Lithium supplement positive pole piece and lithium ion battery

Abstract

The utility model provides a lithium supplement positive pole piece and a lithium ion battery. The lithium-supplementing positive pole piece comprises a current collector; a positive active material layer, an ion transmission layer, a metal lithium layer and a conductive connecting layer are laminated on at least one side of the current collector along the direction from being close to the current collector to being far away from the current collector; wherein the two ends of the conductive connecting layer are connected with the current collector to form a closed structure. According to the lithium supplementing positive pole piece provided by the utility model, the metal lithium layer is used for supplementing lithium, and meanwhile, the metal lithium layer is cooperatively matched with the ion transmission layer and the conductive connecting layer, so that side reaction is avoided, and the lithium supplementing effect and the safety performance are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of lithium ion batteries and relates to a lithium supplemented positive electrode plate and a lithium ion battery. Background Art

[0002] Due to the characteristics of high energy density, long service life, and environmental protection, lithium-ion batteries are widely used in portable electronic products such as mobile phones, laptops, digital cameras, and have good application prospects in electric vehicles and other fields. With the expansion of the scope of application, higher requirements are also placed on the performance of lithium-ion batteries, especially the increasing demand for high-energy-density lithium-ion batteries. During the first cycle of charging and discharging of lithium-ion batteries, a SEI film will be generated on the surface of the negative electrode, consuming some lithium ions. The more lithium ions are consumed in the generation of the SEI film, the lower the first cycle coulomb efficiency of the battery, and the lower the reversible capacity in subsequent cycles.

[0003] Lithium replenishment technology for lithium-ion batteries is an important means to improve battery energy density. The industry generally adopts the method of replenishing lithium at the negative electrode. The existing negative electrode replenishment technology can improve the initial efficiency of the battery and increase the battery capacity and energy density. However, the method of directly bonding the negative electrode with metal lithium foil often has an adverse effect on the battery cycle, especially for silicon-oxygen materials. Directly bonding lithium foil will affect the formation of the negative electrode SEI film, which improves the initial efficiency of the battery but affects the battery cycle.

[0004] Positive electrode lithium replenishment technology has been proposed as a new lithium replenishment solution for lithium-ion batteries. Compared with negative electrode lithium replenishment, positive electrode lithium replenishment has obvious advantages in safety and process convenience. Positive electrode lithium replenishment can avoid the impact of negative electrode lithium replenishment on negative electrode SEI film. In the prior art, the method of positive electrode lithium replenishment is usually: the positive electrode lithium replenisher is mixed and stirred with the main material, conductive agent, and binder in a certain proportion during the homogenization process to form a positive electrode slurry, and then coated with a certain surface density and assembled with the negative electrode sheet to form a battery; for example, CN112447963A discloses a method for preparing a lithium replenishment conductive slurry for the positive electrode of a lithium-ion battery, comprising the following steps: S100, mixing the positive electrode lithium replenishment material, conductive agent, dispersant and solvent evenly to form a mixture; S200, ball milling the mixture until the average particle size of the positive electrode lithium replenishment material reaches 50 to 5000 nm and a uniform lithium replenishment conductive slurry is formed. However, when the positive electrode lithium supplement agent is stirred with the positive electrode slurry, there are often shortcomings such as excessive magnetic substances and large particles of the positive electrode lithium supplement agent clogging the filter holes, resulting in waste of positive electrode slurry and affecting the electrochemical performance of the battery. Moreover, most of the current positive electrode lithium supplement materials have a low capacity (<500mAh / g), resulting in an unobvious lithium supplement effect. At the same time, some positive electrode lithium supplement materials in the prior art contain transition metals, which will dissolve transition metals during the battery charging and discharging process, and there is a risk of precipitation of transition metal dendrites at the negative electrode, which will bring great safety hazards to the battery. For example, the lithium supplement material Li5FeO4 has the risk of iron precipitation at the negative electrode during the charging and discharging process, which brings great safety problems to the battery.

