A battery activator and its preparation method, an activation film, a negative electrode, a battery, a battery pack, and electrical equipment thereof.

Abstract

This invention provides a battery activator and its preparation method, an activation film, a negative electrode, a battery, a battery pack, and an electrical device. The battery activator includes a shell and a slow-release material encapsulated within the shell. The slow-release material includes additives required for forming an SEI film. The shell includes a first polymer layer adjacent to the slow-release material and a second polymer layer away from the slow-release material. The first polymer layer includes a plurality of first micropores, and the second polymer layer includes a plurality of second micropores. The second polymer layer includes a cross-linked polymer formed by cross-linking C-C unsaturated polymers. The pore size of the first micropores is not greater than 0.2 μm, and the pore size of the second micropores is not less than 0.5 μm. The battery activator of this invention can continuously provide the additives required for forming an SEI film in the battery cell, thereby ensuring the capacity utilization and cycle stability of the battery cell.

Description

Technical Field

[0001] This invention relates to the field of batteries, and more particularly to a battery activator and its preparation method, an activation film, a negative electrode sheet, a battery, a battery pack, and electrical equipment. Background Technology

[0002] The solid electrolyte interphase (SEI) membrane is a critical protective layer in lithium-ion batteries, typically formed between the negative electrode material (such as graphite) and the electrolyte. The stability and integrity of the SEI membrane are crucial to the battery's performance and lifespan. As the battery is cycled, the SEI membrane may be damaged or decomposed, leading to a decline in battery performance.

[0003] To form an SEI film, specific additives, such as vinylene carbonate (VC), are usually added to the electrolyte. In order to continuously repair the damaged or decomposed SEI film, the current conventional method is to increase the content of specific additives. However, excessively high content of specific additives will increase the viscosity of the electrolyte, resulting in uneven lithium intercalation in the cell and increased internal resistance of the battery. Summary of the Invention

[0004] This invention provides a battery activator that can continuously provide the additives required for the formation of the SEI film in the battery cell, and can always maintain the concentration of the additives within a certain range, avoiding the difficulty and unevenness of lithium-ion diffusion caused by excessive additive content, thereby ensuring the capacity utilization and cycle stability of the battery cell.

[0005] The present invention also provides a method for preparing a battery activator, which can prepare the battery activator and is simple to operate.

[0006] The present invention also provides an activation membrane that can be combined with a negative electrode, a separator, etc., thereby further improving the uniformity of the distribution of additives required to form the SEI film in the battery cell, ensuring good capacity performance while the battery cell has long cycle life.

[0007] The present invention also provides a negative electrode sheet. Since the surface of the negative electrode sheet includes the above-mentioned activation film, the negative electrode sheet can improve the uniformity of the distribution of additives required to form the SEI film in the cell and maintain the stability of the SEI film, thereby ensuring long cycle life and capacity utilization of the cell.

[0008] The present invention also provides a separator, which, since it includes the above-mentioned activated membrane, can improve the uniformity of the distribution of additives required to form the SEI film in the cell and maintain the stability of the SEI film, thereby ensuring the long cycle life and capacity utilization of the cell.

[0009] The present invention also provides a battery that, since it includes the above-mentioned negative electrode and / or the activated membrane, has advantages such as long cycle life and good capacity utilization.

[0010] The present invention also provides a battery pack, which, because it includes the above-mentioned battery, has good electrical performance and stable cycle life.

[0011] The present invention also provides an electrical device that, since includes the above-mentioned solid-state battery or battery pack, has good electrical performance and a long service life.

[0012] In detail, in a first aspect, the present invention provides a battery activator, comprising a shell and a slow-release material encapsulated within the shell; the slow-release material comprises additives required for forming an SEI film; the shell comprises a first polymer layer adjacent to the slow-release material and a second polymer layer distant from the slow-release material, the first polymer layer comprising a plurality of first micropores, the second polymer layer comprising a plurality of second micropores, the second polymer layer comprising a cross-linked polymer formed by cross-linking of a CC unsaturated polymer, the pore size of the first micropores being no greater than 0.2 μm, and the pore size of the second micropores being no less than 0.5 μm.

[0013] Furthermore, the sustained-release material is in a semi-gel or gel state;

[0014] And / or, and / or, the pore size of the first micropore is 0.001μm-0.2μm, and the pore size of the second micropore is 0.5μm-1μm.

[0015] Furthermore, the additives required to form the SEI film include at least one of vinylene carbonate, propane sulpholactone, methyl methane disulfide, ethylene ethylene carbonate, and fluoroethylene carbonate.

[0016] And / or, the additive accounts for 50%-70% of the weight of the sustained-release material.

[0017] Further, the first polymer layer includes a polymer substrate and a first additive, wherein the polymer substrate includes at least one of polypropylene, polyvinylbenzene, and polycarbonate; and the first additive includes at least one of sulfonic acid polymer, phosphate polymer, and silicon-alkoxy polymer.

