WO2024077514A1 - 电解液、电池单体、电池和用电装置 - Google Patents

电解液、电池单体、电池和用电装置 Download PDF

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WO2024077514A1
WO2024077514A1 PCT/CN2022/124811 CN2022124811W WO2024077514A1 WO 2024077514 A1 WO2024077514 A1 WO 2024077514A1 CN 2022124811 W CN2022124811 W CN 2022124811W WO 2024077514 A1 WO2024077514 A1 WO 2024077514A1
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battery
electrolyte
halogen
optionally
lithium
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PCT/CN2022/124811
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English (en)
French (fr)
Inventor
姚萌
马云建
张建平
李彦辉
黄玉平
王绍东
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宁德时代新能源科技股份有限公司
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Priority to PCT/CN2022/124811 priority Critical patent/WO2024077514A1/zh
Publication of WO2024077514A1 publication Critical patent/WO2024077514A1/zh

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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
    • 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
    • H01M10/0567—Liquid materials characterised by the additives

Definitions

  • the present application relates to the technical field of lithium batteries, and in particular to an electrolyte, a battery cell, a battery and an electrical device.
  • Lithium-ion or sodium-ion secondary batteries have become a hot topic of concern due to their high energy density and environmental friendliness.
  • shortcomings in such secondary batteries which restrict their application prospects.
  • due to the high chemical activity of lithium ions or sodium ions they are easily precipitated on the surface of the negative electrode during the charge and discharge cycle to form chemically inactive dendritic lithium/sodium, which not only causes serious loss of active substances and damages battery performance, but also brings safety hazards to the battery.
  • a lot of work has been done in this field to reduce/eliminate dendrites.
  • such technical solutions in the prior art although they can reduce dendrites, will also damage battery performance.
  • the art needs a technical solution that can reduce dendrites while ensuring that the battery has good performance to solve the above problems.
  • the present application is made in view of the above-mentioned problems, and provides an electrolyte, and a battery cell, a battery and an electrical device containing the electrolyte.
  • the first aspect of the present application provides an electrolyte, which includes an electrolyte salt, a main solvent, a halogen-containing additive and an auxiliary solvent;
  • the halogen-containing additive is selected from at least one of alkali metal iodide, tin iodide, alkali metal bromide, tin bromide, bromine and iodine;
  • the auxiliary solvent is different from the main solvent and is selected from at least one of R1S (O) R2 , benzene and benzene derivatives, wherein R1 and R2 each independently represent a C1-6 alkyl group, and one or more hydrogen atoms on the phenyl group of the benzene derivative are each independently substituted by the same or different C1-6 alkyl groups.
  • the electrolyte of the present application can reduce the dendrite growth of a secondary battery without significantly damaging the performance of the secondary battery (such as reducing the coulombic efficiency, increasing the self-discharge rate,
  • the halogen-containing additive is selected from at least one of alkali metal iodide, tin iodide and iodine; optionally, the halogen-containing additive is selected from at least one of potassium iodide, tin iodide, sodium iodide, potassium triiodide, lithium iodide and iodine. Selecting the above halogen-containing additive can more effectively reduce dendrites, while taking into account the balance between multiple properties of the secondary battery, so that the secondary battery has a larger capacity retention rate, a higher coulombic efficiency and a smaller self-discharge rate.
  • R1 and R2 each independently represent a C1-4 alkyl group, and one or more hydrogen atoms on the phenyl group of the benzene derivative are each independently substituted by the same or different C1-4 alkyl groups; optionally, the auxiliary solvent is selected from one or more of dimethyl sulfoxide, mesitylene or meta-xylene.
  • the solvation effect between these auxiliary solvents and the halogen-containing additives or the oxidizing species generated therefrom is moderate, which is more conducive to achieving a balance between the various properties of the secondary battery (e.g., having a larger capacity retention rate, a higher coulombic efficiency and a smaller self-discharge rate at the same time).
  • the amount of the halogen-containing additive is 0.01 wt % to 10 wt %, optionally 0.01 wt % to 5 wt %, and more optionally 0.01 wt % to 1 wt %. Controlling the amount of the halogen additive is beneficial to inhibiting dendrite growth and achieving a balance between various properties of the secondary battery.
  • the amount of the auxiliary solvent is 0.01 wt % to 10 wt %, optionally 0.1 wt % to 5 wt %, and more optionally 0.5 wt % to 3 wt %. Controlling the amount of the auxiliary solvent is conducive to producing effective solvation, thereby inhibiting dendrites, but will not significantly affect the performance of the electrolyte, thereby balancing the various properties of the secondary battery.
  • the mass ratio of the halogen-containing additive to the auxiliary solvent is 3:1 to 1:305, optionally 1:2-1:20, and more optionally 1:5-1:10.
  • a second aspect of the present application provides a battery cell, comprising the electrolyte of the first aspect of the present application.
  • a third aspect of the present application provides a battery, comprising the battery cell of the second aspect of the present application.
  • a fourth aspect of the present application provides an electrical device, comprising a battery cell selected from the second aspect of the present application and/or a battery according to the third aspect of the present application.
  • the electrolyte of the present application can eliminate dendrites and activate dead lithium without significantly damaging the performance of the secondary battery, thereby enabling the secondary battery to have good overall performance (for example, higher capacity retention rate, higher coulombic efficiency and lower self-discharge rate) while reducing dendrites.
  • FIG1 is a scanning electron microscope image of a negative electrode plate after circulation of an electrolyte according to an embodiment of the present application.
  • FIG. 2 is a scanning electron microscope image of the negative electrode sheet after the electrolyte of Comparative Example 1 is circulated.
  • FIG. 3 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG. 4 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 3 .
  • FIG. 5 is a schematic diagram of a battery module according to an embodiment of the present application.
  • FIG. 6 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 7 is an exploded view of the battery pack shown in FIG. 6 according to an embodiment of the present application.
  • FIG. 8 is a schematic diagram of an electric device using a secondary battery as a power source according to an embodiment of the present application.
  • “Scope” disclosed in the present application is defined in the form of lower limit and upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range.
  • the scope defined in this way can include or exclude end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range.
  • 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 minimum range values 1 and 2 are listed, and if the maximum range values 3, 4 and 5 are listed, the following range can be fully expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5.
  • 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" represents that all real numbers between "0-5" have been fully listed herein, and "0-5" is just the 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 of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • the method may further include step (c), which means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
  • the “include” and “comprising” mentioned in this application represent open-ended or closed-ended expressions.
  • the “include” and “comprising” may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.
  • the term "or” is inclusive.
  • the phrase “A or B” means “A, B, or both A and B”. More specifically, any of the following conditions satisfies the condition "A or B”: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
  • Lithium-ion or sodium-ion secondary batteries have become a hot topic of concern due to their high energy density and environmental friendliness.
  • shortcomings in such secondary batteries which restrict their application prospects.
