Battery cell, battery device and electric device

Abstract

The present application relates to a battery cell, a battery device, and an electric device. The battery cell comprises a positive electrode sheet, a negative electrode sheet, and a separator; the positive electrode sheet comprises a positive electrode current collector and a positive electrode material layer provided on at least one surface of the positive electrode current collector; the positive electrode material layer comprises a positive electrode lithium supplementing agent and metal oxide particles; the metal oxide includes at least one of CeO2, TiO2, Cu2O, CuO, WO3, NiO, Fe2O3, Co3O4, MnO, ZnO, MnO2, and MoO3; and a mass ratio of the positive electrode lithium supplementing agent to the metal oxide particles is 100:(0.1-20). By simultaneously applying the positive electrode lithium supplementing agent and the metal oxide particles, the battery cell mitigates the adverse effects caused by reactive oxygen species while providing the lithium supplementing effect, which is beneficial to improving the capacity utilization and cycle performance of batteries.

Description

Battery monomer, battery device and electric device

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application 202411088219.1, filed on August 8, 2024, entitled "Battery monomer, battery device and electric device", the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the technical field of batteries, in particular to a battery monomer, a battery device and an electric device. BACKGROUND

[0004] Secondary batteries represented by lithium-ion batteries have been widely used in energy storage power systems such as hydroelectric, thermal, wind and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc.

[0005] During the first charge-discharge process of the battery, the electrolyte will form a solid electrolyte interface film (SEI film) on the surface of the negative electrode. The formation of the SEI film will consume a large amount of active lithium ions, and thus cause the loss of recyclable lithium. To this end, pre-lithiation of the positive electrode or the negative electrode is an effective method. However, when applying a positive electrode lithium supplement agent, active oxygen is easily produced, resulting in phenomena such as gas production and heat release. SUMMARY

[0006] The purpose of the present application is to provide a battery monomer, a battery device and an electric device. The battery monomer, by simultaneously applying a positive electrode lithium supplement agent and metal oxide particles, not only plays a lithium supplement role, but also reduces the negative effects of active oxygen, which is beneficial to improve the capacity and cycle performance of the battery.

[0007] To this end, the present application provides a battery monomer, comprising a positive electrode sheet, a negative electrode sheet and a separator, the positive electrode sheet comprising a positive electrode current collector and a positive electrode material layer arranged on at least one surface of the positive electrode current collector; the positive electrode material layer comprising a positive electrode lithium supplement agent and metal oxide particles; the metal oxide comprising at least one of CeO2, TiO2, Cu2O, CuO, WO3, NiO, Fe2O3, Co3O4, MnO, ZnO, MnO2, MoO3; the mass ratio of the positive electrode lithium supplement agent to the metal oxide particles is 100:(0.1-20).

[0008] By applying the positive electrode lithium supplementing agent, excess lithium salt can be provided in the first charging process of the battery to compensate for the consumption of lithium in the formation of SEI film and improve the gram capacity of the battery. The metal oxide particles are applied as additives in the positive electrode material layer, and the metal oxide can react with the superoxide radicals generated by the positive electrode lithium supplementing agent to rapidly convert the superoxide radicals into oxygen, thereby avoiding the decomposition of the electrolyte by the oxygen radicals and reducing the gas and heat generation problems caused by active oxygen. When the mass ratio of the metal oxide is within the above range, the generation amount of oxygen radicals can be reduced, and the positive and negative electrode interfaces can be improved, thereby improving the capacity of the lithium ion battery and improving the safety performance of the battery.

[0009] In some embodiments, the mass ratio of the positive electrode lithium supplementing agent to the metal oxide particles is 100:(0.1-10).

[0010] By further adjusting the mass ratio of the positive electrode lithium supplementing agent to the metal oxide particles to 100:(0.1-10), the improvement of the battery capacity can be improved.

[0011] In some embodiments, the particle size Dv50 of the metal oxide particles is 5-50 nm.

[0012] In the embodiments of the present application, smaller metal oxide particle sizes, such as 5-50 nm, are used to enhance the reaction between the metal oxide and active oxygen, and to better consume active oxygen and avoid the decomposition of electrolyte caused by oxygen radicals.

[0013] In some embodiments, the particle size Dv50 of the metal oxide particles is 5-15 nm.

[0014] By using the above-mentioned particle size of the metal oxide particles, the reactivity between the metal oxide and active oxygen is further improved, which is beneficial to reducing the gas and heat generation problems during the use of the battery.

