the positive electrode is too small, it means that the specific surface contribution of the carbon coating layer is too small, which means that the carbon coating layer is not loose and porous enough, so it is not conducive to the extraction/insertion of lithium ions, thus affecting the energy density and cycle performance of the battery. .
- the carbon content C% in the positive active material affects the specific surface S of the positive active material, and the change of the specific surface S of the positive active material is mainly affected by the carbon content.
- the cycle performance of the lithium ion secondary battery is affected.
- the ratio S/C of the carbon content to the specific surface area of the positive electrode active material of the present application has a great influence on the gram capacity of the positive electrode active material and the cycle performance of the lithium ion secondary battery.
- the ratio S/C of the carbon content and specific surface area of the cathode active material can be interpreted as the specific surface area of the cathode active material per unit carbon content.
- the size of this ratio can reflect, on the one hand, the looseness of the carbon coating layer of the positive electrode active material of the present application, and on the other hand, can reflect the coating integrity of the carbon coating layer in the positive electrode active material.
- the powder compaction density is basically the same, the larger the ratio S/C of the mass percentage of carbon in the positive electrode active material to the specific surface area of the positive electrode active material, the higher the deduction capacity per gram, and the corresponding lithium ion secondary The higher the energy density of the battery, however, when the ratio S/C of the mass percentage of carbon in the positive electrode active material to the specific surface area of the positive electrode active material is too large, the cycle life of the corresponding lithium ion secondary battery will be affected.
- the ratio S/C of the carbon content to the specific surface area of the positive electrode active material may be 9.53, 10.15, 11.67, or a range obtained by combining any two of the above values.
- free lithium is present in the positive electrode active material.
- the pH of the positive active material is not less than 9.
- the free lithium in this application is inactive free lithium that cannot be inserted into/extracted from the positive electrode active material, which is unavoidable in the process of synthesizing lithium iron phosphate positive electrode active materials, and generally exists in the form of lithium iron phosphate in the form of lithium iron phosphate matrix. Outside the phase structure, it is different from the active lithium located in the bulk phase structure of the lithium iron phosphate matrix.
- the existence of the ion conductor layer of the fast ion conductor with the NASICON structure accelerates the dissolution of the active lithium in the lithium iron phosphate matrix phase structure of the present application, so that the positive electrode active material of the present application has a higher energy content than only carbon-coated but no fast-acting lithium.
- the pH of the lithium iron phosphate of the ion conductor layer is the pH of the lithium iron phosphate of the ion conductor layer.
- free lithium exists in the positive electrode active material, and the pH of the positive electrode active material and the mass percentage NLi + % of the free lithium satisfy 0.15 ⁇ pH-(36N Li+ +8 ) ⁇ 1.1.
- the pH is the pH value of the above-mentioned positive electrode active material.
- pH-(36N Li+ +8) is positively correlated with the dissolution of active lithium in the bulk phase structure of lithium iron phosphate matrix.
- the active lithium in the iron-lithium matrix bulk structure is easier to dissolve.
- the value of pH-(36N Li+ +8) is within a reasonable range (0.15 ⁇ pH-(36N Li+ +8) ⁇ 1.1), the corresponding cathode active material has excellent gram capacity and excellent cycle performance .
- pH-(36N Li+ +8) in a physical sense can reflect the positive effect of the introduction of NASICON type fast ion conductors on promoting active lithium dissolution in positive electrode active materials after a lot of experiments and research.
- the value of pH-(36N Li+ +8) has a significant effect on the gram capacity and cycle performance of the corresponding lithium-ion secondary battery.
- pH-(36N Li+ +8) is positively correlated with the dissolution of active lithium in the bulk structure.
- pH-(36N Li+ +8) is too large, it indicates that the active lithium in the bulk structure of the positive electrode active material dissolves too much, which indirectly reflects the structure of the lithium iron phosphate matrix used to provide active lithium at this time. The stability is poor, thereby affecting the cycle performance of the corresponding lithium-ion secondary battery.
- pH-(36N Li+ +8) can also reflect the coating integrity of the carbon coating. Under the condition that the content of NASICON type fast ion conductor remains unchanged, when the pH-(36N Li+ +8) value is larger (over 1.1), it indicates that the carbon coating is poor, which in turn affects the cycle performance of lithium-ion secondary batteries. Conversely, when the pH-(36N Li+ +8) value is small (less than 0.15), the value of S/C is small, indicating that the carbon coating is relatively dense, indicating that the coating integrity of the carbon coating layer is better.
- the value of pH-(36N Li+ +8) may be 0.18, 0.41, 0.53, 1.04, 1.06, or a value within a range obtained by combining any two of the above values.
- the volume average particle size of the positive electrode active material satisfies 1 ⁇ m ⁇ Dv50 ⁇ 2 ⁇ m, and 0.4 ⁇ m ⁇ Dv10 ⁇ 0.7 ⁇ m.
