An organic lithium salt lithium supplement material and a lithium ion battery

Abstract

The present invention provides a cyanophosphate additive, which has a structure as shown in formula (I). The positive electrode lithium supplement material contains a cyano functional group, which can complex with metal ions to inhibit the diffusion of metal ions into the electrolyte, thereby reducing the catalytic reaction of metal ions on organic solvents, reducing gas production, and improving high-temperature cycle performance. At the same time, the presence of the positive electrode additive of the present invention can improve the morphology and composition of the CEI film, promote and participate in the component Li x PO y F z The formation of the positive electrode lithium supplement reduces membrane impedance, polarization, lithium ion consumption, and efficiency. Secondly, the positive electrode lithium supplement additive is insensitive to moisture and has excellent stability in the air. It can reduce the environmental requirements during the preparation of the positive electrode sheet and is a highly potential positive electrode lithium supplement.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion battery positive electrode lithium-replenishing materials, and relates to a cyanophosphate additive and a lithium-ion battery, and in particular to an organic lithium salt lithium-replenishing material and a lithium-ion battery. Background Art

[0002] Lithium-ion batteries are favored by all countries due to their advantages such as high energy density, low self-discharge rate, long cycle life, clean and pollution-free. Electronic mobile devices such as laptops, mobile phones, handheld game consoles, tablet computers, etc. can realize more and more functions, and the application technologies in electric vehicles, smart grids, etc. are becoming more mature. At the same time, consumers have also put forward higher requirements for the balance between battery energy density, cycle life and environmental applicability.

[0003] In order to improve the energy density of lithium-ion batteries, the industry needs to develop higher-performance electrode materials to improve the performance of lithium-ion batteries. The energy density and cycle life of lithium-ion batteries are closely related to the formation of the negative electrode solid electrolyte interface (SEI) film. During the first charging process of lithium-ion batteries, the SEI film formed on the surface of the negative electrode will convert a large amount of active lithium into lithium carbonate, lithium fluoride and alkyl lithium, thereby causing lithium loss in the positive electrode material. In a lithium-ion battery system using graphite as the negative electrode, the first charge will consume about 10% of the lithium source; when alloys (silicon, tin, etc.) and oxides (silicon oxide, tin oxide) and other high-specific capacity materials are used as the negative electrode, the consumption of the positive electrode lithium source will be further aggravated.

[0004] At present, the solution to this problem is to use lithium replenishment technology to replenish the lithium loss during the cycle. There are two main types of lithium replenishment technology: negative electrode lithium replenishment and positive electrode lithium replenishment. Among them, negative electrode lithium replenishment is mainly carried out through metal lithium replenishment at the pole piece end or chemical lithium replenishment at the material end. Negative electrode lithium replenishment at the pole piece end involves the use of flammable and explosive metal lithium, which has a high safety risk. The chemical lithium replenishment process at the material end is complex, and the material is highly alkaline, making it difficult to process the material. Compared with negative electrode lithium replenishment, the positive electrode lithium replenishment process is simple. The lithium source is added through the positive electrode slurry process, which can completely avoid the safety risks and cost increase risks of negative electrode lithium replenishment. However, existing positive electrode lithium replenishment materials (such as L-ascorbic acid lithium, D-isoascorbic acid lithium, lithium pyrosulfite, lithium sulfite, lithium phytate, Li5FeO4, Li2NiO2, etc.) are sensitive to humidity, are easily oxidized in the air, and are difficult to synthesize in large quantities, which is not conducive to large-scale industrial production.

[0005] Therefore, how to find a more suitable positive electrode lithium supplement additive with excellent comprehensive performance to solve the above-mentioned problems of existing positive electrode lithium supplement materials has become one of the urgent problems to be solved by many front-line researchers and scientific research enterprises in this field. Summary of the invention

[0006] In view of this, the present invention provides a cyanophosphate additive and a lithium ion battery. The cyanophosphate additive provided by the present invention is an organic lithium salt lithium supplement material for the positive electrode of a lithium ion battery, which has the advantages of low gas production, good stability and long cycle life. Secondly, the lithium supplement can well improve the lithium ion conductivity.

[0007] The present invention provides a cyanophosphate additive, wherein the additive has a structure as shown in formula (I):

[0008]

[0009] Wherein, the R1 is selected from a group containing a cyano group;

[0010] The R2 is selected from lithium ion, C1-C6 saturated hydrocarbon group, C1-C6 unsaturated hydrocarbon group, alkoxy group, cyanoalkyl group, halogenated alkyl group, phenyl group, silane group or substituted silane group.

[0011] Preferably, the cyano-containing group includes a cyanoalkyl group or a substituted cyanoalkyl group;

[0012] The substitution includes halogen substitution;

[0013] The cyanophosphate additive is a positive electrode additive;

[0014] The positive electrode comprises a lithium ion battery positive electrode.

[0015] Preferably, the cyanophosphate additive has a structure as shown in any one of formulas (1) to (11):

[0016]

[0017] Preferably, the cyanophosphate additive is a positive electrode organic lithium salt lithium supplement material;

[0018] The mass ratio of the cyanophosphate additive to the positive electrode active material is (0.5-5): (75-97.5);

[0019] The cyanophosphate additive is a positive electrode additive that improves the morphology and / or composition of the CEI film;

[0020] The cyanophosphate additive promotes and participates in the component Li x PO y F z formation.

[0021] The present invention provides a lithium ion battery, comprising a positive electrode, a negative electrode and an electrolyte;

[0022] The positive electrode includes the cyanophosphate additive described in any one of the above technical solutions.

[0023] Preferably, the positive electrode further comprises a positive electrode active material, a positive electrode conductor and a positive electrode binder;

[0024] The positive electrode active material includes one or more of lithium cobalt oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium phosphate, lithium vanadate, lithium manganate, lithium nickel oxide, lithium nickel cobalt manganate, lithium-rich manganese-based materials, lithium nickel cobalt aluminum oxide and lithium titanate;

[0025] The positive electrode conductive agent includes one or more of conductive carbon black, carbon fiber, acetylene black, Ketjen black, graphene and carbon nanotubes;

[0026] The positive electrode binder includes one or more of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene and polyhexafluoropropylene;

[0027] The positive electrode preparation process includes: in the positive electrode slurrying process, cyanophosphate additives, positive electrode active materials, positive electrode conductive agents, positive electrode binders and solvents are uniformly mixed, and then coated, rolled and dried to obtain positive electrode sheets.