[0018] Furthermore, the second polymer layer comprises the hydrophobic crosslinked polymer, a second additive, and / or a third additive, wherein the second additive comprises isocyanate polymers and / or epoxy ester polymers, and the third additive is a silicone-alkoxy polymer.

[0019] Furthermore, the structure of the silicon-based alkoxy polymer is as shown in Formula 1:

[0020]

[0021] R1 and R2 are each independently one of -OCH3, -N(CH3)CH3, and -NH-R3, and R3 is a C1-C20 alkyl group with n greater than 0.

[0022] Furthermore, the first additive accounts for 2%-5% of the weight of the polymer substrate.

[0023] Furthermore, the second additive accounts for 2%-5% of the weight of the crosslinked polymer;

[0024] And / or, the third additive accounts for 2%-5% of the weight of the crosslinked polymer.

[0025] Secondly, the present invention provides a method for preparing the above-mentioned battery activator, comprising the following steps:

[0026] 1) The additives and gelling agents required for forming the SEI film are mixed and treated to obtain a semi-gel or gel-state sustained-release material;

[0027] 2) The sustained-release material is added to a dispersion comprising a polymer substrate, a first additive, a dispersant, and a solvent, and the mixture is mixed to obtain a mixed system. The solvent in the mixed system is then evaporated to obtain a sustained-release material encapsulating a first polymer layer. The solid content of the mixed system is 30-40%, and the solvent evaporation rate is >2750 cm / h.

[0028] 3) The slow-release material encapsulating the first polymer layer is added to a dispersion comprising CC unsaturated polymer, a second additive and / or a third additive, a crosslinking curing agent, and a solvent, and a crosslinking reaction is carried out at 50℃-70℃ to obtain the battery activator.

[0029] Thirdly, the present invention provides an activation film formed from the battery activator described in the first aspect.

[0030] Fourthly, the present invention provides a negative electrode sheet, comprising a current collector and a negative electrode material layer and an activation film sequentially disposed on at least one surface of the current collector, wherein the activation film is the activation film described in the third aspect.

[0031] Fifthly, the present invention provides a separator, which is the activated membrane described in the third aspect; or, it includes a separator base layer and an activated membrane, wherein the activated membrane is disposed on the side of the separator base layer near the negative electrode sheet, and the activated membrane is the activated membrane described in the third aspect.

[0032] In a sixth aspect, the present invention provides a battery comprising the negative electrode sheet described in the fourth aspect; and / or the separator described in the fifth aspect.

[0033] In a seventh aspect, the present invention provides a battery pack comprising the battery described in the sixth aspect.

[0034] Eighthly, the present invention provides an electrical device comprising the battery described in the sixth aspect or the battery pack described in the seventh aspect.

[0035] The battery activator provided by this invention can continuously provide the additives required for the formation of the SEI film in the battery cell, and can always maintain the additive concentration in the electrolysis within a certain range, avoiding the difficulty and unevenness of lithium ion diffusion caused by excessive additive content, thereby ensuring the capacity utilization and cycle stability of the battery cell. Attached Figure Description

[0036] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0037] Figure 1 This is a schematic diagram of the structure of a battery according to a specific embodiment of the present invention;

[0038] Figure 2 The diagrams show the interfaces of different battery cells. Specifically, a is the interface diagram of the battery cell prepared in Application Example 1, b is the interface diagram of the battery cell prepared in Application Example 1 using the battery activator of Example 1, c is the interface diagram of the battery cell prepared in Application Example 2 using the battery activator of Example 1, and d is the interface diagram of the battery cell prepared in Application Example 3 using the battery activator of Example 1.

[0039] Figure 3 Comparison chart of the cycle performance of the battery cell prepared in Application Example 1, the battery cell prepared in Application Example 1 using the battery activator of Example 1, the battery cell prepared in Application Example 2 using the battery activator of Example 1, and the battery cell prepared in Application Example 3 using the battery activator of Example 1. Detailed Implementation

[0040] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] In a first aspect, the present invention provides a battery activator, comprising a shell and a slow-release material encapsulated within the shell; the shell comprises a first polymer layer adjacent to the slow-release material and a second polymer layer distant from the slow-release material, the first polymer layer comprising a plurality of first micropores, the second polymer layer comprising a plurality of second micropores, the second polymer layer comprising a cross-linked polymer formed by cross-linking of a CC unsaturated polymer, the pore size of the first micropores being no greater than 0.2 μm, and the pore size of the second micropores being no less than 0.5 μm.