- Dv10 is the particle size (unit: ⁇ m) corresponding to when the cumulative volume distribution percentage of the positive active material reaches 10%
- Dv50 is the corresponding particle size (unit: ⁇ m) when the cumulative volume distribution percentage of the positive active material reaches 50% ).
- the powder compaction density of the positive electrode active material of the present application is related to the particle size distribution of the positive electrode active material and the particle size of the primary particles.
- a reasonable particle size distribution of the positive electrode active material and a larger primary particle size are beneficial to the positive electrode active material powder.
- the Dv50 of the positive electrode active material is large (over 2 ⁇ m), or, when the Dv10 is lower than 0.4 ⁇ m or higher than 0.7 ⁇ m, the particle size distribution of the positive electrode active material is unreasonable, thereby reducing the The compacted density of the powder, thereby reducing the compacted density of the pole piece.
- the Dv50 may be 1.2, 1.3, 1.4, 1.6, 1.7, 1.8, or its value is in the range obtained by combining any two of the above-mentioned values.
- Dv10 can be 0.43, 0.47, 0.49, 0.51, 0.52, 0.54, 0.55, 0.56, 0.58, 0.61, or its value is in the range obtained by combining any two values above.
- the positive electrode active material is primary particle or quasi-single crystal.
- Increasing the particle size of the primary particles of the positive electrode active material is another way to increase the powder compaction density of the positive electrode active material.
- the larger the primary particle size of the positive active material the higher the powder compaction density.
- the black circles in Fig. 2(a) and Fig. 2(b) represent primary particles, and the particle size distribution of the entire positive electrode active material in Fig. 2(a) and Fig. 2(b)
- the particle size of the primary particles in FIG. 2( a ) is large, the compacted density of the powder is higher (there are many voids in FIG. 2( b )).
- the positive electrode active material of the present application compared with lithium iron phosphate coated only with carbon, the positive electrode active material is primary particle or quasi-single crystal, and its primary particle size is larger, so it has improved powder compaction density and The compaction density of the pole piece is beneficial to improve the energy density of the corresponding lithium ion secondary battery.
- the powder compaction density ⁇ of the positive electrode active material is greater than or equal to 2.5 g/cm 3 .
- the powder of the positive electrode active material has high compaction density
- the positive electrode piece prepared therefrom has high compaction density
- the corresponding lithium ion secondary battery has high energy density.
- the powder compaction density ⁇ value of the positive electrode active material may be 2.53, 2.54, 2.55, 2.56, 2.57, 2.59, or the value thereof is in the range obtained by combining any two values above.
- the powder resistivity R of the positive electrode active material is less than or equal to 11 ⁇ cm.
- the positive electrode active material of the present application has significantly lower powder resistivity compared to uncoated lithium iron phosphate (its resistivity exceeds 2E 5 ), indicating that the carbon coating layer can significantly reduce the resistance of the positive electrode active material.
- the powder resistivity R of the positive electrode active material exceeds 11 ⁇ cm, for example, when R is 18.7 ⁇ cm, the gram capacity of the positive electrode active material decreases.
- the value of the powder resistivity R of the positive electrode active material may be 3.5, 4.3, 2.7, 8.7, 9.8, or a value within a range obtained by combining any two of the above values.
- a lithium ion secondary battery is provided.
- a lithium ion secondary battery typically includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator.
- active ions are inserted and extracted back and forth between the positive electrode and the negative electrode.
- the electrolyte plays the role of conducting ions between the positive electrode and the negative electrode.
- the separator is arranged between the positive pole piece and the negative pole piece, and mainly plays the role of preventing the short circuit of the positive and negative poles, and at the same time, it can allow ions to pass through.
- the present application provides a positive electrode sheet including the positive electrode active material described in the present application.
- the positive pole piece of the present application has excellent pole piece compaction density and gram capacity because it includes a positive electrode active material with a NASICON fast ion conductor layer and a carbon coating layer, which is beneficial to improve the energy density of lithium ion secondary batteries.
- the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, and the positive electrode film layer includes the positive electrode active material of the first aspect of the present application.
- the 0.1C charge-discharge curve of the coin-type battery is in the range of 2.5-2.9Vvs Li + There is a charge-discharge platform in the voltage range, which can prove the existence of the NASICON fast ion conductor contained in the positive electrode active material of the present application.
- the positive electrode current collector has two opposite surfaces in its own thickness direction, and the positive electrode film layer is provided on either or both of the two opposite surfaces of the positive electrode current collector.
- the positive electrode current collector may be a metal foil or a composite current collector.
- the metal foil aluminum foil can 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 base layer.
- Composite current collectors can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) It is formed on the substrate of glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
- the positive electrode film layer also optionally includes a conductive agent.
- a conductive agent is not specifically limited, and those skilled in the art can select them according to actual needs.
- the conductive agent for the positive electrode film layer may be one or more selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
- the positive electrode sheet can be prepared according to methods known in the art.