[0028] Preferably, the positive electrode, taking the cyanophosphate additive, the positive electrode active material, the positive electrode conductive agent and the positive electrode binder as a whole, has a mass content of 75% to 97.5% of the positive electrode active material;

[0029] The positive electrode is calculated as a whole based on the cyanophosphate additive, the positive electrode active material, the positive electrode conductive agent and the positive electrode binder, and the mass content of the positive electrode conductive agent is 1% to 10%;

[0030] The positive electrode is calculated as a whole by the cyanophosphate additive, the positive electrode active material, the positive electrode conductive agent and the positive electrode binder, and the mass content of the positive electrode binder is 1% to 10%;

[0031] The positive electrode is calculated as a whole based on the cyanophosphate additive, the positive electrode active material, the positive electrode conductive agent and the positive electrode binder, and the mass content of the cyanophosphate additive is 0.5% to 5%.

[0032] Preferably, the negative electrode comprises a negative electrode active material, a negative electrode conductive agent and a negative electrode binder;

[0033] The negative electrode active material includes graphite and / or silicon-based materials;

[0034] The negative electrode conductive agent includes one or more of conductive carbon black, carbon fiber, acetylene black, Ketjen black, graphene and carbon nanotubes;

[0035] The negative electrode binder includes one or more of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene and polyhexafluoropropylene.

[0036] Preferably, the electrolyte includes a solvent;

[0037] The solvent includes one or more of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, dimethyl ether, diethyl ether, adiponitrile, succinonitrile, glutaronitrile, dimethyl sulfoxide, sulfolane, 1,4-butyrolactone, methyl formate, ethyl acetate, methyl propionate, ethyl propionate, butyl propionate and ethyl butyrate;

[0038] The mass content of the solvent in the electrolyte is 50% to 98%;

[0039] The electrolyte includes a lithium salt;

[0040] The lithium salt includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate and bis(fluorosulfonyl)imide lithium salt;

[0041] The mass content of the lithium salt in the electrolyte is 1% to 18%.

[0042] Preferably, the electrolyte includes a first auxiliary additive;

[0043] The first auxiliary additive includes one or more of 1,3-propane sultone, 1,4-butane sultone, propenyl-1,3-sultone, vinyl sulfate, propylene sulfate, butylene sulfite, vinylene carbonate and fluoroethylene carbonate;

[0044] The mass content of the first auxiliary additive in the electrolyte is 0.1% to 3.0%;

[0045] The electrolyte includes a second auxiliary additive;

[0046] The second auxiliary additive includes one or more of lithium bis(fluorosulfonyl)imide, lithium difluorooxalatoborate, lithium difluorooxalatophosphate, lithium difluorophosphate and lithium tetrafluoroborate;

[0047] The molar content of the second auxiliary additive in the electrolyte is 0.001-1.0M.

[0048] The present invention provides a cyanophosphate additive, the additive having a structure as shown in formula (I). Compared with the prior art, the present invention is based on the problems existing in the existing positive electrode lithium supplement. It is believed that the existing lithium supplement additive will produce gases such as carbon dioxide during the decomposition process, which affects the cycle life. Secondly, the above lithium supplement additive does not contain a group that can capture metal lithium ions, cannot dissolve metal ions consistently, and does not contain a P-containing group, so the interface film formed has a large impedance, etc.

[0049] The present invention specifically designs a cyanophosphate additive with a specific structure and composition, which is an organic lithium salt lithium supplement material. The positive electrode lithium supplement material contains a cyano functional group, which can complex with metal ions to inhibit the diffusion of metal ions into the electrolyte, thereby reducing the catalytic reaction of metal ions on organic solvents, reducing gas production, and improving high-temperature cycle performance. At the same time, the presence of the positive electrode additive of the present invention can improve the morphology and composition of the CEI film, promote and participate in the component Li x PO y F z The formation of can reduce membrane impedance, polarization, lithium ion consumption and improve efficiency. Secondly, the positive electrode lithium supplement additive is insensitive to moisture and has excellent stability in the air. It can reduce the environmental requirements during the preparation of positive electrode sheets and is a highly potential positive electrode lithium supplement.

[0050] The organic lithium phosphate compound containing cyano group provided by the present invention is used as a lithium supplement material. From the perspective of performance, it can complex with metal ions to inhibit the diffusion of metal ions into the electrolyte, thereby reducing the catalytic reaction of metal ions on organic solvents, reducing gas production, and improving high-temperature cycle performance; and the lithium supplement contains phosphate groups. The presence of this structure improves the morphology and composition of the CEI film, promotes and participates in the component Li x PO y F z The formation of a lithium supplement reduces membrane impedance, reduces polarization, reduces lithium ion consumption, and improves efficiency. Compared with carbonate lithium supplements, phosphate groups are less likely to produce gas and have flame retardant properties, thereby improving battery safety. At the same time, the lithium supplement can also introduce corresponding groups as needed to match actual application needs. In addition, the lithium supplement is insensitive to moisture and oxygen, so the preparation of batteries using the lithium supplement does not require a special environment.

[0051] The positive electrode organic lithium salt lithium supplement agent provided by the present invention has the advantages of low gas production, good stability and long cycle life, and can also well improve the lithium ion conductivity. It is a positive electrode lithium supplement additive with excellent comprehensive performance, which can be used to reduce gas production and improve the stability, energy density and high-temperature storage of lithium-ion batteries.

[0052] Experimental results show that the presence of cyano functional group in the positive electrode organic lithium salt lithium supplement provided by the present invention can increase the cycle life of the battery and reduce the gas production rate; the lithium supplement additive contains F, which can reduce the internal resistance of the battery. The use of the additive of the present invention can improve the cycle life and high-temperature storage performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 The infrared spectrum of the cyanophosphate additive of formula (1) prepared by the present invention;

[0054] Figure 2 The H NMR spectrum of the cyanophosphate additive of formula (1) prepared by the present invention;

[0055] Figure 3 It is a comparison curve of the capacity retention rate of Example 1 of the present invention and Comparative Example 1;

[0056] Figure 4 It is a box plot of the first efficiency of Example 1, Comparative Example 1, Example 4 and Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0057] In order to further understand the present invention, the technical solution of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] All raw materials of the present invention are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

[0059] There is no particular restriction on the purity of all raw materials in the present invention. The present invention preferably uses analytically pure materials or materials of conventional purity in the field of positive electrode materials for lithium ion batteries.

[0060] The present invention provides a cyanophosphate additive, wherein the additive has a structure as shown in formula (I):

[0061]

[0062] Wherein, the R1 is selected from a group containing a cyano group;

[0063] The R2 is selected from lithium ion, C1-C6 saturated hydrocarbon group, C1-C6 unsaturated hydrocarbon group, alkoxy group, cyanoalkyl group, halogenated alkyl group, phenyl group, silane group or substituted silane group.

