Electrolyte, lithium supplement battery and electric equipment

Abstract

The invention discloses an electrolyte, a lithium supplement battery and electric equipment, the electrolyte is used for the lithium supplement battery, the electrolyte comprises an additive, and the additive comprises a boron-based organic compound. The components of the electrolyte comprise the boron-based organic compound, so that the lithium supplement agent in the lithium supplement battery can be better dissolved in the electrolyte under the action of the boron-based organic compound, the decomposition voltage of the lithium supplement agent can be reduced, and the decomposition efficiency of the lithium supplement agent can be improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to an electrolyte, a lithium-supplemented battery, and an electrical device. Background Art

[0002] Lithium-ion batteries have been widely used in recent years due to their advantages of high energy density, high operating voltage, long service life and low self-discharge.

[0003] The lithium supplement in the battery can replenish the lithium consumed during the battery cycle. However, the solubility of the lithium supplement in the electrolyte is low, the decomposition voltage of the lithium supplement is high, and the decomposition efficiency is low. Summary of the Invention

[0004] The purpose of this application is to provide an electrolyte, a lithium-supplementing battery, and an electrical device, which can reduce the decomposition voltage of a lithium-supplementing agent and improve the decomposition efficiency of the lithium-supplementing agent.

[0005] To achieve the purpose of this application, this application provides the following technical solutions:

[0006] In a first aspect, the present application provides an electrolyte for replenishing a lithium battery, wherein the electrolyte comprises an additive, and the additive comprises a boron-based organic compound.

[0007] In one embodiment, the boron-based organic compound includes any one or a combination of (CH3O)3B, (CF3CH2O)3B, (C3F7CH2O)3B, (C3F7CH2CH2O)3B, [(CF3)2CHO]3B, [(CF3)3CO]3B, [(CF3)2C(C6H5)O]3B, (C6H5O)3B, (FC6H4O)3B, (F2C6H3O)3B, (F4C6HO)3B, (C6F5O)3B, (CF3C6H4O)3B, ((CF3)2C6H3O)3B, and (C6F5)3B.

[0008] In one embodiment, the concentration of the boron-based organic compound in the electrolyte is A, which satisfies: 5mM≤A≤1000mM.

[0009] In one embodiment, the electrolyte includes a redox mediator.

[0010] In one embodiment, the redox mediator includes any one or more of sulfide, sulfate, nitrate, iodide, bromide, nitrite, chloride, piperidine oxide, phenothiazines, thiazines, organic amines, aminobenzenes, phenazines, anthracenes, thianthrenes, tetrathiafulvalene and its derivatives, benzoquinone and its derivatives, dimethoxybenzene and its derivatives, tetrathiafulvalene, N-methyl-N-propylpyrrolidine bromide, cobalt (II) porphyrin complex, iron phthalocyanine, ethyl viologen, and ferrocene, and / or the concentration of the redox mediator in the electrolyte is G, satisfying: 5mM≤G≤500mM.

[0011] In one embodiment, the electrolyte further includes a solvent and a lithium salt.

[0012] In one embodiment, the lithium salt includes any one or more of lithium hexafluorophosphate, lithium perchlorate, lithium bis(oxalatoborate), lithium bis(trifluoromethanesulfonylimide), and lithium bis(fluorosulfonylimide); and / or the solvent includes any one or more of ethylene carbonate, propylene carbonate, fluoroethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, and diethyl carbonate.

[0013] In one embodiment, the concentration of the lithium salt in the electrolyte is H, satisfying: 0.5M≤H≤5M.

[0014] In a second aspect, the present application further provides a lithium-supplemented battery, comprising an electrolyte as described in any one of the various embodiments of the first aspect.

[0015] In one embodiment, the lithium supplemented battery further includes a positive electrode sheet, and at least one of the positive electrode sheet and the electrolyte contains a lithium supplement agent.

[0016] In one embodiment, the lithium supplement comprises any one or a combination of more of lithium formate, lithium fluoride, lithium chloride, lithium iodide, lithium oxalate, lithium oxide, lithium peroxide, lithium carbonate, lithium sulfide, and lithium disulfide.

[0017] In one embodiment, the electrolyte contains the lithium supplement agent, and the concentration of the lithium supplement agent in the electrolyte is B, satisfying: 5mM≤B≤1000mM.

[0018] In one embodiment, the molar ratio of the boron-based organic compound to the lithium supplement agent is C, which satisfies: 0.01≤C≤100; preferably, it also satisfies: 0.5≤C≤2.

[0019] In one embodiment, the positive electrode sheet includes the lithium supplement agent and a positive electrode active material. In the positive electrode sheet, the mass ratio of the lithium supplement agent to the mass of the positive electrode active material is D, which satisfies: 0.1%≤D≤10%.

[0020] In one embodiment, both the positive electrode sheet and the electrolyte contain the lithium replenisher, and the molar ratio of the lithium replenisher in the electrolyte to the lithium replenisher in the positive electrode sheet is E, which satisfies: 0.01≤E≤100; preferably, it also satisfies: 0.5≤E≤2.

[0021] In a third aspect, the present application further provides an electrical device comprising an electrolyte as described in any one of the various embodiments of the first aspect or a lithium-supplemented battery as described in any one of the various embodiments of the second aspect.

[0022] By setting the electrolyte composition to include additives, and the additives including boron-based organic compounds, the lithium supplement agent in the lithium supplement battery can be better dissolved in the electrolyte under the action of the boron-based organic compounds, which can reduce the decomposition voltage of the lithium supplement agent in the lithium supplement battery and improve the decomposition efficiency of the lithium supplement agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the implementation methods or the description of the prior art. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 is a schematic diagram of a lithium supplement battery according to an embodiment;

[0025] Figure 2 The present invention is a flow chart of a method for preparing an electrolyte according to an embodiment.

[0026] Description of reference numerals:

[0027] 100-Replenish lithium battery;

[0028] 10-negative electrode sheet, 11-negative electrode current collector, 12-negative electrode active layer;

[0029] 20-positive electrode sheet, 21-positive electrode current collector, 22-positive electrode active layer;

[0030] 30-diaphragm. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0032] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may be an intermediate component. When a component is referred to as being "connected to" another component, it may be directly connected to the other component or there may be an intermediate component.

[0033] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art to which this application belongs. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used in this application includes any and all combinations of one or more of the relevant listed items.

[0034] The following describes some embodiments of the present application in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0035] An embodiment of the present application provides an electric device, including an electric device and a lithium supplement battery in the embodiment of the present application, and the lithium supplement battery supplies power to the electric device.

[0036] Optionally, the power-consuming device may be an electric vehicle, a hybrid vehicle, a base station, a household power load, etc. The lithium-ion battery may be a power lithium-ion battery, an energy storage lithium-ion battery, etc., without specific limitation.

[0037] In one embodiment, the power-consuming device is an electric vehicle or a hybrid vehicle, and the lithium-ion battery is a power lithium-ion battery.

[0038] The electrical equipment adopts the lithium-ion battery in the embodiment of the application, and the lithium-ion battery has good cycle performance and long service life.

[0039] Please refer to Figure 1 The embodiment of the present application further provides a lithium supplement battery 100, including an additive, wherein the additive comprises a boron-based organic compound, and the boron-based organic compound is suitable for dissolving the lithium supplement agent.