[0015] In some embodiments, the positive electrode lithium supplementing agent includes at least one of the following group: Li6CoO4, Li5FeO4, Li3VO4, Li2MoO3, Li2RuO3, Li2MnO3, Li2MnO2, Li2NiO2, Li2CuO2, Li2Cu x Ni 1-x M y O2, wherein 0

[0016] By using the above positive electrode lithium supplementing agent, its chemical property in generating active oxygen is more suitable to match the metal oxide particles in the embodiments of the present application, so that the generated active oxygen can be almost completely consumed by the metal oxide, which is beneficial to improve the capacity performance and safety performance of the battery.

[0017] In some embodiments, the particle size Dv50 of the positive electrode lithium supplementing agent is 1-20 μm.

[0018] In some embodiments, the positive electrode material layer further comprises a positive electrode active material, and the particle size Dv50 of the positive electrode active material is 0.1-20 μm.

[0019] By selecting a more suitable particle size of the positive electrode lithium supplementing agent and / or a more suitable particle size of the positive electrode active material, a more optimal effect of improving the capacity of the battery can be achieved.

[0020] In some embodiments, the ratio of the particle size Dv50 of the positive electrode lithium supplementing agent to the particle size Dv50 of the positive electrode active material is A, and 1≤A≤12.

[0021] The ratio of the particle size Dv50 of the positive electrode lithium supplementing agent to the particle size Dv50 of the positive electrode active material affects the lithium ion conductivity of the positive electrode plate. As the ratio A decreases, the ion conductivity of the positive electrode plate increases, but the contact area between the positive electrode lithium supplementing agent and the electrolyte increases, which easily causes the side reaction to increase. When the ratio A is controlled in the range of 1-12, the ion conductivity of the positive electrode plate and the side reaction can be well balanced, and a more optimal comprehensive effect can be achieved.

[0022] In some embodiments, in the positive electrode material layer, the mass percentage of the positive electrode lithium supplementing agent is W1, and 0.1%≤W1≤10%.

[0023] When the mass percentage of the positive electrode lithium supplementing agent is in the above range, the generated oxygen free radicals can be well consumed by the metal oxide, and the positive electrode lithium supplementing agent can have an excellent lithium supplementing effect.

[0024] In a second aspect of the present application, a battery device is provided, which comprises the battery cell according to the first aspect of the present application.

[0025] In a third aspect of the present application, a power utilization device is provided, which comprises the battery cell according to the first aspect of the present application or the battery device according to the second aspect of the present application.

[0026] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, the specific embodiments of the present application are described below according to the content of the description, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand. BRIEF DESCRIPTION OF DRAWINGS

[0027] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments with reference made to the accompanying drawings. The drawings provided herein are for illustrative purposes only and, therefore, should not be considered to be limiting in any way. In the drawings:

[0028] FIG. 1 is a schematic view of a battery cell according to an embodiment of the present application;

[0029] FIG. 2 is an exploded view of the battery cell shown in FIG. 1 according to an embodiment of the present application;

[0030] FIG. 3 is a schematic view of a battery module according to an embodiment of the present application;

[0031] FIG. 4 is a schematic view of a battery pack according to an embodiment of the present application;

[0032] FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application;

[0033] FIG. 6 is a schematic view of an electrical device using the battery cell as a power source according to an embodiment of the present application;

[0034] BRIEF DESCRIPTION OF DRAWINGS DETAILED DESCRIPTION

[0035] Exemplary embodiments of the present disclosure will be described in greater detail below. It should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thoroughly and completely understood, and will fully convey the scope of the present disclosure to those skilled in the art.

[0036] The ranges disclosed herein are intended to be "open" ranges, i.e., the upper and lower limits of the range are not included. The ranges can be "closed" ranges, i.e., the upper and lower limits of the range are included. The ranges can be arbitrarily combined, i.e., any upper limit can be combined with any lower limit to form a range. For example, if a range of 60-120 and a range of 80-110 are listed, it is understood that a range of 60-110 and a range of 80-120 are also contemplated. Furthermore, if a minimum range value of 1 and a maximum range value of 3 are listed, then the following ranges are contemplated: 1-3, 1-2, 2-3, and 2-1. In this application, unless otherwise indicated, a numerical range "a-b" means a range of any combination of the numbers a and b, wherein a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between 0 and 5 have been listed herein, and "0-5" is merely a shorthand for listing all of those numbers. Also, when a parameter is stated to be an integer ≥ 2, it is equivalent to state that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0037] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, unless otherwise specified.

[0038] All technical features and optional technical features of the present application can be combined with each other to form new technical solutions, unless otherwise specified.

[0039] All steps of the present application can be performed in sequence or randomly, preferably in sequence, unless otherwise specified. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, it is mentioned that the method can further comprise step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0040] Unless otherwise specified, "including" and "comprising" mentioned in the present application means open-ended, and can also be closed-ended. For example, "including" and "comprising" can mean that other components not listed can also be included or contained, or only the listed components can be included or contained.