[0064] In the present invention, the C1-C6 saturated hydrocarbon group may also be a C2-C5 saturated hydrocarbon group, or a C3-C4 saturated hydrocarbon group. The C1-C6 unsaturated hydrocarbon group may also be a C2-C5 unsaturated hydrocarbon group, or a C3-C4 unsaturated hydrocarbon group.

[0065] In the present invention, the substituted silyl group may specifically be a halogenated silyl group.

[0066] In the present invention, the cyano group-containing group preferably includes a cyanoalkyl group or a substituted cyanoalkyl group.

[0067] In the present invention, the substitution preferably includes halogen substitution.

[0068] In the present invention, the term "hydrocarbon group" includes alkyl, alkenyl, and alkynyl.

[0069] In the present invention, the term "alkyl" encompasses straight and branched chain alkyl groups, including but not limited to methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, etc. In addition, the alkyl group may be optionally substituted.

[0070] In the present invention, the term "alkenyl" encompasses straight chain and branched alkenyl groups. For example, alkenyl can be C2-C 50 Alkenyl, C2-C 40 Alkenyl, C2-C 30 Alkenyl, C2-C 20 Alkenyl, C2-C 12 Alkenyl, C2-C 10 In addition, the alkenyl group may be optionally substituted.

[0071] In the present invention, the cyanophosphate additive is preferably a positive electrode additive.

[0072] In the present invention, the positive electrode preferably comprises a lithium ion battery positive electrode.

[0073] In the present invention, the cyanophosphate additive preferably has a structure as shown in any one of formulas (1) to (11):

[0074]

[0075] In the present invention, the cyanophosphate additive is preferably a positive electrode organic lithium salt lithium supplement material.

[0076] In the present invention, the mass ratio of the cyanophosphate additive to the positive electrode active material is preferably (0.5-5): (75-97.5), more preferably (1-4): (75-97.5), more preferably (2-3): (75-97.5), more preferably (0.5-5): (80-92), more preferably (0.5-5): (85-87).

[0077] In the present invention, the cyanophosphate additive is preferably a positive electrode additive that improves the morphology and / or composition of the CEI film, and more preferably a positive electrode additive that improves the morphology or composition of the CEI film.

[0078] In the present invention, the cyanophosphate additive preferably promotes and participates in the component Li x PO y F z formation.

[0079] The present invention is to complete and refine the overall technical solution, better ensure the lithium replenishing effect of the positive electrode lithium replenisher, further reduce the gas production, improve the stability and cycle life of the lithium ion battery, and improve the lithium ion conductivity. The above-mentioned cyanophosphate additive preferably includes the following structure and composition:

[0080] The organic lithium salt lithium supplement material has the following characteristics: the organic lithium salt additive is a cyanophosphate additive. Its structure is as follows:

[0081]

[0082] R1 represents a group containing a cyano group, and R2 represents a lithium ion or a saturated or unsaturated hydrocarbon group containing 1 to 6 carbon atoms, an alkoxy group, a cyano-substituted alkyl group, a halogenated alkyl group, a phenyl group, a silane group or a substituted silane group.

[0083] Among them, the hydrocarbon group includes alkyl, alkenyl, and alkynyl;

[0084] Alkyl encompasses straight and branched chain alkyl groups, including but not limited to methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, etc. In addition, the alkyl group may be optionally substituted.

[0085] Alkenyl encompasses straight and branched alkenyl. For example, alkenyl can be C2-C50 alkenyl, C2-C40 alkenyl, C2-C30 alkenyl, C2-C20 alkenyl, C2-C12 alkenyl, C2-C10 alkenyl, C2-C6 alkenyl. In addition, alkenyl can be optionally substituted.

[0086] The substituted silyl group may be a halogen-substituted silyl group.

[0087] The additives include but are not limited to the following structures in formulas (1) to (11), which can also be expressed as formulas ① to

[0088]

[0089] Taking the above structure as an example, the preparation method of the positive electrode lithium supplement material of the present invention is described:

[0090] (1) using 3-hydroxypropionitrile and phosphorus oxyhalide as raw materials, adding a halogen chelating agent, and reacting in an organic solvent environment such as n-hexane for a certain period of time;

[0091] (2) extracting the solution after the reaction with dichloromethane, and distilling the filtrate under reduced pressure to obtain a crude reaction intermediate;

[0092] (3) Add the crude reaction intermediate into ice water to dissolve, then add dichloroethane and stir thoroughly, then use a separatory funnel to separate the liquid to obtain an aqueous phase (the product is extracted into the aqueous phase);

[0093] (4) Adding Li2CO3 to the aqueous phase obtained in (3) and controlling the pH to be 6 to 9, a lithium cyanophosphate mixed solution can be obtained;

[0094] (5) The solution containing lithium cyanophosphate is subjected to reduced pressure distillation to remove the solvent, and then washed with methanol for multiple times, centrifuged, and dried to obtain the product of the present invention.

[0095] See also Figure 1 , Figure 1 The infrared spectrum of the cyanophosphate additive of formula (1) prepared by the present invention;

[0096] See also Figure 2 , Figure 2 The H NMR spectrum of the cyanophosphate additive of formula (1) prepared in the present invention.

[0097] The present invention provides a lithium ion battery, comprising a positive electrode, a negative electrode and an electrolyte;

[0098] In the present invention, the positive electrode preferably includes the cyanophosphate additive described in any one of the above technical solutions.

[0099] In the present invention, the positive electrode also preferably includes a positive electrode active material, a positive electrode conductive agent and a positive electrode binder.

[0100] In the present invention, the positive electrode active material preferably includes one or more of lithium cobalt oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium phosphate, sodium vanadium phosphate, lithium vanadate, lithium manganate, lithium nickel oxide, lithium nickel cobalt manganate, lithium-rich manganese-based materials, lithium nickel cobalt aluminum oxide and lithium titanate, and more preferably includes lithium cobalt oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium phosphate, sodium vanadium phosphate, lithium vanadate, lithium manganate, lithium nickel oxide, lithium nickel cobalt manganate, lithium-rich manganese-based materials, lithium nickel cobalt aluminum oxide or lithium titanate.

[0101] In the present invention, the positive electrode conductive agent preferably includes one or more of conductive carbon black, carbon fiber, acetylene black, Ketjen black, graphene and carbon nanotubes, more preferably conductive carbon black, carbon fiber, acetylene black, Ketjen black, graphene or carbon nanotubes.

[0102] In the present invention, the positive electrode binder preferably includes one or more of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene and polyhexafluoropropylene, and more preferably polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene or polyhexafluoropropylene.