[0040] Optionally, the lithium-supplemented battery 100 may be a laminated battery or a wound battery, and the laminated battery may be, for example, a square laminated battery, a blade laminated battery, etc., without limitation.

[0041] Optionally, the supplementary lithium battery 100 further includes a housing (not shown in the figure). The housing includes a bottom plate and multiple side plates. The side plates are connected to the bottom plate and enclose to form a receiving cavity. One end of the receiving cavity opposite to the bottom plate is open, and the supplementary lithium battery 100 is accommodated in the receiving cavity. Optionally, the housing is made of a material with high structural strength, specifically, it can be a metal material, high-strength plastic, ceramic, etc. The metal material can be, for example, aluminum, aluminum alloy, magnesium alloy, iron and iron alloy, etc. The housing can be an integral structure, that is, the bottom plate and the side plates are an integral structure made by an integral molding process. The integral molding process can be specifically stamping, casting, etc., without limitation. The housing can also be a split structure, and the side plates and the bottom plate can be connected and fixed by welding, bonding, clamping, screwing, etc. The wall thickness of each part of the housing can be substantially uniform, that is, the thickness of the side plates can be substantially uniform and consistent, and the thickness of the bottom plate and the side plates can also be substantially the same.

[0042] Optionally, the supplementary lithium battery 100 further includes a cover plate. The cover plate is connected to the opening of the housing to close the receiving cavity. The connection method between the cover plate and the housing can be welding, bonding, clamping, screwing, etc., without limitation. The shape of the cover plate can be substantially the same as that of the bottom plate.

[0043] Optionally, the positive electrode sheet 20 includes a positive electrode current collector 21. At least one side of the positive electrode current collector 21 is provided with a positive electrode active layer 22. The positive electrode active layer 22 includes components such as a positive electrode material, a conductive agent, and a binder. The present application does not specifically limit these materials, and suitable materials can be selected according to actual application requirements. The positive electrode current collector 21 includes, but is not limited to, any one of copper foil and aluminum foil. The positive electrode active material can be a phosphate positive electrode active material and a ternary positive electrode active material. In specific embodiments, it includes lithium cobaltate, lithium manganate, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium oxyphosphate, lithium fluorovanadate phosphate, lithium titanate, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, binary material LiNi x A(1-k)O2 (where A is selected from one of Co and Mn, 0 < k < 1), ternary material LiNi m E n M(1-i-j)O2 (where E and M are independently selected from at least one of Co, Al, and Mn, and E and M are different, 0 < i < 1, 0 < j < 1)) or more. The conductive agent includes one or more of Super P, Super S, graphene, acetylene black, carbon fiber, Ketjen black, C60, and carbon nanotubes, and the content of the conductive agent in the positive electrode active layer 22 is 3wt% - 5wt%. The types of the binder include one or more of polyvinylidene chloride, soluble polytetrafluoroethylene, styrene-butadiene rubber, hydroxypropyl methyl cellulose, methyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, acrylonitrile copolymer, sodium alginate, chitosan, and chitosan derivatives, and the content of the adhesive in the positive electrode active layer 22 is 2wt% - 4wt%.

[0044] Optionally, the lithium-supplemented battery 100 further includes a negative electrode sheet 10, which includes a negative electrode current collector 11. A negative electrode active layer 12 is disposed on at least one side of the negative electrode current collector 11. The negative electrode active layer 12 includes components such as a negative electrode material, a conductive agent, and a binder. These materials are not specifically limited in this application; appropriate materials can be selected based on actual application requirements. Negative electrode materials include, but are not limited to, carbon-based and silicon-based negative electrodes. Carbon-based negative electrodes may include graphite, hard carbon, soft carbon, and graphene; silicon-based negative electrodes may include silicon, silicon-carbon, silicon-oxygen, and silicon-metal compounds. In some embodiments, the negative electrode active material is selected from at least one of silicon monoxide, silicon carbide, and a silicon-carbon composite. Optionally, a conductive agent may be added to the negative electrode material film to improve its conductivity to the positive electrode active material. The conductive agent may include one or more of acetylene black, Ketjen black, SuperP, SuperS, carbon nanotubes, carbon nanofibers, activated carbon, and graphene.

[0045] Optionally, the lithium-supplemented battery 100 further includes a diaphragm 30 . The diaphragm 30 may be any diaphragm 30 known in the art. This application does not specifically limit these materials, and appropriate materials may be selected according to actual application requirements.

[0046] The rapid development of new energy vehicles, portable electronic devices, and other fields has placed higher demands on the performance of lithium-ion batteries, especially the improvement of battery energy density. In the existing lithium-ion battery system, in addition to improving energy density through optimizing battery structure and iterating positive and negative electrode materials, lithium replenishment technology has also become an important means.

[0047] The lithium supplement battery 100 can add lithium to the battery to supplement lithium ions before operation, which can offset the capacity loss caused by irreversible lithium loss during the first charge and cycle of the battery, thereby improving the total capacity and energy density of the battery.

[0048] During the first charging process of a lithium-ion battery, the organic electrolyte will be reduced and decomposed on the surface of the negative electrode such as graphite to form a solid electrolyte interface (SEI) film. This process will permanently consume a large amount of lithium from the positive electrode, resulting in a low coulombic efficiency (ICE) of the first cycle, which reduces the capacity and energy density of the lithium-ion battery. In addition, processes such as the shedding of negative electrode material particles and the irreversible deposition of lithium metal will also consume the active lithium of the positive electrode, further reducing the capacity and energy density of the battery. Lithium replenishment technology compensates for these irreversible lithium losses by adding lithium to the battery before the battery is working. The lithium replenisher in the lithium replenisher battery 100 can replenish the lithium used by the lithium replenisher battery 100 during the cycle. However, the solubility of the lithium replenisher in the electrolyte is low, the decomposition voltage of the lithium replenisher is high, and the decomposition efficiency is low.

[0049] Furthermore, some lithium supplements leave residues after decomposition, which can easily cause side reactions in the lithium-supplemented battery 100 and affect its performance. For example, residual Li3VO4 in the positive electrode after decomposition can cause gassing in the lithium-supplemented battery 100. Lithium hydroxide can also cross-link the positive electrode binder, causing gelation of the positive electrode slurry and creating manufacturing difficulties.

[0050] The additive component of the lithium-supplemented battery 100 in the embodiments of the present application includes a boron-based organic compound, which is suitable for dissolving the lithium-supplementing agent in the lithium-supplemented battery 100. Because the boron-based organic compound has a good affinity for and solubility in lithium ions, it allows the lithium-supplementing agent to dissolve better in the electrolyte. This dissolution not only facilitates uniform distribution of the lithium-supplementing agent within the lithium-supplemented battery 100 but also increases its utilization rate within the lithium-supplemented battery 100, thereby further enhancing the performance of the lithium-supplemented battery 100.

[0051] For ionically bonded lithium supplements, since the bond energy of ionic bonds is smaller than that of covalent bonds, ionic bonds are more easily dissociated under the action of boron-based organic compounds. Therefore, ionically bonded lithium supplements such as Li2O2, Li2O and LiF have high solubility in electrolytes containing boron-based organic compounds, which can achieve decomposition of lithium supplements at lower voltages (below ~4.3V), reducing side reactions in lithium supplement batteries.