[0042] The battery activator provided by this invention can continuously provide the additives required for SEI film formation in the battery cell, and can always maintain the concentration of the additives within a certain range. This avoids the difficulties and unevenness in lithium-ion diffusion caused by excessive additive content. Furthermore, this structure ensures that there is always a uniform VC content at all positions on the electrode surface, preventing accelerated cell degradation due to uneven VC, thereby ensuring the capacity and cycle stability of the battery cell. The main reasons include: the slow-release material can provide the additives required for SEI film formation in the battery cell; the first polymer layer is the first barrier for the slow-release material's slow release, its pore size only allowing the additives in the slow-release material to enter and exit; while the molecules in the electrolyte are large molecules existing in a solvated structure and cannot pass through the first polymer layer; the second polymer layer is the second barrier for the slow-release material's slow release. After flowing out from the first polymer layer and then through the second polymer layer, the slow-release material can achieve long-term slow release, thus maintaining the additives in the electrolyte within a specific concentration range and avoiding the diffusion difficulties and unevenness caused by high additive content. Furthermore, traditional additives are generally dispersed in the electrolyte, and the additives are very likely to be mainly distributed at the bottom of the cell or on the outermost aluminum-plastic film of the electrode core, without diffusing into the middle of the electrode sheet. This results in uneven current distribution in the cell and makes the cell prone to central cracking. However, since the second polymer layer of this invention includes a cross-linked polymer, the battery activator of this invention can be stretched into a film and used directly as a separator or adhered to the separator or negative electrode sheet, thereby ensuring the uniform distribution of additives in the cell and further extending the battery's service life.

[0043] In an optional embodiment, the sustained-release material is in a semi-gel or gel state. The semi-gel or gel-state sustained-release material can serve as a third barrier for controlling the release rate of the sustained-release material, thereby further ensuring that the concentration of the additive remains within a certain range and achieving long-term sustained release of the additive.

[0044] In an optional embodiment, the pore size of the first micropore is 0.001 μm-0.2 μm, and the pore size of the second micropore is 0.5 μm-1 μm.

[0045] For example, the pore size of the first micropore is 0.001μm, 0.002μm, 0.005μm, 0.007μm, 0.01μm, 0.02μm, 0.03μm, 0.04μm, 0.05μm, 0.06μm, 0.07μm, 0.08μm, 0.09μm, 0.1μm, 0.12μm, 0.15μm, 0.16μm, 0.17μm, 0.18μm, 0.19μm, 0.2μm, etc., or any two of them, and the pore size of the second micropore is 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, etc., or any two of them, etc.

[0046] In an optional embodiment, the additives required to form the SEI film include at least one of vinylene carbonate (VC), propane sulpholactone (PS), methylene disulfide (MMDS), ethylene ethylene carbonate (VEC), and fluoroethylene carbonate (FEC).

[0047] And / or, the additive accounts for 50%-70% of the weight of the sustained-release material.

[0048] In some embodiments, the sustained-release material comprises additives required to form an SEI film and a gelling agent, wherein the gelling agent includes at least one of ethylene carbonate, gelatin, agar, etc.

[0049] In an optional embodiment, the first polymer layer includes a polymer substrate and a first additive, wherein the polymer substrate includes at least one of polypropylene, polystyrene, and polycarbonate; and the first additive includes at least one of sulfonic acid polymers, phosphate polymers, and silicone-alkoxy polymers.

[0050] In this embodiment, the first additive can continue to perform its SEI film repair function after the additives in the slow-release material are consumed. This is because sulfonic acid and phosphate polymers can reduce the sulfonate and phosphate groups that form the SEI film, thereby repairing the SEI film. Silicon-alkoxy polymers, on the other hand, have a high reduction potential. In the presence of the slow-release material, they do not directly reduce the main components constituting the SEI film. However, they can reduce the rupture and regeneration of the SEI film at the negative electrode material interface caused by moisture or acidity in the battery cell by adsorbing moisture or acidity, thereby improving the cycle stability of the battery. Furthermore, since the reduction potentials of sulfonic acid polymers, phosphate polymers, and silicon-alkoxy polymers are lower than those of the additives in the slow-release material, they will not be reduced during the normal slow-release period of the slow-release material and can remain stable.

[0051] In an optional embodiment, the second polymer layer comprises the hydrophobic crosslinked polymer, a second additive, and / or a third additive, wherein the second additive comprises isocyanate polymers and / or epoxy ester polymers, and the third additive is a silicone-alkoxy polymer.

[0052] The hydrophobic crosslinked polymer can make the battery activator of the above embodiments more suitable for lithium-ion batteries, and the second additive has a water removal function, which helps to remove a small amount of water in the lithium-ion battery, thereby further enhancing the life of the cell. The third additive can continue to play the repair function of the SEI film after the additive in the slow-release material is consumed.

[0053] In an alternative embodiment, the structure of the silicon-based alkoxy polymer is as shown in Formula 1:

[0054]

[0055] R1 and R2 are each independently one of -OCH3, -N(CH3)CH3, and -NH-R3, and R3 is a C1-C20 alkyl group with n greater than 0.