[0103] In the present invention, the preparation process of the positive electrode preferably includes, in the positive electrode slurrying process, uniformly mixing the cyanophosphate additive, the positive electrode active material, the positive electrode conductor, the positive electrode binder and the solvent, and then coating, rolling and drying to obtain the positive electrode sheet.

[0104] In the present invention, the positive electrode is calculated as a whole based on the cyanophosphate additive, the positive electrode active material, the positive electrode conductor and the positive electrode binder, and the mass content of the positive electrode active material is preferably 75% to 97.5%, more preferably 80% to 92%, and more preferably 85% to 87%.

[0105] In the present invention, the positive electrode is calculated as a whole based on the cyanophosphate additive, the positive electrode active material, the positive electrode conductor and the positive electrode binder, and the mass content of the positive electrode conductor is preferably 1% to 10%, more preferably 3% to 8%, and more preferably 5% to 6%.

[0106] In the present invention, the positive electrode is calculated as a whole by the cyanophosphate additive, the positive electrode active material, the positive electrode conductor and the positive electrode binder, and the mass content of the positive electrode binder is selected to be 1% to 10%, more preferably 3% to 8%, and more preferably 5% to 6%.

[0107] In the present invention, the positive electrode is calculated as a whole based on the cyanophosphate additive, the positive electrode active material, the positive electrode conductor and the positive electrode binder, and the mass content of the cyanophosphate additive is preferably 0.5% to 5%, more preferably 1% to 4%, and more preferably 2% to 3%.

[0108] In the present invention, the negative electrode preferably includes a negative electrode active material, a negative electrode conductor and a negative electrode binder.

[0109] In the present invention, the negative electrode active material preferably includes graphite and / or silicon-based materials, more preferably graphite or silicon-based materials.

[0110] In the present invention, the negative electrode conductive agent preferably includes one or more of conductive carbon black, carbon fiber, acetylene black, Ketjen black, graphene and carbon nanotubes, more preferably conductive carbon black, carbon fiber, acetylene black, Ketjen black, graphene or carbon nanotubes.

[0111] In the present invention, the negative electrode binder preferably includes one or more of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene and polyhexafluoropropylene, and more preferably polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene or polyhexafluoropropylene.

[0112] In the present invention, the electrolyte preferably includes a solvent.

[0113] In the present invention, the solvent preferably includes one or more of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, dimethyl ether, diethyl ether, adiponitrile, succinonitrile, glutaronitrile, dimethyl sulfoxide, sulfolane, 1,4-butyrolactone, methyl formate, ethyl acetate, methyl propionate, ethyl propionate, butyl propionate and ethyl butyrate, and more preferably ethylene carbonate, propylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, dimethyl ether, diethyl ether, adiponitrile, succinonitrile, glutaronitrile, dimethyl sulfoxide, sulfolane, 1,4-butyrolactone, methyl formate, ethyl acetate, methyl propionate, ethyl propionate, butyl propionate or ethyl butyrate.

[0114] In the present invention, the mass content of the solvent in the electrolyte is preferably 50% to 98%, more preferably 60% to 88%, and more preferably 70% to 78%.

[0115] In the present invention, the electrolyte preferably includes a lithium salt.

[0116] In the present invention, the lithium salt preferably includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate and lithium bis(fluorosulfonyl)imide salt, more preferably lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate or lithium bis(fluorosulfonyl)imide salt.

[0117] In the present invention, the mass content of the lithium salt in the electrolyte is preferably 1% to 18%, more preferably 4% to 15%, and more preferably 7% to 12%.

[0118] In the present invention, the electrolyte preferably includes a first auxiliary additive.

[0119] In the present invention, the first auxiliary additive preferably includes one or more of 1,3-propane sultone, 1,4-butane sultone, propenyl-1,3-sultone, vinyl sulfate, propenyl sulfate, butylene sulfite, vinylene carbonate and fluoroethylene carbonate, and more preferably 1,3-propane sultone, 1,4-butane sultone, propenyl-1,3-sultone, vinyl sulfate, propenyl sulfate, butylene sulfite, vinylene carbonate or fluoroethylene carbonate.

[0120] In the present invention, the mass content of the first auxiliary additive in the electrolyte is preferably 0.1% to 3.0%, more preferably 0.5% to 2.5%, and more preferably 1.0% to 2.0%.

[0121] In the present invention, the electrolyte preferably includes a second auxiliary additive.

[0122] In the present invention, the second auxiliary additive preferably includes one or more of lithium bis(fluorosulfonyl)imide, lithium difluorooxalatoborate, lithium difluorooxalatophosphate, lithium difluorophosphate and lithium tetrafluoroborate, more preferably lithium bis(fluorosulfonyl)imide, lithium difluorooxalatoborate, lithium difluorooxalatophosphate, lithium difluorophosphate or lithium tetrafluoroborate.

[0123] In the present invention, the molar content of the second auxiliary additive in the electrolyte is preferably 0.001 to 1.0M, more preferably 0.01 to 0.5M, and more preferably 0.1 to 0.2M.

[0124] The present invention is a complete and detailed overall technical solution, which better ensures the lithium replenishing effect of the positive electrode lithium replenisher, further reduces the gas production, improves the stability and cycle life of the lithium ion battery, and improves the lithium ion conductivity. The above lithium ion battery preferably includes: a positive electrode, a negative electrode, an electrolyte, and a diaphragm. The negative electrode includes a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder, and the positive electrode includes a positive electrode active material, a positive electrode conductive agent, a positive electrode binder, and a lithium replenishing additive.

[0125] The positive electrode active material may include, but is not limited to, at least one of lithium cobalt oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium phosphate, lithium vanadate, lithium manganate, lithium nickel oxide, lithium nickel cobalt manganese oxide, lithium-rich manganese-based materials, lithium nickel cobalt aluminum oxide and lithium titanate.

[0126] Furthermore, the positive electrode conductive agent is selected from one or more of conductive carbon black, carbon fiber, acetylene black, Ketjen black, graphene or carbon nanotubes.

[0127] Furthermore, the positive electrode binder is selected from one or more of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene or polyhexafluoropropylene.

[0128] Furthermore, the application of the lithium-ion battery positive electrode lithium replenishing additive in the lithium replenishing of the lithium-ion battery positive electrode is to mix the lithium-ion battery positive electrode lithium replenishing additive with the positive electrode active material, conductive agent, binder and solvent evenly during the positive electrode slurrying process, and then prepare the positive electrode sheet by coating, rolling and drying.