[0052] Optionally, the lithium-supplemented battery 100 in the embodiment of the present application may be a positive electrode lithium-supplemented battery, a negative electrode lithium-supplemented battery, a separator lithium-supplemented battery, an electrolyte lithium-supplemented battery, etc., without specific limitation.

[0053] In the lithium-supplemented battery 100 of the embodiment of the present application, the additive component includes a boron-based organic compound. The lithium-supplementing agent in the lithium-supplemented battery 100 can be better dissolved in the electrolyte under the action of the boron-based organic compound, thereby reducing the decomposition voltage of the lithium-supplementing agent and improving the decomposition efficiency of the lithium-supplementing agent.

[0054] Optionally, the molecular formula of the boron-based organic compound is any one or a combination of (CH3O)3B, (CF3CH2O)3B, (C3F7CH2O)3B, (C3F7CH2CH2O)3B, [(CF3)2CHO]3B, [(CF3)3CO]3B, [(CF3)2C(C6H5)O]3B, (C6H5O)3B, (FC6H4O)3B, (F2C6H3O)3B, (F4C6HO)3B, (C6F5O)3B, (CF3C6H4O)3B, ((CF3)2C6H3O)3B, and (C6F5)3B.

[0055] Optionally, the boron-based organic compound can be derived from any one of the above molecular formulas; or, the boron-based organic compound is a combination of any two of the above molecular formulas, which can be mixed in equimolar amounts or in different amounts; or, the boron-based organic compound is a combination of any two or more of the above molecular formulas, without specific limitation.

[0056] Optionally, the molecular formula of the boron-based organic compound is (C6F5)3B.

[0057] By setting the molecular formula of the boron-based organic compound to any one or a combination of (CH3O)3B, (CF3CH2O)3B, (C3F7CH2O)3B, (C3F7CH2CH2O)3B, [(CF3)2CHO]3B, [(CF3)3CO]3B, [(CF3)2C(C6H5)O]3B, (C6H5O)3B, (FC6H4O)3B, (F2C6H3O)3B, (F4C6HO)3B, (C6F5O)3B, (CF3C6H4O)3B, ((CF3)2C6H3O)3B, and (C6F5)3B, the lithium supplement agent in the lithium supplement battery 100 can be better dissolved in the electrolyte under the action of the boron-based organic compound, thereby reducing the decomposition voltage of the lithium supplement agent and improving the decomposition efficiency of the lithium supplement agent.

[0058] Optionally, the concentration of the boron-based organic compound in the electrolyte is A, satisfying: 5mM≤A≤1000mM.

[0059] Optionally, the concentration A of the boron-based organic compound satisfies: 100 mM≤A≤500 mM, where the unit mM represents millimole per cubic decimeter, that is, 1 M=1000 mM.

[0060] Optionally, the concentration A of the boron-based organic compound may be 5 mM, 100 mM, 200 mM, 500 mM, 800 mM, etc., without specific limitation.

[0061] By setting the concentration A of the boron-based organic compound in the electrolyte to satisfy: 5mM≤A≤1000mM, the lithium supplement agent in the lithium supplement battery 100 can be better dissolved in the electrolyte under the action of the boron-based organic compound, which can reduce the decomposition voltage of the lithium supplement agent and improve the decomposition efficiency of the lithium supplement agent.

[0062] Optionally, the electrolyte solution further comprises a redox mediator.

[0063] A redox mediator is an organic compound that can be reversibly oxidized and reduced in a redox reaction. It plays the role of an electron carrier in the reaction and can promote the transfer of electrons from electron donors to electron acceptors.

[0064] By configuring the electrolyte to further include a redox mediator, the addition of the redox mediator can increase the charge transfer path, further reduce the decomposition potential of the lithium supplement, and accelerate the decomposition rate of the lithium supplement.

[0065] Optionally, the redox mediator is any one or more of sulfide, sulfate, nitrate, iodide, bromide, nitrite, chloride, piperidine oxide, phenothiazines, thiazines, organic amines, aminobenzenes, phenazines, anthracenes, thianthrenes, tetrathiafulvalene and its derivatives, benzoquinone and its derivatives, dimethoxybenzene and its derivatives, tetrathiafulvalene, N-methyl-N-propylpyrrolidine bromide, cobalt (II) porphyrin complex, iron phthalocyanine, ethyl viologen, and ferrocene.

[0066] Optionally, the redox mediator can be any one of the above-mentioned redox mediators; or, the redox mediator is a combination of any two of the above-mentioned redox mediators, which can be mixed in equimolar amounts or in unequal molar amounts; or, the redox mediator is a combination of any two or more of the above-mentioned redox mediators; or, the redox mediator can also be other redox mediators known in the art, without specific limitation.

[0067] Optionally, the redox mediator is 2,2,6,6-tetramethylpiperidinyloxide.

[0068] By setting the redox mediator to be any one or a combination of more than one of sulfide, sulfate, nitrate, iodide, bromide, nitrite, chloride, piperidine oxide, phenothiazines, thiazines, organic amines, aminobenzenes, phenazines, anthracenes, thianthrenes, tetrathiafulvalene and its derivatives, benzoquinone and its derivatives, dimethoxybenzene and its derivatives, tetrathiafulvalene, N-methyl-N-propylpyrrolidine bromide, cobalt (II) porphyrin complex, iron phthalocyanine, ethyl viologen, and ferrocene, the redox mediator can increase the charge transfer path, further reduce the decomposition potential of the lithium supplement agent, and accelerate the decomposition rate of the lithium supplement agent.

[0069] Optionally, the concentration of the redox mediator in the electrolyte is G, which satisfies: 5 mM ≤ G ≤ 500 mM.

[0070] Optionally, the concentration G of the redox mediator satisfies: 5 mM ≤ G ≤ 400 mM.

[0071] Optionally, the concentration G of the redox mediator may be 5 mM, 10 mM, 50 mM, 100 mM, 200 mM, 400 mM, etc., without specific limitation.

[0072] By setting the concentration G of the redox mediator in the electrolyte to satisfy 5mM≤B≤500mM, the redox mediator can increase the charge transfer path, further reduce the decomposition potential of the lithium supplement agent, and accelerate the decomposition rate of the lithium supplement agent.

[0073] Optionally, the electrolyte includes a lithium salt, which can ensure that there are sufficient lithium ions in the electrolyte for transmission, thereby maintaining the high efficiency of the lithium-supplemented battery 100 .

[0074] Optionally, the lithium salt is one of lithium hexafluorophosphate, lithium perchlorate, lithium bis(oxalatoborate), lithium bis(trifluoromethanesulfonyl imide), and lithium bis(fluorosulfonyl imide), and the solvent is a carbonate solvent, at least one of ethylene carbonate, propylene carbonate, fluoroethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, and diethyl carbonate, or a combination of more.

[0075] Optionally, the lithium salt may be other lithium salts commonly used in the art without limitation.

[0076] Optionally, the lithium salt is lithium hexafluorophosphate (LiPF6).

[0077] As the main source of lithium ions in the electrolyte, lithium salt can ensure that there are enough lithium ions to transmit during the charge and discharge process of the lithium battery 100, and can also improve the ionic conductivity of the solution and reduce the Li + The diffusion distance in the solution is increased, thereby improving the charge and discharge efficiency of the lithium-ion battery 100. The lithium salt can form a stable solution system with the solvent in the electrolyte, improving the conductivity of the electrolyte and the diffusion speed of lithium ions, thereby improving the energy density, capacity and other performance of the lithium-ion battery 100.