[0005] In summary, the positive electrode lithium replenishment plate prepared in the prior art has poor actual lithium replenishment effect and also has many problems such as high safety risks. At present, there is no literature or patent mentioning that positive electrode lithium replenishment is carried out by using a metal lithium layer in the positive electrode plate.

[0006] Therefore, how to improve the lithium replenishment effect of the positive terminal without affecting the normal performance of the battery and improving the safety performance of the battery is a technical problem that needs to be solved urgently. Utility Model Content

[0007] In view of the shortcomings of the prior art, the purpose of the utility model is to provide a lithium-supplementing positive electrode plate and a lithium-ion battery. In the lithium-supplementing positive electrode plate provided by the utility model, a metal lithium layer is used for lithium replenishment, and an ion transport layer and a conductive connection layer are coordinated to avoid the generation of side reactions, thereby improving the lithium replenishment effect and safety performance.

[0008] To achieve this purpose, the utility model adopts the following technical solutions:

[0009] In a first aspect, the utility model provides a lithium-supplemented positive electrode plate, the lithium-supplemented positive electrode plate comprising:

[0010] current collector;

[0011] Along the direction from close to the current collector to far away from the current collector, at least one side of the current collector is stacked with a positive electrode active material layer, an ion transport layer, a metal lithium layer and a conductive connection layer;

[0012] Wherein, two ends of the conductive connection layer are connected to the current collector to form a closed structure.

[0013] The lithium-supplementing positive electrode sheet provided by the utility model selects a conventional metal lithium layer as the lithium-supplementing layer. The ion transport layer not only plays the role of transmitting lithium ions, but also can separate the metal lithium layer from the positive electrode active material layer, thereby avoiding direct contact between the metal lithium in the metal lithium layer and the positive electrode active material layer, thereby causing a short circuit. Moreover, the existence of the ion transport layer can also avoid side reactions caused by the activity of the metal lithium. The ion transport layer and the positive electrode active material layer are bonded together, which can effectively prevent thermal runaway, improve the thermal stability of the battery, and avoid the influence on the cycle. The conductive connection layer is in direct contact with the current collector, realizing electronic conduction. The combined action of the active material layer, ion transport layer, metal lithium layer and conductive connection layer realizes a micro-battery of metal lithium and positive electrode inside the battery. As the formation proceeds, lithium ions are released from the positive electrode, the potential of the positive electrode increases, the micro-battery formed by the metal lithium and the positive electrode automatically discharges, and the lithium ions are replenished into the positive electrode, thereby realizing the overall lithium replenishment of the battery. At the same time, the electronic conductivity of the conductive connection layer can be regulated by selecting conductive agents with different conductive properties or adjusting the content of the conductive agent in the conductive connection layer, thereby adjusting the lithium replenishment rate to prevent the destruction of the positive electrode active material layer due to excessive lithium replenishment during the lithium replenishment process, thereby controlling the temperature rise during the lithium replenishment process and improving the process safety.

[0014] As a preferred technical solution in the present invention, the thickness of the metal lithium layer is 1 to 10 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] As a preferred technical solution in the present invention, the thickness of the ion transport layer is 0.5 to 5 μm, for example, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm or 5 μm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] As a preferred technical solution in the present invention, the electronic conductivity of the ion transport layer is less than 0.001mS / cm, for example, 0.0009mS / cm, 0.0005mS / cm or 0.0001mS / cm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] As a preferred technical solution in the present invention, the ion conductivity of the ion transport layer after being infiltrated with the electrolyte is greater than 0.1mS / cm, for example, 0.15mS / cm, 0.2mS / cm, 0.3mS / cm, 0.4mS / cm, 0.5mS / cm, 0.6mS / cm, 0.7mS / cm, 0.8mS / cm, 0.9mS / cm, 1mS / cm, 1.3mS / cm, 1.5mS / cm or 2mS / cm, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0018] The ion transport layer provided by the utility model has a structure with high ion conductivity and low electronic conductivity, which is more conducive to the transmission of lithium ions to the positive electrode active material layer.