- the positive electrode active material, conductive agent and binder of the present application can be dispersed in a solvent (such as N-methylpyrrolidone (NMP)) to form a uniform positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector On the fluid, after drying, cold pressing and other processes, the positive pole piece is obtained.
- NMP N-methylpyrrolidone
- the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.
- the negative electrode current collector has two surfaces opposite in its own thickness direction, and the negative electrode film layer is provided on either or both of the two opposite surfaces of the negative electrode current collector.
- the negative electrode current collector may be a metal foil or a composite current collector.
- the metal foil copper foil can be used.
- the composite current collector may include a base layer of polymer material and a metal layer formed on at least one surface of the base body of polymer material.
- Composite current collectors can be formed by forming metal materials (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material matrix (such as polypropylene (PP), polyethylene terephthalate) It is formed on the substrate of glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
- the negative electrode film layer usually contains a negative electrode active material and an optional binder, an optional conductive agent and other optional auxiliary agents, which are usually obtained by coating and drying the negative electrode slurry. completed.
- the negative electrode slurry coating is usually formed by dispersing the negative electrode active material and optional conductive agent and binder in a solvent and stirring uniformly.
- the solvent can be N-methylpyrrolidone (NMP) or deionized water.
- the conductive agent may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
- the binder may be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), One or more of 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
- auxiliary agents are, for example, thickeners (such as sodium carboxymethyl cellulose (CMC-Na)) and the like.
- the negative electrode film layer may optionally include other common negative electrode active materials.
- other common negative electrode active materials artificial graphite, natural graphite can be listed. , soft carbon, hard carbon, silicon matrix, tin matrix and lithium titanate, etc.
- the silicon matrix material can be selected from one or more of elemental silicon, silicon-oxygen compound, silicon-carbon composite, silicon-nitrogen composite and silicon alloy.
- the tin matrix material can be selected from one or more of elemental tin, tin oxide compounds and tin alloys.
- the electrolyte plays the role of conducting ions between the positive electrode and the negative electrode.
- the type of electrolyte in this application which can be selected according to requirements.
- the electrolyte may be selected from at least one of solid electrolytes and liquid electrolytes (ie, electrolytes).
- the electrolyte is an electrolyte.
- the electrolyte solution includes an electrolyte salt and a solvent.
- the electrolyte salt may be selected from LiPF 6 (lithium hexafluorophosphate), LiBF 4 (lithium tetrafluoroborate), LiClO 4 (lithium perchlorate), LiAsF 6 (lithium hexafluoroarsenate), LiFSI (lithium hexafluoroarsenate), LiFSI (lithium tetrafluoroborate) Lithium Imide), LiTFSI (Lithium Bistrifluoromethanesulfonimide), LiTFS (Lithium Trifluoromethanesulfonate), LiDFOB (Lithium Difluorooxalate Borate), LiBOB (Lithium Dioxalate Borate), LiPO 2 F 2 One or more of (lithium difluorophosphate), LiDFOP (lithium difluorobisoxalate phosphate) and LiTFOP (lithium tetrafluorooxalate phosphate).
- LiPF 6
- the solvent may be selected from 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 (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate ester (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB) , one or more of ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) and diethyl s
- EC
- the electrolyte also optionally includes additives.
- the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain performance of the battery, such as additives to improve battery overcharge performance, additives to improve battery high temperature performance, and battery low temperature performance. additives, etc.
- a separator is also included in the lithium ion secondary battery using an electrolyte, and some lithium ion secondary batteries using a solid electrolyte.
- the separator is arranged between the positive pole piece and the negative pole piece, and plays the role of isolation.
- the type of separator in the present application, and any well-known porous-structure separator with good chemical stability and mechanical stability can be selected.
- the material of the separator can be selected from one or more of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
- the separator may be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, and are not particularly limited.
- the positive electrode sheet, the negative electrode sheet and the separator may be fabricated into an electrode assembly through a winding process or a lamination process.
- the lithium ion secondary battery may include an outer package.
- the outer package can be used to encapsulate the above-mentioned electrode assembly and electrolyte.
- the outer packaging of the lithium ion secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, and the like.
- the outer package of the secondary battery may also be a soft package, such as a pouch-type soft package.
- the material of the soft bag may be plastic, and examples of the plastic include polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), and the like.
- the shape of the lithium ion secondary battery is not particularly limited in the present application, and it can be cylindrical, square or any other shape.
- FIG. 5 is a lithium ion secondary battery 5 of a square structure as an example.
- the outer package may include a housing 51 and a cover 53 .
- the housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate are enclosed to form a accommodating cavity.
- the housing 51 has an opening that communicates with the accommodating cavity, and a cover plate 53 can cover the opening to close the accommodating cavity.
- the positive electrode sheet, the negative electrode sheet and the separator may be formed into the electrode assembly 52 through a winding process or a lamination process.
- the electrode assembly 52 is packaged in the accommodating cavity.
- the electrolyte solution is infiltrated in the electrode assembly 52 .
- the number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and those skilled in the art may select them according to specific actual needs.