  • due to the high chemical activity of lithium ions or sodium ions they are easily precipitated on the surface of the negative electrode during the charge and discharge cycle to form chemically inactive dendrites, which not only causes serious loss of active substances and damages battery performance, but also brings safety hazards to the battery. Therefore, a lot of work has been done in this field to reduce/eliminate dendrites.
  • such technical solutions in the prior art although they can reduce lithium dendrites, will also damage battery performance.
  • the present application provides an electrolyte that can effectively reduce the dendrite formation of secondary batteries without significantly affecting the battery performance. Therefore, the secondary battery can have good comprehensive performance, such as a larger capacity retention rate and coulombic efficiency and a smaller self-discharge rate.
  • an electrolyte comprising an electrolyte salt, a main solvent, a halogen-containing additive and an auxiliary solvent;
  • the halogen-containing additive is selected from at least one of alkali metal iodides, tin iodide, alkali metal bromides, tin bromide, bromine and iodine;
  • the auxiliary solvent is different from the main solvent and is selected from at least one of R1S (O) R2 , benzene and a benzene derivative, wherein R1 and R2 each independently represent a C1-6 alkyl group, and one or more hydrogen atoms on the phenyl group of the benzene derivative are each independently substituted by the same or different C1-6 alkyl groups.
  • the electrolyte of the present application can effectively reduce the dendrite growth of the secondary battery and enable the secondary battery to have good comprehensive performance (such as a larger capacity retention rate and coulombic efficiency and a smaller self-discharge rate).
  • this may be because after the above-mentioned halogen-containing additive is introduced into the electrolyte, taking the iodine-containing additive and lithium-ion secondary battery as an example, when the secondary battery is charged (the cathode potential can generally reach at least 2.8V, at which time the electrochemical reaction described below can occur), the halogen-containing additive itself or under the action of current, through a reaction such as formula (I), generates a halogen-containing intermediate (that is, a halogen-containing active species; for example, I 3 - and/or I 2 ), which reacts with the lithium (lithium dendrites or "dead lithium") precipitated on the surface of the negative electrode plate, such as formula (II), thereby converting the "dead lithium” into lithium ions (Li + ) and returning them to the system - achieving the effect of reducing lithium dendrites.
  • the active species are also converted into iodine ions,
  • the above process can be considered to be an advantageous use of the "shuttle effect" of iodine.
  • the active species therein may have an adverse effect on the battery parts such as the negative electrode plate, thereby increasing the self-discharge rate of the battery, reducing the coulombic efficiency, etc.
  • An auxiliary solvent is introduced into the electrolyte of the present application; in the presence of the above auxiliary solvent, the halogen-containing additive or the active species formed by it can undergo a solvation reaction with the auxiliary solvent, and the solvated active species diffuse to the negative electrode and cannot directly act, but desolvate under the action of electrochemical potential, concentration gradient, electric field force, etc.
  • shuttle effect has the meaning generally understood by those skilled in the art, which means that during the charge and discharge process, the halogen-containing intermediates generated by the halogen-containing additives at the positive electrode diffuse through the diaphragm to the negative electrode in the electrolyte and react with the metallic lithium at the negative electrode (including precipitated lithium, metallic lithium contained in the pole piece itself, etc.).
  • the shuttle effect is unfavorable, which causes irreversible loss of effective substances in the battery, battery life attenuation, and low coulomb efficiency. Therefore, the auxiliary solvent is used in the present invention to slow down the shuttle effect and reduce the adverse effects of the device.
  • solvation effect means that solute molecules or ions form complexes through interactions with solvent molecules (e.g., coordination, intermolecular forces).
  • the halogen-containing additive is selected from at least one of alkali metal iodides, tin iodide and elemental iodine. In some embodiments, the halogen-containing additive is selected from at least one of potassium iodide (KI), tin iodide (SnI 4 ), sodium iodide (NaI), potassium triiodide (KI 3 ), lithium iodide (LiI) and elemental iodine (I 2 ).
  • Selecting the above halogen-containing additives can more effectively reduce dendrites, while taking into account the balance between multiple performances of the secondary battery, so that the secondary battery has a larger capacity retention rate, a higher coulombic efficiency and a smaller self-discharge rate.
  • At least two hydrogen atoms in the meta position on the phenyl group of the benzene derivative in the auxiliary solvent are independently replaced by the same or different C 1-6 alkyl groups, and preferably replaced by the same C 1-6 alkyl groups.
  • R 1 and R 2 each independently represent a C 1-4 alkyl group, and one or more hydrogen atoms on the phenyl group of the benzene derivative are independently replaced by the same or different C 1-4 alkyl groups.
  • one or more hydrogen atoms on the phenyl group of the benzene derivative are independently replaced by the same C 1-4 alkyl group.
  • the auxiliary solvent is selected from dimethyl sulfoxide (DMSO), mesitylene (1,3,5-trimethylbenzene) or meta-xylene (1,3-xylene).
  • DMSO dimethyl sulfoxide
  • mesitylene 1,3,5-trimethylbenzene
  • meta-xylene 1,3-xylene
  • the amount of the halogen-containing additive is 0.01 wt % to 10 wt %, optionally 0.01 wt % to 5 wt %, and more optionally 0.01 wt % to 1 wt %.
  • Controlling the amount of the halogen additive is beneficial for it to interact with lithium and Li 2 O precipitated on the surface of the negative electrode to inhibit dendrite growth; specifically, when the content of the halogen-containing additive is within the above range, it can effectively eliminate “dead lithium” or inhibit dendrites, and make the "shuttle effect” not too severe to have a significant adverse effect on battery performance (for example, it will not significantly increase the self-discharge rate or reduce the coulombic efficiency).
  • the amount of the auxiliary solvent is 0.1 wt % to 10 wt %, optionally 0.1 wt % to 5 wt %, and more optionally 0.5 wt % to 3 wt %.
  • the amount of the auxiliary solvent is within the above range, it has sufficient solvation effect on the halogen-containing additive without significantly deteriorating the performance of the electrolyte (for example, not significantly increasing the viscosity or reducing the conductivity, etc.), thereby helping to make the secondary battery have good overall performance.
  • the mass ratio of the halogen-containing additive to the auxiliary solvent is 3:1 to 1:300, optionally 1:2-1:20, and more optionally 1:5-1:10.
  • the diffusion rate and reaction rate of the additive can be controlled, thereby achieving a controlled "shuttle effect", reducing the adverse effects on the system while reducing dendrites, and balancing the various performances of the secondary battery.
  • primary solvent means a solvent that is present in a larger amount than the auxiliary solvent.
  • the primary solvent may be a conventional solvent in the art.
  • the primary solvent may be selected from at least one of ethylene carbonate (EC), propylene carbonate (PC), dimethoxyethane (DME), dioxolane (DOL), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC).
  • the electrolyte salt is a substance different from the halogen-containing additive; in other words, the electrolyte salt is selected from a substance that does not belong to the halogen-containing additive.