[0041] During the first charge-discharge process of the battery, the electrolyte will form a solid electrolyte interface film (SEI film) on the surface of the negative electrode. The formation of the SEI film will consume a large amount of active lithium ions, thereby causing the loss of circulatable lithium. In this regard, pre-supplementing lithium to the positive electrode or the negative electrode is an effective method. However, when the positive electrode lithium supplementing agent is applied, active oxygen is easily produced, and phenomena such as gas production and heat release occur.

[0042] The present application eliminates active oxygen by applying a metal oxide with a certain mass ratio in the positive electrode material layer containing a lithium supplementing agent, improves the problems of battery gas production and heat production, and thus improves the battery capacity and safety performance.

[0043] The scheme described in the embodiments of the present application is applicable to a battery monomer, a battery device using the battery monomer, and a power consumption device using at least one of the battery monomer and the battery device.

[0044] Battery monomer

[0045] In the embodiments of the present application, the battery monomer can be a secondary battery, which refers to a battery monomer that can be activated by charging after discharging.

[0046] The battery monomer can be a lithium ion battery, a sodium ion battery, a sodium-lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium-sulfur battery, a magnesium ion battery, a nickel-hydrogen battery, a nickel-cadmium battery, a lead-acid battery, etc. In some embodiments, the battery monomer is a lithium ion battery.

[0047] [Electrode assembly]

[0048] The battery monomer generally includes an electrode assembly. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. The separator is arranged between the positive electrode sheet and the negative electrode sheet. During the charge-discharge process of the battery monomer, active ions (such as lithium ions) are inserted and extracted between the positive electrode sheet and the negative electrode sheet. The separator arranged between the positive electrode sheet and the negative electrode sheet can prevent the short circuit of the positive and negative electrodes, and at the same time, the active ions can pass through.

[0049] [Positive electrode sheet]

[0050] In some embodiments, a battery monomer is provided, including a positive electrode sheet, a negative electrode sheet, and a separator, the positive electrode sheet including a positive electrode current collector and a positive electrode material layer arranged on at least one surface of the positive electrode current collector; the positive electrode material layer including a positive electrode lithium supplementing agent and metal oxide particles; the metal oxide including at least one of CeO2, TiO2, Cu2O, CuO, WO3, NiO, Fe2O3, Co3O4, MnO, ZnO, MnO2, and MoO3; and the mass ratio of the positive electrode lithium supplementing agent to the metal oxide particles is 100:(0.1-20).

[0051] By applying the positive electrode lithium supplementing agent, excess lithium salt can be provided in the first charging process of the battery to make up for the consumption of lithium in the formation of the SEI film, thereby improving the gram capacity of the battery. The positive electrode lithium supplementing agent will undergo structural changes during the first charging (delithiation) process, generating superoxide radicals. The superoxide radicals have extremely high chemical activity and can cause decomposition reactions of the electrolyte, easily releasing a large amount of heat and gas, and even possibly causing thermal runaway, resulting in problems such as combustion or explosion of the battery. In the embodiments of the present application, metal oxide particles are applied as additives in the positive electrode material layer. The metal oxide can react with the superoxide radicals generated by the positive electrode lithium supplementing agent, allowing the superoxide radicals to rapidly convert into oxygen, thereby avoiding the decomposition of the electrolyte by the oxygen radicals. When the mass ratio of the metal oxide is within the above range, the amount of oxygen radicals generated can be reduced, and the positive and negative electrode interfaces can be improved, thereby improving the capacity of the lithium ion battery and improving the safety performance of the battery.

[0052] In some embodiments, the mass ratio of the positive electrode lithium supplementing agent to the metal oxide particles is 100:(0.1-10)

[0053] By further adjusting the mass ratio of the positive electrode lithium supplementing agent to the metal oxide particles to 100:(0.1-10), the improvement in the capacity of the battery can be improved.

[0054] In some embodiments, the mass ratio of the positive electrode lithium supplementing agent to the metal oxide particles can be selected from about 100:0.01, 100:0.05, 100:0.1, 100:0.2, 100:0.5, 100:1, 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, 100:8, 100:9, 100:10, 100:11, 100:12, 100:13, 100:14, 100:15, 100:16, 100:17, 100:18, 100:19, 100:20, etc.

[0055] In some embodiments, the particle size Dv50 of the metal oxide particles is 5-50 nm; for example, it can be selected from about 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, etc.

[0056] In the embodiments of the present application, smaller metal oxide particle sizes, for example 5-50 nm, are used, which can enhance the reaction between the metal oxide and active oxygen, and better consume active oxygen, thereby avoiding the decomposition of the electrolyte by oxygen radicals and other adverse effects.