- the secondary battery can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.
- FIG. 7 shows the battery module 4 as an example.
- the plurality of secondary batteries 5 may be arranged in sequence along the longitudinal direction of the battery module 4 .
- the plurality of secondary batteries 5 can be fixed with fasteners.
- the battery module 4 may further include a housing having an accommodating space in which the plurality of secondary batteries 5 are accommodated.
- the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules included in the battery pack can be selected by those skilled in the art according to the application and capacity of the battery pack.
- the battery pack 1 may include a battery case and a plurality of battery modules 4 disposed in the battery case.
- 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 module 4 .
- the plurality of battery modules 4 may be arranged in the battery case in any manner.
- the present application also provides an electrical device comprising one or more of the lithium ion secondary batteries, battery modules, or battery packs provided by the present application.
- the lithium ion secondary battery, battery module, or battery pack can be used as a power source of the electrical device, and can also be used as an energy storage unit of the electrical device.
- the electrical device can be, but is not limited to, mobile devices (such as mobile phones, laptop computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric vehicles, etc.) Golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
- a lithium ion secondary battery, a battery module or a battery pack can be selected according to its usage requirements.
- FIG. 10 is an electrical device as an example.
- the electrical device may be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
- a battery pack or a battery module may be employed.
- the electrical device may be a mobile phone, a tablet computer, a notebook computer, and the like.
- the electric device is generally required to be light and thin, and a lithium-ion secondary battery can be used as a power source.
- the mass ratio of solid raw material: water 1:1:1:1, deionized water is added to the solid raw material, and wet grinding is performed to obtain the ground slurry.
- the obtained slurry was spray-dried, then put into a roller furnace for sintering, sintered at 780 for 24 hours, and nitrogen was introduced into the sintering process.
- the material is naturally cooled until the material temperature is less than 80°C, and then the material is discharged to obtain a calcined material.
- the calcined material is crushed, sieved, demagnetized, and then vacuum-packed to obtain the positive electrode active material of Example 1 of the present application.
- the positive electrode active material obtained above, the binder polyvinylidene fluoride (PVDF), and the conductive agent acetylene black are mixed according to the mass ratio of 96.5:2.0:1.5, and an appropriate amount of N-methylpyrrolidone (NMP) solvent is added, and fully stirred and mixed , to form a uniform cathode slurry.
- the slurry was coated on a carbon-coated aluminum foil with a thickness of 13 ⁇ m for the positive electrode current collector, and the coating surface density was 26 mg/cm 2 . Subsequently, drying, cold pressing and slitting are carried out to obtain a positive pole piece.
- the negative electrode active material graphite, thickener sodium carboxymethyl cellulose, binder styrene-butadiene rubber, and conductive agent acetylene black are mixed according to the mass ratio of 97:1:1:1, and deionized water is added.
- a negative electrode slurry was obtained.
- the negative electrode slurry was uniformly coated on a copper foil with a thickness of 8 ⁇ m. Then drying, cold pressing and slitting are carried out to obtain a negative pole piece.
- Ethylene carbonate, ethyl methyl carbonate and diethyl carbonate are prepared into a mixed solution in a volume ratio of 20:20:60, then fully dried lithium salt is dissolved in the above mixed solution, and then 10wt% of fluorocarbonic acid is added Add vinyl ester additives and mix them uniformly to obtain an electrolyte.
- the concentration of the lithium salt was 1 mol/L. The entire operation was carried out in an argon atmosphere glove box with a water content of ⁇ 10 ppm.
- a polyethylene film with a thickness of 12 ⁇ m was used as the separator.
- Example 2 The other steps of Example 2 were the same as those of Example 1, except that in the section [Preparation of Positive Electrode Active Material], titanium oxide was replaced with zirconium oxide.
- Example 3 The other steps of Example 3 were the same as those of Example 1, except that in the section [Preparation of Positive Electrode Active Material], titanium oxide was replaced with tin oxide.
- Example 4 The other steps in Example 4 are the same as those in Example 1, except that in the [Preparation of Positive Electrode Active Material] section, the added mass ratio of glucose and polyethylene glycol is replaced by 7:3.
- Example 4 The other steps in Example 4 are the same as those in Example 1, except that in the [Preparation of Positive Electrode Active Material] section, the added mass ratio of glucose and polyethylene glycol is replaced by 3:7.
- Example 9 The other steps of Example 9 were the same as those of Example 1, except that in the [Preparation of Positive Electrode Active Material] section, the carbon source was completely replaced with glucose.
- the mass ratio of solid raw material: water 1:1:1:1:1, deionized water is added to the solid raw material, and wet grinding is performed to obtain the ground slurry.
- the obtained slurry was spray-dried, then put into a roller furnace for sintering, sintered at 780 for 24 hours, and nitrogen was introduced into the sintering process.
- the material After the sintering is completed, the material is naturally cooled until the material temperature is less than 80°C, and then the material is discharged to obtain a calcined material.