[0078] Optionally, the concentration of the lithium salt is H, satisfying: 0.5M≤H≤5M, where the unit M represents moles per cubic decimeter.

[0079] Optionally, the concentration H of the lithium salt satisfies: 0.9M≤H≤1.1M.

[0080] Specifically, the value of H can be 0.9M, 1M, 1.1M, etc., without specific limitation.

[0081] An appropriate lithium salt concentration ensures sufficient lithium ion transport within the electrolyte, thereby maintaining the high performance of the lithium-ion battery 100. If the lithium salt concentration is too low, lithium ion transport may be hindered, reducing the charge and discharge efficiency and capacity of the lithium-ion battery 100. However, if the concentration is too high, the internal resistance of the electrolyte may be increased, reducing the discharge voltage and energy density of the lithium-ion battery 100.

[0082] By setting the concentration H of the lithium salt to satisfy 0.5M≤H≤5M, the excellent performance, cycle life and safety of the lithium-supplemented battery 100 can be ensured.

[0083] Optionally, the electrolyte further comprises a solvent, wherein the solvent comprises cyclic organic matter and / or chain organic matter.

[0084] The cyclic organic compound is any one or a combination of fluoroethylene carbonate (FEC), ethylene carbonate (EC), and propylene carbonate (PC). The cyclic organic compound can dissolve lithium salts, helping to form a stable electrolyte system with good chemical stability, which helps extend the life of the electrolyte. Fluoroethylene carbonate also has excellent high and low temperature performance and anti-flatulence properties, which can increase the capacity and cycle life of the lithium-ion battery 100.

[0085] The chain organic compound is any one or a combination of ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and diethyl carbonate (DEC). Chain organic compounds can dissolve lithium salts and transport lithium ions. Furthermore, chain carbonates (such as dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC)) have lower viscosity than cyclic carbonates and better electrochemical stability, thus improving the low-temperature performance of the electrolyte.

[0086] Optionally, the solvent comprises a cyclic organic compound and a chain organic compound, and the mass ratio of the two can be adjusted according to actual needs, with no specific restrictions. Since cyclic organic compounds and chain organic compounds have different properties as solvent components of the electrolyte, chain organic compounds have lower viscosity and better electrochemical stability, which helps improve the low-temperature performance of the electrolyte, while cyclic organic compounds have a higher dielectric constant, which helps improve the energy density and safety of the lithium-supplemented battery 100. Therefore, by adjusting the ratio of chain solvents to cyclic solvents, the performance of the electrolyte can be balanced to meet the needs of different lithium-supplemented batteries 100.

[0087] Please refer to Figure 2 , the present application also provides a method for preparing an electrolyte, comprising:

[0088] Step S10, providing a solvent and a lithium salt;

[0089] In step S20 , an additive is added to the solvent to mix the solvent, lithium salt and the additive. The additive comprises a boron-based organic compound suitable for dissolving the lithium supplement of the lithium supplement battery 100 .

[0090] Optionally, the solvent comprises cyclic organic matter and / or chain organic matter.

[0091] Due to the good affinity and solubility of boron-based organic compounds for lithium ions, the inclusion of boron-based organic compounds in the electrolyte allows the lithium supplement agent to dissolve better in the electrolyte. By configuring the electrolyte to include a solvent, a lithium salt, and an additive, the boron-based organic compound in the additive component allows the lithium supplement agent in the lithium supplement battery 100 to dissolve better in the electrolyte, thereby reducing the decomposition voltage of the lithium supplement agent and improving its decomposition efficiency.

[0092] Optionally, also include:

[0093] Step S30: adding a redox mediator into the solvent.

[0094] By configuring the electrolyte to further include a redox mediator, the addition of the redox mediator can increase the charge transfer path, further reduce the decomposition potential of the lithium supplement, and accelerate the decomposition rate of the lithium supplement.

[0095] Optionally, also include:

[0096] Step S40: adding a lithium supplement agent to the solvent.

[0097] Optionally, the concentration B of the lithium supplement satisfies: 5mM≤B≤1000mM.

[0098] In one embodiment, the lithium supplement is lithium oxide.

[0099] Optionally, step S30 and step S40 can be performed simultaneously, that is, the redox mediator and the lithium supplement agent are added to the solvent at the same time; or, step S30 is performed first and then step S40. Under the action of the redox mediator, the decomposition potential of the lithium supplement agent can be further reduced, so that the added lithium supplement agent can be quickly decomposed.

[0100] By adding a lithium supplement agent to the components of the electrolyte, the lithium supplement agent can be dissolved in the electrolyte under the action of the boron-based organic compound in the electrolyte, thereby reducing the decomposition voltage of the lithium supplement agent and improving the decomposition efficiency of the lithium supplement agent, which can meet the lithium supplement requirements of the lithium supplement battery 100.

[0101] Alternatively, the electrolyte preparation method includes only steps S10 and S20, i.e., the electrolyte comprises only a solvent and a boron-containing organic compound additive. Alternatively, the electrolyte preparation method includes steps S10 to S30, and the electrolyte comprises a solvent, a lithium salt, a boron-containing organic compound additive, and a redox mediator. In both of these embodiments, the lithium supplement for the lithium supplement battery 100 needs to be added to the positive electrode of the lithium supplement battery 100.

[0102] In another embodiment, the method for preparing the electrolyte includes steps S10, S20 and S40, wherein the electrolyte prepared at this time includes a solvent, a lithium salt, an additive containing a boron-based organic compound, a redox mediator and a lithium supplement; in another embodiment, as Figure 2 As shown, the electrolyte preparation method includes steps S10 to S40. The prepared electrolyte includes a solvent, a lithium salt, an additive containing a boron-based organic compound, a redox mediator, and a lithium supplement. In the above two embodiments, the positive electrode of the lithium supplement battery 100 may include a lithium supplement or may not include a lithium supplement, without specific limitation.

[0103] Optionally, the lithium-supplemented battery 100 in the embodiment of the present application further includes a positive electrode sheet, and at least one of the positive electrode sheet and the electrolyte includes a lithium-supplementing agent.

[0104] The electrolyte additive includes a boron-based organic compound, which is suitable for dissolving the lithium supplement agent in the lithium supplement battery 100. The boron-based organic compound allows the lithium supplement agent in the lithium supplement battery 100 to dissolve better in the electrolyte, thereby reducing the decomposition voltage of the lithium supplement agent and improving the decomposition efficiency of the lithium supplement agent.

[0105] In one embodiment, the lithium supplement is any one or a combination of more of lithium formate, lithium fluoride, lithium chloride, lithium iodide, lithium oxalate, lithium oxide, lithium peroxide, lithium carbonate, lithium sulfide, and lithium disulfide.

[0106] Optionally, the lithium supplement can be any one of the above-mentioned lithium supplements; or, the lithium supplement is a combination of any two of the above-mentioned lithium supplements, which can be mixed in equimolar amounts or in unequal molar amounts; or, the lithium supplement is a combination of any two or more of the above-mentioned lithium supplements; or, the lithium supplement can also be other lithium supplements known in the art, without specific limitation.

[0107] Optionally, the lithium supplement is lithium oxide.