[0057] The particle size Dv50, also referred to as median diameter or median particle size, refers to the particle size corresponding to 50% of the volume cumulative particle size distribution of a sample; its physical meaning is that the particles with a particle size greater than it account for 50% by volume, and the particles with a particle size less than it also account for 50% by volume. The Dv50 can be tested by a method known in the art. As an example, reference can be made to GB / T 19077-2016, and a Malvern laser particle size analyzer can be used for characterization testing, for example, a Malvern Mastersizer-3000 instrument can be used for testing.

[0058] In some embodiments, the metal oxide particles have a particle size Dv50 of 5-15 nm.

[0059] By applying the above-mentioned particle size of the metal oxide particles, the reactivity between the metal oxide particles and the active oxygen is further improved, which is beneficial to reducing the gas and heat generation problems during the use of the battery.

[0060] In some embodiments, the positive electrode lithium supplementing agent comprises at least one of the following group: Li6CoO4, Li5FeO4, Li3VO4, Li2MoO3, Li2RuO3, Li2MnO3, Li2MnO2, Li2NiO2, Li2CuO2, Li2Cu x Ni 1-x M y O2, wherein 0

[0061] By using the above-mentioned positive electrode lithium supplementing agent, its chemical properties in generating active oxygen are more suitable to match the metal oxide particles in the embodiments of the present application, so that the generated active oxygen can be almost completely consumed by the metal oxide, which is beneficial to improving the capacity performance and safety performance of the battery.

[0062] In some embodiments, the positive electrode lithium supplementing agent has a particle size Dv50 of 1-20 μm, for example, it can be selected from about 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, etc.

[0063] In some embodiments, the positive electrode material layer further comprises a positive electrode active material, and the positive electrode active material has a particle size Dv50 of 0.1-20 μm, for example, it can be selected from about 0.1 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, etc.

[0064] By selecting a more suitable particle size of the positive electrode lithium supplement agent and / or a more suitable particle size of the positive electrode active material, a more optimal battery capacity improvement effect can be achieved.

[0065] In some embodiments, the positive electrode material layer further comprises a positive electrode active material, and a ratio of the particle size Dv50 of the positive electrode lithium supplement agent to the particle size Dv50 of the positive electrode active material is A, 1≤A≤12; for example, A can be selected from about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0066] The ratio of the particle size Dv50 of the positive electrode lithium supplement agent to the particle size Dv50 of the positive electrode active material affects the lithium ion conductivity of the positive electrode tab. As the ratio A decreases, the ion conductivity of the positive electrode tab increases, but the contact area between the positive electrode lithium supplement agent and the electrolyte increases, which can easily increase the side reaction. When the ratio A is controlled in the range of 1-12, the ion conductivity of the positive electrode tab and the side reaction can be well balanced, and a more optimal comprehensive effect can be achieved.

[0067] In some embodiments, in the positive electrode material layer, the mass percentage of the positive electrode lithium supplement agent is W1, 0.1%≤W1≤10%; for example, W1 can be selected from about 0.1%, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, etc.

[0068] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, an aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0069] In some embodiments, the positive active material can employ a positive active material for lithium ion batteries known in the art. As an example, the positive active material can include at least one of a lithium-containing phosphate of an olivine structure, a lithium transition metal oxide, and a modified compound of each thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive active material can also be used. These positive active materials can be used alone only one or two or more in combination. Among them, examples of the lithium transition metal oxide can include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2(also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2(also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2(also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2(also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2), and modified compounds thereof. Examples of the lithium-containing phosphate of an olivine structure can include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite of lithium manganese iron phosphate and carbon.

[0070] In some embodiments, the positive active material layer can also optionally include a binder. For example, the binder can include one or a combination of two or more selected from the group consisting of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0071] In some embodiments, the positive electrode material layer can further optionally include a conductive agent. For example, the conductive agent can include one or more than one selected from the group consisting of Super P, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, carbon nanofibers.

[0072] In some embodiments, the positive electrode tab can be prepared by dispersing the above-mentioned positive electrode lithium supplement agent, metal oxide particles, positive electrode active material, and optionally conductive agent, binder and any other components in a solvent (e.g., N-methyl pyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on a positive electrode current collector, and after drying, cold pressing, etc., a positive electrode tab can be obtained.

[0073] [Positive electrode tab]

[0074] The negative electrode tab includes a negative electrode current collector and a negative electrode material layer disposed on at least one surface of the negative electrode current collector, the negative electrode material layer including a negative electrode active material.

