Organic positive electrode additive and lithium ion battery

Abstract

The present invention provides a positive electrode additive, which is an organic lithium salt lithium supplement material having a structure as shown in formula (I). This positive electrode supplement contains a silyl group, which can be oxidized to form a film on the positive electrode surface before the electrolyte, thereby inhibiting the dissolution of metal ions, reducing gas production, and improving battery cycle stability. Secondly, the presence of the additive can improve the morphology and composition of the CEI film, promote and participate in the formation of the component LixPOyFz, reduce membrane impedance, reduce polarization, reduce lithium ion consumption, and improve efficiency. Thirdly, the additive contains Si-N bonds, and the cleavage of Si-N bonds can remove water and HF, further improving the cycle stability of the electrode. Finally, this positive electrode supplement is insensitive to moisture and has excellent stability in air, which can reduce the environmental requirements during the preparation of positive electrode sheets. It is a highly promising positive electrode supplement. #imgabs0#

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium supplementation for lithium-ion battery positive electrodes, and relates to a positive electrode additive and a lithium-ion battery, in particular to an organic positive electrode additive and a lithium-ion battery. Background Art

[0002] Lithium-ion batteries are favored worldwide for their high energy density, low self-discharge rate, long cycle life, and clean, pollution-free design. Mobile devices such as laptops, mobile phones, handheld game consoles, and tablets are becoming increasingly versatile, and the technologies used in electric vehicles and smart grids are maturing. At the same time, consumers are demanding a balance between battery energy density, cycle life, and environmental compatibility. The energy density and cycle life of lithium-ion batteries are closely related to the formation of the solid electrolyte interface (SEI) film on the anode. During the initial charge of a lithium-ion battery, the SEI film formed on the anode surface converts a significant amount of active lithium into lithium carbonate, lithium fluoride, and alkyl lithium, resulting in lithium loss from the cathode material. In lithium-ion battery systems using graphite as the anode, the initial charge consumes approximately 10% of the lithium source. When high-capacity materials such as alloys (silicon, tin, etc.) or oxides (silicon oxide, tin oxide) are used as the anode, the consumption of the cathode lithium source is further exacerbated.

[0003] The current 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. Lithium replenishment at the pole piece end involves the use of flammable and explosive metallic 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 material processing difficult. 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-lithium ascorbate, D-lithium isoascorbate, lithium metabisulfite, 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.

[0004] Therefore, how to find a more suitable positive electrode lithium replenishing additive with excellent comprehensive performance to solve the above-mentioned problems of existing positive electrode lithium replenishing 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

[0005] In view of this, the present invention provides a positive electrode additive and a lithium ion battery. The positive electrode lithium supplement additive provided by the present invention has the advantages of low gas production, good stability, and long cycle life, and the lithium supplement can well improve lithium ion conductivity.

[0006] The present invention provides a positive electrode additive, which is an organic lithium salt lithium supplement material having a structure as shown in formula (I):

[0007]

[0008] The R1 and R2 are each independently selected from a lithium ion, a C1-C6 saturated hydrocarbon group, a C1-C6 unsaturated hydrocarbon group, an alkoxy group, a cyanoalkyl group, a substituted cyanoalkyl group, a haloalkyl group, a phenyl group, an ether group or a silane group.

[0009] Preferably, at least one of R1 and R2 is selected from a C1-C6 saturated hydrocarbon group, a C1-C6 unsaturated hydrocarbon group, an alkoxy group, a cyanoalkyl group, a substituted cyanoalkyl group, a haloalkyl group, a phenyl group, an ether group or a silane group;

[0010] The positive electrode additive is a silane amine phosphate additive;

[0011] The positive electrode comprises a lithium ion battery positive electrode.

[0012] Preferably, the cathode additive has a structure as shown in any one of formulas (1) to (12):

[0013]

[0014]

[0015] Preferably, the positive electrode additive is a positive electrode lithium supplement additive;

[0016] The mass ratio of the positive electrode active material to the positive electrode additive is (75-97.5): (0.1-10);

[0017] The positive electrode additive is a positive electrode additive that improves the morphology and / or composition of the CEI film;

[0018] The positive electrode additive promotes and participates in the component Li x PO y F z formation.

[0019] The present invention provides a lithium ion battery comprising a positive electrode, a negative electrode and an electrolyte;

[0020] The positive electrode includes the positive electrode additive described in any one of the above technical solutions.

[0021] Preferably, the positive electrode further comprises a positive electrode active material, a positive electrode conductor and a positive electrode binder;

[0022] The positive electrode active material includes one or more of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate and nickel cobalt lithium manganese oxide ternary positive electrode materials;

[0023] The positive electrode conductive agent includes one or more of conductive carbon black, carbon fiber, acetylene black, Ketjen black, graphene and carbon nanotubes;

[0024] The positive electrode binder includes one or more of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene and polyhexafluoropropylene;

[0025] The positive electrode preparation process includes: in the positive electrode slurrying process, the positive electrode additive, the positive electrode active material, the positive electrode conductive agent, the positive electrode binder and the solvent are uniformly mixed, and then coated, rolled and dried to obtain the positive electrode sheet.