[0108] By setting the lithium replenisher to any one or a combination of lithium formate, lithium fluoride, lithium chloride, lithium iodide, lithium oxalate, lithium oxide, lithium peroxide, lithium carbonate, lithium sulfide, and lithium disulfide, under the action of the boron-based organic compound in the electrolyte, the ionically bonded lithium replenisher can be dissolved in the electrolyte, thereby reducing the decomposition voltage of the lithium replenisher and improving the decomposition efficiency of the lithium replenisher, which can meet the lithium replenishment requirements of the lithium replenisher battery 100.

[0109] Optionally, the electrolyte includes a lithium supplement.

[0110] During the formation process of the lithium-ion supplemented battery 100, the formation of the negative electrode SEI film consumes a large amount of active lithium. This, especially when high-capacity silicon-based negative electrode materials are added, can result in low initial coulombic efficiency and capacity of the supplemented battery 100. Replenishing active lithium with a lithium supplement is an effective way to address this issue.

[0111] By adding a lithium supplement agent to the components of the electrolyte, the lithium supplement agent can be dissolved in the electrolyte under the action of the boron-based organic compound in the electrolyte, thereby reducing the decomposition voltage of the lithium supplement agent and improving the decomposition efficiency of the lithium supplement agent, which can meet the lithium supplement requirements of the lithium supplement battery 100.

[0112] Optionally, the concentration of the lithium supplement after dissolving in the electrolyte is B, which satisfies: 5mM≤B≤1000mM.

[0113] Optionally, B also satisfies: 100mM≤B≤600mM.

[0114] Optionally, the concentration B of the lithium supplement may be 5 mM, 100 mM, 200 mM, 400 mM, 600 mM, 800 mM, etc., without specific limitation.

[0115] By setting the concentration B of the lithium supplement agent to meet 5mM≤B≤1000mM, the lithium supplement agent can be dissolved in the electrolyte under the action of the boron-based organic compound in the electrolyte, thereby reducing the decomposition voltage of the lithium supplement agent and improving the decomposition efficiency of the lithium supplement agent, which can meet the lithium supplement requirements of the lithium supplement battery 100.

[0116] Optionally, the molar ratio of the boron-based organic compound to the lithium replenisher is C, satisfying: 0.01≤C≤100. Optionally, when the electrolyte includes a lithium replenisher, the molar amount of the boron-based organic compound in the electrolyte can be equal to the molar amount of the lithium replenisher, that is, C=1; or the molar amount of the boron-based organic compound is less than the molar amount of the lithium replenisher, that is, 0.01≤C<1; or the molar amount of the boron-based organic compound is greater than the molar amount of the lithium replenisher, that is, 1<C≤100.

[0117] Optionally, the molar ratio C of the boron-based organic compound to the lithium replenisher further satisfies: 0.5≤C≤2.

[0118] Optionally, the specific value of C can be 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.4, 1.6, 1.8, 2, etc., without specific limitation.

[0119] By setting the molar ratio C of the boron-based organic compound to the lithium supplement agent to satisfy: 0.01≤C≤100, the lithium supplement agent can be dissolved in the electrolyte under the action of the boron-based organic compound in the electrolyte, thereby reducing the decomposition voltage of the lithium supplement agent and improving the decomposition efficiency of the lithium supplement agent, which can meet the lithium supplement requirements of the lithium supplement battery 100.

[0120] Optionally, the positive electrode plate includes a lithium supplement.

[0121] Optionally, the components of the positive electrode sheet include a lithium supplement agent. In this case, the components of the electrolyte may include the lithium supplement agent or may not include the lithium supplement agent, and there is no specific limitation.

[0122] Optionally, the lithium replenisher is disposed in the positive electrode active layer. When the electrolyte is added, the lithium replenisher will dissolve into the electrolyte under the action of the boron-based organic compound in the electrolyte.

[0123] The lithium supplement battery 100 in the present application includes a lithium supplement agent in the components of the positive electrode sheet. Under the action of the boron-based organic compound in the electrolyte, the lithium supplement agent can be better dissolved in the electrolyte, which can reduce the decomposition voltage of the lithium supplement agent and improve the decomposition efficiency of the lithium supplement agent.

[0124] Optionally, the components of the positive electrode sheet further include a positive electrode active material, and the ratio of the mass of the lithium supplement agent in the positive electrode sheet to the mass of the positive electrode active material is D, which satisfies: 0.1%≤D≤10%.

[0125] Optionally, the positive electrode active material layer further includes a positive electrode active material. The lithium supplement agent is mixed with the positive electrode active material to prepare a slurry and is coated on at least one side of the positive electrode current collector to form a positive electrode sheet.

[0126] Optionally, the ratio D of the mass of the lithium supplement agent to the mass of the positive electrode active material satisfies 1%≤D≤5%.

[0127] Optionally, the mass of the lithium supplement agent may be 1%, 2%, 3%, 5%, etc., of the mass of the positive electrode active material, and there is no specific limitation.

[0128] By setting the positive electrode sheet to also include a positive electrode active material, the ratio D of the mass of the lithium supplement agent to the mass of the positive electrode active material in the positive electrode sheet satisfies 0.1%≤D≤10%, and the proportion of the lithium supplement agent in the positive electrode active material layer is controlled within an appropriate range to avoid excessive pores in the positive electrode active material layer after the lithium supplement agent dissolves.

[0129] Optionally, the electrolyte includes a lithium replenisher, and the molar ratio of the lithium replenisher in the electrolyte to the lithium replenisher in the positive electrode sheet is E, satisfying: 0.01≤E≤100.

[0130] Optionally, when both the components of the positive electrode sheet and the electrolyte include a lithium supplement agent, the molar amount of the lithium supplement agent in the electrolyte can be equal to the molar amount of the lithium supplement agent in the positive electrode sheet, that is, E=1; or, the molar amount of the lithium supplement agent in the electrolyte is less than the molar amount of the lithium supplement agent in the positive electrode sheet, that is, 0.01≤E<1; or, the molar amount of the lithium supplement agent in the electrolyte is greater than the molar amount of the lithium supplement agent in the positive electrode sheet, that is, 1<E≤100. All of the above methods are possible and are not specifically limited.

[0131] Optionally, the molar ratio E of the lithium replenishing agent in the electrolyte to the lithium replenishing agent in the positive electrode sheet further satisfies: 0.5≤E≤2.

[0132] Optionally, the specific value of E can be 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.4, 1.6, 1.8, 2, etc., without specific limitation.

[0133] By setting the electrolyte to include a lithium replenisher, the molar ratio E of the lithium replenisher in the electrolyte to the lithium replenisher in the positive electrode sheet satisfies: 0.01≤E≤100. The components of the positive electrode sheet and the electrolyte both include a lithium replenisher, which can be added according to actual needs to meet the lithium replenishment requirements of the lithium replenishment battery 100.

[0134] The technical solution of the present invention is described in detail below through specific embodiments.

[0135] Example 1

[0136] This embodiment provides an electrolyte, a preparation method thereof, and a lithium-supplemented battery. The lithium-supplemented battery includes a positive electrode plate and an electrolyte, wherein the electrolyte additive includes a boron-based organic compound.

[0137] The preparation method of the electrolyte comprises the following steps:

[0138] (1) Trispentafluorophenylborane (C6F5)3B (abbreviated as TFPPB) is added to the base liquid (including solvent and lithium salt, the same below) to a total concentration of 0.2M after dissolution.