- the material After crushing the calcined material, use chemical vapor deposition (CVD) method to deposit a dense carbon coating layer on the surface of the broken calcined material (the carbon source used in the CVD method is ethylene, and the ratio of the carbon source to the crushed material is 1: 20), and then sieving and demagnetizing to obtain the positive electrode active material of Example 10 of the present application.
- CVD chemical vapor deposition
- Example 13 the calcined material was put into the jet mill and pulverized by adjusting the rotational speed of the classification wheel to make the Dv50 and Dv10 of the positive electrode active material larger.
- the other steps of Example 11 are the same as those of Example 1.
- Example 13 In the [Preparation of Positive Electrode Active Material] section, the sintering temperature of Example 13 was 760, and other steps of Example 13 were the same as those of Example 1.
- the material is naturally cooled until the material temperature is less than 80°C, and then the material is discharged to obtain a calcined material.
- the calcined material is crushed, sieved, demagnetized, and then vacuum-packed to obtain the positive electrode active material of Comparative Example 1 of the present application.
- the positive electrode pieces, separators, and negative electrode pieces in Examples 1 to 13 and Comparative Examples 1 to 2 were stacked in sequence, with the separator between the positive and negative electrode pieces, and then wound into a bare cell. Solder tabs to the bare cell, put the bare cell into an aluminum case, bake at 80°C to remove water, then inject electrolyte and seal to obtain an uncharged secondary battery. The uncharged secondary battery then goes through the processes of standing, hot and cold pressing, formation, shaping, and capacity testing in order to obtain a lithium ion secondary battery product.
- the test of free lithium content N Li+ % is based on the standard GB/T 9725-2007.
- 30 g of positive active materials of all examples and all comparative examples were taken, respectively, added to 100 mL of water, stirred for 30 min, and filtered.
- N Li+ % C ⁇ V ⁇ 4 ⁇ 6.941/30 ⁇ 100%.
- the pH test of positive active material is based on GB/T 9724-2007. At room temperature, 10 g of positive active materials of all examples and all comparative examples were taken, respectively, added to 100 mL of water, stirred for 30 min, and filtered after standing for 90 min. Use a pH meter (model pHS-3C) to measure the pH of the filtrates of all the examples and all the comparative examples respectively, which is the pH value of the corresponding positive active material.
- a pH meter model pHS-3C
- the pole piece is cut into a diaphragm with a length of 1000mm, and the pole piece is rolled by a certain pressure. Due to the ductility of the aluminum foil, the length of the diaphragm is 1006mm. Then die-cut 1540.25mm 2 small discs on the diaphragm, and measure the weight M and thickness L of the small discs.
- the pure aluminum foil is punched into small discs of 1540.25 mm 2 , and the mass M0 of the empty aluminum foil is weighed, then the compaction density of the positive electrode pieces corresponding to all the examples and all the comparative examples can be calculated by the following formula:
- the positive electrode active material was burned in a high-frequency induction furnace to test the carbon content with an infrared absorption method, and the specific test process was based on the standard GB/T 20123-2006/ISO 15350:2000.
- the specific surface area of the positive active materials of all the above-mentioned embodiments and comparative examples is tested by Tristar3020 instrument, and the specific testing process is based on the standard GB/T 19587-2004.
- Dv10, Dv50 of the positive active material of all above-mentioned embodiments and comparative examples adopt the Mastersizer 2000E type laser particle size analyzer of Malvern Instrument Co., Ltd., UK, analyze and test according to the particle size distribution laser diffraction method of standard GB/T 19077-2016 .
- the powder resistivity of the positive active materials of all the above examples and comparative examples was tested using a powder resistivity tester (ST2722), and analyzed and tested according to the standard GB/T 30835-2014.
- Inductively coupled plasma atomic emission spectrometry was used for elemental testing of the positive electrode active materials of all the above examples and comparative examples.
- the test instrument uses ICP-OES.
- Example 1 Mix the positive active material of Example 1, the binder polyvinylidene fluoride (PVDF), and the conductive agent acetylene black according to the mass ratio of 95:5:5, add an appropriate amount of N-methylpyrrolidone (NMP) solvent, and stir well Mix to form a homogeneous positive slurry.
- the slurry was coated on an aluminum foil with a thickness of 1 ⁇ m for the positive current collector, followed by drying and cold pressing. Then, small circular pieces with a diameter of 14 mm were punched out to be used as positive electrode pieces.
- a coin-type half-cell was assembled with a lithium sheet as the negative electrode, a 12 ⁇ m thick polypropylene separator and the electrolyte in the example. The coin-type half-cell was charged and discharged with a rate of 0.1C and 1C, respectively, and the gram capacity at different rates was recorded.
- the galvanic capacity test of the positive electrode active materials of other examples and comparative examples is the same as that of the positive electrode active material of the above-mentioned Example 1.
- a charge and discharge cycle process is as follows: 1C current constant current charge to 3.65V, continue constant voltage charging, until the charging current is less than 0.05C and then cut off; pause for 5min; 1C current constant current discharge to 2.5V; pause for 5min.