[0056] In some embodiments, n is any value from 1 to 200, any value from 2 to 100, any value from 5 to 50, and more specifically, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, etc.

[0057] In some embodiments, the method for preparing the silicon-based alkoxy polymer includes the following steps:

[0058] In a vacuum or rare gas atmosphere, polydimethylsiloxane, tetramethoxysiloxane, monomethylamine, etc. are mixed at a mass ratio of 1:1.5 and reacted at about 100°C. After vacuum stirring for 30 minutes, water is added, and after stirring and separating into layers, the upper layer product is taken, which is the silicon-based alkoxy polymer.

[0059] In an optional embodiment, the first additive accounts for 5%-8% of the weight of the polymer substrate.

[0060] In an optional embodiment, the second additive accounts for 3%-5% of the weight of the crosslinked polymer; and / or, the third additive accounts for 2%-5% of the weight of the crosslinked polymer.

[0061] The second additive has the effect of adsorbing moisture and acidity; however, its content should not be too high. If the content is too high, it may cause a decrease in the content of cross-linked structure and damage to the pore structure of the activator in the later stage of the cycle.

[0062] In some embodiments, the degree of crosslinking of the CC unsaturated polymer is >80%; and / or, the sustained release rate of the battery activator is 1 to 1000 μg / day.

[0063] The sustained release rate can meet the continuous repair of the SEI membrane during the cyclic process by continuous VC. The degree of crosslinking of the CC unsaturated polymer can be obtained by calculation, for example: degree of crosslinking = m(crosslinking agent + mass of crosslinked additive) / m(amount of crosslinking agent + amount of additive).

[0064] In a first aspect, the present invention provides a method for preparing the above-mentioned battery activator, comprising the following steps:

[0065] 1) The additives and gelling agents required for forming the SEI film are mixed and treated to obtain a semi-gel or gel-state sustained-release material;

[0066] 2) The sustained-release material is added to a dispersion comprising a polymer substrate, a first additive, a dispersant, and a solvent, and the mixture is mixed to obtain a mixed system. The solvent in the mixed system is then evaporated to obtain a sustained-release material encapsulating a first polymer layer. The solid content of the mixed system is 30-40%, and the evaporation rate of the solvent is >2750 cm / h.

[0067] 3) The slow-release material encapsulating the first polymer layer is added to a dispersion comprising CC unsaturated polymer, a second additive and / or a first additive crosslinking curing agent and a solvent, and a crosslinking reaction is carried out at 50℃-70℃ to obtain the battery activator.

[0068] The evaporation rate of the solvent is the vacuum evaporation rate; in some embodiments, the evaporation rate of the solvent is 2800-3000 cm / h (vacuum evaporation rate).

[0069] In some embodiments, the content of the first additive is 1 to 3%, and the first additive can assist in the pore formation of the first polymer layer.

[0070] For example, the gelling agent can be any substance that makes the additive into a semi-gel state, including but not limited to: ethylene carbonate, gelatin, agar, etc.; the dispersant includes but is not limited to: sodium methylene cellulose, triethylhexyl phosphate, sodium dodecyl sulfate, etc.; the solvents in steps 2) and 3) can be the same or different, preferably volatile solvents, including but not limited to: dichloromethane, ethanol, etc.; the crosslinking curing agent is any curing agent that can accelerate the crosslinking of CC unsaturated polymers, including but not limited to: polyamide crosslinking curing agents, aliphatic amine crosslinking curing agents, aromatic amine crosslinking curing agents, etc.

[0071] The time of the crosslinking reaction is not particularly limited in this invention. Those skilled in the art can adjust it according to the degree of crosslinking. For example, when the mass of the CC unsaturated polymer is 100g, the temperature of the crosslinking reaction is 50-70℃ and the time is 48h.

[0072] The amount of the crosslinking curing agent added is not particularly limited in this invention. Those skilled in the art can adjust it according to the required crosslinking rate. For example, the crosslinking curing agent accounts for 20%-40% of the mass of the CC unsaturated polymer.

[0073] Thirdly, the present invention provides an activation film formed from the battery activator described in the first aspect.

[0074] In some embodiments, the activated membrane is prepared by the following process:

[0075] An appropriate amount of battery activator is added to a high-speed mixer for stirring, and the resulting material is calendered using an electric heated roller press to prepare the activated film.

[0076] For example, the high-speed mixer has a rotational speed of 200-1000 r / min and a mixing time of 1 h-5 h; during the calendering process, the gap width between the two hot press rollers is 1-500 μm, the roller speed is 1.0 m / min to 5 m / min, and the roller temperature is 40-80℃.

[0077] Furthermore, the thickness of the activated membrane can be adjusted by adjusting the parameters of the calendering process. In one specific embodiment, the thickness of the activated membrane is 100-150 μm.

