Lithium ion battery and electric device

Abstract

The invention relates to a lithium ion battery and an electric device. The lithium ion battery comprises a positive pole piece and an electrolyte, the positive pole piece comprises a positive current collector and a positive film layer arranged on at least one side of the surface of the positive current collector, the positive film layer and / or the electrolyte comprise / comprises an additive, the additive comprises humic acid, the positive film layer further comprises a positive active material, and the positive active material comprises a negative active material. And the positive active material comprises a manganese element. According to the lithium ion battery provided by the invention, the humic acid is added into the positive electrode film layer and / or the electrolyte, the positive electrode active material of the positive electrode film layer comprises the manganese element, and the complexing ability of functional groups such as hydroxyl and carboxyl on the surface of the humic acid to manganese ions is greater than the complexing ability to lithium ions, so that the humic acid is preferentially subjected to a complexing reaction with the manganese ions; therefore, the manganese ions are prevented from being dissolved out and migrated to the negative electrode side to damage the SEI membrane.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, in particular to a lithium ion battery and an electrical device. Background Art

[0002] Lithium-ion batteries are widely used in mobile phones, computers, electric vehicles and other fields due to their advantages such as high energy density, wide operating temperature range, long cycle life and fast charging and discharging.

[0003] Manganese-based materials such as lithium iron manganese phosphate, lithium manganese oxide and lithium nickel manganese oxide have the advantages of being environmentally friendly, low price, good rate performance, long cycle life and good safety performance, and are often used as positive electrode materials for lithium-ion batteries.

[0004] However, during the cycle of manganese-based positive electrode materials, especially under high temperature and high voltage environments, manganese ions are easily dissolved and migrated to the negative electrode side, destroying the SEI film. At the same time, a large amount of active lithium ions are consumed, leading to problems such as capacity decay and gas production. Summary of the invention

[0005] Based on this, it is necessary to provide a lithium-ion battery and an electrical device to inhibit the dissolution of manganese ions, reduce the capacity decay of the battery, and reduce the gas production problem.

[0006] The first aspect of the present application provides a lithium-ion battery, which includes a positive electrode plate and an electrolyte, the positive electrode plate includes a positive electrode collector and a positive electrode film layer provided on at least one side of the surface of the positive electrode collector, the positive electrode film layer and / or the electrolyte includes an additive, the additive includes humic acid, the positive electrode film layer also includes a positive electrode active substance, and the positive electrode active substance includes manganese.

[0007] In some embodiments, the positive electrode film layer includes a positive electrode active layer and a functional layer, the positive electrode active layer is arranged on the surface of the positive electrode current collector, the functional layer is arranged on the surface of the positive electrode active layer, the positive electrode active layer includes a positive electrode active material, and the functional layer includes an additive.

[0008] In some embodiments, the functional layer further includes one or more of porous carbon, a solid electrolyte, and aluminum oxide.

[0009] In some embodiments, the functional layer further comprises porous carbon, and the mass ratio of the porous carbon to humic acid is (1-5):(3-10).

[0010] In some embodiments, the functional layer further comprises a solid electrolyte, and the mass ratio of the solid electrolyte to humic acid is (1-5):(3-10).

[0011] In some embodiments, the solid electrolyte includes one or more of a polymer solid electrolyte, an oxide solid electrolyte, a sulfide solid electrolyte, and a halide solid electrolyte.

[0012] In some embodiments, the thickness of the functional layer is 2 μm to 13 μm.

[0013] In some embodiments, the electrolyte includes an additive, and the mass percentage of humic acid in the electrolyte is 0.5% to 1%.

[0014] In some embodiments, the positive electrode film layer is a single layer, and the mass percentage of humic acid in the positive electrode film layer is 0.5% to 1%.

[0015] In some embodiments, the positive electrode active material includes one or more of lithium iron manganese phosphate, lithium manganese oxide, and lithium nickel manganese oxide.

[0016] A second aspect of the present application provides an electrical device, which includes the lithium-ion battery provided by the first aspect.