[0026] Preferably, the positive electrode, taking the positive electrode additive, positive electrode active material, positive electrode conductive agent and positive electrode binder as a whole, has a mass content of the positive electrode active material of 75% to 97.5%;

[0027] The positive electrode comprises the positive electrode additive, the positive electrode active material, the positive electrode conductive agent and the positive electrode binder as a whole, and the mass content of the positive electrode conductive agent is 1% to 10%;

[0028] The positive electrode is calculated as a whole based on the positive electrode additive, positive electrode active material, positive electrode conductive agent and positive electrode binder, and the mass content of the positive electrode binder is 1% to 10%;

[0029] The positive electrode is calculated as a whole based on the positive electrode additive, the positive electrode active material, the positive electrode conductive agent and the positive electrode binder, and the mass content of the positive electrode additive is 0.1% to 10%.

[0030] Preferably, the negative electrode comprises a negative electrode active material, a negative electrode conductive agent and a negative electrode binder;

[0031] The negative electrode active material includes graphite and / or silicon-based materials;

[0032] The negative electrode conductive agent includes one or more of conductive carbon black, carbon fiber, acetylene black, Ketjen black, graphene and carbon nanotubes;

[0033] The negative electrode binder includes one or more of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene, and polyhexafluoropropylene.

[0034] Preferably, the electrolyte includes a solvent;

[0035] 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;

[0036] The mass content of the solvent in the electrolyte is 50% to 98%;

[0037] The electrolyte includes a lithium salt;

[0038] The lithium salt includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate and lithium bis(fluorosulfonyl)imide;

[0039] The mass content of the lithium salt in the electrolyte is 1% to 18%.

[0040] Preferably, the electrolyte includes a first auxiliary additive;

[0041] 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;

[0042] The mass content of the first auxiliary additive in the electrolyte is 0.1% to 3.0%;

[0043] The electrolyte includes a second auxiliary additive;

[0044] The second auxiliary additive includes one or more of lithium bis(fluorosulfonyl)imide, lithium difluorooxalatoborate, lithium difluorooxalatophosphate, lithium difluorophosphate and lithium tetrafluoroborate;

[0045] The content of the second auxiliary additive in the electrolyte is 0.001-1.0M.

[0046] The present invention provides a positive electrode additive, which is an organic lithium salt-based lithium-supplementing material having a structure as shown in Formula (I). Compared with the prior art, the present invention addresses the problems of existing positive electrode lithium-supplementing agents. Research indicates that existing lithium-supplementing agents produce gases such as carbon dioxide during decomposition, which affects cycle life. Furthermore, these additives do not contain P-containing groups, resulting in an interfacial film with high impedance.

[0047] The present invention specifically designs a positive electrode additive with a specific structure and composition, which is an organic lithium salt lithium supplement material. The positive electrode lithium supplement contains a silyl group, which can be oxidized to form a film on the positive electrode surface before the electrolyte, thereby inhibiting the dissolution of metal ions, reducing the gas production rate, and improving the battery cycle stability. Secondly, the presence of the additive 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 ions can reduce membrane impedance, polarization, lithium ion consumption and improve efficiency. Secondly, the additive contains Si-N bonds, and the breaking of Si-N bonds can remove H2O and HF, further improving the cycle stability of the electrode. Secondly, the positive electrode lithium replenishing additive is insensitive to moisture and has excellent stability in the air, which can reduce the environmental requirements during the preparation of positive electrode sheets. It is a highly potential positive electrode lithium replenishing agent.

[0048] The silyl phosphate amine additive provided by the present invention is used as a lithium supplement for the positive electrode of lithium ion batteries. From the perspective of performance, it can be oxidized to form a film on the positive electrode surface before the electrolyte, thereby inhibiting the dissolution of metal ions, reducing the gas production rate, and improving the cycle stability of the battery; and the presence of the additive 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 a lithium supplement agent reduces membrane impedance, polarization, lithium ion consumption, and efficiency. At the same time, the additive contains Si-N bonds, and the breaking of Si-N bonds can remove H2O and HF, further improving the cycle stability of the electrode. Furthermore, the lithium supplement agent can also introduce corresponding groups as needed to match actual application needs, and is insensitive to moisture and oxygen, so the preparation of batteries using the lithium supplement agent does not require a special environment.

[0049] The positive electrode lithium supplement additive provided by the present invention has excellent comprehensive performance, has the advantages of low gas production, good stability, and long cycle life, and can also greatly improve the lithium ion conductivity, thereby reducing the gas production of lithium-ion batteries and improving the battery's stability, energy density and high-temperature storage performance.

[0050] Experimental results show that the lithium-ion battery positive electrode lithium replenisher provided by the present invention significantly improves the first efficiency, first cycle positive electrode gram capacity, internal resistance, capacity retention, high-temperature storage and gas production of the lithium-ion battery. The presence of the cyano functional group further increases the battery cycle life and reduces the gas production rate. The presence of the branched ether group and the F-generation group is beneficial to reducing the battery internal resistance. The silylamine phosphate lithium replenisher is more conducive to inhibiting gas production and improving the battery cycle life. In short, the additive of the present invention is an excellent positive electrode lithium replenisher. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 The positive electrode lithium supplement material prepared by the present invention uses deuterated DMSO as solvent 1 HNMR spectrum;

[0052] Figure 2 The positive electrode lithium supplement material prepared by the present invention uses deuterated DMSO as solvent 13 C NMR spectrum; Figure 3 This is a comparison curve of the capacity retention rate after 500 cycles in the performance test of Example 1 of the present invention and Comparative Example 1;

[0053] Figure 4 It is a box plot of the gas production of Example 1, Example 2, Example 3 and Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0054] To further understand the present invention, the following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0055] 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.

[0056] There is no particular limitation 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 lithium-ion battery positive electrode materials.