[0139] (2) Add lithium oxide Li2O with a concentration of 0.2 M after dissolution, shake thoroughly and let it stand to obtain an electrolyte solution.

[0140] The preparation method of the positive electrode sheet comprises the following steps:

[0141] (a) Lithium iron phosphate powder is mixed with a dispersant, conductive carbon, N-methylpyrrolidone, and a binder to prepare a positive electrode slurry.

[0142] (b) The mixed positive electrode slurry was coated on both sides of the positive electrode current collector, dried at 85°C, and then cold pressed.

[0143] (c) trimming, cutting, and slitting the substrate, drying the substrate at 85° C. under vacuum for 4 hours, and welding the tabs to obtain a positive electrode sheet.

[0144] Example 2

[0145] This embodiment provides an electrolyte, a preparation method thereof, and a lithium-supplemented battery. The lithium-supplemented battery includes a positive electrode plate and an electrolyte, wherein the electrolyte additive includes a boron-based organic compound.

[0146] The preparation method of the electrolyte comprises the following steps:

[0147] (1) Add trispentafluorophenylborane (C6F5)3B (abbreviated as TFPPB) to a total concentration of 0.2 M after dissolution into the base liquid, shake thoroughly and let it stand to obtain an electrolyte solution.

[0148] The preparation method of the positive electrode sheet comprises the following steps:

[0149] (a) Lithium iron phosphate powder is mixed with a dispersant, conductive carbon, lithium oxide, N-methylpyrrolidone, and a binder to prepare a positive electrode slurry.

[0150] (b) The mixed positive electrode slurry was coated on both sides of the positive electrode current collector, dried at 85°C, and then cold pressed.

[0151] (c) trimming, cutting, and slitting the substrate, drying the substrate at 85° C. under vacuum for 4 hours, and welding the tabs to obtain a positive electrode sheet.

[0152] Among them, if the lithium oxide in the positive electrode is fully dissolved, the lithium oxide concentration in the electrolyte is 0.2M.

[0153] Example 3

[0154] The difference between this embodiment and Example 2 is that the lithium oxide concentration in the electrolyte after being assembled into a lithium-supplemented battery is 0.4M.

[0155] Example 4

[0156] This embodiment provides an electrolyte, a preparation method thereof, and a lithium-supplemented battery. The lithium-supplemented battery includes a positive electrode plate and an electrolyte, wherein the electrolyte additive includes a boron-based organic compound.

[0157] The preparation method of the electrolyte comprises the following steps:

[0158] (1) Trispentafluorophenylborane (C6F5)3B (abbreviated as TPFPB) was added to the base liquid to a total concentration of 0.2 M after dissolution.

[0159] (2) Add lithium oxide Li2O with a concentration of 0.2 M after dissolution, shake thoroughly and let it stand to obtain an electrolyte solution.

[0160] The preparation method of the positive electrode sheet comprises the following steps:

[0161] (a) Lithium iron phosphate powder is mixed with a dispersant, conductive carbon, lithium oxide, N-methylpyrrolidone, and a binder to prepare a positive electrode slurry.

[0162] (b) The mixed positive electrode slurry was coated on both sides of the positive electrode current collector, dried at 85°C, and then cold pressed.

[0163] (c) trimming, cutting, and slitting the substrate, drying the substrate at 85° C. under vacuum for 4 hours, and welding the tabs to obtain a positive electrode sheet.

[0164] Among them, if the lithium oxide in the positive electrode is fully dissolved, the total concentration of lithium oxide in the electrolyte after assembly into a lithium-supplemented battery is 0.4M, and 0.2M of lithium oxide comes from the positive electrode sheet.

[0165] Example 5

[0166] This embodiment provides an electrolyte, a preparation method thereof, and a lithium-supplemented battery. The lithium-supplemented battery includes a positive electrode plate and an electrolyte, wherein the electrolyte additive includes a boron-based organic compound.

[0167] The preparation method of the electrolyte comprises the following steps:

[0168] (1) Trispentafluorophenylborane (C6F5)3B (abbreviated as TFPPB) with a total concentration of 0.2 M after dissolution and 2,2,6,6-tetramethylpiperidinyl oxide with a total concentration of 0.01 M after dissolution were added to the base liquid.

[0169] (2) Add lithium oxide Li2O with a concentration of 0.2 M after dissolution, shake thoroughly and let it stand to obtain an electrolyte solution.

[0170] The preparation method of the positive electrode sheet comprises the following steps:

[0171] (a) Lithium iron phosphate powder is mixed with a dispersant, conductive carbon, N-methylpyrrolidone, and a binder to prepare a positive electrode slurry.

[0172] (b) The mixed positive electrode slurry was coated on both sides of the positive electrode current collector, dried at 85°C, and then cold pressed.

[0173] (c) trimming, cutting, and slitting the substrate, drying the substrate at 85° C. under vacuum for 4 hours, and welding the tabs to obtain a positive electrode sheet.

[0174] Example 6

[0175] This embodiment provides an electrolyte, a preparation method thereof, and a lithium-supplemented battery. The lithium-supplemented battery includes a positive electrode plate and an electrolyte, wherein the electrolyte additive includes a boron-based organic compound.

[0176] The preparation method of the electrolyte comprises the following steps:

[0177] (1) Trispentafluorophenylborane (C6F5)3B (abbreviated as TFPPB) with a total concentration of 0.2 M after dissolution and 2,2,6,6-tetramethylpiperidinyl oxide with a total concentration of 0.01 M after dissolution were added to the base liquid.

[0178] The preparation method of the positive electrode sheet comprises the following steps:

[0179] (a) Lithium iron phosphate powder is mixed with a dispersant, conductive carbon, lithium oxide, N-methylpyrrolidone, and a binder to prepare a positive electrode slurry.

[0180] (b) The mixed positive electrode slurry was coated on both sides of the positive electrode current collector, dried at 85°C, and then cold pressed.

[0181] (c) trimming, cutting, and slitting the substrate, drying the substrate at 85° C. under vacuum for 4 hours, and welding the tabs to obtain a positive electrode sheet.

[0182] Among them, if the lithium oxide of the positive electrode is fully dissolved, the lithium oxide concentration in the electrolyte after assembling into a lithium-supplemented battery is 0.4M.

[0183] Example 7

[0184] This embodiment provides an electrolyte, a preparation method thereof, and a lithium-supplemented battery. The lithium-supplemented battery includes a positive electrode plate and an electrolyte, wherein the electrolyte additive includes a boron-based organic compound.

[0185] The preparation method of the electrolyte comprises the following steps:

[0186] (1) Trispentafluorophenylborane (C6F5)3B (abbreviated as TFPPB) with a total concentration of 0.2M after dissolution and 2,2,6,6-tetramethylpiperidinyl oxide with a concentration of 0.01M were added to the base liquid.

[0187] (2) Add lithium oxide Li2O with a concentration of 0.2 M after dissolution, shake thoroughly and let it stand to obtain an electrolyte solution.

[0188] The preparation method of the positive electrode sheet comprises the following steps:

[0189] (a) Lithium iron phosphate powder is mixed with a dispersant, conductive carbon, lithium oxide, N-methylpyrrolidone, and a binder to prepare a positive electrode slurry.