[0017] Compared with the traditional technology, this application has at least the following beneficial effects:

[0018] The lithium-ion battery provided by the present application is provided by adding additives to the positive electrode film layer and / or the electrolyte, wherein the additives include humic acid, and the positive electrode active material of the positive electrode film layer also includes manganese element. The hydroxyl group, carboxyl group and other functional groups on the surface of the humic acid have a greater complexing ability for manganese ions than for lithium ions. Therefore, the humic acid preferentially reacts with the manganese ions to fix the manganese ions, thereby preventing the manganese ions from dissolving and migrating to the negative electrode side to destroy the SEI film. In addition, even if a small amount of lithium ions react with the humic acid to form a humic acid-lithium ion complex, the lithium ions can enter and exit the complex during the charge and discharge process, thereby performing ion exchange, and the addition of the humic acid additive will not affect the transmission of lithium ions. Therefore, the use of humic acid as an additive will not affect the transmission of lithium ions while adsorbing the manganese ions dissolved from the positive electrode. On the basis of not increasing the internal resistance, the integrity of the SEI film is protected, the consumption of active lithium ions is reduced, the capacity decay of the lithium ion battery is reduced, and the gas production problem is reduced. DETAILED DESCRIPTION

[0019] References to embodiments of the present application will now be provided in detail, one or more examples of which are described below. Each example is provided as an explanation rather than a limitation of the present application. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the present application without departing from the scope or spirit of the present application. For example, a feature described or described as part of one embodiment may be used in another embodiment to produce a further embodiment.

[0020] Therefore, it is intended that the present application covers such modifications and variations that fall within the scope of the appended claims and their equivalents. Other objects, features and aspects of the present application are disclosed in or are apparent from the following detailed description. It will be appreciated by those of ordinary skill in the art that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of the present application.

[0021] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0022] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0023] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0024] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0025] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, a method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, a method may also include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0026] If there is no special explanation, the "include" and "comprising" mentioned in this application represent open-ended or closed-ended expressions. For example, "include" and "comprising" may represent that other components not listed may also be included or only listed components may be included or only listed components may be included.

[0027] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0028] The first aspect of the present application provides a lithium-ion battery, which includes a positive electrode plate and an electrolyte, the positive electrode plate includes a positive electrode collector and a positive electrode film layer provided on at least one side of the surface of the positive electrode collector, the positive electrode film layer and / or the electrolyte includes an additive, the additive includes humic acid, the positive electrode film layer also includes a positive electrode active substance, and the positive electrode active substance includes manganese.

[0029] The lithium-ion battery provided by the present application is provided by adding additives to the positive electrode film layer and / or the electrolyte, wherein the additives include humic acid, and the positive electrode active material of the positive electrode film layer also includes manganese element. The hydroxyl group, carboxyl group and other functional groups on the surface of the humic acid have a greater complexing ability for manganese ions than for lithium ions. Therefore, the humic acid preferentially reacts with the manganese ions to fix the manganese ions, thereby preventing the manganese ions from dissolving and migrating to the negative electrode side to destroy the SEI film. In addition, even if a small amount of lithium ions react with the humic acid to form a humic acid-lithium ion complex, the lithium ions can enter and exit the complex during the charge and discharge process, thereby performing ion exchange, and the addition of the humic acid additive will not affect the transmission of lithium ions. Therefore, the use of humic acid as an additive will not affect the transmission of lithium ions while adsorbing the manganese ions dissolved from the positive electrode. On the basis of not increasing the internal resistance, the integrity of the SEI film is protected, the consumption of active lithium ions is reduced, the capacity decay of the lithium ion battery is reduced, and the gas production problem is reduced.

[0030] Humic acid is a mixture of aromatic amorphous polymer compounds rich in oxygen-containing functional groups such as carboxyl, phenolic hydroxyl, and methoxyl groups, which are formed by the decomposition and transformation of animal and plant residues, mainly plant residues, as well as a series of geophysical and chemical interactions. Humic acid has a wide range of sources, abundant reserves in nature, is green and environmentally friendly, and can reduce battery costs, reduce battery internal resistance, and improve battery cycle capacity and cycle stability.