[0075] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, a copper foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material base layer (e.g., a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0076] In some embodiments, the negative electrode active material layer can use a negative electrode active material known in the art for lithium ion batteries. For example, the negative electrode active material can include one or more than one selected from the group consisting of natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, TiO2-Li4Ti5O12, Li-Al alloy. 12

[0077] In some embodiments, the negative electrode material layer can further optionally include a binder. For example, the binder can include one or more than one selected from the group consisting of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), carboxymethyl chitosan (CMCS).

[0078] ​In some embodiments, the negative material layer can also optionally include a conductive agent. For example, the conductive agent can include one or more than two combinations selected from the group consisting of Super P, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0079] In some embodiments, the negative material layer can also optionally include other auxiliary agents. For example, the other auxiliary agent can be a thickening agent (such as sodium carboxymethyl cellulose (CMC-Na)).

[0080] In some embodiments, the negative electrode sheet can be prepared by dispersing the components of the negative material layer described above, such as the negative active material, the conductive agent, the binder, and any other components, in a solvent (such as deionized water) to form a negative electrode slurry; coating the negative electrode slurry on a negative electrode current collector, and after processes such as drying, cold pressing, etc., the negative electrode sheet can be obtained.

[0081] [Electrolyte]

[0082] In some embodiments, the battery cell further includes an electrolyte; the electrolyte functions to conduct ions between the positive electrode sheet and the negative electrode sheet. The type of electrolyte is not specifically limited in the present application and can be selected as needed. The electrolyte can be liquid, gel, or solid.

[0083] In some embodiments, the electrolyte can be a liquid electrolyte. The liquid electrolyte can include an electrolyte salt and a solvent.

[0084] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro oxalate borate, lithium di-oxalate borate, lithium difluoro di-oxalate phosphate, and lithium tetrafluoro oxalate phosphate.

[0085] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, butanedisulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent can also be an ether solvent. The ether solvent can include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ether.

[0086] In some embodiments, the electrolyte solution can also optionally include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and an additive capable of improving certain performance of the battery cell, such as an additive capable of improving overcharge / fast charge performance of the battery cell, an additive capable of improving high-temperature performance of the battery cell, an additive capable of improving low-temperature performance of the battery cell, and the like.

[0087] In some embodiments, the gel electrolyte includes a polymer as a skeleton network and can be used in combination with an ionic liquid-lithium salt.

[0088] In some embodiments, the solid electrolyte includes a polymer solid electrolyte, an inorganic solid electrolyte, and a composite solid electrolyte.

[0089] As an example, the polymer of the polymer solid electrolyte can include a polyether (polyethylene oxide), a polysiloxane, a polycarbonate, a polyacrylonitrile, a polyvinylidene fluoride, a polymethyl methacrylate, a single-ion polymer, a polyionic liquid, cellulose, and the like.

[0090] As an example, the inorganic solid electrolyte can be one or more of an oxide solid electrolyte (crystalline perovskite, sodium superionic conductor, garnet, amorphous LiPON thin film), a sulfide solid electrolyte (crystalline lithium superionic conductor (lithium-ephosphorus-sulfur, sulfur-silver-ephemeral mineral), amorphous sulfide), and a halide solid electrolyte, a nitride solid electrolyte, and a hydride solid electrolyte.

[0091] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0092] [Separator]

[0093] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode tab and the negative electrode tab.

[0094] In some embodiments, the separator is a separator film. The type of the separator film is not particularly limited in the present application, and any known porous structure separator film having good chemical stability and mechanical stability can be used.

[0095] As an example, the main material of the separator film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride, and ceramic. The separator film can be a single layer film or a multi-layer composite film, and is not particularly limited. When the separator film is a multi-layer composite film, the materials of the respective layers can be the same or different, and are not particularly limited. The separator can be a separate component located between the positive and negative electrodes, or can be attached to the surface of the positive and negative electrodes. An inorganic particle coating layer, an organic particle coating layer, or an organic / inorganic composite coating layer can be applied to the surface of the separator film.

[0096] In some embodiments, the separator is a solid-state electrolyte. The solid-state electrolyte is disposed between the positive electrode and the negative electrode, and functions to transport ions and separate the positive electrode and the negative electrode.

[0097] [Structure of electrode assembly]

[0098] The electrode assembly can be in a jelly-roll structure, a stack structure, or a hybrid structure of a jelly-roll and a stack.

[0099] In some embodiments, the electrode assembly is in a jelly-roll structure. The positive electrode sheet and the negative electrode sheet are wound into a jelly-roll structure.

[0100] In some embodiments, the electrode assembly is in a stack structure.

[0101] For example, a plurality of positive electrode sheets and a plurality of negative electrode sheets can be alternately stacked.

[0102] For example, a plurality of positive electrode sheets can be provided, and the negative electrode sheet can be folded to form a plurality of folded segments that are stacked. One positive electrode sheet can be interposed between adjacent folded segments.