[0190] (b) The mixed positive electrode slurry was coated on both sides of the positive electrode current collector, dried at 85°C, and then cold pressed.

[0191] (c) trimming, cutting, and slitting the substrate, drying the substrate at 85° C. under vacuum for 4 hours, and welding the tabs to obtain a positive electrode sheet.

[0192] Among them, if the lithium oxide in the positive electrode is fully dissolved, the total concentration of lithium oxide in the electrolyte after assembly into a lithium-supplemented battery is 0.4M, and 0.2M of lithium oxide comes from the positive electrode sheet.

[0193] Example 8

[0194] The difference between this embodiment and Example 1 is that the total concentration of trispentafluorophenylborane is 0.1M.

[0195] Example 9

[0196] The difference between this embodiment and Example 1 is that the total concentration of trispentafluorophenylborane is 0.4M.

[0197] Example 10

[0198] The difference between this embodiment and Example 1 is that the concentration of trispentafluorophenylborane is 1 mM.

[0199] Example 11

[0200] The difference between this embodiment and Example 1 is that the concentration of trispentafluorophenylborane is 1.5M.

[0201] Example 12

[0202] The difference between this embodiment and Example 5 is that the concentration of 2,2,6,6-tetramethylpiperidinyloxide is 1 mM.

[0203] Example 13

[0204] The difference between this embodiment and Example 5 is that the concentration of 2,2,6,6-tetramethylpiperidinyloxide is 0.7M.

[0205] Example 14

[0206] The difference between this embodiment and Example 1 is that the concentration of lithium oxide is 1 mM.

[0207] Example 15

[0208] The difference between this embodiment and Example 1 is that the concentration of lithium oxide is 1.05M; and the total concentration of trispentafluorophenylborane is 1.0M.

[0209] Comparative Example 1

[0210] This comparative example provides a lithium supplement battery, an electrolyte and a preparation method thereof. The lithium supplement battery comprises a positive electrode sheet and an electrolyte.

[0211] The electrolyte comprises only a base fluid.

[0212] The preparation method of the positive electrode sheet comprises the following steps:

[0213] (a) Lithium iron phosphate powder is mixed with a dispersant, conductive carbon, lithium oxide, N-methylpyrrolidone, and a binder to prepare a positive electrode slurry.

[0214] (b) The mixed positive electrode slurry was coated on both sides of the positive electrode current collector, dried at 85°C, and then cold pressed.

[0215] (c) trimming, cutting, and slitting the substrate, drying the substrate at 85° C. under vacuum for 4 hours, and welding the tabs to obtain a positive electrode sheet.

[0216] Among them, the lithium oxide concentration in the electrolyte after assembly into a lithium-supplemented battery is 0.2M.

[0217] Comparative Example 2

[0218] This comparative example provides a lithium supplement battery, an electrolyte and a preparation method thereof. The lithium supplement battery comprises a positive electrode sheet and an electrolyte.

[0219] The preparation method of the electrolyte comprises the following steps:

[0220] (1) Add 2,2,6,6-tetramethylpiperidinyl oxide at a concentration of 0.01 M to the base solution.

[0221] The preparation method of the positive electrode sheet comprises the following steps:

[0222] (a) Lithium iron phosphate powder is mixed with a dispersant, conductive carbon, lithium oxide, N-methylpyrrolidone, and a binder to prepare a positive electrode slurry.

[0223] (b) The mixed positive electrode slurry was coated on both sides of the positive electrode current collector, dried at 85°C, and then cold pressed.

[0224] (c) trimming, cutting, and slitting the substrate, drying the substrate at 85° C. under vacuum for 4 hours, and welding the tabs to obtain a positive electrode sheet.

[0225] Among them, the lithium oxide concentration in the electrolyte after assembly into a lithium-supplemented battery is 0.2M.

[0226] The lithium-supplemented battery also includes a negative electrode sheet. The preparation process of the negative electrode sheet is: graphite powder is evenly mixed with conductive carbon, binder, water, etc. to make a negative electrode slurry, the negative electrode slurry is coated on the negative electrode collector, and the negative electrode sheet is obtained after drying and rolling. The surface capacity of the negative electrode sheet is 1.15 times the surface capacity of the positive electrode sheet (N / P=1.15).

[0227] The positive electrode sheet, negative electrode sheet and separator prepared according to the above process are assembled into a soft-pack lithium-supplemented battery, and the electrolyte provided in the above embodiment and comparative example is injected to complete the assembly of the lithium-supplemented battery.

[0228] The electrochemical performance test of the lithium-supplemented battery assembled in the above lithium-supplemented battery embodiment was carried out under the following test conditions:

[0229] The lithium-supplemented battery example was charged at room temperature at a rate of 0.05C for 2 hours, then at a rate of 0.33C to 3.8V. It was then charged at a constant voltage at 3.8V until the current decreased to 0.05C. After standing for 1 hour, it was then charged at a constant current of 0.01C to 4.6V to decompose the lithium-supplemented agent. After standing for 1 hour, it was discharged at 0.2C to 2.0V, then charged at 0.33C to 3.8V, and then discharged at 0.1C to 2.0V. The average decomposition voltage during the lithium-supplemented agent decomposition stage can be read from the lithium-supplemented battery testing software.

[0230] 0.1C discharge capacity: After exhausting, the lithium battery was placed at 60℃ for 48 hours, then charged to 3.8V at 0.33C, then charged at a constant voltage at 3.8V until the current decreased to 0.05C, and then discharged to 2.0V at a current of 0.1C to obtain the capacity of the lithium battery after aging.

[0231] After 200 cycles, the battery was discharged at 0.1C with a capacity of 1.5 GPa and then charged and discharged at 0.33C. After 200 cycles, the battery was discharged at 0.1C with a capacity of 1.5 GPa.

[0232] Based on the above test data, the 0.1C discharge capacity retention rate after 200 cycles (0.1C discharge capacity after 200 cycles / 0.1C discharge capacity after aging) and the lithium supplement agent utilization rate {utilization rate = (capacity of the lithium supplement battery - capacity of the corresponding non-lithium supplement battery) / theoretical lithium supplement amount of the lithium supplement agent} were calculated.

[0233] The contents of the components in the above examples are shown in Table 1, and the test results and calculation results are shown in Table 2 below.

[0234] Table 1

[0235]

[0236]

[0237] Table 2

[0238]

[0239]

[0240] The test results of Examples 1 to 15 and Comparative Examples 1 and 2 in Tables 1 and 2 show that adding a boron-based organic compound to the electrolyte can effectively reduce the decomposition voltage of the lithium supplement and improve its decomposition efficiency. The test results of Example 1, Comparative Examples 1, and 2 show that omitting the boron-based organic compound and adding only a redox mediator to the electrolyte can slightly reduce the decomposition potential of the lithium supplement and accelerate its decomposition rate, but the effect is relatively limited.