[0031] The present application has no particular restrictions on the positive electrode collector, as long as it has conductivity without causing chemical changes in the battery. Specifically, copper, stainless steel, aluminum, nickel, titanium, or a metal collector with a surface treated with carbon or other substances can be used. The positive electrode collector can generally have a thickness of 3μm to 500μm. The positive electrode collector may have fine concave-convex formed on its surface to improve the adhesion of the positive electrode active material. For example, positive electrode collectors in various shapes such as films, sheets, foils, nets, porous bodies, foams, and non-woven fabrics can be used.

[0032] In addition to the positive electrode active material, the positive electrode film layer may further include a positive electrode binder and / or a positive electrode conductive material.

[0033] The positive electrode binder is used to bind the components such as active materials, conductive materials and current collectors together, and specifically, it can include at least one selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, styrene-butadiene rubber and fluororubber, preferably polyvinylidene fluoride. The amount of the positive electrode binder contained in the positive electrode film layer can be 1wt% to 20wt%, preferably 1.2wt% to 10wt%.

[0034] The positive electrode conductive material is mainly used to assist and improve the conductivity in the secondary battery, and there is no particular limitation as long as it has conductivity without causing chemical changes. Specifically, the conductive material may include graphite, such as natural graphite or artificial graphite; carbon materials, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black and thermal black; conductive fibers, such as carbon fibers and metal fibers; conductive tubes, such as carbon nanotubes; metal powders, such as fluorocarbon powders, aluminum powders and nickel powders; conductive whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxide; and polyphenylene derivatives, and from the aspect of improving conductivity, carbon black may be preferably included. The specific surface area of ​​the positive electrode conductive material may be 80m 2 / g~200m 2 / g, preferably 100m 2 / g~150m 2 The amount of the positive electrode conductive material contained in the positive electrode active material layer may be 1 wt% to 20 wt%, preferably 1.2 wt% to 10 wt%.

[0035] The thickness of the positive electrode film layer may be 30 μm to 400 μm, preferably 50 μm to 110 μm.

[0036] The positive electrode sheet may be manufactured by coating a positive electrode slurry containing the above-mentioned materials with a solvent on a positive electrode collector, followed by drying and roll-pressing.

[0037] The positive electrode slurry forming solvent may include an organic solvent, such as N-methyl-2-pyrrolidone (NMP), and may be used in an amount such that a preferred viscosity is obtained when the positive electrode active material is included and a positive electrode binder, a positive electrode conductive material, etc. are selectively included. For example, the amount of the positive electrode slurry forming solvent included in the positive electrode slurry may be such that the concentration of the solid containing the positive electrode active material, and selectively containing the positive electrode binder and the positive electrode conductive material is 50 wt % to 95 wt %, preferably 70 wt % to 90 wt %.

[0038] In some embodiments, the positive electrode film layer includes a positive electrode active layer and a functional layer, the positive electrode active layer is arranged on the surface of the positive electrode current collector, the functional layer is arranged on the surface of the positive electrode active layer, the positive electrode active layer includes a positive electrode active material, and the functional layer includes an additive.

[0039] The functional layer is arranged on the surface of the positive electrode active layer, and the manganese ions dissolved from the positive electrode can fully contact and complex with humic acid, thereby improving the adsorption adequacy of manganese ions. In addition, humic acid itself has good bonding properties, which can reduce the amount of binder added or eliminate the need for a binder.

[0040] In some embodiments, the functional layer further includes one or more of porous carbon, a solid electrolyte and aluminum oxide.

[0041] The functional layer includes porous carbon and humic acid, and has good electronic conductivity, ionic conductivity and manganese ion adsorption.

[0042] The functional layer includes a solid electrolyte and humic acid, and has both good ion conductivity and manganese ion adsorption.

[0043] In some embodiments, the functional layer further comprises porous carbon, and the mass ratio of porous carbon to humic acid is (1-5):(3-10), including but not limited to 1:3, 1:6, 1:10, 2:6, 2:10, 3:7, 3:10, 4:6, 4:10, 5:6, 5:10. Further, the mass ratio of porous carbon to additive is 3:7.

[0044] In some embodiments, the functional layer further comprises a solid electrolyte, and the mass ratio of the solid electrolyte to the humic acid is (1-5):(3-10), including but not limited to 1:3, 1:6, 1:10, 2:6, 2:10, 3:6, 3:10, 4:6, 4:10, 5:6, 5:10. Further, the mass ratio of the solid electrolyte to the additive is 3:7.