  • the electrolyte salt includes suitable salts known in the art, but does not include iodides or bromides of lithium or sodium. In other words, the electrolyte salt includes other applicable salts other than iodides or bromides of lithium and iodine compounds and bromides of sodium.
  • the electrolyte of the present application may include (if present) iodides or bromides of lithium and/or iodine compounds and bromides of sodium as halogen-containing additives.
  • the electrolyte salt may be selected from at least one of lithium hexafluorophosphate (LiPF 6 ), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium bisfluorosulfonyl imide (LiFSI), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), and lithium difluorooxalatoborate (LiDFOB).
  • LiPF 6 lithium hexafluorophosphate
  • LiTFSI lithium bistrifluoromethanesulfonyl imide
  • LiFSI lithium bisfluorosulfonyl imide
  • LiBF 4 lithium tetrafluoroborate
  • LiClO 4 lithium perchlorate
  • LiAsF 6 lithium hexafluoroarsenate
  • LiDFOB lithium difluorooxala
  • the electrolyte salt may also be selected from one or more of sodium hexafluorophosphate (NaPF 6 ), sodium hexafluoroborate (NaBF 4 ), NaN(SO 2 F) 2 (abbreviated as NaFSI), NaClO 4 , NaAsF 6 , NaB(C 2 O 4 ) 2 (abbreviated as NaBOB), NaBF 2 (C 2 O 4 ) (abbreviated as NaDFOB), NaN(SO 2 RF ) 2 and NaN(SO 2 F)(SO 2 RF ); wherein RF represents C b F 2b+1 , b is an integer in the range of 1-10, and can be optionally an integer in the range of 1-3, and more optionally, RF is -CF 3 , -C 2 F 5 or -CF 2 CF 2 CF 3 .
  • 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 battery cell secondary battery
  • battery including, for example, a battery module, a battery pack
  • electric device of the present application are described below with appropriate reference to the drawings.
  • a battery cell comprising the electrolyte described above.
  • battery cell battery cell
  • secondary battery battery
  • a battery cell includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator.
  • 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 ions between the positive electrode sheet and the negative electrode sheet.
  • the separator is set 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 or a sodium ion secondary battery, optionally a lithium ion secondary battery.
  • 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, wherein the positive electrode film layer includes a positive electrode active material.
  • the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one 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.
  • aluminum foil may be used as the metal foil.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate 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 may be a positive electrode active material for a battery known in the art.
  • the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides and their respective modified compounds, sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds.
  • the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more.
  • lithium transition metal oxides may include, but are not limited to , lithium cobalt oxide (such as LiCoO2 ), lithium nickel oxide (such as LiNiO2 ), lithium manganese oxide (such as LiMnO2 , LiMn2O4 ), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi1 / 3Co1 / 3Mn1 / 3O2 (also referred to as NCM333 ), LiNi0.5Co0.2Mn0.3O2 (also referred to as NCM523 ) , LiNi0.5Co0.25Mn0.25O2 (also referred to as NCM211 ) , LiNi0.6Co0.2Mn0.2O2 (also referred to as NCM622 ), LiNi0.8Co0.1Mn0.1O2 (also referred to as NCM811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05
  • lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also referred to as LFP)
  • LiMnPO 4 lithium manganese phosphate
  • LiMnPO 4 lithium manganese phosphate
  • LiMnPO 4 lithium manganese phosphate and carbon
  • the transition metal in the sodium transition metal oxide, may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce.
  • the sodium transition metal oxide is, for example, Na x M y O 2 , wherein M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, 0 ⁇ x ⁇ 1, 0.5 ⁇ y ⁇ 1.5.
  • the positive electrode active material may be Na 0.88 Cu 0.24 Fe 0.29 Mn 0.47 O 2 .
  • the polyanionic compound may be a compound having sodium ions, transition metal ions and tetrahedral (YO 4 ) n- anion units.
  • the transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce;
  • Y may be at least one of P, S and Si; and
  • n represents the valence state of (YO 4 ) n- .
  • the polyanionic compound may also be a compound having sodium ions, transition metal ions, tetrahedral (YO 4 ) n- anion units and halogen anions.
  • the transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce;
  • Y may be at least one of P, S and Si, and n represents the valence state of (YO 4 ) n- ;
  • the halogen may be at least one of F, Cl and Br.
  • the polyanionic compound may also be a compound having sodium ions, tetrahedral (YO 4 ) n- anion units, polyhedral units (ZO y ) m+ and optional halogen anions.
  • Y may be at least one of P, S and Si
  • n represents the valence state of (YO 4 ) n-
  • Z represents a transition metal, which may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce
  • m represents the valence state of (ZO y ) m+
  • the halogen may be at least one of F, Cl and Br.
  • the polyanionic compound is at least one of NaFePO 4 , Na 3 V 2 (PO 4 ) 3 , NaM′PO 4 F (M′ is one or more of V, Fe, Mn and Ni), and Na 3 (VO y ) 2 (PO 4 ) 2 F 3-2y (0 ⁇ y ⁇ 1).
  • the Prussian blue compound may be a compound having sodium ions, transition metal ions and cyanide ions (CN - ).
  • the transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce.
  • the Prussian blue compound is, for example, Na a Me b Me' c (CN) 6 , wherein Me and Me' are each independently at least one of Ni, Cu, Fe, Mn, Co and Zn, 0 ⁇ a ⁇ 2, 0 ⁇ b ⁇ 1, 0 ⁇ c ⁇ 1.
  • the positive electrode film layer may also optionally include a binder.
  • the binder may include at least one 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-tetrafluoroethylene-propylene terpolymer vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer
  • the positive electrode film layer may further include a conductive agent, which may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • a conductive agent which may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N-methylpyrrolidone
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer optionally disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.
  • 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 (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate 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 current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode active material may adopt the negative electrode active material for the battery known in the art.
  • the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys.
  • the present application is not limited to these materials, and other traditional materials 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 may also include a metal material, such as lithium foil.
  • the negative electrode plate is a current collector, but does not include a negative electrode film layer; in this case, the battery cell (or secondary battery) is a lithium metal battery or a sodium metal battery, optionally a lithium metal battery.
  • the negative electrode film layer may further include a binder.
  • the binder may be selected from at least one 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).
  • the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • a conductive agent which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).
  • a thickener eg, sodium carboxymethyl cellulose (CMC-Na)
  • 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 (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.
  • a solvent such as deionized water
  • the battery cell (secondary battery) further includes a separator.
  • the present application has no particular restrictions on the type of separator, and any known porous structure separator with good chemical stability and mechanical stability can be selected.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation.
  • the materials of each layer can be the same or different, without particular limitation.
  • 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.
  • 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 examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.
  • FIG3 is a secondary battery 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 secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • Another aspect of the present application relates to a battery, including the battery cell of the present application, including a battery pack or a battery module, including a battery module or a battery pack.
  • battery cells may be assembled into a battery module or a battery pack.