[0057] The present invention provides a positive electrode additive, which is an organic lithium salt lithium supplement material having a structure as shown in formula (I):

[0058]

[0059] The R1 and R2 are each independently selected from a lithium ion, a C1-C6 saturated hydrocarbon group, a C1-C6 unsaturated hydrocarbon group, an alkoxy group, a cyanoalkyl group (cyano-substituted alkyl group), a substituted cyanoalkyl group, a haloalkyl group, a phenyl group, an ether group or a silane group.

[0060] 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.

[0061] In the present invention, at least one of R1 and R2 is preferably selected from a C1-C6 saturated hydrocarbon group, a C1-C6 unsaturated hydrocarbon group, an alkoxy group, a cyanoalkyl group, a substituted cyanoalkyl group, a haloalkyl group, a phenyl group, an ether group or a silane group, more preferably a C2-C5 saturated hydrocarbon group, a C2-C5 unsaturated hydrocarbon group, an alkoxy group, a cyanoalkyl group, a substituted cyanoalkyl group, a haloalkyl group, a phenyl group, an ether group or a silane group, more preferably a C3-C4 saturated hydrocarbon group, a C3-C4 unsaturated hydrocarbon group, an alkoxy group, a cyanoalkyl group (cyano-substituted alkyl group), a substituted cyanoalkyl group, a haloalkyl group, a phenyl group, an ether group or a silane group.

[0062] In the present invention, the positive electrode additive is preferably a silylamine phosphate additive.

[0063] In the present invention, the positive electrode additive preferably has a structure as shown in any one of formulas (1) to (12):

[0064]

[0065]

[0066] In the present invention, the positive electrode preferably comprises a lithium ion battery positive electrode.

[0067] In the present invention, the mass ratio of the positive electrode active material to the positive electrode additive is preferably (75-97.5): (0.1-10), more preferably (80-92): (0.1-10), more preferably (85-87): (0.1-10), more preferably (75-97.5): (1-7), and more preferably (75-97.5): (3-4).

[0068] In the present invention, the positive electrode additive is preferably a positive electrode lithium supplement additive.

[0069] In the present invention, the cathode additive is preferably a cathode additive that improves the morphology and / or composition of the CEI film, and more preferably a cathode additive that improves the morphology or composition of the CEI film.

[0070] In the present invention, the positive electrode additive preferably promotes and participates in the component Li x PO y F z in the process of formation.

[0071] 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, and improves the stability and cycle life of the lithium ion battery and the lithium ion conductivity. The above-mentioned positive electrode additive preferably includes the following structure and composition:

[0072]

[0073] R1 and R2 represent lithium ions or saturated or unsaturated hydrocarbon groups, alkoxy groups, cyano-substituted alkyl groups, haloalkyl groups, phenyl groups, ether groups or silane groups containing 1 to 6 carbon atoms;

[0074] The additive includes the following but is not limited to the structure represented by any one of the aforementioned formulas (1) to (12).

[0075] Furthermore, taking the above structure as an example, the preparation method of the positive electrode lithium supplement material described in this article is explained:

[0076] (1) Dissolve diethyl chlorophosphate in an organic solvent such as ether, introduce NH3 into it, and react at low temperature for a period of time to obtain the intermediate product diethyl pyrophosphoramide.

[0077] (2) adding the intermediate product obtained in (1) to a solution of lithium trimethylsilanol and reacting for a certain period of time;

[0078] (3) extracting the reaction solution with an organic solvent, and distilling the filtrate under reduced pressure to obtain a crude product;

[0079] (4) The crude product is further separated and purified to obtain the positive electrode lithium supplement material of the present invention.

[0080] The specific reaction process is as follows:

[0081]

[0082] R1 and R2 represent lithium ions or saturated or unsaturated hydrocarbon groups containing 1 to 6 carbon atoms, alkoxy groups, cyano-substituted alkyl groups, halogenated alkyl groups, phenyl groups, ether groups or silane groups.

[0083] The silylamine phosphate lithium salt compound provided by the present invention has the following advantages as a lithium supplement:

[0084] A: It can form a film on the positive electrode surface before the electrolyte, thereby inhibiting the dissolution of metal ions, reducing gas production rate, and improving battery cycle stability;

[0085] B: Secondly, the presence of additives can improve the morphology and composition of CEI membranes, promote and participate in the Li component x PO y F z The formation of , reduces membrane impedance, reduces polarization, reduces lithium ion consumption, and improves efficiency;

[0086] C: This additive contains Si-N bonds, and the breaking of Si-N bonds can remove H2O and HF, further improving the cycling stability of the electrode;

[0087] D: The lithium supplement can also introduce corresponding groups as needed to match the actual application needs;

[0088] F: This lithium supplement is insensitive to moisture and oxygen, so the preparation of batteries using this lithium supplement does not require a special environment.

[0089] See also Figure 1 , Figure 1 The positive electrode lithium supplement material prepared by the present invention uses deuterated DMSO as solvent 1 H NMR spectrum.

[0090] See also Figure 2 , Figure 2 The positive electrode lithium supplement material prepared by the present invention uses deuterated DMSO as solvent 13 C NMR spectrum.

[0091] The present invention also provides a lithium ion battery comprising a positive electrode, a negative electrode and an electrolyte.

[0092] In the present invention, the positive electrode preferably contains the positive electrode additive described in any one of the above technical solutions.

[0093] In the present invention, the positive electrode preferably further includes a positive electrode active material, a positive electrode conductor, and a positive electrode binder.