[0103] For example, a plurality of positive electrode sheets and a plurality of negative electrode sheets can be alternately stacked.

[0104] For example, a plurality of separators can be provided, and each of the plurality of separators can be interposed between any adjacent positive electrode sheet or negative electrode sheet.

[0105] For example, a plurality of separators can be provided, and each of the plurality of separators can be interposed between any adjacent positive electrode sheet or negative electrode sheet.

[0106] In some embodiments, the electrode assembly can have a cylindrical shape, a flat shape, or a polygonal shape.

[0107] In some embodiments, the electrode assembly can be provided with a tab. The tab can be used to guide current out of the electrode assembly. The tab can include a positive tab and a negative tab.

[0108] [Shell]

[0109] In some embodiments, the battery cell can include a shell. The shell can be a steel shell, an aluminum shell, a plastic shell (e.g., a polypropylene shell), a composite metal shell (e.g., a copper-aluminum composite shell), or an aluminum-plastic film, etc. In some embodiments, the shell can be a sealed structure or a non-sealed structure. For example, when the shell is a non-sealed structure, the shell can function to protect the electrode assembly, and a sealing bag can be interposed between the shell and the electrode assembly. The sealing bag can be used to encapsulate the electrode assembly and the electrolyte. Specifically, the sealing bag can be a bag-shaped insulating member or an aluminum-plastic film. When the shell is a sealed structure, the shell can be used to encapsulate the electrode assembly and the electrolyte, etc.

[0110] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes, the prismatic battery cell including a square battery cell, a blade battery cell, a multi-prismatic battery cell, for example, a hexagonal battery cell, etc., without particular limitation. For example, FIG. 1 is a square battery cell 5 as an example.

[0111] In some embodiments, referring to FIG. 2, the housing includes an end cap 53 and a case 51, the case 51 being provided with an opening, and the end cap 53 being provided on the opening. The case 51 can be provided with one or more openings. The end cap 53 can also be provided with one or more openings. The positive electrode tab, the negative electrode tab, and the separator can form an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is encapsulated in a receiving cavity enclosed by the case 51 and the end cap 53. The electrolyte is impregnated in the electrode assembly 52.

[0112] [Electrode terminal]

[0113] In some embodiments, at least one electrode terminal is provided on the housing, and the electrode terminal is electrically connected to the electrode tab. The electrode terminal can be directly connected to the electrode tab or indirectly connected to the electrode tab through a current collecting member. The electrode terminal can be provided on the end cap or on the case.

[0114] [Pressure relief mechanism]

[0115] In some embodiments, a pressure relief mechanism is provided on the housing. The pressure relief mechanism is used to discharge the internal gas of the battery cell.

[0116] As an example, the pressure relief mechanism is actuated to release the internal pressure or temperature of the battery cell when the internal pressure or temperature of the battery cell reaches a predetermined threshold. When the internal pressure or temperature of the battery cell reaches the predetermined threshold, the pressure relief mechanism performs an action or a weak structure provided in the pressure relief mechanism is broken, thereby forming an opening or a passage for the internal pressure or temperature to be released. The threshold is designed differently according to different design requirements. The threshold can depend on the material of one or more of the positive electrode tab, the negative electrode tab, the electrolyte, and the separator in the battery cell.

[0117] As an example, the pressure relief mechanism can be integrally formed with the housing.

[0118] As an example, the pressure relief mechanism can also be provided separately from the housing and connected to the housing.

[0119] As used herein, "actuation" of a pressure relief mechanism refers to the pressure relief mechanism being activated or moved to a state in which the internal pressure and temperature of a battery cell can be released. The movement of the pressure relief mechanism can include, but is not limited to, movement of a component of the pressure relief mechanism to form a venting path, at least a portion of the pressure relief mechanism rupturing, breaking, tearing, or opening, and the like. Upon actuation of the pressure relief mechanism, the high temperature and pressure material inside the battery cell can be expelled as a discharge from the actuated portion. In this manner, the battery cell can be depressurized and cooled in a controlled manner to avoid potentially more severe accidents.

[0120] In some embodiments, the housing is not a sealed structure, and the pressure relief mechanism can be a through hole for venting the gas inside the battery cell.

[0121] As used herein, the discharge from a battery cell can include, but is not limited to, electrolyte, dissolved or broken positive and negative electrode sheets, fragments of separators, high temperature and pressure gases generated by reactions, flames, and the like.

[0122] Battery apparatus

[0123] As used herein, a battery apparatus can include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly can include a plurality of battery cells connected in series, in parallel, or in a mixed connection through a busbar.

[0124] In some embodiments, a battery cell assembly is generally formed by a plurality of battery cells arranged in a row.