[0045] In some embodiments, the solid electrolyte includes one or more of a polymer solid electrolyte, an oxide solid electrolyte, a sulfide solid electrolyte, and a halide solid electrolyte.

[0046] In some embodiments, the polymer solid electrolyte includes, but is not limited to, one or more of polytetrafluoroethylene and polyvinylidene fluoride doped with lithium salt.

[0047] In some embodiments, the oxide solid electrolyte includes, but is not limited to, one or more of doped or undoped lithium lanthanum zirconium oxide, doped or undoped lithium lanthanum titanium oxide, doped or undoped lithium aluminum titanium phosphate, and doped or undoped lithium aluminum germanium phosphate.

[0048] In some embodiments, the sulfide solid electrolyte is selected from one or more sulfide-based materials of the following: Li2S-P2S5, Li2S-P2S5-MS X (where M is Si, Ge and Sn and 0≤x≤2), Li 3.4 Si 0.4 P 0.6 S4, Li 10 GeP2s 11.700.3 , Li 9.6 P3S 12 、Li7P3S 11 、Li9P3S9O3、Li 10.35 Si 1.35 P 1.65 S 12 , Li 9.81 Sn 0.81 P 2.19 S 12 , Li 10 (Si 0.5 Ge 0.5 )P2S 12 、Li(Ge 0.5 Sn 0.5 )P2S 12 、Li(Si 0.5 Sn 0.5 )PsS 12 , Li 10 GeP2S 12 (LGPS), Li6PS5X (where X is Cl, Br or I), Li7P2S8I, Li 10.35 Ge 1.35 P 1.65 S 12 , Li 3.25 Ge 0.25 P 0.75 S4, Li 10 SnP2S 12 , Li 10 SiP2S 12 , Li 9.54 Si 1.74 P 1.44 S11.7 CI 0.3 、(1-x)P2S 5-x Li2S (where 0.5 ≤ x ≤ 0.7) and their combinations.

[0049] In some embodiments, the halide solid electrolyte includes, but is not limited to, Li2CdC l4 、Li2MgC l4 、Li2Cd I4 、Li2ZnI4, Li3OCl, LiI, Li5ZnI4, Li3OCl 1-x Br x (where 0 < x < 1) one or more halide-based materials.

[0050] In some embodiments, the thickness of the functional layer is 2 μm to 13 μm, including but not limited to 2 μm, 4 μm, 6 μm, 8 μm, 10 μm, 13 μm. Within the above thickness range, while ensuring the ion transport efficiency, the occurrence of side reactions is reduced, the dissolution and migration of the positive electrode active material are inhibited, the integrity of the SEI film is protected, gas generation is reduced, and the safety of the battery is improved.

[0051] In some embodiments, the electrolyte includes an additive, and the mass percentage of humic acid in the electrolyte is 0.5% to 1%, including but not limited to 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%. Within the above mass percentage range, while inhibiting the dissolution and migration of the positive electrode active material, the battery capacity is ensured.

[0052] In some embodiments, the electrolyte further includes a lithium salt and a solvent.

[0053] It can be understood that this application has no special requirements for the types of solvents and lithium salts. Based on the inventive concept of this application, any known solvents and lithium salts can be used in this application.

[0054] Merely as an illustrative example and not a limitation of the scope of protection, the solvent is various alkyl carbonates, such as cyclic carbonates (e.g., ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), fluoroethylene carbonate (FEC)), linear carbonates (e.g., dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC)), aliphatic carboxylates (e.g., methyl formate, methyl acetate, methyl propionate), γ-lactones (e.g., γ-butyrolactone, γ-valerolactone), chain structure ethers (e.g., 1,2-dimethoxyethane (DME), 1-2-diethoxyethane, ethoxymethoxyethane), cyclic ethers (e.g., tetrahydrofuran, 2-methyltetrahydrofuran), 1,3-dioxolane (DOL), sulfur compounds (e.g., cyclopentane) and combinations thereof.