[0094] In the present invention, the positive electrode active material preferably includes one or more of lithium cobalt oxide, lithium manganate, lithium iron phosphate and nickel cobalt lithium manganate ternary positive electrode materials, more preferably lithium cobalt oxide, lithium manganate, lithium iron phosphate or nickel cobalt lithium manganate ternary positive electrode materials.

[0095] 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.

[0096] In the present invention, the positive electrode binder preferably includes one or more of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene and polyhexafluoropropylene, more preferably polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene or polyhexafluoropropylene.

[0097] In the present invention, the preparation process of the positive electrode preferably includes, in the positive electrode slurrying process, uniformly mixing the positive electrode additive, positive electrode active material, positive electrode conductive agent, positive electrode binder and solvent, and then coating, rolling and drying to obtain the positive electrode sheet.

[0098] In the present invention, the positive electrode is calculated as a whole based on the positive electrode additive, positive electrode active material, positive electrode conductor and 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%.

[0099] In the present invention, the positive electrode is calculated as a whole based on the positive electrode additive, positive electrode active material, positive electrode conductor and 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%.

[0100] In the present invention, the positive electrode is calculated as a whole based on the positive electrode additive, positive electrode active material, positive electrode conductor and positive electrode binder, and the mass content of the positive electrode binder is preferably 1% to 10%, more preferably 3% to 8%, and more preferably 5% to 6%.

[0101] In the present invention, the positive electrode is calculated as a whole based on the positive electrode additive, positive electrode active material, positive electrode conductor and positive electrode binder, and the mass content of the positive electrode additive is preferably 0.1% to 10%, more preferably 1% to 7%, and more preferably 3% to 4%.

[0102] In the present invention, the negative electrode preferably includes a negative electrode active material, a negative electrode conductor, and a negative electrode binder.

[0103] In the present invention, the negative electrode active material preferably includes graphite and / or silicon-based materials, more preferably graphite or silicon-based materials.

[0104] 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.

[0105] In the present invention, the negative electrode binder preferably includes one or more of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene and polyhexafluoropropylene, more preferably polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene or polyhexafluoropropylene.

[0106] In the present invention, the electrolyte preferably includes a solvent.

[0107] 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 includes 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.

[0108] In the present invention, the mass content of the solvent in the electrolyte is preferably 50% to 98%, more preferably 60% to 90%, and even more preferably 70% to 80%.

[0109] In the present invention, the electrolyte preferably includes a lithium salt.

[0110] In the present invention, the lithium salt preferably includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate and lithium bis(fluorosulfonyl)imide salts, more preferably lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate or lithium bis(fluorosulfonyl)imide salts.

[0111] In the present invention, the mass content of the lithium salt in the electrolyte is preferably 1% to 18%, more preferably 5% to 14%, and even more preferably 9% to 10%.

[0112] In the present invention, the electrolyte preferably includes a first auxiliary additive.

[0113] 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, propylene sulfate, butylene sulfite, vinylene carbonate and fluoroethylene carbonate, more preferably 1,3-propane sultone, 1,4-butane sultone, propenyl-1,3-sultone, vinyl sulfate, propylene sulfate, butylene sulfite, vinylene carbonate or fluoroethylene carbonate.

[0114] 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 even more preferably 1.0% to 2.0%.

[0115] In the present invention, the electrolyte preferably includes a second auxiliary additive.

[0116] 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.

[0117] In the present invention, the content of the second auxiliary additive in the electrolyte is preferably 0.001 to 1.0 M, more preferably 0.01 to 0.5 M, and even more preferably 0.1 to 0.2 M.

[0118] The present invention provides a complete and detailed overall technical solution, better ensuring the lithium replenishment effect of the positive electrode lithium replenisher, further reducing gas production, and improving the stability, cycle life, and lithium ion conductivity of the lithium-ion battery. The lithium-ion battery preferably comprises a positive electrode, a negative electrode, an electrolyte, and a separator. The negative electrode comprises a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder, while the positive electrode comprises a positive electrode active material, a positive electrode conductive agent, a positive electrode binder, and a lithium replenisher additive.

[0119] Furthermore, the positive electrode active material is selected from one or more of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, and nickel cobalt lithium manganese oxide ternary positive electrode materials.

[0120] 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.

[0121] Furthermore, the positive electrode binder is selected from one or more of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene or polyhexafluoropropylene.

[0122] The application of lithium-ion battery positive electrode lithium replenishing additives in lithium-ion battery positive electrode lithium replenishment is to mix the lithium-ion battery positive electrode lithium replenishing additives with positive electrode active materials, conductive agents, binders and solvents in the positive electrode slurry making process, and then prepare positive electrode sheets through coating, rolling and drying.

[0123] The application of the lithium-ion battery positive electrode lithium replenishing additive in the lithium replenishing of the lithium-ion battery positive electrode is based on the lithium-ion battery positive electrode lithium replenishing additive, the positive electrode active material, the conductive agent, and the binder as a whole. The mass percentage of each component is: 75-97.5% of the positive electrode active material, 1-10% of the conductive agent, 1-10% of the binder, and 0.1-10% of the lithium-ion battery positive electrode lithium replenishing additive.

[0124] Furthermore, the negative electrode active material is selected from one or more of graphite and silicon-based materials.

[0125] 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.

[0126] Furthermore, the electrolyte also includes: 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, 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%.