[0129] Furthermore, taking the lithium-ion battery positive electrode lithium supplement additive, positive electrode active material, conductive agent, and binder as a whole, the mass percentage of each component is: positive electrode active material 75-97.5%, conductive agent 1-10%, binder 1-10%, lithium-ion battery positive electrode lithium supplement additive 0.5-5%

[0130] Furthermore, the negative electrode active material is selected from one or more of graphite and silicon-based materials.

[0131] Furthermore, the negative electrode conductive agent is selected from one or more of conductive carbon black, carbon fiber, acetylene black, Ketjen black, graphene or carbon nanotubes; the negative electrode binder is selected from one or more of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene or polyhexafluoropropylene.

[0132] Furthermore, the electrolyte further comprises: at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, dimethyl ether, diethyl ether, adiponitrile, succinonitrile, glutaronitrile, dimethyl sulfoxide, cyclopentane sulfone, 1,4-butyrolactone, methyl formate, ethyl acetate, methyl propionate, ethyl propionate, butyl propionate and ethyl butyrate, and the mass percentage in the electrolyte is 50-98%;

[0133] Furthermore, the electrolyte also includes: one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, and bis(fluorosulfonyl)imide lithium salt, and the mass percentage of the lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, and lithium bis(fluorosulfonyl)imide in the electrolyte is 1-18%.

[0134] Furthermore, the auxiliary additive 1,3-propane sultone, 1,4-butane sultone, propenyl-1,3-sultone, vinyl sulfate, propylene sulfate, butylene sulfite, vinylene carbonate or fluoroethylene carbonate accounts for 0.1% to 3.0% of the total mass of the electrolyte; the auxiliary additive lithium bis(fluorosulfonyl)imide, lithium difluorooxalatoborate, lithium difluorooxalatophosphate, lithium difluorophosphate or lithium tetrafluoroborate has a molar content in the electrolyte of 0 to 1.0M.

[0135] The above content of the present invention provides an organic lithium salt lithium supplement material and a lithium ion battery. The cyanophosphate additive with a specific structure and composition designed by the present invention is an organic lithium salt lithium supplement material for lithium supplementation of the positive electrode of a lithium ion battery. The positive electrode lithium supplement material contains a cyano functional group, which can complex with metal ions to inhibit the diffusion of metal ions into the electrolyte, thereby reducing the catalytic reaction of metal ions on organic solvents, reducing gas production, and improving high temperature cycle performance. At the same time, the presence of the positive electrode additive of the present invention can improve the morphology and composition of the CEI film, promote and participate in the component Li x PO y F z The formation of can reduce membrane impedance, polarization, lithium ion consumption and improve efficiency. Secondly, the positive electrode lithium supplement additive is insensitive to moisture and has excellent stability in the air. It can reduce the environmental requirements during the preparation of positive electrode sheets and is a highly potential positive electrode lithium supplement.

[0136] The organic lithium phosphate compound containing cyano group provided by the present invention is used as a lithium supplement material. From the perspective of performance, it can complex with metal ions to inhibit the diffusion of metal ions into the electrolyte, thereby reducing the catalytic reaction of metal ions on organic solvents, reducing gas production, and improving high-temperature cycle performance; and the lithium supplement contains phosphate groups. The presence of this structure improves the morphology and composition of the CEI film, promotes and participates in the component Li x PO y F z The formation of a lithium supplement reduces membrane impedance, reduces polarization, reduces lithium ion consumption, and improves efficiency. Compared with carbonate lithium supplements, phosphate groups are less likely to produce gas and have flame retardant properties, thereby improving battery safety. At the same time, the lithium supplement can also introduce corresponding groups as needed to match actual application needs. In addition, the lithium supplement is insensitive to moisture and oxygen, so the preparation of batteries using the lithium supplement does not require a special environment.

[0137] The positive electrode organic lithium salt lithium supplement agent provided by the present invention has the advantages of low gas production, good stability and long cycle life, and can also well improve the lithium ion conductivity. It is a positive electrode lithium supplement additive with excellent comprehensive performance, which can be used to reduce gas production and improve the stability, energy density and high-temperature storage of lithium-ion batteries.

[0138] Experimental results show that the presence of cyano functional group in the positive electrode organic lithium salt lithium supplement provided by the present invention can increase the cycle life of the battery and reduce the gas production rate; the lithium supplement additive contains F, which can reduce the internal resistance of the battery. The use of the additive of the present invention can improve the cycle life and high-temperature storage performance of the battery.

[0139] In order to further illustrate the present invention, a cyanophosphate additive and a lithium-ion battery provided by the present invention are described in detail in combination with the embodiments below. However, it should be understood that these embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating processes are given only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention, and the protection scope of the present invention is not limited to the following embodiments.

[0140] The reagents used in the following examples of the present invention are all commercially available products.

[0141] Example 1

[0142] Preparation of positive electrode sheet: LiNi 0.6 Co 0.2 Mn 0.2 O2, the above-mentioned positive electrode lithium supplement material structure ①, positive electrode conductive agent acetylene black, positive electrode binder polyvinylidene fluoride are mixed in a mass ratio of 92:4:2:2 and added to NMP, and stirred evenly to prepare positive electrode slurry, and the positive electrode slurry is coated on aluminum foil, and dried, rolled, and cut into pieces to make positive electrode sheets;

[0143] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, wherein the amorphous carbon coating amount is 3% of the mass of SiO), graphite, negative electrode conductive agent carbon black, negative electrode binder sodium carboxymethyl cellulose and styrene-butadiene rubber are mixed in a mass ratio of 11.5:84.5:2:1.5:1.5, dissolved in deionized water, stirred evenly and prepared negative electrode slurry, coated the negative electrode slurry on copper foil, dried, rolled and cut into negative electrode sheets;

[0144] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0145] Example 2

[0146] Preparation of positive electrode sheet: LiNi 0.6 Co 0.2 Mn 0.2 O2, the positive electrode lithium supplement material structure ②, the positive electrode conductive agent carbon nanotubes, and the positive electrode binder polyvinylidene fluoride are mixed in a mass ratio of 92:4:2:2 and added to NMP, and stirred evenly to prepare a positive electrode slurry, and the positive electrode slurry is coated on aluminum foil, and dried, rolled, and cut into pieces to make a positive electrode sheet;

[0147] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, wherein the amorphous carbon coating amount is 3% of the mass of SiO), graphite, negative electrode conductive agent carbon black, and negative electrode binder polyacrylic acid are mixed in a mass ratio of 11.5:84.5:2:1.5:1.5, dissolved in deionized water, and stirred evenly to prepare negative electrode slurry, and the negative electrode slurry is coated on copper foil, and the negative electrode sheet is made by drying, rolling, and cutting;