[0055] As an illustrative example only, and not a limitation of the scope of protection, the lithium salt is lithium hexafluorophosphate (LiPF6); lithium perchlorate (LiClO4), lithium tetrachloroaluminate (LiAlCl4), lithium iodide (LiI), lithium bromide (LiBr), lithium thiocyanate (LiSCN), lithium tetrafluoroborate (LiBF4), lithium difluorooxalatoborate (LiBF2(C2O4))(LiODFB), lithium tetraphenylborate (LiB(C6H5)4), bis(oxalate) Lithium borate (LiB(C2O4)2) (LiBOB), lithium tetrafluorooxalophosphate (LiPF4(C2O4)) (LiFOP), lithium nitrate (LiNO3), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethanesulfonyl imide) (LITFSI) (LiN(CF3SO2)2), lithium bis(fluorosulfonyl imide) (LiN(FSO2)2) (LIFSI) and combinations thereof. In certain particularly preferred embodiments, the lithium salt is selected from lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl imide) (LiTFSI) (LiN(CF3SO2)2), lithium bis(fluorosulfonyl imide) (LiN(FSO2)2) (LiFSI), lithium fluoroalkyl phosphonate (LiFAP), lithium phosphate (Li3PO4) and combinations thereof.

[0056] In some embodiments, the positive electrode film layer is a single layer, and the mass percentage of humic acid in the positive electrode film layer is 0.5% to 1%, including but not limited to 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, and 1%. Within the above mass percentage range, the dissolution and migration of the positive electrode active material are suppressed while ensuring the battery capacity.

[0057] In some embodiments, the positive electrode active material includes one or more of lithium iron manganese phosphate, lithium manganese oxide, and lithium nickel manganese oxide.

[0058] In some embodiments, the lithium-ion battery further includes a negative electrode sheet.

[0059] The present application does not specifically limit the negative electrode sheet. As an illustrative example, the negative electrode sheet includes a negative electrode active material. In some embodiments, the negative electrode sheet may include a plurality of negative electrode active materials. Such negative electrode active materials may be arranged in one or more layered structures. In some variations, the negative electrode sheet may also include an electrolyte.

[0060] The negative electrode active material can be a lithium-based negative electrode active material, which contains, for example, lithium metal and / or a lithium alloy. In other embodiments, the negative electrode is a silicon-based negative electrode active material, which contains silicon, such as a silicon alloy, silicon oxide, or a combination thereof, which may also be mixed with graphite in some cases. In other embodiments, the negative electrode may include a carbonaceous-based negative electrode active material, which contains one or more of graphite, graphene, carbon nanotubes (CNTs), and combinations thereof. In yet another embodiment, the negative electrode includes one or more negative electrode active materials that accept lithium, such as lithium titanium oxide (Li4Ti5O 12 ), one or more transition metals (e.g., tin (Sn)), one or more metal oxides (e.g., vanadium oxide (V2O5), tin oxide (SnO), titanium dioxide (TiO2)), titanium niobium oxide (Ti x Nb y O z , where 0≤x≤2, 0≤y≤24 and 0≤z≤64), a metal alloy such as copper tin alloy (Cu6Sn5) and one or more metal sulfides such as iron sulfide (FeS).

[0061] Optionally, the negative electrode active material in the negative electrode sheet may be doped with one or more negative electrode conductors providing an electronic conduction path and / or at least one polymer negative electrode binder material that improves the structural integrity of the negative electrode sheet. For example, optionally, the negative electrode active material may be doped with a negative electrode binder such as poly (tetrafluoroethylene) (PTFE), sodium carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile rubber (NBR), styrene ethylene butylene styrene copolymer (SEBS), styrene butadiene styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, and combinations thereof. The negative electrode conductor may include carbon-based materials, powdered nickel or other metal particles or conductive polymers. Carbon-based materials may include particles such as carbon black, graphite, superP, acetylene black (such as, KETCHENTM black or DENKATM black), carbon fibers and nanotubes, graphene, and the like. Examples of the conductive polymer include polyaniline, polythiophene, polyacetylene, polypyrrole, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate, and the like.