[0127] Furthermore, the electrolyte further comprises: one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, and lithium bis(fluorosulfonyl)imide salt, and the mass percentage of the lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, and lithium bis(fluorosulfonyl)imide salt in the electrolyte is 1 to 18%.

[0128] Furthermore, the auxiliary additives include 1,3-propane sultone, 1,4-butane sultone, propenyl-1,3-sultone, vinyl sulfate, propylene sulfate, butylene sulfite, vinylene carbonate or fluoroethylene carbonate, accounting for 0.1% to 3.0% of the total mass of the electrolyte.

[0129] Furthermore, the auxiliary additive further includes lithium bis(fluorosulfonyl)imide, lithium difluorooxalatoborate, lithium difluorooxalatophosphate, lithium difluorophosphate or lithium tetrafluoroborate, and the content of the auxiliary additive in the electrolyte is 0-1.0M.

[0130] Backup Then the above content provides an organic positive electrode additive and lithium ion battery. The positive electrode additive specially designed by the present invention with a specific structure and composition is an organic lithium salt lithium supplement material. The positive electrode lithium supplement contains a silyl group, which can be oxidized to form a film on the positive electrode surface before the electrolyte, thereby inhibiting the dissolution of metal ions, reducing the gas production rate, and improving the battery cycle stability. Secondly, the presence of the additive 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 replenisher reduces membrane impedance, polarization, lithium ion consumption and improves efficiency. Secondly, the additive contains Si-N bonds, and the breaking of Si-N bonds can remove H2O and HF, further improving the cycle stability of the electrode. Thirdly, the positive electrode lithium replenisher additive is insensitive to moisture and has excellent stability in the air, which can reduce the environmental requirements during the preparation of the positive electrode sheet. It is a highly potential positive electrode lithium replenisher.

[0131] The silyl phosphate amine additive provided by the present invention is used as a lithium supplement for the positive electrode of lithium ion batteries. From the perspective of performance, it can be oxidized to form a film on the positive electrode surface before the electrolyte, thereby inhibiting the dissolution of metal ions, reducing the gas production rate, and improving the cycle stability of the battery; and the presence of the additive can improve the morphology and composition of the CEI film, promote and participate in the component Li x PO y Fz The formation of a lithium supplement agent reduces membrane impedance, polarization, lithium ion consumption, and efficiency. At the same time, the additive contains Si-N bonds, and the breaking of Si-N bonds can remove H2O and HF, further improving the cycle stability of the electrode. Furthermore, the lithium supplement agent can also introduce corresponding groups as needed to match actual application needs, and is insensitive to moisture and oxygen, so the preparation of batteries using the lithium supplement agent does not require a special environment.

[0132] The positive electrode lithium supplement additive provided by the present invention has excellent comprehensive performance, has the advantages of low gas production, good stability, and long cycle life, and can also greatly improve the lithium ion conductivity, thereby reducing the gas production of lithium-ion batteries and improving the battery's stability, energy density and high-temperature storage performance.

[0133] Experimental results show that the lithium-ion battery positive electrode lithium replenisher provided by the present invention significantly improves the first efficiency, first cycle positive electrode gram capacity, internal resistance, capacity retention, high-temperature storage and gas production of the lithium-ion battery. The presence of the cyano functional group further increases the battery cycle life and reduces the gas production rate. The presence of the branched ether group and the F-generation group is beneficial to reducing the battery internal resistance. The silylamine phosphate lithium replenisher is more conducive to inhibiting gas production and improving the battery cycle life. In short, the additive of the present invention is an excellent positive electrode lithium replenisher.

[0134] To further illustrate the present invention, a positive electrode additive and a lithium-ion battery provided by the present invention are described in detail below in conjunction with examples. However, it should be understood that these examples are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating processes are provided only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention. The scope of protection of the present invention is not limited to the following examples.

[0135] Example 1

[0136] 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), acetylene black as a positive electrode conductive agent, and polyvinylidene fluoride as 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 coated on aluminum foil, dried, rolled, and cut into pieces to form a positive electrode sheet;

[0137] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, wherein the amorphous carbon coating is 3% by 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, and stirred evenly to prepare a negative electrode slurry. The negative electrode slurry is coated on copper foil, dried, rolled, and cut into pieces to form a negative electrode sheet;

[0138] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0139] Example 2

[0140] Preparation of positive electrode sheet: LiNi 0.6 Co 0.2 Mn 0.2 O2, the above-mentioned positive electrode lithium supplement material structure (2), positive electrode conductive agent carbon nanotubes, and 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 prepare positive electrode sheets;

[0141] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, where the amorphous carbon coating is 3% by 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. The negative electrode slurry is coated on copper foil, dried, rolled, and cut into pieces to form negative electrode sheets;

[0142] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0143] Example 3

[0144] Preparation of positive electrode sheet: LiNi 0.6 Co 0.2 Mn 0.2 O2, the above-mentioned positive electrode lithium supplement material structure (3), positive electrode conductive agent carbon nanotubes, and 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 prepare positive electrode sheets;

[0145] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, wherein the amorphous carbon coating is 5% by mass of SiO), graphite, acetylene black as a negative electrode conductive agent, and polyvinylidene fluoride as a negative electrode binder 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 a negative electrode slurry. The negative electrode slurry is coated on copper foil, dried, rolled, and cut into pieces to form a negative electrode sheet;

[0146] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0147] Example 4

[0148] Preparation of positive electrode sheet: LiNi 0.6 Co 0.2 Mn 0.2 O2, the above-mentioned positive electrode lithium supplement material structure (4), positive electrode conductive agent carbon nanotubes, and 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 prepare positive electrode sheets;