[0148] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0149] Example 3

[0150] Preparation of positive electrode sheet: LiN i0.6 Co 0.2 Mn 0.2 O2, the positive electrode lithium supplement material structure ③, the positive electrode conductive agent carbon nanotubes, and the positive electrode binder polyvinylidene fluoride are mixed in a mass ratio of 92:4:2:2 and added to NMP, and stirred evenly to prepare a positive electrode slurry, and the positive electrode slurry is coated on aluminum foil, and dried, rolled, and cut into pieces to make a positive electrode sheet;

[0151] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, wherein the amorphous carbon coating amount is 5% of the mass of SiO), graphite, negative electrode conductive agent acetylene black, and negative electrode binder polyvinylidene fluoride are mixed in a mass ratio of 11.5:84.5:2:1.5:1.5, dissolved in deionized water, stirred evenly, and prepared negative electrode slurry, coated the negative electrode slurry on copper foil, and dried, rolled, and cut into pieces to prepare negative electrode sheets;

[0152] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0153] Example 4

[0154] Preparation of positive electrode sheet: positive electrode active material LiCoO2, the positive electrode lithium supplement material structure ④, positive electrode conductive agent acetylene black, positive electrode binder polyvinylidene fluoride are mixed in a mass ratio of 92:4:2:2 and added to NMP, and the positive electrode slurry is prepared after stirring evenly, and the positive electrode slurry is coated on aluminum foil, and the positive electrode sheet is made by drying, rolling and cutting;

[0155] Preparation of negative electrode sheet: Graphite, negative electrode conductive agent carbon black, negative electrode binder sodium carboxymethyl cellulose and styrene-butadiene rubber are mixed in a mass ratio of 95:2:1.5:1.5, dissolved in deionized water, stirred evenly and prepared to obtain negative electrode slurry, the negative electrode slurry is coated on copper foil, dried, rolled and cut into negative electrode sheets;

[0156] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0157] Example 5

[0158] Preparation of positive electrode sheet: positive electrode active material LiCoO2, the positive electrode lithium supplement material structure ⑤, positive electrode conductive agent acetylene black, positive electrode binder polyvinylidene fluoride are mixed in a mass ratio of 92:4:2:2 and added to NMP, stirred evenly to prepare positive electrode slurry, coated on aluminum foil, dried, rolled, and cut into positive electrode sheets;

[0159] Preparation of negative electrode sheet: Graphite, negative electrode conductive agent carbon black, negative electrode binder sodium carboxymethyl cellulose and styrene-butadiene rubber are mixed in a mass ratio of 95:2:1.5:1.5, dissolved in deionized water, stirred evenly and prepared to obtain negative electrode slurry, the negative electrode slurry is coated on copper foil, dried, rolled and cut into negative electrode sheets;

[0160] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0161] Example 6

[0162] Preparation of positive electrode sheet: positive electrode active material LiCoO2, the positive electrode lithium supplement material structure ⑥, positive electrode conductive agent acetylene black, positive electrode binder polyvinylidene fluoride are mixed in a mass ratio of 92:4:2:2 and added to NMP, and stirred evenly to prepare positive electrode slurry, and the positive electrode slurry is coated on aluminum foil, and dried, rolled, and cut into pieces to make positive electrode sheets;

[0163] Preparation of negative electrode sheet: Graphite, negative electrode conductive agent carbon black, negative electrode binder sodium carboxymethyl cellulose and styrene-butadiene rubber are mixed in a mass ratio of 95:2:1.5:1.5, dissolved in deionized water, stirred evenly and prepared to obtain negative electrode slurry, the negative electrode slurry is coated on copper foil, dried, rolled and cut into negative electrode sheets;

[0164] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0165] Example 7

[0166] Preparation of positive electrode sheet: LiNi 0.6 Co 0.2 Mn 0.2 O2, the positive electrode lithium supplement material structure ⑦, the positive electrode conductive agent carbon nanotubes, and the positive electrode binder polyvinylidene fluoride are mixed in a mass ratio of 94:2:2:2 and added to NMP, and stirred evenly to prepare a positive electrode slurry, and the positive electrode slurry is coated on aluminum foil, and dried, rolled, and cut into pieces to make a positive electrode sheet;

[0167] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, wherein the amorphous carbon coating amount is 3% of the mass of SiO), graphite, negative electrode conductive agent carbon black, and negative electrode binder polyacrylic acid are mixed in a mass ratio of 11.5:84.5:2:1.5:1.5, dissolved in deionized water, and stirred evenly to prepare negative electrode slurry, and the negative electrode slurry is coated on copper foil, and the negative electrode sheet is made by drying, rolling, and cutting;

[0168] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0169] Example 8

[0170] Preparation of positive electrode sheet: LiNi 0.6 Co 0.2 Mn 0.2 O2, the positive electrode lithium supplement material structure ⑧, the positive electrode conductive agent carbon nanotubes, and the positive electrode binder polyvinylidene fluoride are mixed in a mass ratio of 92:4:2:2 and added to NMP, and stirred evenly to prepare a positive electrode slurry, and the positive electrode slurry is coated on aluminum foil, and dried, rolled, and cut into pieces to make a positive electrode sheet;

[0171] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, wherein the amorphous carbon coating amount is 3% of the mass of SiO), graphite, negative electrode conductive agent carbon black, and negative electrode binder polyacrylic acid are mixed in a mass ratio of 11.5:84.5:2:1.5:1.5, dissolved in deionized water, and stirred evenly to prepare negative electrode slurry, and the negative electrode slurry is coated on copper foil, and the negative electrode sheet is made by drying, rolling, and cutting;

[0172] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0173] Example 9

[0174] Preparation of positive electrode sheet: LiNi 0.6 Co 0.2 Mn 0.2 O2, the positive electrode lithium supplement material structure ⑧, the positive electrode conductive agent carbon nanotubes, and the positive electrode binder polyvinylidene fluoride are mixed in a mass ratio of 94:2:2:2 and added to NMP, and stirred evenly to prepare a positive electrode slurry, and the positive electrode slurry is coated on aluminum foil, and then dried, rolled, and cut into pieces to make a positive electrode sheet;

[0175] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, wherein the amorphous carbon coating amount is 3% of the mass of SiO), graphite, negative electrode conductive agent carbon black, and negative electrode binder polyacrylic acid are mixed in a mass ratio of 11.5:84.5:2:1.5:1.5, dissolved in deionized water, and stirred evenly to prepare negative electrode slurry, and the negative electrode slurry is coated on copper foil, and the negative electrode sheet is made by drying, rolling, and cutting;