- the above is a charge-discharge cycle of the battery, which is repeated continuously until the battery capacity decays to 80% of the initial value, and the number of cycles is recorded.
- Table 1 Table of relevant parameters of cathode active materials of Examples and Comparative Examples
- the positive electrode active materials of Examples 1 to 13 comprise fast ion conductor layers with NASICON structure fast ion conductors, and have significantly improved gram capacity of positive electrode active materials compared to Comparative Examples 1 and 2. , whether it is 0.1C discharge gram capacity or 1C discharge gram capacity.
- Examples 1 to 3 show that the fast ion conductors Li 2 FeTi(PO 4 ) 3 , Li 2 FeZr(PO 4 ) 3 , and Li 2 FeSn(PO 4 ) 3 containing different metal element species are better than those of the comparative example.
- 1 and Comparative Example 2 have significantly improved gram capacity of the cathode active material, both 0.1C discharge gram capacity and 1C discharge gram capacity.
- Comparative Example 1 has only a carbon coating layer and no fast ion conductor layer
- Comparative Example 2 has neither a carbon coating layer nor a fast ion conductor layer.
- the corresponding positive electrode active materials are discharged at 0.1C. Both the gram capacity and the 1C discharge gram capacity are significantly lower than those of Examples 1-13.
- this application is not limited to the said embodiment.
- the above-described embodiments are merely examples, and embodiments having substantially the same configuration as the technical idea and exhibiting the same effects within the scope of the technical solution of the present application are all included in the technical scope of the present application.
- various modifications that can be conceived by those skilled in the art are applied to the embodiment, and other modes constructed by combining some of the constituent elements of the embodiment are also included in the scope of the present application. .
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Composite Materials (AREA)
- Crystallography & Structural Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Secondary Cells (AREA)
Abstract
Description
Claims (14)
- 一种正极活性材料,其中,包括基体和包覆层,所述包覆层包覆所述基体,所述包覆层包覆快离子导体层和碳包覆层,所述基体包括如式(I)所述的化合物中的一种以上:LiFe 1-aM1 aPO 4 式(I),在所述式(I)中,M1选自Cu、Mn、Cr、Zn、Pb、Ca、Co、Ni、Sr、Nb以及Ti中的一种以上,0≤a≤0.01,所述快离子导体层包含如式(II)所示的具有NASICON结构的快离子导体,Li 3-bFe 2-bM2 b(PO 4) 3 式(II),在所述式(II)中,M2选自+4价的Ti、Zr、Hf、Ge以及Sn中的一种以上,0≤b≤1。
- 根据权利要求1所述的正极活性材料,其中,在所述正极活性材料中,所述LiFe 1-aM1 aPO 4与所述Li 3-bFe 2-bM2 b(PO 4) 3的摩尔量之比为(1-x):x,且0<x≤0.005。
- 根据权利要求1或2所述的正极活性材料,其中,所述正极活性材料中碳的质量百分含量C%为1%~1.5%,所述正极活性材料的比表面积S为10~15m 2/g,所述正极活性材料的比表面积S与碳含量C%的比值满足9≤S/C≤12。
- 根据权利要求1~3中任一项所述的正极活性材料,其中,所述正极活性材料的pH不小于9。
- 根据权利要求1~4所述的正极活性材料,其中,所述正极活性材料中存在游离锂,所述正极活性材料的pH与所述游离锂的质量百分含量N Li+%满足0.15≤pH-(36N Li++8)≤1.1。
- 根据权利要求1~5中任一项所述的正极活性材料,其中,所述正极活性材料的体积平均粒径满足1μm≤Dv50≤2μm,0.4μm≤Dv10≤0.7μm,可选地,所述正极活性材料为一次颗粒或类单晶。
- 根据权利要求1~6中任一项所述的正极活性材料,其中,所述正极活性材料的粉体压实密度ρ≥2.5g/cm 3。
- 根据权利要求1~7中任一项所述的正极活性材料,其中,所述正极活性材料的粉末电阻率R≤11Ω·cm。
- 根据权利要求1~8中任一项所述的正极活性材料,其中,由所述正极材料制备的正极极片的极片压实密度为2.5g/cm 3。
- 一种锂离子二次电池,包括权利要求1~9中任一项所述的正极活性材料。
- 根据权利要求10所述的锂离子二次电池,其中,包括正极极片,所述正极极片包括正极集流体以及设置在所述正极集流体至少一个表面上且包含所述正极活性材料的正极膜层,当将所述正极极片与锂金属片组成扣式电池时,所述扣式电池的0.1C充放电曲线中,在2.5~2.9Vvs Li +电压范围内存在充放电平台。
- 一种电池模块,其中,包括权利要求10或11所述的锂离子二次电池。
- 一种电池包,其中,包括权利要求10或11所述的锂离子二次电池或权利要求12所述的电池模块中的一种以上。