[0125] As an example, a battery cell assembly can be a battery module formed by a plurality of battery cells arranged and fixed into a single module. As an example, a battery module can be formed by bundling a plurality of battery cells with a cable tie. FIG. 3 is a battery module 4 as an example. Referring to FIG. 3, in the battery module 4, a plurality of battery cells 5 can be arranged in a row along the length of the battery module 4. Of course, the battery cells can be arranged in any other manner.

[0126] In some embodiments, a battery apparatus can be a battery pack including a case and one or more battery cell assemblies housed in the case.

[0127] As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be accommodated in the case by fixing the battery module in the case. FIGS. 4 and 5 are a battery pack 1 as an example. Referring to FIGS. 4 and 5, the battery pack 1 can include a case and a plurality of battery modules 4 disposed in the case. The case includes an upper case 2 and a lower case 3, and the upper case 2 can be disposed to cover the lower case 3 and form an enclosed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery case in any manner.

[0128] As an example, the battery cell assembly can also be accommodated in the case by directly fixing a plurality of battery cells in the case.

[0129] As an example, the case can include a first case and a second case. The first case and the second case are coupled so that an enclosed space is formed inside the case to accommodate the battery cell assembly. Here, the enclosed means covered or closed, and can be sealed or unsealed. The first case can be a top cover or a bottom plate.

[0130] As an example, the case can include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected to the frame so that an enclosed space is formed inside the case to accommodate the battery cell assembly.

[0131] In some embodiments, the case can be part of a chassis structure of a vehicle. For example, part of the case can be at least part of a floor of the vehicle, or part of the case can be at least part of a cross beam and a longitudinal beam of the vehicle.

[0132] Electric device

[0133] The technical solutions described in the embodiments of the present application are applicable to various electric devices using battery cells, such as mobile phones, portable devices, notebook computers, electric vehicles, electric toys, electric tools, vehicles, ships, and spacecraft, such as aircraft, rockets, space shuttles, and spacecraft. FIG. 6 is an electric device as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0134] Embodiment 1

[0135] The embodiment provides a lithium ion secondary battery, and a preparation method thereof is as follows:

[0136] (1) Positive electrode sheet

[0137] In the positive electrode material layer, the mass percentage of the positive electrode lithium supplement agent is W1 (3%); the mass percentage of the metal oxide particles based on the mass of the positive electrode lithium supplement agent is W2 (0.5%). Lithium iron phosphate (Dv50 is 1.5 μm) as the positive electrode active material, Li5FeO4 (Dv50 is 9 μm) as the positive electrode lithium supplement agent, CeO2 (Dv50 is 8 nm) as the metal oxide particles, polyvinylidene fluoride (PVDF) as the binder, acetylene black as the conductive agent are dissolved in a solvent N-methyl pyrrolidone (NMP) according to a mass ratio of 97-(100×W1)-(100×W1×W2):(100×W1):(100×W1×W2):2:1, and a positive electrode slurry is obtained after the mixture is uniformly mixed by fully stirring. Then, the positive electrode slurry is uniformly coated on a positive electrode current collector, and a positive electrode sheet is obtained after drying, cold pressing and slitting.

[0138] (2) Negative electrode sheet

[0139] Artificial graphite as the negative electrode active material, acetylene black as the conductive agent, butadiene styrene rubber (SBR) as the binder, and sodium carboxymethyl cellulose (CMC) as the thickening agent are dissolved in deionized water according to a mass ratio of 95:2:2:1, and a negative electrode slurry is prepared after the mixture is uniformly mixed. Then, the negative electrode slurry is uniformly coated on a negative electrode current collector copper foil, and a negative electrode film is obtained after drying. The negative electrode sheet is obtained after cold pressing and slitting.

[0140] (3) Preparation of electrolyte

[0141] In an argon atmosphere glove box (H2O <0.1 ppm, O2 <0.1 ppm), 1 mol / L LiPF6 is dissolved in an organic solvent (EC / DMC / EMC = 1 / 1 / 1) and stirred uniformly to obtain a corresponding electrolyte.

[0142] (4) Preparation of separator: a conventional polypropylene film is used as the separator.

[0143] (5) Preparation of lithium ion battery

[0144] The positive electrode sheet, the separator and the negative electrode sheet are stacked in order, and the separator is between the positive electrode sheet and the negative electrode sheet to play a role of isolation. Then, an electrode assembly is obtained by winding. The electrode assembly is placed in a battery shell, and after drying, an electrolyte is injected. Then, a lithium ion battery is obtained after processes such as formation and standing.

[0145] The lithium ion battery is subjected to the following tests, and the test results are shown in Table 1.