  • the number of battery cells contained in the battery module or the battery pack may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG5 is a battery module 4 as an example.
  • a plurality of secondary batteries 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 secondary batteries 5 may be fixed by fasteners.
  • the battery module 4 may further include a housing having a receiving space, and the plurality of secondary batteries 5 are received in the receiving space.
  • Another aspect of the present application relates to a battery pack, including the battery cell or battery module of the present application.
  • the battery modules may be assembled into a battery pack.
  • the battery pack may contain one or more battery cells or battery modules. The specific number may be selected by those skilled in the art according to the application and capacity of the battery cells or battery pack.
  • FIG6 and FIG7 are battery packs 1 as an example.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be covered on the lower box body 3 to 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 including at least one selected from the secondary battery of the present application, the battery module of the present application, or the battery pack of the present application.
  • the secondary battery, battery module, or battery pack can be used as a power source for the electrical device, and can also be used as an energy storage unit for the electrical device.
  • the electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.
  • a secondary battery, a battery module or a battery pack may be selected according to its usage requirements.
  • FIG8 is an example of an electric device.
  • 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.
  • the positive electrode active material NCM811, the binder polyvinylidene fluoride (PVDF), and the conductive carbon black SP in a mass ratio of 97:2:1 were added to N-methylpyrrolidone and mixed evenly to obtain a positive electrode slurry (solid content of 65%); then the positive electrode slurry was evenly coated on an aluminum foil with a loading amount of 0.28g/ 1540.25mm2 , and the electrode sheet was dried, cold pressed, and punched to obtain a positive electrode sheet.
  • the negative electrode active material graphite, conductive carbon black SP, binder styrene-butadiene rubber (SBR) and thickener sodium carboxymethyl cellulose (CMC-Na) in a mass ratio of 96.5:1:1.8: 0.7 were added to deionized water and mixed evenly to obtain a negative electrode slurry (solid content of 50%).
  • the negative electrode slurry was coated on a copper foil with a loading amount of 0.198 g/1540.25 mm2, and a negative electrode sheet was obtained after drying, cold pressing and punching.
  • a polyethylene (PE) porous membrane was used as the separator.
  • the above-mentioned positive and negative electrode sheets and separators are stacked in the order of "positive electrode sheet-separator film-negative electrode sheet", inserted and encapsulated in an aluminum-plastic film, and then 0.5 g of electrolyte is filled into it to assemble a lithium-ion secondary battery.
  • the secondary battery assembled as above is charged at 3C constant current to an upper limit voltage of 4.25V at 25°C, charged at constant voltage until the current decays to 0.05C, and then discharged at 0.5C constant current to 2.5V. This is one cycle.
  • the charging capacity of the first cycle is recorded as C ⁇ 1
  • the discharge capacity is recorded as C ⁇ 1 .
  • This cycle is repeated for 10 cycles.
  • the charging capacity of the 10th cycle is recorded as C ⁇ 10
  • the discharge capacity is recorded as C ⁇ 10 .
  • the capacity retention rate and coulomb efficiency are calculated according to the following formulas:
  • Capacity retention rate (C discharge 10 /C discharge 1 ) ⁇ 100%;
  • the coulomb efficiency of the nth cycle ( Cdischarge n / Ccharge n ) ⁇ 100%, and the average value of 10 cycles is calculated, which is the coulomb efficiency value of 10 cycles.
  • the test results are shown in Table 1.
  • the battery cell was fully charged and disassembled.
  • the disassembled electrode was soaked in DMC for 12 hours to remove the lithium salt and then vacuum dried at 55°C for 30 minutes.
  • the interface of the negative electrode was then observed under a scanning electron microscope to confirm the growth of lithium dendrites.
  • the preparation method of the electrolyte and the secondary battery of Example 8 is similar to that of Example 2, but the negative electrode plate is copper foil; that is, in this case, the secondary battery is a metal negative electrode secondary battery, that is, a lithium metal battery. See Table 1 for details.
  • Comparative Example 5 The difference between Comparative Example 5 and Example 8 is that the electrolyte does not contain the halogen-containing additive and auxiliary solvent of the present application.
  • Example 8 in a metal negative electrode secondary battery (ie, a lithium metal battery), the electrolyte of the present application can also achieve the above-mentioned desired effect.
  • FIG1 shows a scanning electron microscope image of the interface of the negative electrode sheet obtained by disassembling the secondary battery of Example 2 after cycling
  • FIG2 shows a scanning electron microscope image of the interface of the negative electrode sheet obtained by disassembling the secondary battery of Comparative Example 1 after cycling.
  • the secondary battery including the electrolyte of the present application has better comprehensive performance, such as having a higher capacity retention rate and coulombic efficiency, and a lower self-discharge rate.
  • Examples 19-23 were prepared in a similar manner to Example 2, except that the mass ratio of the additive to the auxiliary solvent was changed.
  • Table 3 shows the type, content and ratio of the additive and auxiliary solvent in each example, as well as the test results.