[0062] The negative electrode sheet may include 50 wt % to 97 wt % of a negative electrode active material, optionally 0 wt % to 60 wt % of a solid electrolyte, optionally 0 wt % to 15 wt % of a negative electrode conductor, and optionally 0 wt % to 10 wt % of a negative electrode binder.

[0063] A second aspect of the present application provides an electrical device, which includes the lithium-ion battery provided by the first aspect.

[0064] The electric device of the present application includes the lithium-ion battery provided by the present application, and thus has at least the same advantages as the lithium-ion battery.

[0065] Lithium-ion batteries can be used as power sources for electrical devices or as energy storage units for electrical devices. Electrical devices may include mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto. Among them, mobile devices may be, for example, mobile phones, laptop computers, etc.; electric vehicles may be, for example, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc., but are not limited thereto. The present application will be further described below in conjunction with specific embodiments and comparative examples.

[0066] Example 1

[0067] This embodiment provides a lithium-ion battery, comprising:

[0068] Positive electrode sheet: The positive electrode sheet includes a positive current collector aluminum foil and a positive electrode film layer provided on at least one side of the positive current collector surface, the positive electrode film layer includes 96wt% of positive electrode active material lithium manganese iron phosphate, 2wt% of positive electrode conductive agent super-P and 2wt% of positive electrode binder PVDF.

[0069] Electrolyte: The electrolyte includes 13 wt % of lithium salt LiPF6, 86.3 wt % of solvent (mass ratio EC:DEC=3:7) and 0.7 wt % of additive humic acid.

[0070] Negative electrode sheet: The negative electrode sheet includes a negative electrode collector copper foil and a negative electrode film layer provided on at least one side of the surface of the negative electrode collector, and the negative electrode film layer includes 95wt% of negative electrode active material graphite, 2wt% of negative electrode conductive agent conductive carbon black and 3wt% of negative electrode binder (mixed binder of CMC and SBR).

[0071] Example 2

[0072] The lithium ion battery provided in this embodiment is substantially the same as that in embodiment 1, except that:

[0073] The mass percentage of the additive humic acid in the electrolyte is 0.5%.

[0074] Example 3

[0075] The lithium ion battery provided in this embodiment is substantially the same as that in embodiment 1, except that:

[0076] The mass percentage of the additive humic acid in the electrolyte is 1%.

[0077] Example 4

[0078] The lithium ion battery provided in this embodiment is substantially the same as that in embodiment 1, except that:

[0079] The mass percentage of the additive humic acid in the electrolyte is 2%.

[0080] Example 5

[0081] This embodiment provides a lithium-ion battery, comprising:

[0082] Positive electrode sheet: The positive electrode sheet includes a positive electrode collector aluminum foil and a positive electrode film layer provided on at least one side of the surface of the positive electrode collector, and the positive electrode film layer includes 95.3wt% of positive electrode active material lithium manganese iron phosphate, 0.7wt% of additive humic acid, 2wt% of positive electrode conductive agent super-P and 2wt% of positive electrode binder PVDF.

[0083] Electrolyte: The electrolyte includes 13 wt % of lithium salt LiPF6 and 87 wt % of solvent (mass ratio EC:DEC=3:7).

[0084] Negative electrode sheet: The negative electrode sheet includes a negative electrode collector copper foil and a negative electrode film layer provided on at least one side of the surface of the negative electrode collector, and the negative electrode film layer includes 95wt% of negative electrode active material graphite, 2wt% of negative electrode conductive agent conductive carbon black and 3wt% of negative electrode binder (mixed binder of CMC and SBR).

[0085] Example 6

[0086] The lithium ion battery provided in this embodiment is substantially the same as that in embodiment 5, except that:

[0087] The mass percentage of the additive humic acid in the positive electrode film layer is 0.5%.

[0088] Example 7

[0089] The lithium ion battery provided in this embodiment is substantially the same as that in embodiment 5, except that:

[0090] The mass percentage of the additive humic acid in the positive electrode film layer is 1%.

[0091] Example 8

[0092] The lithium ion battery provided in this embodiment is substantially the same as that in embodiment 5, except that:

[0093] The mass percentage of the additive humic acid in the positive electrode film layer is 2%.