[0149] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, wherein the amorphous carbon coating is 5% by mass of SiO), graphite, acetylene black as a negative electrode conductive agent, and polyvinylidene fluoride as a negative electrode binder 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 a negative electrode slurry. The negative electrode slurry is coated on copper foil, dried, rolled, and cut into pieces to form a negative electrode sheet;

[0150] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0151] Example 5

[0152] Preparation of positive electrode sheet: LiNi 0.6 Co 0.2 Mn 0.2 O2, the above-mentioned positive electrode lithium supplement material structure (5), positive electrode conductive agent carbon nanotubes, and positive electrode binder polyvinylidene fluoride are mixed in a mass ratio of 94:4:2:2 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 prepare positive electrode sheets;

[0153] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, wherein the amorphous carbon coating is 5% by mass of SiO), graphite, acetylene black as a negative electrode conductive agent, and polyvinylidene fluoride as a negative electrode binder 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 a negative electrode slurry. The negative electrode slurry is coated on copper foil, dried, rolled, and cut into pieces to form a negative electrode sheet;

[0154] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0155] Example 6

[0156] Preparation of positive electrode sheet: LiNi 0.6 Co 0.2 Mn 0.2 O2, the above-mentioned positive electrode lithium supplement material structure (5), positive electrode conductive agent carbon nanotubes, and positive electrode binder polyvinylidene fluoride are mixed in a mass ratio of 88:8:2:2 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 prepare positive electrode sheets;

[0157] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, wherein the amorphous carbon coating is 5% by mass of SiO), graphite, acetylene black as a negative electrode conductive agent, and polyvinylidene fluoride as a negative electrode binder 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 a negative electrode slurry. The negative electrode slurry is coated on copper foil, dried, rolled, and cut into pieces to form a negative electrode sheet;

[0158] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0159] Example 7

[0160] Preparation of positive electrode sheet: LiNi 0.6 Co 0.2 Mn 0.2 O2, the above-mentioned positive electrode lithium supplement material structure (5), positive electrode conductive agent carbon nanotubes, and positive electrode binder polyvinylidene fluoride are mixed in a mass ratio of 95.8:0.2:2:2 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 prepare positive electrode sheets;

[0161] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, wherein the amorphous carbon coating is 5% by mass of SiO), graphite, acetylene black as a negative electrode conductive agent, and polyvinylidene fluoride as a negative electrode binder 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 a negative electrode slurry. The negative electrode slurry is coated on copper foil, dried, rolled, and cut into pieces to form a negative electrode sheet;

[0162] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0163] Example 8

[0164] Preparation of positive electrode sheet: LiNi 0.6 Co 0.2 Mn 0.2 O2, the above-mentioned positive electrode lithium supplement material structure (6), positive electrode conductive agent carbon nanotubes, and 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 prepare positive electrode sheets;

[0165] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, wherein the amorphous carbon coating is 5% by mass of SiO), graphite, acetylene black as a negative electrode conductive agent, and polyvinylidene fluoride as a negative electrode binder 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 a negative electrode slurry. The negative electrode slurry is coated on copper foil, dried, rolled, and cut into pieces to form a negative electrode sheet;

[0166] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0167] Example 9

[0168] Preparation of positive electrode sheet: LiNi 0.6 Co 0.2 Mn 0.2 O2, the above-mentioned positive electrode lithium supplement material structure (7), positive electrode conductive agent carbon nanotubes, and 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 prepare positive electrode sheets;

[0169] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, wherein the amorphous carbon coating is 5% by mass of SiO), graphite, acetylene black as a negative electrode conductive agent, and polyvinylidene fluoride as a negative electrode binder 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 a negative electrode slurry. The negative electrode slurry is coated on copper foil, dried, rolled, and cut into pieces to form a negative electrode sheet;

[0170] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0171] Example 10

[0172] Preparation of positive electrode sheet: LiNi 0.6 Co 0.2 Mn 0.2 O2, the above-mentioned positive electrode lithium supplement material structure (8), positive electrode conductive agent carbon nanotubes, and 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 prepare positive electrode sheets;

[0173] Preparation of negative electrode sheet: SiO@C (amorphous carbon-coated silicon oxide, wherein the amorphous carbon coating is 5% by mass of SiO), graphite, acetylene black as a negative electrode conductive agent, and polyvinylidene fluoride as a negative electrode binder 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 a negative electrode slurry. The negative electrode slurry is coated on copper foil, dried, rolled, and cut into pieces to form a negative electrode sheet;

[0174] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0175] Example 11

[0176] Preparation of positive electrode sheet: mixing the positive electrode active material LiCoO2, the positive electrode lithium supplement material structure (9), the positive electrode conductive agent acetylene black, and the positive electrode binder polyvinylidene fluoride in a mass ratio of 92:4:2:2, adding the mixture to NMP, stirring evenly to obtain positive electrode slurry, coating the positive electrode slurry on aluminum foil, drying, rolling, and cutting to obtain positive electrode sheet;

[0177] Preparation of negative electrode sheet: Graphite, negative electrode conductive agent carbon black, negative electrode binder sodium carboxymethyl cellulose and styrene-butadiene rubber were mixed in a mass ratio of 95:2:1.5:1.5, dissolved in deionized water and stirred evenly to prepare negative electrode slurry. The negative electrode slurry was coated on copper foil, dried, rolled and cut into pieces to make negative electrode sheets;