[0078] Fourthly, the present invention provides a negative electrode sheet, comprising a current collector and a negative electrode material layer and an activation film sequentially disposed on at least one surface of the current collector, wherein the activation film is the activation film described in the first aspect.

[0079] For example, the thickness of the activated membrane can be 1-3 μm. If it is too thick, it will lead to an increase in cell impedance; if it is too thin, it may cause excessive compression and deformation of the semi-permeable membrane structure inside the cross-linked structure, or even cause an accelerated permeation rate.

[0080] It is understood that the aforementioned negative electrode material layer also includes a negative electrode active material and optionally a binder. The negative electrode active material is a variety of lithium-intercalation / deintercalation-capable negative electrode active materials commonly used by those skilled in the art. For example, it can be selected from one or more of carbon materials, tin alloys, silicon alloys, silicon, tin, and germanium. The carbon material can be non-graphitized carbon, graphite, or carbon or pyrolytic carbon, coke, organic polymer sintered materials, activated carbon, etc., obtained by high-temperature oxidation of polyyne-based polymer materials. When the negative electrode active material is a silicon-based material, the negative electrode coating also contains a conductive agent. The conductive agent is a material commonly used by those skilled in the art that can enhance electron transport. For example, it can be selected from at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotubes, metal powder, graphene, etc. The binder can be selected from at least one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polytetrafluoroethylene, polyacrylonitrile, polypropylene carbonate, styrene-butadiene rubber, nitrile rubber, sodium carboxymethyl cellulose, polyethylene oxide, and ethylene oxide-propylene oxide copolymer.

[0081] Fifthly, the present invention provides a separator, which is the activated membrane described in the third aspect; or, it includes a separator base layer and an activated membrane, wherein the activated membrane is disposed on the side of the separator base layer near the negative electrode sheet, and the activated membrane is the activated membrane described in the first aspect.

[0082] For example, when the activated membrane is used directly as a separator, the thickness of the activated membrane can be 1-15 μm. If it is too thick, it may lead to an increase in cell impedance; if it is too thin, it may cause excessive compression and deformation of the semi-permeable membrane structure inside the cross-linked structure, or even cause an increase in the permeation rate. When the activated membrane is used in combination with a conventional separator, the thickness of the activated membrane can be 1-5 μm. If it is too thick, it will lead to an increase in cell impedance; if it is too thin, it will cause excessive compression and deformation of the semi-permeable membrane structure inside the cross-linked structure, or even cause an increase in the permeation rate.

[0083] The present invention does not impose any particular limitation on the above-mentioned membrane base layer, and any known porous membrane base layer with electrochemical stability and chemical stability can be selected, such as at least one of glass fiber, non-woven fabric, polyethylene, polypropylene or polyvinylidene fluoride.

[0084] In a sixth aspect, the present invention provides a battery comprising the negative electrode sheet described in the fourth aspect or the separator described in the fifth aspect.

[0085] It should be noted that the above-mentioned battery may include, but is not limited to, single cell, battery module, battery pack, etc. That is, the actual application form of the battery provided by the present invention may be, but is not limited to, the listed products, or other application forms. When the battery is a single cell, it includes at least one of cylindrical battery, prismatic battery, etc.

[0086] In some embodiments, the battery includes a positive electrode sheet, a negative electrode sheet, and the separator described in the fifth aspect, and the schematic structural diagram thereof is shown in Figure 1 as follows.

[0087] It can be understood that the above positive electrode sheet includes a current collector and a positive electrode material layer sequentially provided on at least one surface of the current collector. The positive electrode material layer includes a positive electrode active material, a conductive agent, and optionally a binder. The positive electrode active material is selected from at least one of lithium cobalt oxide (LiCoO₂), lithium nickel oxide (LiNiO₂), lithium iron phosphate (LiFePO₄), lithium cobalt phosphate (LiCoPO₄), lithium manganese phosphate (LiMnPO₄), lithium nickel phosphate (LiNiPO₄), lithium manganate (LiMnO₂), binary material LiNi x A (1-x) O₂ (where A is selected from one of Co and Mn, 0 < x < 1), ternary material LiNimBnC (1-m-n) O₂ (where B and C are independently selected from at least one of Co, Al, and Mn, and B and C are different, 0 < m < 1, 0 < n < 1); the conductive agent is a material commonly used by those skilled in the art that can enhance the electron transport effect. For example, it can be selected from at least one of natural graphite, artificial graphite, carbon black, acetylene black, graphene, carbon fiber, carbon nanotube, and Ketjen black, etc.; the binder can be selected from at least one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polytetrafluoroethylene, polyacrylonitrile, polycarbonate propylene, styrene-butadiene rubber, nitrile rubber, sodium carboxymethyl cellulose, poly(ethylene oxide), ethylene oxide-propylene oxide copolymer, polyethylene, polypropylene, polyamideimide, polyvinyl alcohol, and sodium polyacrylate.