[0176] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0177] Example 10

[0178] Preparation of positive electrode sheet: LiNi 0.6 Co 0.2 Mn 0.2 O2, the positive electrode lithium supplement material structure ⑨, the positive electrode conductive agent carbon nanotubes, and the positive electrode binder polyvinylidene fluoride are mixed in a mass ratio of 94:2:2:2 and added to NMP, and stirred evenly to prepare a positive electrode slurry, and the positive electrode slurry is coated on an aluminum foil, and then dried, rolled, and cut into pieces to make a positive electrode sheet;

[0179] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, wherein the amorphous carbon coating amount is 3% of the mass of SiO), graphite, negative electrode conductive agent carbon black, and negative electrode binder polyacrylic acid are mixed in a mass ratio of 11.5:84.5:2:1.5:1.5, dissolved in deionized water, and stirred evenly to prepare negative electrode slurry, and the negative electrode slurry is coated on copper foil, and the negative electrode sheet is made by drying, rolling, and cutting;

[0180] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0181] Embodiment 11

[0182] Preparation of positive electrode sheet: LiNi 0.6 Co 0.2 Mn 0.2 O2, the positive electrode lithium supplement material structure ⑩, the positive electrode conductive agent carbon nanotubes, and the positive electrode binder polyvinylidene fluoride are mixed in a mass ratio of 92:4:2:2 and added to NMP, and stirred evenly to prepare a positive electrode slurry, and the positive electrode slurry is coated on aluminum foil, and dried, rolled, and cut into pieces to make a positive electrode sheet;

[0183] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, wherein the amorphous carbon coating amount is 5% of the mass of SiO), graphite, negative electrode conductive agent acetylene black, and negative electrode binder polyvinylidene fluoride are mixed in a mass ratio of 11.5:84.5:2:1.5:1.5, dissolved in deionized water, stirred evenly, and prepared negative electrode slurry, coated the negative electrode slurry on copper foil, and dried, rolled, and cut into pieces to prepare negative electrode sheets;

[0184] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0185] Example 12

[0186] Preparation of positive electrode sheet: positive electrode active material LiCoO2, the positive electrode lithium supplement material structure Acetylene black, a positive electrode conductive agent, and polyvinylidene fluoride, a positive electrode binder, are mixed in a mass ratio of 92:4:2:2 and added to NMP, and stirred evenly to prepare a positive electrode slurry, which is then coated on an aluminum foil, dried, rolled, and cut into a positive electrode sheet;

[0187] Preparation of negative electrode sheet: Graphite, negative electrode conductive agent carbon black, negative electrode binder sodium carboxymethyl cellulose and styrene-butadiene rubber are mixed in a mass ratio of 95:2:1.5:1.5, dissolved in deionized water, stirred evenly and prepared to obtain negative electrode slurry, the negative electrode slurry is coated on copper foil, dried, rolled and cut into negative electrode sheets;

[0188] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0189] Comparative Example 1

[0190] Except that no lithium supplement agent is added to the positive terminal, the rest is the same as in Example 1;

[0191] Comparative Example 2

[0192] Except that no lithium supplement agent is added to the positive terminal, the rest is the same as Example 4;

[0193] Comparative Example 3

[0194] A cyanide-free lithium salt is added to the positive terminal, and its structure is shown in the figure Others are consistent with Example 1;

[0195] Since the lithium supplement is insensitive to moisture and oxygen, the above experiments do not require special control of the environment for preparing the electrode.

[0196] The preparation method of the battery is as follows:

[0197] The coating surface density is determined according to the battery capacity design (2000mAh) and the capacity of the positive and negative electrode materials.

[0198] Electrolyte composition: 1.1MLiPF6, EC:EMC=30:70, 1%VC, 1%FEC.

[0199] Preparation of lithium-ion batteries: The positive electrode sheet, negative electrode sheet and separator (PE film, containing ceramic coating) of the lithium-ion battery prepared according to the above process are wound into square cells, the bare cells are placed in an outer package, the prepared electrolyte is injected into the dried battery, and the preparation of lithium-ion batteries is completed through the steps of packaging, standing, formation, shaping, and capacity division.

[0200] In order to verify the performance of the product of the present application, the performance test was carried out on the 2Ah soft-pack battery cells prepared in Examples 1 to 12 and Comparative Examples 1 to 3. The specific method is as follows and the results are shown in Table 1.

[0201] (1) Battery cell initial efficiency test: battery cell initial discharge capacity / battery cell initial charge capacity.

[0202] (2) Test of the positive electrode capacity in the first cycle of the battery cell: the discharge capacity of the battery cell in the first cycle (mAh) / mass of positive electrode active material (g).

[0203] (3) Cell DC internal resistance DCR test: The battery capacity is divided and adjusted to 50% SOC, 5C 10S discharge, and the discharge resistance is tested. Resistance DCR = (V0-V10) / I, where V0 is the potential before discharge, V10 is the potential after 10S of discharge, and I is the discharge current 2C;

[0204] (4) 45℃ capacity retention test: ① Charging: 1C constant current and constant voltage charging to 4.2V, let stand for 10min; ② Discharging: 1C constant current and constant voltage charging to 2.8V; ③ Repeat “①, ②” for 500 cycles.

[0205] After 500 cycles of charge and discharge, the retention rate of the 500th cycle capacity is calculated using the following formula:

[0206] 500th cycle capacity retention rate (%)=(500th cycle discharge capacity / 1st cycle discharge capacity)×100%.

[0207] Among them, the upper limit of the voltage cycle range of the lithium cobalt oxide system, i.e., Example 456 and Comparative Example 2, was changed to 4.45V, and the others remained unchanged.

[0208] (5) High temperature storage test

[0209] The capacity of the battery cell is divided at 1C at room temperature 25°C, and the obtained capacity is recorded as D0;

[0210] The battery cell is fully charged at 1C, then placed in a 60℃ oven for 20 days, then taken out and tested for recovery capacity after cooling to room temperature, recorded as D1. The recovery rate of the battery cell's high temperature storage capacity is calculated as: D1 / D0

[0211] (6) High temperature gas production test

[0212] Fully charge the battery cell and use the exclusion method to test the initial volume V0. Then place the battery cell in a 60℃ oven and leave it for 30 days. Then use the drainage method to test the volume V1. The high-temperature gas production volume growth rate is V1 / V0-1.

[0213] See Table 1, which shows the performance test data of the soft-pack batteries prepared in Examples 1 to 12 and Comparative Examples 1 to 3 of the present invention.

[0214] Table 1

[0215]

[0216]

[0217] It can be seen from Table 1 that, compared with Examples 1 to 12 and Comparative Examples 1 to 2, the first efficiency, first cycle positive electrode gram capacity, internal resistance, capacity retention, high temperature storage and gas production of the 2Ah soft-pack batteries prepared in Examples 1 to 12 are significantly improved.