[0094] Example 9

[0095] This embodiment provides a lithium-ion battery, comprising:

[0096] Positive electrode sheet: The positive electrode sheet includes a positive current collector aluminum foil and a positive electrode film layer disposed on at least one side of the positive current collector surface. The positive electrode film layer includes a positive electrode active layer and a functional layer. The positive electrode active layer includes 96wt% of positive electrode active material lithium manganese iron phosphate, 2wt% of positive electrode conductive agent super-P and 2wt% of positive electrode binder PVDF. The functional layer includes a solid electrolyte lithium lanthanum zirconium oxide with a mass ratio of 30:70:2, an additive humic acid and a positive electrode binder PVDF, and the thickness of the functional layer is 7.5μm.

[0097] Electrolyte: The electrolyte includes 13 wt % of lithium salt LiPF6 and 87 wt % of solvent (mass ratio EC:DEC=3:7).

[0098] Negative electrode sheet: The negative electrode sheet includes a negative electrode collector copper foil and a negative electrode film layer provided on at least one side of the surface of the negative electrode collector, and the negative electrode film layer includes 95wt% of negative electrode active material graphite, 2wt% of negative electrode conductive agent conductive carbon black and 3wt% of negative electrode binder (mixed binder of CMC and SBR).

[0099] Example 10

[0100] The lithium ion battery provided in this embodiment is substantially the same as that in embodiment 9, except that:

[0101] The mass ratio of the solid electrolyte lithium lanthanum zirconium oxygen and the additive humic acid is 1:10, and the thickness of the functional layer is 2μm.

[0102] Embodiment 11

[0103] The lithium ion battery provided in this embodiment is substantially the same as that in embodiment 9, except that:

[0104] The mass ratio of the solid electrolyte lithium lanthanum zirconium oxide and the additive humic acid is 5:3, and the thickness of the functional layer is 13μm.

[0105] Example 12

[0106] This embodiment provides a lithium-ion battery, comprising:

[0107] Positive electrode sheet: The positive electrode sheet includes a positive current collector aluminum foil and a positive electrode film layer disposed on at least one side of the positive current collector surface. The positive electrode film layer includes a positive electrode active layer and a functional layer. The positive electrode active layer includes 96wt% of positive electrode active material lithium manganese iron phosphate, 2wt% of positive electrode conductive agent super-P and 2wt% of positive electrode binder PVDF. The functional layer includes mesoporous porous carbon, additive humic acid and positive electrode binder PVDF in a mass ratio of 30:70:2, and the thickness of the functional layer is 7.5μm.

[0108] Electrolyte: The electrolyte includes 13 wt % of lithium salt LiPF6 and 87 wt % of solvent (mass ratio EC:DEC=3:7).

[0109] Negative electrode sheet: The negative electrode sheet includes a negative electrode collector copper foil and a negative electrode film layer provided on at least one side of the surface of the negative electrode collector, and the negative electrode film layer includes 95wt% of negative electrode active material graphite, 2wt% of negative electrode conductive agent conductive carbon black and 3wt% of negative electrode binder (mixed binder of CMC and SBR).

[0110] Example 13

[0111] The lithium ion battery provided in this embodiment is substantially the same as that in embodiment 12, except that:

[0112] The mass ratio of mesoporous carbon to additive humic acid is 1:10, and the thickness of the functional layer is 2 μm.

[0113] Embodiment 14

[0114] The lithium ion battery provided in this embodiment is substantially the same as that in embodiment 12, except that:

[0115] The mass ratio of mesoporous carbon and additive humic acid is 5:3, and the thickness of the functional layer is 13 μm.

[0116] Comparative Example 1

[0117] This embodiment provides a lithium-ion battery, comprising:

[0118] Positive electrode sheet: The positive electrode sheet includes a positive current collector aluminum foil and a positive electrode film layer provided on at least one side of the positive current collector surface, the positive electrode film layer includes 96wt% of positive electrode active material lithium manganese iron phosphate, 2wt% of positive electrode conductive agent super-P and 2wt% of positive electrode binder PVDF.

[0119] Electrolyte: The electrolyte includes 13 wt % of lithium salt LiPF6 and 87 wt % of solvent (mass ratio EC:DEC=3:7).