[0146] 1. Capacity test of lithium ion battery

[0147] The lithium ion battery was charged at 0.33C constant current to 3.65V at 25℃, then charged at 3.65V constant voltage until the current was less than 0.05C, then discharged at 0.33C constant current to 2.5V, and the actual capacity was recorded as C0(mAh).

[0148] 2, cycle performance (45℃ Fading 80% cycle number)

[0149] The lithium ion battery was charged at 0.5C constant current to 4.45V at 45℃, then charged at 4.45V constant voltage until the current was less than 0.05mA, then discharged at 0.5C constant current to 2.5V, which was one charge-discharge process, and the discharge capacity at this time was recorded as the discharge capacity of the first cycle of the battery. The charging and discharging cycles were repeated in this way, and the cycle number corresponding to the capacity retention rate of 80% was calculated.

[0150] The capacity retention rate (%) of the battery after 45℃ cycling N times = (the discharge capacity of the battery in the Nth cycle / the discharge capacity of the battery in the first cycle) x 100%.

[0151] Examples 2-5

[0152] In addition to the mass percentage W2 of the metal oxide particles relative to the positive electrode lithium supplement agent as shown in Table 1, the preparation and testing were carried out in the same way as in Example 1, and the results are shown in Table 1.

[0153] Comparative Example 1

[0154] In addition to not using metal oxide particles, the preparation and testing were carried out in the same way as in Example 1, and the results are shown in Table 1.

[0155] Comparative Example 2

[0156] In addition to not using the positive electrode lithium supplement agent, the preparation and testing were carried out in the same way as in Example 1, and the results are shown in Table 1. Among them, the mass ratio of the positive electrode active material lithium iron phosphate, metal oxide particles, binder and conductive agent is 97-(100x3% x 0.5%):(100x3% x 0.5%):2:1.

[0157] Table 1

[0158] Examples 6-9

[0159] In addition to the Dv50 of the metal oxide particles as shown in Table 2, the preparation and testing were carried out in the same way as in Example 1, and the results are shown in Table 2.

[0160] Table 2

[0161] Examples 10-12

[0162] Except for the specific material of the metal oxide particles as shown in Table 3, the preparation and testing were performed in the same manner as Example 1, and the results are shown in Table 3.

[0163] Table 3

[0164] Examples 13-14

[0165] Except for the particle size Dv50 of the positive electrode lithium supplementing agent and the positive electrode active material as shown in Table 4, the preparation and testing were performed in the same manner as Example 1, and the results are shown in Table 4.

[0166] Table 4

[0167] Examples 15-16

[0168] Except for the specific material of the positive electrode lithium supplementing agent as shown in Table 5, the preparation and testing were performed in the same manner as Example 1, and the results are shown in Table 5.

[0169] Table 5

[0170] The above description is merely preferred embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A battery cell, characterized by, The battery device comprises the battery cell according to any one of claims 1-9.

2. The battery cell of claim 1, wherein, The battery device comprises the battery cell according to any one of claims 1-9.

3. The battery cell according to claim 1 or 2, wherein The metal oxide particle has a particle size Dv50 of 5-50 nm.

4. The battery cell according to claim 1 or 2, wherein The metal oxide particle has a particle size Dv50 of 5-15 nm.

5. The battery cell according to any one of claims 1 to 4, wherein The positive electrode lithium supplementing agent includes at least one of the following group: Li6CoO4, Li5FeO4, Li3VO4, Li2MoO3, Li2RuO3, Li2MnO3, Li2MnO2, Li2NiO2, Li2CuO2, Li2Cu x Ni 1-x M y O2, wherein 0 < x < 1, 0≤y<0.1, M is selected from one or several of Zn, Sn, Mg, Fe and Mn.

6. The battery cell according to any one of claims 1 to 5, wherein The positive electrode lithium supplement agent has a particle size Dv50 of 1-20 μm.

7. The battery cell according to any one of claims 1 to 6, wherein The positive electrode material layer further comprises a positive electrode active material, and the positive electrode active material has a particle size Dv50 of 0.1-20 μm.

8. The battery cell according to any one of claims 1 to 7, wherein The positive electrode material layer further comprises a positive electrode active material, and the ratio of the particle size Dv50 of the positive electrode lithium supplement agent to the particle size Dv50 of the positive electrode active material is A, 1≤A≤12.

9. The battery cell according to any one of claims 1 to 8, wherein In the positive electrode material layer, the mass ratio of the positive electrode lithium supplement agent is W1, and 0.1%≤W1≤10%.

10. A battery device characterized by comprising: The battery device comprises the battery cell according to any one of claims 1-9.

11. An electrical device, characterized by The battery device comprises the battery cell according to any one of claims 1-9.

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