[0241] From the test results of Example 1 and Example 2 in Table 1 and Table 2, it can be seen that for Example 1 and Example 2 with the same lithium supplement agent concentration in the electrolyte after assembly, Example 1, in which the lithium supplement agent is directly added to the electrolyte during preparation, has better 0.1C discharge capacity, 0.1C discharge capacity after 200 cycles, 0.1C discharge capacity retention rate after 200 cycles (0.1C discharge capacity after 200 cycles / 0.1C discharge capacity), and lithium supplement agent utilization rate than Example 2 in which the lithium supplement agent is added to the positive electrode sheet during preparation, and the average decomposition voltage of Example 1 is lower than that of Example 2. This shows that the lithium supplement agent directly added to the electrolyte can more effectively reduce the decomposition voltage of the lithium supplement agent and improve the decomposition efficiency of the lithium supplement agent. This is because the lithium supplement agent is directly added to the electrolyte during preparation, and the lithium supplement agent dissolves under the action of the boron-based organic compound. At this time, when the electrolyte in Example 1 is injected into the lithium-supplemented battery, the electrolyte and the positive electrode react in a solid-liquid manner, the decomposition voltage is lower, and the decomposition is more complete. The lithium supplement agent added to the positive electrode during preparation can also be dissolved under the action of the boron-based organic compound in the electrolyte, but at this time the lithium supplement agent and the positive electrode are in solid-solid contact, the reaction is slower, and the reaction cannot continue after the electrical contact point reacts. Therefore, the decomposition efficiency of the lithium supplement agent is low.

[0242] From the test results of Examples 1 to 2 and Examples 4 to 7 in Tables 1 and 2, it can be seen that adding a redox mediator to the electrolyte composition can further reduce the decomposition potential of the lithium supplement agent, accelerate the decomposition rate of the lithium supplement agent, and improve the utilization rate of the lithium supplement agent.

[0243] From the test results of Examples 1 and 8 to 11 in Tables 1 and 2, it can be seen that when the concentration A of the boron-based organic compound satisfies the range of 5 mM (0.005 M) ≤ A ≤ 1000 mM (1 M), the decomposition voltage of the lithium supplement can be effectively reduced, and the 0.1C discharge capacity retention rate after 200 cycles can be improved. At this time, the utilization rate of the lithium supplement is relatively high.

[0244] From the test results of Examples 1 and 8 to 9 in Tables 1 and 2, it can be seen that the molar ratio C of the boron-based organic compound to the lithium supplement agent in the electrolyte satisfies 0.5≤C≤2, which can effectively reduce the decomposition voltage of the lithium supplement agent and has a high utilization rate of the lithium supplement agent.

[0245] From the test results of Example 5 and Examples 12 to 13 in Table 1 and Table 2, it can be seen that when the concentration G of the redox mediator in the electrolyte satisfies 5mM≤G≤500mM, the utilization rate of the lithium supplement agent is high.

[0246] From the test results of Example 1 and Examples 14 to 15 in Table 1 and Table 2, it can be seen that, while effectively improving the discharge capacity in grams of the lithium-supplemented battery and the 0.1C discharge capacity retention rate after 200 cycles, the utilization rate of the lithium-supplemented agent is high when the concentration B of the lithium-supplemented agent in the electrolyte satisfies 5mM≤B≤1000mM.

[0247] In the description of the embodiments of the present application, it should be noted that the orientation or positional relationship of terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", and "outside" are based on the orientation or positional relationship described in the accompanying drawings. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present application.

[0248] The above disclosure is only a preferred embodiment of the present application, and certainly cannot be used to limit the scope of rights of the present application. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made in accordance with the claims of the present application are still within the scope covered by the present application.

Claims

1. An electrolyte, characterized in that Used to replenish lithium batteries, the electrolyte includes additives, and the additives include boron-based organic compounds.

2. The electrolyte according to claim 1, characterized in that The boron-based organic compound includes any one or a combination of (CH3O)3B, (CF3CH2O)3B, (C3F7CH2O)3B, (C3F7CH2CH2O)3B, [(CF3)2CHO]3B, [(CF3)3CO]3B, [(CF3)2C(C6H5)O]3B, (C6H5O)3B, (FC6H4O)3B, (F2C6H3O)3B, (F4C6HO)3B, (C6F5O)3B, (CF3C6H4O)3B, ((CF3)2C6H3O)3B, and (C6F5)3B.

3. The electrolyte according to claim 1, characterized in that The concentration of the boron-based organic compound in the electrolyte is A, which satisfies: 5mM≤A≤1000mM.

4. The electrolyte according to any one of claims 1 to 3, characterized in that The electrolyte includes a redox mediator.

5. The electrolyte according to claim 4, characterized in that The redox mediator includes any one or more of sulfide, sulfate, nitrate, iodide, bromide, nitrite, chloride, piperidine oxide, phenothiazines, thiazines, organic amines, aminobenzenes, phenazines, anthracenes, thianthrenes, tetrathiafulvalene and its derivatives, benzoquinone and its derivatives, dimethoxybenzene and its derivatives, tetrathiafulvalene, N-methyl-N-propylpyrrolidine bromide, cobalt (II) porphyrin complex, iron phthalocyanine, ethyl viologen, and ferrocene, and / or the concentration of the redox mediator in the electrolyte is G, satisfying: 5mM≤G≤500mM.

6. The electrolyte according to claim 5, characterized in that The electrolyte further includes a solvent and a lithium salt.

7. The electrolyte according to claim 6, characterized in that The lithium salt includes any one or more of lithium hexafluorophosphate, lithium perchlorate, lithium bis(oxalatoborate), lithium bis(trifluoromethanesulfonylimide), and lithium bis(fluorosulfonylimide); and / or the solvent includes any one or more of ethylene carbonate, propylene carbonate, fluoroethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, and diethyl carbonate.

8. The electrolyte according to claim 6, characterized in that The concentration of the lithium salt in the electrolyte is H, which satisfies: 0.5M≤H≤5M.

9. A lithium supplement battery, characterized in that: The electrolyte comprises the electrolyte according to any one of claims 1 to 8.

10. The lithium supplement battery according to claim 9, characterized in that: The lithium supplemented battery further includes a positive electrode sheet, and at least one of the positive electrode sheet and the electrolyte contains a lithium supplement agent.

11. The lithium supplement battery according to claim 10, characterized in that: The lithium supplement includes any one or a combination of more of lithium formate, lithium fluoride, lithium chloride, lithium iodide, lithium oxalate, lithium oxide, lithium peroxide, lithium carbonate, lithium sulfide, and lithium disulfide.

12. The lithium supplement battery according to claim 10 or 11, characterized in that: The electrolyte contains the lithium supplement agent, and the concentration of the lithium supplement agent in the electrolyte is B, satisfying: 5mM≤B≤1000mM.

13. The lithium supplement battery according to claim 12, characterized in that: The molar ratio of the boron-based organic compound to the lithium supplement agent is C, which satisfies: 0.01≤C≤100; preferably, it also satisfies: 0.5≤C≤2.

14. The lithium supplement battery according to claim 10 or 11, characterized in that: The positive electrode sheet includes the lithium supplement agent and a positive electrode active material. In the positive electrode sheet, the mass ratio of the lithium supplement agent to the mass of the positive electrode active material is D, which satisfies: 0.1%≤D≤10%.

15. The lithium supplement battery according to claim 10 or 11, characterized in that: The positive electrode sheet and the electrolyte both contain the lithium replenisher, and the molar ratio of the lithium replenisher in the electrolyte to the lithium replenisher in the positive electrode sheet is E, which satisfies: 0.01≤E≤100; preferably, further satisfies: 0.5≤E≤2.

16. An electrical device, characterized in that: The invention comprises the electrolyte according to any one of claims 1 to 8 or the lithium-supplemented battery according to any one of claims 9 to 15.

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