[0019] As a preferred technical solution in the present invention, the conductive connecting layer is composed of 80-99% of a conductive material and 1-20% of a binder by mass. For example, the conductive material may have a mass fraction of 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99%, etc., and the binder may have a mass fraction of 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0020] As a preferred technical solution in the present invention, the thickness of the conductive connection layer is 1 to 10 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] As a preferred technical solution in the present invention, the electronic conductivity of the conductive connecting layer is greater than 0.0001mS / cm, for example, 0.0005mS / cm, 0.001mS / cm, 0.005mS / cm, 0.01mS / cm, 0.05mS / cm, 0.1mS / cm, 0.5mS / cm or 1mS / cm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0022] As a preferred technical solution in the present invention, the ionic conductivity of the conductive connecting layer after being infiltrated with the electrolyte is greater than 0.1mS / cm, for example, 0.15mS / cm, 0.2mS / cm, 0.3mS / cm, 0.4mS / cm, 0.5mS / cm, 0.6mS / cm, 0.7mS / cm, 0.8mS / cm, 0.9mS / cm, 1mS / cm, 1.3mS / cm, 1.5mS / cm or 2mS / cm, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0023] In a second aspect, the utility model further provides a lithium-ion battery, wherein the lithium-ion battery comprises the lithium-supplemented positive electrode plate as described in the first aspect.

[0024] Compared with the prior art, the beneficial effects of the utility model are:

[0025] The lithium-supplementing positive electrode plate provided by the utility model selects a conventional metal lithium layer as the lithium-supplementing layer. The ion transport layer not only plays the role of transmitting lithium ions, but also can separate the metal lithium layer from the positive electrode active material layer, thereby avoiding direct contact between the metal lithium in the metal lithium layer and the positive electrode active material layer, thereby causing a short circuit. Moreover, the existence of the ion transport layer can also avoid side reactions caused by the activity of the metal lithium. The ion transport layer and the positive electrode active material layer are bonded together, which can effectively prevent thermal runaway, improve the thermal stability of the battery, and avoid the influence on the cycle. The conductive connection layer is in direct contact with the current collector to realize electronic conduction. Through the joint action of the current collector, the positive electrode active material layer, the ion transport layer, the metal lithium layer and the conductive connection layer, the metal lithium and the positive electrode are connected inside the battery. In the micro-battery of the positive electrode, as the formation proceeds, lithium ions are released from the positive electrode, the potential of the positive electrode increases, the micro-battery formed by the metallic lithium and the positive electrode discharges automatically, and the lithium ions are replenished into the positive electrode, thereby realizing the overall lithium replenishment of the battery; at the same time, the electronic conductivity of the conductive connection layer can be regulated by selecting conductive agents with different conductive properties or adjusting the content of the conductive agent in the conductive connection layer, thereby adjusting the lithium replenishment rate, preventing the destruction of the positive electrode active material layer caused by excessively fast lithium replenishment during the lithium replenishment process, thereby controlling the temperature rise during the lithium replenishment process and improving the process safety; that is, in the utility model, the effective lithium replenishment of the positive terminal can be realized, and the safety problems such as short circuit caused by the dissolution of the positive terminal metal can be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic structural diagram of a lithium-supplemented positive electrode plate provided in a specific embodiment of the utility model.

[0027] Among them, 1 is current collector, 2 is positive electrode active material layer, 3 is ion transport layer, 4 is metal lithium layer, and 5 is conductive connection layer. DETAILED DESCRIPTION

[0028] It should be understood that, in the description of the present utility model, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present utility model, unless otherwise specified, "multiple" means two or more.

[0029] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0030] Those skilled in the art should understand that the present invention necessarily includes necessary pipelines, conventional valves and general pump equipment for realizing a complete process, but the above content does not belong to the main invention point of the present invention. Those skilled in the art can add layouts on their own based on the process flow and equipment structure selection, and the present invention does not make special requirements and specific limitations on this.