[0178] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0179] Example 12

[0180] Preparation of positive electrode sheet: mixing the positive electrode active material LiCoO2, the positive electrode lithium supplement material structure (10), the positive electrode conductive agent acetylene black, and the positive electrode binder polyvinylidene fluoride in a mass ratio of 92:4:2:2, adding the mixture to NMP, stirring evenly to prepare positive electrode slurry, coating the positive electrode slurry on aluminum foil, drying, rolling, and cutting to prepare positive electrode sheet;

[0181] Preparation of negative electrode sheet: Graphite, negative electrode conductive agent carbon black, negative electrode binder sodium carboxymethyl cellulose and styrene-butadiene rubber were mixed in a mass ratio of 95:2:1.5:1.5, dissolved in deionized water and stirred evenly to prepare negative electrode slurry. The negative electrode slurry was coated on copper foil, dried, rolled and cut into pieces to make negative electrode sheets;

[0182] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0183] Example 13

[0184] Preparation of positive electrode sheet: mixing the positive electrode active material LiCoO2, the positive electrode lithium supplement material structure (11), the positive electrode conductive agent acetylene black, and the positive electrode binder polyvinylidene fluoride in a mass ratio of 92:4:2:2, adding the mixture to NMP, stirring evenly to prepare positive electrode slurry, coating the positive electrode slurry on aluminum foil, drying, rolling, and cutting to prepare positive electrode sheet;

[0185] Preparation of negative electrode sheet: Graphite, negative electrode conductive agent carbon black, negative electrode binder sodium carboxymethyl cellulose and styrene-butadiene rubber were mixed in a mass ratio of 95:2:1.5:1.5, dissolved in deionized water and stirred evenly to prepare negative electrode slurry. The negative electrode slurry was coated on copper foil, dried, rolled and cut into pieces to make negative electrode sheets;

[0186] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0187] Example 14

[0188] Preparation of positive electrode sheet: mixing the positive electrode active material LiCoO2, the positive electrode lithium supplement material structure (12), the positive electrode conductive agent acetylene black, and the positive electrode binder polyvinylidene fluoride in a mass ratio of 92:4:2:2, adding the mixture to NMP, stirring evenly to prepare positive electrode slurry, coating the positive electrode slurry on aluminum foil, drying, rolling, and cutting to prepare positive electrode sheet;

[0189] Preparation of negative electrode sheet: Graphite, negative electrode conductive agent carbon black, negative electrode binder sodium carboxymethyl cellulose and styrene-butadiene rubber were mixed in a mass ratio of 95:2:1.5:1.5, dissolved in deionized water and stirred evenly to prepare negative electrode slurry. The negative electrode slurry was coated on copper foil, dried, rolled and cut into pieces to make negative electrode sheets;

[0190] The positive electrode sheet and the negative electrode sheet prepared above were assembled into a 2Ah soft-pack battery cell.

[0191] Comparative Example 1

[0192] Except that no lithium supplement agent is added to the positive terminal, the other steps are the same as those in Example 1.

[0193] Comparative Example 2

[0194] Except that no lithium supplement agent is added to the positive terminal, the rest is consistent with Example 12.

[0195] Comparative Example 3

[0196] The positive terminal is added with a silane amine-based lithium supplement containing no phosphate, and its structure is as follows:

[0197]

[0198] Other details are the same as those in Example 1.

[0199] Since lithium supplements are insensitive to moisture and oxygen, the above experiments do not require special control of the electrode preparation environment.

[0200] The preparation method of the battery is as follows:

[0201] The coating surface density is determined according to the battery capacity design (2000mAh) and the capacity of the positive and negative electrode materials.

[0202] Electrolyte composition: 1M LiPF6, 1% VC, 2% FEC, inEC:EMC=3:7.

[0203] 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 a square battery cell, the bare battery cell is placed in the outer packaging, and the above-prepared electrolyte is injected into the dried battery. The preparation of the lithium-ion battery is completed through the steps of packaging, standing, formation, shaping, and capacity division.

[0204] In order to verify the performance of the product of the present application, the performance tests were carried out on the 2Ah soft-pack batteries prepared in Examples 1 to 14 and Comparative Examples 1 to 3. The specific methods are as follows, and the results are shown in Table 1.

[0205] 1) Battery cell first-cycle test: battery cell first-cycle discharge capacity / battery cell first-cycle charge capacity.

[0206] 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 is mAh / mass of positive electrode active material in g.

[0207] 3) Cell DC internal resistance (DCR) test: The battery capacity is divided and adjusted to 50% SOC, and discharged at 5C for 10 seconds. The discharge resistance is measured: resistance DCR = (V0-V10) / I, where V0 is the potential before discharge, V10 is the potential after 10 seconds of discharge, and I is the discharge current 2C.

[0208] 4) 45°C Capacity Retention Test: ① Charge: 1C constant current and constant voltage charge to 4.2V, let stand for 10 minutes; ② Discharge: 1C constant current discharge to 2.8V; ③ Repeat "①, ②" 500 times.

[0209] After 500 cycles of charge and discharge, the capacity retention rate of the 500th cycle is calculated using the following formula:

[0210] 500th cycle capacity retention rate (%)=(500th cycle discharge capacity / 1st cycle discharge capacity)×100%.

[0211] In the lithium cobalt oxide system, that is, the upper limit of the voltage cycle range of Examples 12-14 and Comparative Example 2 was changed to 4.4 V, while the others remained unchanged.