[0088] The thickness and surface density of the above positive electrode sheet and negative electrode sheet are not specifically limited in the present invention. However, in order to balance the battery capacity, cycle life, and energy density, in a specific embodiment, the thickness of the positive electrode sheet or the negative electrode sheet is 20 - 120 μm, specifically including but not limited to: 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, etc.; the surface density of the positive electrode sheet or the negative electrode sheet is 2 - 25 mg / cm 2 , specifically including but not limited to: 3.5 mg / cm 2 , 4 mg / cm 2 , 4.5 mg / cm 2 , 5 mg / cm 2 , 5.5 mg / cm 2 , 6 mg / cm 2 , 6.5 mg / cm 2 , 7 mg / cm 2 , 7.5 mg / cm 2 , 8 mg / cm 28.5 mg / cm 2 9mg / cm 2 9.5 mg / cm 2 mg / cm 2 10mg / cm 2 10.5 mg / cm 2 11mg / cm 2 11.5 mg / cm 2 12mg / cm 2 12.5 mg / cm 2 13mg / cm 2 13.5 mg / cm 2 14mg / cm 2 14.5 mg / cm 2 15mg / cm 2 16mg / cm 2 17mg / cm 2 18mg / cm 2 18mg / cm 2 19mg / cm 2 20mg / cm 2 21mg / cm 2 22mg / cm 2 23mg / cm 2 24mg / cm 2 25mg / cm 2 wait.

[0089] In a seventh aspect, the present invention provides a battery pack comprising the solid-state battery described in the sixth aspect.

[0090] Eighthly, the present invention provides an electrical device comprising the battery described in the sixth aspect or the battery pack described in the seventh aspect.

[0091] It should be noted that the aforementioned electronic devices can be any conventional device that requires electricity, such as, but not limited to, computers, electric vehicles, air conditioners, refrigerators, washing machines, microwave ovens, printers, fax machines, etc.

[0092] The present invention will be further described below with reference to specific embodiments:

[0093] The sources of some of the raw materials involved in the following experiments are shown in Table 1:

[0094] Table 1:

[0095] polypropylene CAS: 9003-07-0 42.0804 - polystyrene CAS: 9003-53-6 104.1491 - polycarbonate CAS:25037-45-0 290.311 - polyphosphate CAS: 5945-33-5 692.63 - Sulfonated styrene CAS: 9037-24-5 138.9911 - Polyacrylate CAS: 228863-31-8 1511.47994661331 287K styrene CAS:1321-74-0 104.14 295K Hexamethylene diisocyanate CAS:822-06-0 168.19 - m-phenylenediamine CAS: 108-45-2 108.14 -

[0096] In Table 1, "-" indicates that this parameter was not recorded.

[0097] Example 1

[0098] This example provides a battery activator, including a shell and a slow-release material encapsulated within the shell; the shell includes a first polymer layer adjacent to the slow-release material and a second polymer layer away from the slow-release material, the first polymer layer including a plurality of first micropores, the pore size of the first micropores being approximately 0.1 μm; the first polymer layer includes polypropylene and polyphosphate, wherein the mass ratio of polyphosphate to polypropylene is 3%;

[0099] The second polymer layer includes a plurality of second micropores, the pore size of which is approximately 0.5 μm; by mass percentage, the second polymer layer includes a cross-linked polymer formed by cross-linking CC unsaturated polymer polyacrylate (cross-linking degree > 80%), hexamethylene diisocyanate, and a silicone-alkoxy polymer; the mass ratio of hexamethylene diisocyanate to cross-linked polymer is 5%, and the mass ratio of silicone-alkoxy polymer to cross-linked polymer is 3%; the structure of the silicone-alkoxy polymer is shown in Formula 1, wherein R1 is -OCH3, R2 is -N(CH3)CH3, and n is 2.

[0100] The sustained-release material is in a semi-gel state and, by mass, comprises 75 parts of vinylene carbonate (VC) and 25 parts of ethylene carbonate (EC).

[0101] Its preparation method includes the following steps:

[0102] 1) In a nitrogen atmosphere, polydimethylsiloxane and monomethylamine are reacted at 100°C in a molar ratio of 1:1.5. After vacuum stirring for 30 min, water is added, and after stirring and separating into layers, the upper layer product is taken out, which is the silicon-based alkoxy polymer, for later use.

[0103] 2) The 75g and 25g of vinylene carbonate were stirred at 300 rpm / s for 1 hour to obtain a semi-gel-like sustained-release material.