[0031] The technical solution of the utility model is further explained below with reference to the accompanying drawings and through specific implementation methods.

[0032] In a specific embodiment, Figure 1 As shown, the utility model provides a lithium-supplemented positive electrode plate, and the lithium-supplemented positive electrode plate comprises:

[0033] current collector 1;

[0034] Along the direction from close to the current collector 1 to far away from the current collector 1, at least one side of the current collector 1 is stacked with a positive electrode active material layer 2, an ion transport layer 3, a metal lithium layer 4 and a conductive connection layer 5;

[0035] The two ends of the conductive connection layer 5 are connected to the current collector 1 to form a closed structure.

[0036] As a preferred technical solution in a specific implementation, the thickness of the metal lithium layer 4 is 1 to 10 μm.

[0037] Furthermore, the thickness of the ion transport layer 3 is 0.5-5 μm.

[0038] As a preferred technical solution in a specific implementation, the electronic conductivity of the ion transport layer 3 is less than 0.001 mS / cm, and at the same time, the ion conductivity of the ion transport layer 3 after being infiltrated with the electrolyte is greater than 0.1 mS / cm.

[0039] As a preferred technical solution in a specific implementation, the conductive connection layer 5 is composed of 80-99% by mass of conductive material and 1-20% by mass of adhesive; specifically, the thickness of the conductive connection layer 5 is 1-10 μm.

[0040] As a preferred technical solution in a specific implementation, the electronic conductivity of the conductive connection layer 5 is greater than 0.0001 mS / cm and the ionic conductivity of the conductive connection layer 5 after being infiltrated with the electrolyte is greater than 0.1 mS / cm.

[0041] It should be noted that in the present invention, the specific materials and proportions in the current collector, positive electrode active material layer, ion transport layer, metal lithium layer and conductive connection layer are not particularly limited. The present invention is applicable to any material that can achieve the above-mentioned effects.

[0042] In some embodiments, the positive electrode current collector is not particularly limited as long as it has conductivity and does not cause chemical changes in the battery. Specifically, a metal current collector such as aluminum foil, carbon-coated aluminum foil, composite aluminum foil, etc. can be used.

[0043] The positive electrode active material layer includes a positive electrode active material, a conductive agent, and a binder.

[0044] In some embodiments, the positive electrode active material includes, but is not limited to, one or more of lithium iron phosphate, lithium iron manganese phosphate, lithium cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium manganese oxide, and lithium-rich positive electrode materials.

[0045] In some embodiments, the binder includes but is not limited to 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.

[0046] In some embodiments, the conductive agent 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, etc. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, poly (3,4 ethylenedioxythiophene) polystyrene sulfonate, etc.

[0047] In some embodiments, the material in the ion transport layer includes any one or a combination of at least two of a compound containing X, a solid electrolyte material, or a diaphragm material, wherein X includes any one or a combination of at least two of Al, Si, Ti, Zn, Mg, Zr, Ca, or Ba.

[0048] In some embodiments, the X-containing compound includes any one of an oxide of element X, a nitride of element X, or a halide of element X, or a combination of at least two thereof.

[0049] Specifically, the halide of element X includes one or more of fluoride of element X, chloride of element X, bromide of element X and iodide of element X, preferably fluoride of element X.

[0050] As an example, the ion transport layer material can be selected from one or more of Al oxide (such as Al2O3, AlO(OH), etc.), Al nitride, Al fluoride, Si oxide, Si nitride, Si fluoride, Ti oxide, Ti nitride, Ti fluoride, Zn oxide, Zn nitride, Zn fluoride, Mg oxide, Mg nitride, Mg fluoride, Zr oxide, Zr nitride, Zr fluoride, Ca oxide, Ca nitride, Ca fluoride, Ba oxide, Ba nitride and Ba fluoride.

[0051] In some embodiments, when the ion transport layer material is selected from a solid electrolyte material, the ion transport layer further includes a lithium salt.