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Abstract

本发明涉及一种电解液，其包括电解质盐、主溶剂、含卤素添加剂和辅助溶剂；所述含卤素添加剂选自碱金属碘化物、碘化锡、碱金属溴化物、溴化锡、溴单质和碘单质中的至少一种；所述辅助溶剂不同于所述主溶剂，且选自R 1S(O)R 2、苯和苯衍生物中的至少一种，其中，R 1和R 2各自独立地表示C 1-6烷基，并且所述苯衍生物的苯基上的一个或多个氢原子各自独立地被相同或不同的C 1-6烷基取代。本申请的电解液可使二次电池枝晶减少且综合性能良好。

Description

电解液、电池单体、电池和用电装置 技术领域
本申请涉及锂电池技术领域，尤其涉及一种电解液、电池单体、电池和用电装置。
背景技术
锂离子或钠离子二次电池因其能量密度高、环境友好等优势，成为人们关注的热点。但是，目前此类二次电池仍存在诸多不足，制约其应用前景。其中，由于锂离子或钠离子化学活性较高，因此容易在充放电循环中在负极极片表面析出并形成无化学活性的枝晶状锂/钠，这不仅造成活性物质的严重损耗而损害电池性能，还会为电池带来安全隐患。本领域在减少/消除枝晶方面做了大量工作。但是现有技术中的此类技术方案，尽管能够减少枝晶，但同时也会损害电池性能。
本领域需要一种能够减少枝晶同时能够保证电池具有良好性能的技术方案来解决上述问题。
发明内容
本申请是鉴于上述课题而进行的，其提供一种电解液，以及包含这种电解液的电池单体、电池和用电装置。
本申请的第一方面提供了一种电解液，其包括电解质盐、主溶剂、含卤素添加剂和辅助溶剂；所述含卤素添加剂选自碱金属碘化物、碘化锡、碱金属溴化物、溴化锡、溴单质和碘单质中的至少一种；所述辅助溶剂不同于所述主溶剂，且选自R 1S(O)R 2、苯和苯衍生物中的至少一种，其中，R 1和R 2各自独立地表示C 1-6烷基，并且所述苯衍生物的苯基上的一个或多个氢原子各自独立地被相同或不同的C 1-6烷基取代。本申请的电解液能够减少二次电池的枝晶生长，而不会明显损害二次电池的性能(如降低库伦效率、增大自放电率等)。
在任意实施方式中，所述含卤素添加剂选自碱金属碘化物、碘化锡和碘单质中的至少一种；可选地，所述含卤素添加剂选自碘化钾、 碘化锡、碘化钠、三碘化钾、碘化锂和碘单质中的至少一种。选择上述含卤素添加剂能够更有效地减少枝晶，同时可兼顾二次电池的多项性能之间的平衡，使二次电池同时具备较大的容量保持率、较高的库伦效率和较小的自放电率。
在任意实施方式中，R 1和R 2各自独立地表示C 1-4烷基，并且所述苯衍生物的苯基上的一个或多个氢原子各自独立地被相同或不同的C 1-4烷基取代；可选地，所述辅助溶剂选自二甲基亚砜、均三甲苯或间二甲苯中的一种或多种。这些辅助溶剂与含卤素添加剂或由其生成的氧化性物种之间的溶剂化效应适中，更有利于实现二次电池各性能之间的平衡(如，同时具备较大的容量保持率、较高的库伦效率和较小的自放电率)。
在任意实施方式中，基于所述电解液的总重量计，所述含卤素添加剂的量为0.01重量％至10重量％，可选地为0.01重量％至5重量％，更可选地为0.01重量％至1重量％。控制卤素添加剂的添加量有利于抑制枝晶生长，并实现二次电池多种性能间的平衡。
在任意实施方式中，基于所述电解液的总重量计，所述辅助溶剂的量为0.01重量％至10重量％，可选地为0.1重量％至5重量％，更可选地为0.5重量％至3重量％。控制辅助溶剂的量有利于产生有效的溶剂化作用，从而抑制枝晶，但又不会明显影响电解液性能，从而平衡二次电池多种性能。
在任意实施方式中，所述含卤素添加剂与所述辅助溶剂之间的质量比为3:1～1:305，可选地为1:2-1:20，更可选地为1:5-1:10。通过调整卤素添加剂和辅助溶剂的重量比，可在减少枝晶生长的同时减少对体系的不利影响，平衡二次电池各项性能。
本申请的第二方面提供一种电池单体，包括本申请第一方面的电解液。
本申请的第三方面提供一种电池，包括本申请的第二方面的电池单体。
本申请的第四方面提供一种用电装置，包括选自本申请的第二方面的电池单体和/或本申请的第三方面的电池。
本申请的电解液能够消除枝晶、激活死锂，而同时不会显著损害二次电池的性能，从而能够使二次电池在减少枝晶的同时具有良好的综合性能(例如，较高的容量保持率、较高的库伦效率和较低的自放电率)。
附图说明
图1为采用本申请一实施方式的电解液经循环后的负极极片的扫描电镜图。
图2为采用对比例1的电解液经循环后的负极极片的扫描电镜图。
图3是本申请一实施方式的二次电池的示意图。
图4是图3所示的本申请一实施方式的二次电池的分解图。
图5是本申请一实施方式的电池模块的示意图。
图6是本申请一实施方式的电池包的示意图。
图7是图6所示的本申请一实施方式的电池包的分解图。
图8是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电池包；2上箱体；3下箱体；4电池模块；5二次电池；51壳体；52电极组件；53顶盖组件
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的电解液、二次电池、电池模块、电池包和电学装置的实施方式。但是会有省略不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”以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，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，如果列出的最小范围值1和2，和如果列出了最大范围值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。
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。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
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，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法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，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(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。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
锂离子或钠离子二次电池因其能量密度高、环境友好等优势，成 为人们关注的热点。但是，目前此类二次电池仍存在多种不足，制约其应用前景。其中，由于锂离子或钠离子化学活性较高，因此容易在充放电循环中在负极极片表面析出并形成无化学活性的枝晶，这不仅造成活性物质的严重损耗而损害电池性能，还会为电池带来安全隐患。因此，本领域在减少/消除枝晶方面做了大量工作。但是现有技术中的此类技术方案，尽管能够减少锂枝晶，但同时也会损害电池性能。
为解决上述问题，本申请提供了一种电解液，其可有效减少二次电池的枝晶生成，但不会明显影响电池性能，因此二次电池可具有良好的综合性能，如，较大的容量保持率和库伦效率以及较小的自放电率。
电解液
本申请的一个实施方式中，提出了一种电解液，其包括电解质盐、主溶剂、含卤素添加剂和辅助溶剂；所述含卤素添加剂选自碱金属碘化物、碘化锡、碱金属溴化物、溴化锡、溴单质和碘单质中的至少一种；所述辅助溶剂不同于所述主溶剂，且选自R 1S(O)R 2、苯和苯衍生物中的至少一种，其中，R 1和R 2各自独立地表示C 1-6烷基，并且所述苯衍生物的苯基上的一个或多个氢原子各自独立地被相同或不同的C 1-6烷基取代。
本申请的电解液能够有效减少二次电池的枝晶生长，并使二次电池具有良好的综合性能(如，较大的容量保持率和库伦效率以及较小的自放电率)。
不希望囿于任何理论，这可能是因为在电解液中引入上述含卤素添加剂后，以含碘添加剂和锂离子二次电池为例，在二次电池充电时(阴极电势一般能达到至少2.8V，此时即可发生下文所述的电化学反应)，该含卤素添加剂本身或其在电流作用下经例如式(I)的反应生成含卤素中间体(也即，含卤素活性物种；例如，I 3 -和/或I 2)，其与负极极片表面析出的锂(锂枝晶或“死锂”)发生例如式(II)的反应，从而将“死锂”转化为锂离子(Li +)回到体系中——实现了减少锂枝晶的效果。同时，活性物种也被转化成碘离子，可再次回到正极，继续参与下述反应循环。
I -–e -→I 3 -/I 2       (I)
I 3 -/I 2+Li→Li ++I -     (II)