- 一种用电装置,其中,包括权利要求10或11所述的锂离子二次电池、权利要求12所述的电池模块或权利要求13所述的电池包中的一种以上,所述锂离子二次电池或所述电池模块或所述电池包用作所述用电装置的电源或所述用电装置的能量存储单元。
Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP21920263.7A EP4131492A4 (en) | 2021-01-21 | 2021-01-21 | ACTIVE MATERIAL OF POSITIVE ELECTRODE, SECONDARY LITHIUM BATTERY, BATTERY MODULE, BATTERY PACK AND POWER DEVICE |
KR1020227032770A KR20220143926A (ko) | 2021-01-21 | 2021-01-21 | 양극 활성 재료, 리튬 이온 이차전지, 전지 모듈, 전지 팩 및 전기 장치 |
JP2022557160A JP7375222B2 (ja) | 2021-01-21 | 2021-01-21 | 正極活性材料、リチウムイオン二次電池、電池モジュール、電池パックおよび電気装置 |
PCT/CN2021/073158 WO2022155861A1 (zh) | 2021-01-21 | 2021-01-21 | 正极活性材料、锂离子二次电池、电池模块、电池包和用电装置 |
CN202180043383.9A CN115885396A (zh) | 2021-01-21 | 2021-01-21 | 正极活性材料、锂离子二次电池、电池模块、电池包和用电装置 |
US17/935,125 US20230035380A1 (en) | 2021-01-21 | 2022-09-25 | Positive active material, lithium ion secondary battery, battery module, battery pack and electric device |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/CN2021/073158 WO2022155861A1 (zh) | 2021-01-21 | 2021-01-21 | 正极活性材料、锂离子二次电池、电池模块、电池包和用电装置 |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US17/935,125 Continuation US20230035380A1 (en) | 2021-01-21 | 2022-09-25 | Positive active material, lithium ion secondary battery, battery module, battery pack and electric device |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2022155861A1 true WO2022155861A1 (zh) | 2022-07-28 |
Family
ID=82548315
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/CN2021/073158 WO2022155861A1 (zh) | 2021-01-21 | 2021-01-21 | 正极活性材料、锂离子二次电池、电池模块、电池包和用电装置 |
Country Status (6)
Country | Link |
---|---|
US (1) | US20230035380A1 (zh) |
EP (1) | EP4131492A4 (zh) |
JP (1) | JP7375222B2 (zh) |
KR (1) | KR20220143926A (zh) |
CN (1) | CN115885396A (zh) |
WO (1) | WO2022155861A1 (zh) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN115448281B (zh) * | 2022-09-13 | 2023-10-24 | 宜都兴发化工有限公司 | 一种表面包覆LiAlF4快离子导体的低温型磷酸铁锂的制备方法 |
CN116259736B (zh) * | 2023-05-15 | 2023-11-07 | 宁德时代新能源科技股份有限公司 | 正极活性材料及其制备方法、正极极片、二次电池和用电装置 |
CN117423829B (zh) * | 2023-12-19 | 2024-04-23 | 湖南长远锂科新能源有限公司 | 一种锂离子电池正极材料及其制备方法和应用 |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103094580A (zh) * | 2013-01-25 | 2013-05-08 | 复旦大学 | 一种复合正极材料及其合成方法与应用 |
CN103400962A (zh) * | 2013-08-08 | 2013-11-20 | 湘潭大学 | 一种球形LiFePO4/(C+La2/3-xLi3xTiO3)复合物正极材料及其制备方法 |
US8906553B1 (en) * | 2010-02-26 | 2014-12-09 | Nei Corporation | High voltage cathode material for Li-ion batteries |
CN108206276A (zh) * | 2016-12-19 | 2018-06-26 | 天津国安盟固利新材料科技股份有限公司 | 一种复合包覆的锂离子正极材料及其制备方法 |
CN110858643A (zh) * | 2018-08-24 | 2020-03-03 | 湖南杉杉新能源有限公司 | 一种快离子导体改性锂离子电池正极材料及其制备方法 |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5017778B2 (ja) | 2005-01-05 | 2012-09-05 | 株式会社Gsユアサ | 非水電解質電池用正極及び非水電解質電池 |
JP5332983B2 (ja) | 2009-07-08 | 2013-11-06 | トヨタ自動車株式会社 | 電池システム |
JP5981101B2 (ja) | 2011-06-15 | 2016-08-31 | 株式会社東芝 | 非水電解質二次電池 |
JP6035669B2 (ja) | 2012-07-20 | 2016-11-30 | 住友金属鉱山株式会社 | 非水電解質二次電池用正極活物質およびその製造方法 |
JP6288340B1 (ja) | 2017-03-24 | 2018-03-07 | 住友大阪セメント株式会社 | リチウムイオン二次電池用電極材料、及びリチウムイオン二次電池 |
-
2021
- 2021-01-21 JP JP2022557160A patent/JP7375222B2/ja active Active
- 2021-01-21 EP EP21920263.7A patent/EP4131492A4/en active Pending
- 2021-01-21 WO PCT/CN2021/073158 patent/WO2022155861A1/zh unknown
- 2021-01-21 CN CN202180043383.9A patent/CN115885396A/zh active Pending
- 2021-01-21 KR KR1020227032770A patent/KR20220143926A/ko not_active Application Discontinuation
-
2022