[0104] 3) Mix 20g polypropylene, 5g polyphosphate, 10g divinyltriamine and 65g dichloromethane, add the slow-release material to the mixture to make the solid content of the mixture 30-40%, stir at 40°C for 3h, the volatilization rate of dichloromethane is >2750cm / h, after the dichloromethane has volatilized completely, wash the surface with alcohol to remove the residual vinylene carbonate, and obtain the slow-release material coated with the first polymer layer;

[0105] 4) Add the slow-release material encapsulating the first polymer layer obtained in step 3) to a dispersion comprising 30g polyacrylate, 5g m-phenylenediamine, 60g dimethyl carbonate, 3g hexamethylene diisocyanate and 2g silicone-alkoxy polymer, and stir for 12h at 50℃-70℃ to carry out a crosslinking reaction. After the reaction, remove the solvent and wash the surface with alcohol to remove the residual polyacrylate to obtain the battery activator.

[0106] Example 2

[0107] This example provides a battery activator, which is basically the same as that in Example 1, except that the first polymer layer does not contain polyphosphate ester; its preparation is in accordance with Example 1, and the pore size of the first micropore is 1nm to 10nm.

[0108] Example 3

[0109] This example provides a battery activator that is basically the same as that in Example 1, except that the second polymer layer does not contain hexamethylene diisocyanate; its preparation is the same as in Example 1.

[0110] Example 4

[0111] This example provides a battery activator that is basically the same as that in Example 1, except that the second polymer layer does not contain a silicon-based alkoxy polymer; its preparation is the same as that in Example 1.

[0112] Example 5

[0113] This example provides a battery activator, which is basically the same as Example 1, except that the sustained-release material is in a gel state. Its preparation is the same as in Example 1, except that in step 2), 75g of vinylene carbonate, 25g of EC and 10g of vinyltriamine are mixed and stirred at 300rpm / s for 1h to obtain a gel-state sustained-release material.

[0114] Comparative Example 1

[0115] This example provides a battery activator, including a casing and a slow-release material encapsulated within the casing; the casing is polystyrene, and the slow-release material is the same as in Example 1.

[0116] Its preparation method includes the following steps:

[0117] Polystyrene (PS) was dissolved in dichloromethane (DCM) to prepare a 25 mL dispersion (a). Additionally, a 250 mL aqueous solution (b) was prepared, comprising 5 wt% dichloroethylene (VC) and 0.5 wt% gelatin as a stabilizer. This dispersion (a) was added to the aqueous solution (b) to form an oil / water emulsion. The DCM was then evaporated to obtain capsules containing VC. These capsules were washed several times with distilled water to prepare the battery activator.

[0118] Comparative Example 2

[0119] The only difference from Example 1 is that the second polymer layer is not included.

[0120] Experimental Example 1

[0121] The preparation of the activated film using the battery activators of the above embodiments and comparative examples includes the following steps:

[0122] The battery activator is dispersed in dimethyl carbonate to obtain a slurry. The slurry is extruded at a high temperature of 70°C and rolled into a sheet of a certain thickness. The sheet is then stretched longitudinally or laterally to form an activation film of the required thickness.

[0123] Tests showed that the tensile strength of the 3μm thick activation film was ≥1500kgf.

[0124] Application Example 1

[0125] A series of negative electrode sheets are provided, each negative electrode sheet comprising a current collector and a negative electrode material layer and an activation film sequentially disposed on at least one surface of the current collector, wherein the activation film is an activation film prepared in Example 1 with a thickness of 1 μm.

[0126] The preparation of the above-mentioned negative electrode includes the following steps:

[0127] 100g of sodium carboxymethyl cellulose aqueous solution (sodium carboxymethyl cellulose accounts for 2wt% of deionized water) was added to 100g of artificial graphite and stirred under vacuum until a homogeneous and fluid slurry was formed. Then, 3g of styrene-butadiene latex was added and stirred under vacuum until a homogeneous and fluid negative electrode slurry was formed. The negative electrode slurry was uniformly coated onto both sides of an 8μm thick aluminum foil. The coated aluminum foil was baked in ovens at different temperature gradients and then dried in an oven at 120℃ for 8 hours. After that, the negative electrode sheet was obtained by rolling and slitting. The single-sided areal density of the negative electrode sheet was 220mg / cm³. 2 Compacted density: 1.5 g / cm³ 3 The activated membrane is then evenly stacked on the negative electrode sheet and lightly rolled (the hot pressing pressure of the upper and lower pressure plates is set within the range of 8900 kgf ± 100 kgf).

[0128] This example also provides a series of battery cells.