[0052] When a solid electrolyte material is selected as the ion transport layer material, it can act as both an ion conductor and an electrical insulator.

[0053] The present invention does not specifically limit the types of solid electrolyte materials, which include but are not limited to polymer solid electrolytes, oxide solid electrolytes, sulfide solid electrolytes, etc.

[0054] Exemplarily, the polymer solid electrolyte includes, but is not limited to, at least one of polyvinyl chloride (PVC), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), and polyethylene oxide (PEO).

[0055] The oxide solid electrolyte may comprise one or more garnet ceramics, LISICON-type oxides, NASICON-type oxides, and perovskite ceramics.

[0056] For example, one or more garnet ceramics may be selected from the group consisting of: Li 6.5 La3Zr 1.75 Te 0.25 O 12 , Li7La3Zr2O 12 , Li 6.2 Ga 0.3 La 2.95 Rb 0.05 Zr2O 12 , Li 6.8 5La 2.9 Ca 0.1 Zr 1.75 Nb 0.25 O 12 and combinations thereof. One or more LISICON-type oxides may be selected from the group consisting of: Li 14 Zn(GeO4)4, Li 3+x (P 1-x Si x )O4 (where 0 < x < 1), Li 3+x Ge x V 1-x O4 (where 0 < x < 1) and combinations thereof. One or more NASICON-type oxides may be defined by LiMM′(PO4)3, where M and M′ are independently selected from Al, Ge, Ti, Sn, Hf, Zr, and La. One or more NASICON-type oxides may be selected from the group consisting of: Li 1.3 Al 0.3 Ti 1.7 (PO4)3, LiTi2(PO4)3, LiGeTi(PO4)3, LiGe2(PO4)3, LiHf2(PO4)3, and combinations thereof. One or more perovskite ceramics may be selected from the group consisting of: Li 3.3 La 0.53 TiO3, LiSr 1.65 Zr 1.3 Ta 1.7 O9, Li 2x-y Sr 1-x Ta y Zr 1-y O3 (where x = 0.75y and 0.60 < y < 0.75) and combinations thereof.

[0057] The sulfide solid electrolyte may include one or more sulfide-based materials selected from the group consisting of: 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 11.7 O 0.3 、Li6PS5X (wherein X is Cl, Br or I), Li7P2S8I, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 、(1-x)P2S 5-x Li2S (wherein 0.5≤x≤0.7) and combinations thereof.

[0058] The lithium salt includes, but is not limited to, at least one of lithium perchlorate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(trifluoromethylsulfonyl)imide, lithium trifluoromethylsulfonate, lithium difluorooxalatoborate, and lithium bis(oxalatoborate).

[0059] In some embodiments, when the ion transport layer is a membrane, the membrane can be selected from polyethylene membrane, polypropylene membrane, polyvinylidene fluoride membrane and a multilayer composite membrane composed of at least two of polyethylene (PE), polypropylene (PP) and polyvinylidene fluoride (PVDF) materials.

[0060] In some embodiments, the material in the metal lithium layer includes any one of metal lithium, lithium silicon alloy, lithium aluminum alloy, lithium boron alloy or lithium magnesium alloy, or a combination of at least two thereof.

[0061] The material in the above-mentioned metal lithium layer can be in the form of a sheet layer, a foil or a film layer.

[0062] In some embodiments, the conductive connecting layer includes a conductive material and a binder.

[0063] The specific substance of the conductive material provided in the present invention is not particularly limited, as long as it has conductivity and does not cause chemical changes.

[0064] Exemplarily, the conductive material may include graphite, such as natural graphite or artificial graphite; carbon-based 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 preferably includes carbon black from the aspect of improving conductivity.

[0065] The conductive material accounts for 80-99% by weight of the conductive connection layer.

[0066] In the utility model, by selecting conductive agents with different conductive properties or adjusting the content of the conductive agent in the conductive connecting layer, the electronic conductivity of the conductive connecting layer is regulated, thereby adjusting the lithium replenishment rate, and further controlling the temperature rise of the lithium replenishment process, thereby improving process safety.