[0120] Negative electrode sheet: The negative electrode sheet includes a negative electrode collector copper foil and a negative electrode film layer provided on at least one side of the surface of the negative electrode collector, and the negative electrode film layer includes 95wt% of negative electrode active material graphite, 2wt% of negative electrode conductive agent conductive carbon black and 3wt% of negative electrode binder (mixed binder of CMC and SBR).

[0121] Performance Testing

[0122] 1. Cycle life test

[0123] (1) Charge at 1C to the final voltage, cut-off current 0.05C, and let stand for 30 minutes;

[0124] (2) Discharge at 1C to the final discharge voltage, record the discharge capacity, and let stand for 30 minutes;

[0125] Steps (1) to (2) were repeated to test the cycle life at room temperature until the capacity reached 80%. The test results are shown in Table 1.

[0126] 2. ICP test

[0127] Weigh about 0.1 g of negative electrode powder (accurate to ±0.0003 g) of each embodiment and comparative example, place it in a 100 mL beaker, add a small amount of distilled water to moisten the bottom of the cup, then add 5 mL of 12 mol / L HCl (produced in Shandong, GR) to dissolve, heat on an electric heating plate for 20 min, remove and cool, and dilute for testing.

[0128] The prepared series of standard solutions were introduced into the iCAP7000 inductively coupled plasma spectrometer (ICP) (made in the United States), and the intensity of each element in the standard solution was measured at the wavelength of the element to be measured (nickel, cobalt, manganese, lithium). When the linear correlation coefficient of the working curve r ≥ 0.9995, the measurement can be carried out. The test results are shown in Table 1.

[0129] Table 1

[0130]

[0131] As shown in Table 1, by comparing Examples 1 to 14 with Comparative Example 1, it can be seen that the lithium ion battery provided by the present application, by adding additives to the positive electrode film layer and / or the electrolyte, the additives include humic acid, which improves the cycle life of the battery, effectively adsorbs manganese ions, prevents manganese ions from dissolving and migrating to the negative electrode, reduces the content of manganese ions on the negative electrode side, and avoids damage to the SEI film.

[0132] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0133] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the technical concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A lithium ion battery, characterized in that: It includes a positive electrode plate and an electrolyte, wherein the positive electrode plate includes a positive electrode collector and a positive electrode film layer provided on at least one side of the surface of the positive electrode collector, the positive electrode film layer and / or the electrolyte include an additive, the additive includes humic acid, the positive electrode film layer also includes a positive electrode active substance, and the positive electrode active substance includes manganese.

2. The lithium-ion battery according to claim 1, characterized in that The positive electrode film layer includes a positive electrode active layer and a functional layer, the positive electrode active layer is arranged on the surface of the positive electrode current collector, the functional layer is arranged on the surface of the positive electrode active layer, the positive electrode active layer includes the positive electrode active material, and the functional layer includes the additive. 3 . The lithium ion battery according to claim 2 , wherein the functional layer further comprises one or more of porous carbon, a solid electrolyte and aluminum oxide.

4. The lithium-ion battery according to claim 3, characterized in that: The functional layer further comprises the porous carbon, and the mass ratio of the porous carbon to the humic acid is (1-5):(3-10).

5. The lithium-ion battery according to claim 3, characterized in that: The functional layer further comprises the solid electrolyte, and the mass ratio of the solid electrolyte to the humic acid is (1-5):(3-10).

6. The lithium ion battery according to any one of claims 2 to 5, characterized in that: The thickness of the functional layer is 2 μm to 13 μm.

7. The lithium-ion battery according to claim 1, characterized in that: The electrolyte includes the additive, and the mass percentage of the humic acid in the electrolyte is 0.5% to 1%.

8. The lithium-ion battery according to claim 1, characterized in that The positive electrode film layer is a single layer, and the mass percentage of the humic acid in the positive electrode film layer is 0.5% to 1%.

9. The lithium-ion battery according to claim 1, characterized in that: The positive electrode active material includes one or more of lithium iron manganese phosphate, lithium manganese oxide and lithium nickel manganese oxide.

10. An electrical device, characterized in that: A lithium ion battery comprising any one of claims 1 to 9.

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