[0212] 5) High temperature storage test

[0213] The capacity of the battery cell is divided into 1C at room temperature of 25℃, and the obtained capacity is recorded as D0;

[0214] Fully charge the battery cell at 1C, then place it in a 60℃ oven for 20 days. Then take it out and test the recovered capacity after cooling to room temperature. This is recorded as D1. The recovery rate of the battery cell's high temperature storage capacity is calculated as: D1 / D0

[0215] 6) High temperature gas production test

[0216] 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 growth rate of high-temperature gas production volume is V1 / V0-1.

[0217] See Table 1, which shows the performance test data of batteries prepared in Examples of the present invention and Comparative Examples.

[0218] Table 1

[0219]

[0220]

[0221] As can be seen from Table 1, compared with Comparative Example 1-2, the first efficiency, first cycle positive electrode gram capacity, internal resistance, capacity retention, high temperature storage and gas production of the 2Ah soft-pack battery cells prepared in Examples 1-14 are significantly improved.

[0222] Comparison of Example 1, Example 2, and Example 3 shows that the presence of cyano functionality further increases the battery cycle life and reduces the gas production rate;

[0223] Comparison between Example 1 and Example 5 shows that the higher the lithium content in the positive electrode lithium replenishment additive, the more lithium can be provided during the positive electrode lithium replenishment process, the better the lithium replenishment effect, the higher the first effect / the better the positive electrode specific capacity.

[0224] Comparison of Example 5, Example 6 and Example 7 shows that when the amount of positive electrode lithium replenisher added is too small, the lithium replenishment effect cannot be achieved. When the amount added is too much, although the initial effect and capacity are better, the cycle performance, high temperature storage and gas production inhibition performance are reduced.

[0225] Comparison of Example 1 with Example 4, Example 8, Example 9 and Example 10 shows that the presence of the branched ether group and the F-generation group is beneficial to reducing the internal resistance of the battery.

[0226] Comparison of Example 1 with Comparative Example 3 shows that the silylamine phosphate lithium supplement is more conducive to inhibiting gas production and improving the cycle life of the battery.

[0227] See also Figure 3 , Figure 3 This is a comparison curve of the capacity retention rate after 500 cycles in the performance test of Example 1 of the present invention and Comparative Example 1.

[0228] See also Figure 4 , Figure 4 It is a box plot of the gas production of Example 1, Example 2, Example 3 and Comparative Example 1 of the present invention.

[0229] In summary, the organic cathode lithium replenishing material of the present invention has a good lithium replenishing effect, can effectively inhibit gas production, reduce internal resistance, and improve high-temperature cycle life.

[0230] The above is a detailed introduction to an organic positive electrode additive and lithium-ion battery provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only intended to help understand the method and core concept of the present invention, including the best mode, and also to enable any person skilled in the art 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 noted that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, 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 conceived by those skilled in the art. If these other embodiments have structural elements similar to the literal description of the claims, or if they include equivalent structural elements that are not substantially different from the literal description of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A positive electrode additive, characterized in that The positive electrode additive is an organic lithium salt lithium supplement material having a structure as shown in formula (I): The R1 and R2 are each independently selected from a lithium ion, a C1-C6 saturated hydrocarbon group, a C1-C6 unsaturated hydrocarbon group, an alkoxy group, a cyanoalkyl group, a substituted cyanoalkyl group, a haloalkyl group, a phenyl group, an ether group or a silane group.

2. The positive electrode additive according to claim 1, characterized in that At least one of R1 and R2 is selected from a C1-C6 saturated hydrocarbon group, a C1-C6 unsaturated hydrocarbon group, an alkoxy group, a cyanoalkyl group, a substituted cyanoalkyl group, a haloalkyl group, a phenyl group, an ether group or a silane group; The positive electrode additive is a silane amine phosphate additive; The positive electrode comprises a lithium ion battery positive electrode.

3. The positive electrode additive according to claim 1, characterized in that The positive electrode additive has a structure as shown in any one of formulas (1) to (12):

4. The positive electrode additive according to claim 1, characterized in that The positive electrode additive is a positive electrode lithium supplement additive; The mass ratio of the positive electrode active material to the positive electrode additive is (75-97.5): (0.1-10); The positive electrode additive is a positive electrode additive that improves the morphology and / or composition of the CEI film; The positive electrode additive promotes and participates in the component Li x PO y F z formation.

5. A lithium-ion battery, characterized in that: including positive electrode, negative electrode and electrolyte; The positive electrode comprises the positive electrode 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 manganese oxide, lithium iron phosphate and nickel cobalt lithium manganese oxide ternary positive electrode materials; 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, the positive electrode additive, the positive electrode active material, the positive electrode conductive agent, the positive electrode binder and the solvent are uniformly mixed, and then coated, rolled and dried to obtain the positive electrode sheet.

7. The lithium-ion battery according to claim 6, characterized in that The positive electrode comprises the positive electrode additive, the positive electrode active material, the positive electrode conductive agent and the positive electrode binder as a whole, and the mass content of the positive electrode active material is 75% to 97.5%; The positive electrode comprises the positive electrode additive, the positive electrode active material, the positive electrode conductive agent and the positive electrode binder as a whole, 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 positive electrode additive, positive electrode active material, positive electrode conductive agent and 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 positive electrode additive, the positive electrode active material, the positive electrode conductive agent and the positive electrode binder, and the mass content of the positive electrode additive is 0.1% to 10%.

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 lithium bis(fluorosulfonyl)imide; 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 content of the second auxiliary additive in the electrolyte is 0.001-1.0M.

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