[0067] It should also be noted that the preparation method of the lithium-supplemented positive electrode plate in the present invention is a conventional technical means, and the preparation method can be adaptively adjusted according to the type of material selected in each structure.

[0068] In an application example, the utility model further provides a lithium-ion battery, which includes the lithium-supplemented positive electrode plate provided in the above specific embodiment.

[0069] The lithium-ion battery provided by the utility model includes, in addition to the lithium-supplemented positive electrode plate provided in the above specific implementation manner, a diaphragm, an electrolyte and a negative electrode plate.

[0070] The above-mentioned diaphragm, electrolyte and negative electrode plate are all selected by conventional technology.

[0071] The negative electrode plate comprises a negative electrode active material, a conductive agent and a binder.

[0072] In some embodiments, the negative electrode is a silicon-based negative electrode active material, which includes 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 includes 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 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).

[0073] The shape of the negative electrode current collector includes a foil shape, a plate shape, a grid shape, and the like.

[0074] The negative electrode current collector includes any one of aluminum, copper, nickel or zinc.

[0075] In some embodiments, the separator includes, but is not limited to, a polyethylene film, a polypropylene film, a polyvinylidene fluoride film, and a multilayer composite film composed of the above materials.

[0076] In some embodiments, the electrolyte includes an electrolyte salt and a solvent. The electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate and lithium tetrafluorooxalate phosphate. The solvent may be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl 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, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone. In some embodiments, the electrolyte may also optionally include an additive. The additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0077] In some embodiments, the organic solvent is selected from any one or a combination of two or more of acetone, acetonitrile, tetrahydrofuran, N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, anisole, pyridine, methanol, and ethylene glycol.

[0078] Example 1

[0079] This embodiment provides a lithium-supplemented positive electrode plate. The lithium-supplemented positive electrode plate provided by the above specific embodiment of the substrate:

[0080] The lithium-supplemented positive electrode includes:

[0081] current collector 1;

[0082] Along the direction from close to the current collector 1 to far away from the current collector 1, at least one side of the current collector 1 is stacked with a positive electrode active material layer 2, an ion transport layer 3, a metal lithium layer 4 and a conductive connection layer 5;

[0083] The two ends of the conductive connection layer 5 are connected to the current collector 1 to form a closed structure.

[0084] The thickness of the ion transport layer 3 is 3 μm, the thickness of the metal lithium layer 4 is 5 μm, and the thickness of the conductive connection layer 5 is 5 μm.

[0085] The preparation method of the lithium-supplemented positive electrode plate is as follows:

[0086] (1) Obtaining a positive electrode active material layer:

[0087] The positive electrode slurry is obtained by mixing and stirring the positive electrode active material lithium iron phosphate, the conductive agent (superP), the binder sodium carboxymethyl cellulose (CMC) and the solvent N-methyl pyrrolidone, wherein the total mass of the positive electrode active material, the conductive agent and the binder is 100%, the mass content of the positive electrode active material is 95%, the content of the conductive agent is 3%, and the content of the binder is 2%; the positive electrode slurry is evenly coated on one side of the positive electrode current collector composite aluminum foil, and then dried, cold pressed, and cut to form a positive electrode active material layer;

[0088] (2) rolling a layer of LiTi2(PO4)3 solid electrolyte membrane as an ion transport layer on the surface of the positive electrode active material layer, and then pressing a layer of lithium aluminum alloy sheet on the surface of the ion transport layer to form a metal lithium layer;

[0089] The conductive connecting layer is a mixture of 90% conductive material (polyaniline) and 10% binder polyvinylidene fluoride (PVDF). The conductive connecting layer is pressed on the surface of the metal lithium layer, and the two ends of the conductive connecting layer are adhered to the composite aluminum foil to form a lithium-supplemented positive electrode plate.