[0218] Comparison between Example 1 and Example 2 shows that the presence of multiple cyano functional groups increases the battery cycle life and reduces the gas generation rate;

[0219] Comparison of Example 1 with Comparative Example 3 shows that the lithium supplement containing cyanide is more conducive to inhibiting gas production and improving the cycle life of the battery;

[0220] Comparison between Example 4 and Example 5 shows that the lithium supplement additive contains F, which is beneficial to reducing the internal resistance of the battery;

[0221] By comparing Example 5 with Example 8, it can be seen that in the positive electrode lithium replenishment additive, the higher the lithium content, the more lithium can be provided in the corresponding positive electrode lithium replenishment process, the better the lithium replenishment effect, the higher the first effect / the better the positive electrode gram capacity.

[0222] See also Figure 3 , Figure 3 It is a comparison curve of the capacity retention rate between Example 1 of the present invention and Comparative Example 1.

[0223] See also Figure 4 , Figure 4 It is a box plot of the first efficiency of Example 1, Comparative Example 1, Example 4 and Comparative Example 2 of the present invention.

[0224] In summary, the organic positive electrode lithium replenishing material provided by the present invention has a good lithium replenishing effect, can effectively inhibit gas production, reduce internal resistance, and improve high-temperature cycle life.

[0225] The above is a detailed introduction to an organic lithium salt lithium supplement material and a lithium ion battery provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enables any technician in the field to practice the present invention, including the manufacture and use of any device or system, and the implementation of any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. Application of cyanophosphate additives as positive electrode lithium supplement additives in lithium-ion batteries; The cyanophosphate additive is specifically a positive electrode organic lithium salt lithium supplement material; The mass ratio of the cyanophosphate additive to the positive electrode active material is (0.5-5): (75-97.5); The additive has a structure as shown in formula (I): in, The R1 is selected from a group containing a cyano group; The R2 is selected from lithium ion, C1-C6 saturated hydrocarbon group, C1-C6 unsaturated hydrocarbon group, alkoxy group, cyanoalkyl group, halogenated alkyl group, phenyl group, silane group or substituted silane group.

2. The use according to claim 1, characterized in that: The cyano group includes a cyanoalkyl group or a substituted cyanoalkyl group; The substitution includes halogen substitution; The cyanophosphate additive is a positive electrode additive; The positive electrode comprises a lithium ion battery positive electrode.

3. The use according to claim 1, characterized in that: The cyanophosphate additive has a structure as shown in any one of formulas (1) to (11):

4. The use according to claim 1, characterized in that: The cyanophosphate additive is a positive electrode additive that improves the morphology and / or composition of the CEI film; The cyanophosphate additive promotes and participates in the component Li x PO y F z formation.

5. A lithium ion battery, characterized in that: including a positive electrode, a negative electrode and an electrolyte; The positive electrode comprises the cyanophosphate additive according to any one of claims 1 to 4.

6. The lithium-ion battery according to claim 5, characterized in that: The positive electrode further comprises a positive electrode active material, a positive electrode conductor and a positive electrode binder; The positive electrode active material includes one or more of lithium cobalt oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium phosphate, lithium vanadate, lithium manganate, lithium nickel oxide, lithium nickel cobalt manganate, lithium-rich manganese-based materials, lithium nickel cobalt aluminum oxide and lithium titanate; The positive electrode conductive agent includes one or more of conductive carbon black, carbon fiber, acetylene black, Ketjen black, graphene and carbon nanotubes; The positive electrode binder includes one or more of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene and polyhexafluoropropylene; The positive electrode preparation process includes: in the positive electrode slurrying process, cyanophosphate additives, positive electrode active materials, positive electrode conductive agents, positive electrode binders and solvents are uniformly mixed, and then coated, rolled and dried to obtain positive electrode sheets.

7. The lithium-ion battery according to claim 6, characterized in that: The positive electrode is calculated as a whole by taking the cyanophosphate additive, the positive electrode active material, the positive electrode conductive agent and the positive electrode binder as the whole, and the mass content of the positive electrode active material is 75% to 97.5%; The positive electrode is calculated as a whole based on the cyanophosphate additive, the positive electrode active material, the positive electrode conductive agent and the positive electrode binder, and the mass content of the positive electrode conductive agent is 1% to 10%; The positive electrode is calculated as a whole based on the cyanophosphate additive, the positive electrode active material, the positive electrode conductive agent and the positive electrode binder, and the mass content of the positive electrode binder is 1% to 10%; The positive electrode is calculated as a whole based on the cyanophosphate additive, the positive electrode active material, the positive electrode conductive agent and the positive electrode binder, and the mass content of the cyanophosphate additive is 0.5% to 5%.

8. The lithium-ion battery according to claim 5, characterized in that: The negative electrode comprises a negative electrode active material, a negative electrode conductive agent and a negative electrode binder; The negative electrode active material includes graphite and / or silicon-based materials; The negative electrode conductive agent includes one or more of conductive carbon black, carbon fiber, acetylene black, Ketjen black, graphene and carbon nanotubes; The negative electrode binder includes one or more of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene and polyhexafluoropropylene.

9. The lithium-ion battery according to claim 5, characterized in that: The electrolyte includes a solvent; The solvent includes one or more of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, dimethyl ether, diethyl ether, adiponitrile, succinonitrile, glutaronitrile, dimethyl sulfoxide, sulfolane, 1,4-butyrolactone, methyl formate, ethyl acetate, methyl propionate, ethyl propionate, butyl propionate and ethyl butyrate; The mass content of the solvent in the electrolyte is 50% to 98%; The electrolyte includes a lithium salt; The lithium salt includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate and bis(fluorosulfonyl)imide lithium salt; The mass content of the lithium salt in the electrolyte is 1% to 18%.

10. The lithium ion battery according to claim 5, characterized in that: The electrolyte includes a first auxiliary additive; The first auxiliary additive includes one or more of 1,3-propane sultone, 1,4-butane sultone, propenyl-1,3-sultone, vinyl sulfate, propylene sulfate, butylene sulfite, vinylene carbonate and fluoroethylene carbonate; The mass content of the first auxiliary additive in the electrolyte is 0.1% to 3.0%; The electrolyte includes a second auxiliary additive; The second auxiliary additive includes one or more of lithium bis(fluorosulfonyl)imide, lithium difluorooxalatoborate, lithium difluorooxalatophosphate, lithium difluorophosphate and lithium tetrafluoroborate; The molar content of the second auxiliary additive in the electrolyte is 0.001-1.0M.

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