上述过程可认为是有利地利用了碘的“穿梭效应”。但是，发明人注意到，上述过程如果不加控制，则其中的活性物种可能会对负极极片等电池部分带来不利影响，从而可能会增大电池的自放电率、降低库伦效率等。在本申请的电解液中引入了辅助溶剂；在上述辅助溶剂的存在下，含卤素添加剂或由其形成的活性物种与辅助溶剂可发生溶剂化作用，而溶剂化的活性物种扩散到负极处，不能直接发生作用，而是在电化学势、浓度梯度、电场力等作用下发生脱溶剂化后方可与析出的锂发生上述反应，从而减缓了活性物种的上述“穿梭效应”，减轻其不利作用，从而在减少枝晶的同时，不会明显损害二次电池的性能，确保二次电池的综合性能良好(自放电速率较小、库伦效率较高)。
本文中，“穿梭效应”具有本领域技术人员通常理解的含义，意为在充放电过程中，含卤素添加剂在正极产生的含卤素中间体在电解液中，穿过隔膜扩散至负极，并且与负极的金属锂(包括析出的锂、极片本身含有的金属锂等)发生反应。在一些情况下，穿梭效应是不利的，其造成电池中有效物质不可逆损失、电池寿命衰减、低库伦效率，因此本发明中采用辅助溶剂来减缓穿梭效应，并减轻器不利作用。
本文中，“溶剂化效应”、“溶剂化”或其类似表达具有本领域技术人员通常理解的含义，意为溶质分子或离子通过与溶剂分子之间的相互作用(例如，配位作用、分子间作用力)而形成络合物。
本文中，“-S(O)-”表示亚砜基。
在一些实施方式中，所述含卤素添加剂选自碱金属碘化物、碘化锡和碘单质中的至少一种。在一些实施方式中，所述含卤素添加剂选自碘化钾(KI)、碘化锡(SnI 4)、碘化钠(NaI)、三碘化钾(KI 3)、碘化锂(LiI)和碘单质(I 2)中的至少一种。选择上述含卤素添加剂能够更有效地减少枝晶，同时可兼顾二次电池的多项性能之间的平衡，使二次电池同时具备较大的容量保持率、较高的库伦效率和较小的自放电率。
在一些实施方式中，所述辅助溶剂中所述苯衍生物的苯基上处于 间位的至少两个氢原子各自独立地被相同或不同的C 1-6烷基取代，且优选地被相同的C 1-6烷基取代。在一些实施方式中，R 1和R 2各自独立地表示C 1-4烷基，并且所述苯衍生物的苯基上的一个或多个氢原子各自独立地被相同或不同的C 1-4烷基取代。在一些实施方式中，所述苯衍生物的苯基上的一个或多个氢原子各自独立地被相同的C 1-4烷基取代。在一些实施方案中，所述辅助溶剂选自二甲基亚砜(DMSO)、均三甲苯(1,3,5-三甲苯)或间二甲苯(1,3-二甲苯)。上述辅助溶剂与含卤素添加剂或由其生成的氧化性物种之间的溶剂化效应适中，有利于实现温和、受控的“穿梭效应”而减少枝晶，并有利于实现二次电池的各项性能之间的平衡。
在一些实施方式中，基于所述电解液的总重量计，所述含卤素添加剂的量为0.01重量％至10重量％，可选地为0.01重量％至5重量％，更可选地为0.01重量％至1重量％。控制卤素添加剂的添加量有利于其与负极表面析出的锂及Li 2O等发生作用而抑制枝晶生长；具体而言，当含卤素添加剂的含量在上述范围内时，其可有效消除“死锂”或抑制枝晶，并且使“穿梭效应”不过于剧烈而对电池性能产生明显的不利影响(例如，不会明显增大自放电率或降低库伦效率)。
在一些实施方式中，基于所述电解液的总重量计，所述辅助溶剂的量为0.1重量％至10重量％，可选地为0.1重量％至5重量％，更可选地为0.5重量％至3重量％。当辅助溶剂的量在上述范围内，则其具有足够对含卤素添加剂产生有效的溶剂化作用，又不会使电解液性能明显变差(例如，不会明显提高粘度或降低电导率等)，从而有助于使二次电池具有良好的综合性能。
在一些实施方式中，所述含卤素添加剂与所述辅助溶剂的质量比为3:1～1:300，可选地为1:2-1:20，更可选地为1:5-1:10。通过调整卤素添加剂和辅助溶剂的重量比，可以控制添加剂的扩散速度和反应速度，进而实现受控的“穿梭效应”，在减少枝晶的同时减少对体系的不利影响，平衡二次电池各项性能。
本文中，“主溶剂”意为相比于辅助溶剂以较大量存在的溶剂。 在一些实施方式中，所述主溶剂可采用本领域内常规溶剂。所述主溶剂可选自碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、二甲氧基乙烷(DME)、二氧戊环(DOL)、碳酸二甲酯(DMC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)中的至少一种。
在本申请中，所述电解质盐是不同于所述含卤素添加剂的物质；换言之，所述电解质盐选自不属于所述含卤素添加剂的物质。所述电解质盐包括本领域已知的合适的盐，但不包括锂或钠的碘化物或溴化物。或者说，所述电解质盐包括除锂的碘化物或溴化物和钠的碘化合物和溴化物之外的其他适用的盐。但是，应当理解的是，在一些实施方式中，本申请的电解液可包括(如果存在的话)锂的碘化物或溴化物和/或钠的碘化合物和溴化物作为含卤素添加剂。
在一些实施方式中，所述电解质盐可选自六氟磷酸锂(LiPF 6)、双三氟甲磺酰亚胺锂(LiTFSI)、双氟磺酰亚胺锂(LiFSI)、四氟硼酸锂(LiBF 4)、高氯酸锂(LiClO 4)、六氟砷酸锂(LiAsF 6)、二氟草酸硼酸锂(LiDFOB)中的至少一种。
在一些实施方式中，所述电解质盐还可选自六氟磷酸钠(NaPF 6)、六氟硼酸钠(NaBF 4)、NaN(SO 2F) 2(简写为NaFSI)、NaClO 4、NaAsF 6、NaB(C 2O 4) 2(简写为NaBOB)、NaBF 2(C 2O 4)(简写为NaDFOB)、NaN(SO 2R F) 2和NaN(SO 2F)(SO 2R F)中的一种或多种；其中，R F代表C bF 2b+1，b为1-10范围内的整数，可选为1-3范围内的整数，更可选地，R F为-CF 3、-C 2F 5或-CF 2CF 2CF 3。
在一些实施方式中，所述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。
电池单体、电池和用电装置
以下适当参照附图对本申请的电池单体(二次电池)、电池(包括，例如，电池模块、电池包)和用电装置进行说明。
本申请的一个实施方式中，提供一种电池单体，包括上文所述的电解液。
本文中，“电池单体”与“二次电池”具有相似的含义。
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。
在一些实施方案中，所述二次电池是锂离子二次电池或钠离子二次电池，可选地是锂离子二次电池。
[正极极片]
正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，所述正极膜层包括正极活性材料。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施方式中，所述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(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(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)等的基材)上而形成。
在一些实施方式中，正极活性材料可采用本领域公知的用于电池的正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物、钠过渡金属氧化物、聚阴离子型化合物和普鲁士蓝类化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 2)、锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧 化物、锂镍钴锰氧化物(如LiNi 1/3Co 1/3Mn 1/3O 2(也可以简称为NCM 333)、LiNi 0.5Co 0.2Mn 0.3O 2(也可以简称为NCM 523)、LiNi 0.5Co 0.25Mn 0.25O 2(也可以简称为NCM 211)、LiNi 0.6Co 0.2Mn 0.2O 2(也可以简称为NCM 622)、LiNi 0.8Co 0.1Mn 0.1O 2(也可以简称为NCM 811)、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO 4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。
在一些实施方式中，钠过渡金属氧化物中，过渡金属可以是Mn、Fe、Ni、Co、Cr、Cu、Ti、Zn、V、Zr及Ce中的至少一种。钠过渡金属氧化物例如为Na xM yO 2，其中M为Ti、V、Mn、Co、Ni、Fe、Cr及Cu中的一种或几种，0＜x≤1，0.5＜y≤1.5。在一些实施方式中，正极活性材料可采用Na 0.88Cu 0.24Fe 0.29Mn 0.47O 2。