[0090] Example 2

[0091] This embodiment provides a lithium-supplemented positive electrode plate. The lithium-supplemented positive electrode plate provided by the above specific embodiment of the substrate:

[0092] The lithium-supplemented positive electrode includes:

[0093] current collector 1;

[0094] Along the direction from close to the current collector 1 to far away from the current collector 1, at least one side of the current collector 1 is stacked with a positive electrode active material layer 2, an ion transport layer 3, a metal lithium layer 4 and a conductive connection layer 5;

[0095] The two ends of the conductive connection layer 5 are connected to the current collector 1 to form a closed structure.

[0096] The thickness of the ion transport layer 3 is 0.5 μm, the thickness of the metal lithium layer 4 is 1 μm, and the thickness of the conductive connection layer 5 is 1 μm.

[0097] The rest of the preparation methods and parameters were the same as those in Example 1.

[0098] Example 3

[0099] This embodiment provides a lithium-supplemented positive electrode plate. The lithium-supplemented positive electrode plate provided by the above specific embodiment of the substrate:

[0100] The lithium-supplemented positive electrode includes:

[0101] current collector 1;

[0102] Along the direction from close to the current collector 1 to far away from the current collector 1, at least one side of the current collector 1 is stacked with a positive electrode active material layer 2, an ion transport layer 3, a metal lithium layer 4 and a conductive connection layer 5;

[0103] The two ends of the conductive connection layer 5 are connected to the current collector 1 to form a closed structure.

[0104] The thickness of the ion transport layer 3 is 5 μm, the thickness of the metal lithium layer 4 is 10 μm, and the thickness of the conductive connection layer 5 is 10 μm.

[0105] The rest of the preparation methods and parameters were the same as those in Example 1.

[0106] In summary, in the lithium-replenishing positive electrode plate provided by the utility model, a metal lithium layer is used for lithium replenishment, and at the same time, an ion transport layer and a conductive connection layer are coordinated to avoid the occurrence of side reactions and improve the lithium replenishment effect and safety performance.

[0107] The applicant declares that the above is only a specific implementation method of the present utility model, but the protection scope of the present utility model is not limited thereto. The technicians in the relevant technical field should understand that any changes or substitutions that can be easily thought of by the technicians in the relevant technical field within the technical scope disclosed in the present utility model fall within the protection scope and disclosure scope of the present utility model.

Claims

1. A lithium-supplemented positive electrode plate, characterized in that: The lithium-supplemented positive electrode plate comprises: current collector; Along the direction from close to the current collector to far away from the current collector, at least one side of the current collector is stacked with a positive electrode active material layer, an ion transport layer, a metal lithium layer and a conductive connection layer; Wherein, two ends of the conductive connection layer are connected to the current collector to form a closed structure.

2. The lithium-supplemented positive electrode plate according to claim 1, characterized in that: The thickness of the metal lithium layer is 1 to 10 μm.

3. The lithium-supplemented positive electrode plate according to claim 1, characterized in that: The thickness of the ion transport layer is 0.5-5 μm.

4. The lithium-supplemented positive electrode plate according to claim 1, characterized in that: The electronic conductivity of the ion transport layer is less than 0.001 mS / cm.

5. The lithium-supplemented positive electrode plate according to claim 4, characterized in that: The ion conductivity of the ion transport layer after being infiltrated with electrolyte is greater than 0.1 mS / cm.

6. The lithium-supplemented positive electrode plate according to claim 1, characterized in that: The thickness of the conductive connection layer is 1-10 μm.

7. The lithium-supplemented positive electrode plate according to claim 1, characterized in that: The electronic conductivity of the conductive connection layer is greater than 0.0001 mS / cm.

8. The lithium-supplemented positive electrode plate according to claim 7, characterized in that: The ionic conductivity of the conductive connection layer after being infiltrated with electrolyte is greater than 0.1 mS / cm.

9. A lithium ion battery, characterized in that: The lithium-ion battery comprises the lithium-supplemented positive electrode plate as described in any one of claims 1 to 8.

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