- 2022-09-25 US US17/935,125 patent/US20230035380A1/en active Pending
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8906553B1 (en) * | 2010-02-26 | 2014-12-09 | Nei Corporation | High voltage cathode material for Li-ion batteries |
CN103094580A (zh) * | 2013-01-25 | 2013-05-08 | 复旦大学 | 一种复合正极材料及其合成方法与应用 |
CN103400962A (zh) * | 2013-08-08 | 2013-11-20 | 湘潭大学 | 一种球形LiFePO4/(C+La2/3-xLi3xTiO3)复合物正极材料及其制备方法 |
CN108206276A (zh) * | 2016-12-19 | 2018-06-26 | 天津国安盟固利新材料科技股份有限公司 | 一种复合包覆的锂离子正极材料及其制备方法 |
CN110858643A (zh) * | 2018-08-24 | 2020-03-03 | 湖南杉杉新能源有限公司 | 一种快离子导体改性锂离子电池正极材料及其制备方法 |
Also Published As
Publication number | Publication date |
---|---|
JP7375222B2 (ja) | 2023-11-07 |
US20230035380A1 (en) | 2023-02-02 |
EP4131492A4 (en) | 2023-06-14 |
JP2023517773A (ja) | 2023-04-26 |
CN115885396A (zh) | 2023-03-31 |
EP4131492A1 (en) | 2023-02-08 |
KR20220143926A (ko) | 2022-10-25 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
WO2021057428A1 (zh) | 二次电池及含有该二次电池的电池模块、电池包、装置 | |
WO2022155861A1 (zh) | 正极活性材料、锂离子二次电池、电池模块、电池包和用电装置 | |
WO2021008429A1 (zh) | 二次电池及其相关的电池模块、电池包和装置 | |
EP4131487A1 (en) | Lithium-ion secondary battery and preparation method therefor, battery module, battery pack, and device | |
JP2023503688A (ja) | 二次電池及び当該二次電池を含む装置 | |
WO2022109886A1 (zh) | 复合正极材料、其制备方法、正极极片、二次电池及包含该二次电池的电池模块、电池包和装置 | |
EP4362137A1 (en) | Carbon material and preparation method therefor and use thereof, negative electrode sheet, secondary battery and electric device | |
US20230146274A1 (en) | Silicon carbon negative electrode material, negative electrode sheet, secondary battery, battery module, battery pack and power consumption apparatus | |
US20220102788A1 (en) | Secondary battery and apparatus containing the same | |
US20220367871A1 (en) | Lithium secondary battery and battery module, battery pack, and electric apparatus containing same | |
WO2022241712A1 (zh) | 锂离子二次电池、电池模块、电池包以及用电装置 | |
CN115133020B (zh) | 锰酸锂正极活性材料及包含其的正极极片、二次电池、电池模块、电池包和用电装置 | |
KR102514891B1 (ko) | 이차 전지 및 이를 포함하는 장치 | |
WO2022140902A1 (zh) | 负极极片及其制备方法、二次电池、电池模块、电池包和装置 | |
US20210175499A1 (en) | Silicon-oxygen compound, preparation method thereof, and related battery module, battery pack and device | |
CN116897442A (zh) | 正极极片及包含所述极片的锂离子电池 | |
CN116670846A (zh) | 二次电池以及包含其的用电装置 | |
WO2022099561A1 (zh) | 硅基材料、其制备方法及其相关的二次电池、电池模块、电池包和装置 | |
WO2023133833A1 (zh) | 一种二次电池、电池模块、电池包和用电装置 | |
EP4358192A1 (en) | Negative electrode sheet and preparation method therefor, secondary battery, battery module, battery pack, and electric device | |
WO2024113080A1 (zh) | 一种正极活性材料、制法、二次电池和用电装置 | |
US20230282829A1 (en) | Artificial graphite and prepartion method thereof, negative electrode plate, secondary battery, battery module, battery pack and electrical device | |
WO2024065151A1 (zh) | 隔离膜及其制备方法、二次电池、电池模块、电池包及用电装置 | |
US20230352667A1 (en) | Positive electrode plate, secondary battery, battery module, battery pack, and power consuming device | |
WO2023044625A1 (zh) | 复合人造石墨及其制备方法及包含所述复合人造石墨的二次电池和用电装置 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 21920263 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2022557160 Country of ref document: JP Kind code of ref document: A Ref document number: 20227032770 Country of ref document: KR Kind code of ref document: A |
|
ENP | Entry into the national phase |
Ref document number: 2021920263 Country of ref document: EP Effective date: 20221024 |
|
NENP | Non-entry into the national phase |
Ref country code: DE |