在一些实施方式中，聚阴离子型化合物可以是具有钠离子、过渡金属离子及四面体型(YO 4) n-阴离子单元的一类化合物。过渡金属可以是Mn、Fe、Ni、Co、Cr、Cu、Ti、Zn、V、Zr及Ce中的至少一种；Y可以是P、S及Si中的至少一种；n表示(YO 4) n-的价态。
在一些实施方式中，聚阴离子型化合物还可以是具有钠离子、过渡金属离子、四面体型(YO 4) n-阴离子单元及卤素阴离子的一类化合物。过渡金属可以是Mn、Fe、Ni、Co、Cr、Cu、Ti、Zn、V、Zr及Ce中的至少一种；Y可以是P、S及Si中的至少一种，n表示(YO 4) n-的价态；卤素可以是F、Cl及Br中的至少一种。
在一些实施方式中，聚阴离子型化合物还可以是具有钠离子、四面体型(YO 4) n-阴离子单元、多面体单元(ZO y) m+及可选的卤素阴离子的一类化合物。Y可以是P、S及Si中的至少一种，n表示(YO 4) n-的价态；Z表示过渡金属，可以是Mn、Fe、Ni、Co、Cr、Cu、Ti、Zn、V、Zr及Ce中的至少一种，m表示(ZO y) m+的价态；卤素可以是F、Cl及Br中的至少一种。
在一些实施方式中，聚阴离子型化合物例如是NaFePO 4、 Na 3V 2(PO 4) 3、NaM’PO 4F(M’为V、Fe、Mn及Ni中的一种或几种)及Na 3(VO y) 2(PO 4) 2F 3-2y(0≤y≤1)中的至少一种。
在一些实施方式中，普鲁士蓝类化合物可以是具有钠离子、过渡金属离子及氰根离子(CN -)的一类化合物。过渡金属可以是Mn、Fe、Ni、Co、Cr、Cu、Ti、Zn、V、Zr及Ce中的至少一种。普鲁士蓝类化合物例如为Na aMe bMe’ c(CN) 6，其中Me及Me’各自独立地为Ni、Cu、Fe、Mn、Co及Zn中的至少一种，0＜a≤2，0＜b＜1，0＜c＜1。
在一些实施方式中，正极膜层还可选地包括粘结剂。作为示例，所述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至少一种。
在一些实施方式中，正极膜层还可选地包括导电剂。作为示例，所述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至少一种。
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，例如正极活性材料、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。
[负极极片]
负极极片包括负极集流体和任选地设置在负极集流体至少一个表面上的负极膜层，所述负极膜层包括负极活性材料。
在一些实施方式中，所述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(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(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)等的基材)上而形成。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极膜层设置在负极集流体相对的两个表面中的任意一者或两者上。
在一些实施方式中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：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。所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。所述锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性材料的传统材料。这些负极活性材料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，负极活性材料还可包括金属材料，例如，锂箔。在一些实施方式中，负极极片为集流体，而不包括负极膜层；在此情况下，所述电池单体(或二次电池)为锂金属电池或钠金属电池，可选地为锂金属电池。
在一些实施方式中，负极膜层还可选地包括粘结剂。所述粘结剂可选自丁苯橡胶(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)中的至少一种。
在一些实施方式中，负极膜层还可选地包括导电剂。导电剂可选自超导碳、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至少一种。
在一些实施方式中，负极膜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))等。
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，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，即可得到负极极片。
[隔离膜]
在一些实施方式中，电池单体(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，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。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，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。
[外包装]
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，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
本申请对二次电池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3是作为一个示例的方形结构的二次电池5。
在一些实施方式中，参照图4，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能够盖设于所述开口，以封闭所述容纳腔。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封装于所述容纳腔内。电解液浸润于电极组件52中。二次电池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具体实际需求进行选择。
本申请的又一方面涉及一种电池，包括本申请的电池单体。所述电池包括电池组或电池模块。所述电池包括电池模块或电池包。
在一些实施方式中，电池单体可以组装成电池模块或电池包，电池模块或电池包所含电池单体的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
图5是作为一个示例的电池模块4。参照图5，在电池模块4中，多个二次电池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二次电池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，多个二次电池5容纳于该容纳空间。
本申请的再一方面涉及一种电池包，包括本申请的电池单体或电池模块。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池单体或电池模块的数量可以为一个或多个，具体数量本领域技术人员可根据电池单体或电池包的应用和容量进行选择。
图6和图7是作为一个示例的电池包1。参照图6和图7，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。
本申请的再一方面涉及一种用电装置，包括选自本申请的二次电池、本申请的电池模块或本申请的电池包中的至少一种。所述二次电池、电池模块、或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、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、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。
作为所述用电装置，可以根据其使用需求来选择二次电池、电池模块或电池包。
图8是作为一个示例的用电装置。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。
实施例
以下，说明本申请的实施例。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。实施例中未注明具体技术或条件的，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。
实施例1
1.电解液的制备
在手套箱中，于25℃温度下，称取质量比0.5:2.5:97的KI、DMSO和电解液(将LiPF 6溶于EC与DMC体积比为1:1的混合溶剂中，浓度为1M)，充分搅拌使之均匀混合，即得到本申请的电解液。
2.正极极片的制备
将质量比为97:2:1的正极活性材料NCM811、粘结剂聚偏氟乙烯(PVDF)、导电炭黑SP加入N-甲基吡咯烷酮中混合均匀，得到正极浆料(固含量为65％)；然后将正极浆料以负载量0.28g/1540.25mm 2均匀涂覆在铝箔上，将极片烘干、冷压、冲切后得到正极极片。
3.负极极片的制备
将质量比为96.5:1:1.8:0.7的负极活性材料石墨、导电炭黑SP、粘结剂丁苯橡胶(SBR)和增稠剂羧甲基纤维素钠(CMC-Na)加入去离子水中，混合均匀后得到负极浆料(固含量为50％)，将负极浆料以负载量0.198g/1540.25mm 2涂覆在铜箔上，经烘干、冷压、冲切后得到负极极片。
4.隔离膜
采用聚乙烯(PE)多孔膜作为隔离膜。
5.电池的制备
在低湿恒温房内用上述正、负极极片和隔离膜(面积分别为48×48mm，50×50mm，52×52mm)，以“正极片-隔离膜-负极片”的顺序叠置，将其插入并封装在铝塑膜中，再向其中充入0.5g电解液，组装成锂离子二次电池。
6.二次电池循环性能测试：
将如上文那样组装好的二次电池在25℃下以3C恒流充电到上限电压4.25V，恒压充电至电流衰减至0.05C，再以0.5C恒流放电至2.5V，此为循环1圈，记第1圈的充电容量为C 充1，放电容量记为C 放1。如此循环10圈。记第10圈的充电容量为C 充10，放电容量记为C 放10。分别按照下式计算容量保持率和库伦效率：
容量保持率＝(C 放10/C 放1)×100％；
第n圈的库伦效率＝(C 放n/C 充n)×100％，计算循环10圈的平均值，即为循环10圈的库伦效率值。测试结果详见表1。
7.二次电池自放电率测试：
在25℃下，以0.33C恒流充电至4.25V，再以0.33C恒流放电至2.5V，则此时的放电容量即为满放容量，记首次放电的满放容量为C1；然后在25℃下，再将电芯0.33C恒流充电至4.25V(此时即为“满充”状态)，然后将满充后的电芯在25℃静置30天后，将电芯在25℃下以0.33C恒流放电至2.5V(此时即为“满放”状态)，记满放容量为C2，以以下公式计算自放电率：
自放电率＝[1-(C2/C1)]×100％。
测试结果详见表1。
8.负极极片的扫描电镜测试：
循环10圈后的电芯满充后拆解，使用DMC将拆解得到的极片浸泡12h除去锂盐后以55℃温度真空烘干30min，然后在扫描电镜下观察该负极极片的界面，以确认锂枝晶生长的状况。
实施例2-7和对比例1-4
实施例2-7的电解液及二次电池的制备方法均与实施例1相似，但是调整了电解液中的含卤素添加剂和辅助溶剂种类，详见表1。
实施例8和对比例5
实施例8的电解液及二次电池的制备方法均与实施例2相似，但其中的负极极片是铜箔；也即，在此情况下，二次电池为金属负极二次电池，也即，锂金属电池。详见表1。
对比例5与实施例8的区别在于，电解液中不包含本申请的含卤素添加剂和辅助溶剂。
表1
Figure PCTCN2022124811-appb-000001
由表1可见，本申请实施例1-7的电解液与对比例1-5相比，明显改善了容量保持率，并且未明显增大自放电率或降低库伦效率，从而使二次电池具有良好的综合性能。
另外，实施例8和对比例6相比较可见，在金属负极二次电池(也即，锂金属电池)中，本申请的电解液液也能实现上述期望效果。
此外，图1示出了实施例2的二次电池在循环后拆解得到的负极极片的界面的扫描电镜图，图2示出了对比例1中的二次电池经循环后拆解得到的负极极片的界面的扫描电镜图。可见，本申请的电解液实现了良好的减少(或抑制)枝晶的效果。
实施例9-18
实施例9-18的电解液与实施例1的制备方法相似，但是调整了含卤素添加剂的含量，而实施例13至18则是调整了辅助溶剂的含量，详见表2。
表2
Figure PCTCN2022124811-appb-000002
由表2可见，当添加剂和辅助溶剂符合一定的重量百分比范围时，包括本申请的电解液的二次电池具备更好的综合性能，如同时具备较高的容量保持率和库伦效率，以及较低的自放电率。
实施例19-23
实施例19-23与实施例2采用类似的方法制备，其中不同之处在于改变了添加剂与辅助溶剂之间的质量比。表3示出了各个实施例中的添加剂和辅助溶剂的种类、含量及其比例，以及测试结果。
表3
Figure PCTCN2022124811-appb-000003
由表3可见，使添加剂与辅助溶剂的质量比在一定范围内，能够使包括本申请的电解液的二次电池具备更好的综合性能，如同时具备较高的容量保持率和库伦效率，以及较低的自放电率。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，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。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式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 (9)

  1. 一种电解液，其包括电解质盐、主溶剂、含卤素添加剂和辅助溶剂；所述含卤素添加剂选自碱金属碘化物、碘化锡、碱金属溴化物、溴化锡、溴单质和碘单质中的至少一种；所述辅助溶剂不同于所述主溶剂，且选自R 1S(O)R 2、苯和苯衍生物中的至少一种，其中，R 1和R 2各自独立地表示C 1-6烷基，并且所述苯衍生物的苯基上的一个或多个氢原子各自独立地被相同或不同的C 1-6烷基取代。
  2. 根据权利要求1所述的电解液，其中所述含卤素添加剂选自碱金属碘化物、碘化锡和碘单质中的至少一种；可选地，所述含卤素添加剂选自碘化钾、碘化锡、碘化钠、三碘化钾、碘化锂和碘单质中的至少一种。
  3. 根据权利要求1或2所述的电解液，其中R 1和R 2各自独立地表示C 1-4烷基，并且所述苯衍生物的苯基上的一个或多个氢原子各自独立地被相同或不同的C 1-4烷基取代；可选地，所述辅助溶剂选自二甲基亚砜、均三甲苯或间二甲苯中的一种或多种。
  4. 根据权利要求1至3中任一项所述的电解液，其中基于所述电解液的总重量计，所述含卤素添加剂的量为0.01重量％至10重量％，可选地为0.01重量％至5重量％，更可选地为0.01重量％至1重量％。
  5. 根据权利要求1至4中任一项所述的电解液，其中基于所述电解液的总重量计，所述辅助溶剂的量为0.01重量％至10重量％，可选地为0.1重量％至5重量％，更可选地为0.5重量％至3重量％。
  6. 根据权利要求1至5中任一项所述的电解液，其中所述含卤素添加剂与所述辅助溶剂之间的质量比为3:1～1:305，可选地为1:2-1:20，更可选地为1:5-1:10。
  7. 一种电池单体，包括权利要求1至6中任一项所述的电解液。
  8. 一种电池，包括权利要求7所述的电池单体。
  9. 一种用电装置，包括选自权利要求7所述的电池单体、权利要求8所述的电池中的至少一种。
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JP2000260469A (ja) * 1999-03-09 2000-09-22 Ngk Insulators Ltd リチウム二次電池
CN1501539A (zh) * 2002-11-16 2004-06-02 ����Sdi��ʽ���� 非水电解液及使用它的锂电池
CN103378370A (zh) * 2012-04-24 2013-10-30 张家港市国泰华荣化工新材料有限公司 一种锂铁电池用碘化锂有机电解液及其制备方法
CN106463711A (zh) * 2014-03-24 2017-02-22 康奈尔大学 用于金属基蓄电池的枝晶抑制性电解质
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* Cited by examiner, † Cited by third party
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JP2000260469A (ja) * 1999-03-09 2000-09-22 Ngk Insulators Ltd リチウム二次電池
CN1501539A (zh) * 2002-11-16 2004-06-02 ����Sdi��ʽ���� 非水电解液及使用它的锂电池
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