[0129] 1) Preparation of the positive electrode sheet: The positive electrode active materials LiFePO4, polyvinylidene fluoride, and acetylene black were mixed in a weight ratio of 95.7:0.96:1.91, and then PVDF slurry was added. The mixture was stirred under vacuum until a homogeneous and fluid positive electrode slurry was formed. The positive electrode slurry was uniformly coated onto an aluminum foil with a thickness of 13 μm. The coated aluminum foil was baked in ovens at different temperature gradients, and then dried in an oven at 120°C for 8 hours. After that, the positive electrode sheet was obtained by rolling and slitting. The single-sided areal density of the positive electrode sheet was 400 mg / cm³. 2 Compacted density: 2.4 g / cm³ 3 );

[0130] 2) Preparation of electrolyte: After mixing ethylene carbonate: dimethyl carbonate: ethyl methyl carbonate in a mass ratio of 2:2:3, add 5% vinylene carbonate (VC) and 13% lithium hexafluorophosphate (LiPF6) of the total electrolyte mass, and mix and stir to obtain the electrolyte.

[0131] 3) Each cell consists of one electrode core, and each electrode core consists of 7 positive electrode sheets prepared as described above, 8 negative electrode sheets prepared as described above, and 16 separators (ion exchange membranes).

[0132] Application Example 2

[0133] This example provides a series of separators, including a 12μm separator base layer and a 2μm activation membrane, wherein the activation membrane is disposed on the side of the separator base layer near the negative electrode, and the activation membrane is the activation membrane of Experimental Example 1 (see Table 2 for details).

[0134] The process of preparing a battery cell using the above-mentioned separator includes the following steps:

[0135] Preparation of the negative electrode sheet: Add 100g of sodium carboxymethyl cellulose aqueous solution (sodium carboxymethyl cellulose accounts for 2wt% of deionized water) to 100g of artificial graphite, and stir under vacuum until the mixture becomes a homogeneous and fluid slurry. Then add 3g of styrene-butadiene latex and stir under vacuum until the mixture becomes a homogeneous and fluid negative electrode slurry. Coat the negative electrode slurry evenly onto both sides of an 8μm thick aluminum foil. Bake the coated aluminum foil in ovens at different temperature gradients, then dry it in an oven at 120℃ for 8 hours. Finally, roll and slit the foil to obtain the negative electrode sheet. The single-sided areal density of the negative electrode sheet is 220mg / cm³. 2 Compacted density: 1.5 g / cm³ 3 ;

[0136] Example 1: Application of both positive electrode and electrolyte;

[0137] Each battery assembly consists of one electrode core, and each electrode core consists of 7 positive electrode sheets prepared as described above, 8 negative electrode sheets prepared as described above, and 16 separators (the separators consist of a 12μm ion exchange membrane and a 2μm activation membrane, wherein the activation membrane is disposed on the side of the ion exchange membrane close to the negative electrode sheet).

[0138] Application Example 3

[0139] The battery activator of Example 1 and Comparative Example 1 was directly added to the electrolyte. The negative electrode and separator did not contain the battery activator. The process of preparing the battery cell is described in Application Example 1.

[0140] Compare with application example 1

[0141] The battery cell is prepared using a negative electrode and a separator that do not include the activation membrane, and the process is described in Application Example 1.

[0142] Related tests:

[0143] The DCIR and cycle performance of the cells from Application Examples 1-3 and Control Application Example 1 were tested, and the results are recorded in Table 2. The tests included the following procedures:

[0144] 50% SOC DC internal resistance test method: At room temperature (25±3℃), charge the cell to 3.7V with a constant current of 1 / 3C to 50% SOC, discharge the cell to 50% SOC with a constant current of 1 / 3C, and let it rest for 30 minutes; discharge the cell to 3C constant current for 10 seconds, limit the cell to 2.2V, and test the DC internal resistance at 50% SOC.

[0145] 100% DOD 45℃ Cyclic Test Method: The test steps are 1C-100% DOD charge and discharge, which is to charge at 1C constant current and constant voltage to 3.7V, let stand for 10 minutes, discharge at 1C to 2.2V, and cycle 2000 times.

[0146] Table 2:

[0147]

[0148] As shown in Table 2, compared with the comparative example or control group, the activation film prepared by the battery activator in the embodiment can significantly reduce the DCIR of the battery cell and improve the cycle stability of the battery cell.

[0149] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A battery activator, characterized in that, The device includes a housing and a sustained-release material encapsulated within the housing; the sustained-release material includes additives required to form an SEI film; the housing includes a first polymer layer adjacent to the sustained-release material and a second polymer layer distant from the sustained-release material, the first polymer layer including a plurality of first micropores, the second polymer layer including a plurality of second micropores, the second polymer layer including a cross-linked polymer formed by cross-linking polyacrylate, the pore size of the first micropores not greater than 0.2µm, and the pore size of the second micropores not less than 0.5µm; the first polymer layer includes a polymer substrate and a first additive, the polymer substrate including at least one of polypropylene, polyvinylbenzene, and polycarbonate; the first additive including at least one of polyphosphate and a silicone-alkoxy polymer; the structure of the silicone-alkoxy polymer is as shown in Formula 1: Formula 1, R1 and R2 are each independently one of -OCH3, -N(CH3)CH3, and -NH-R3, and R3 is a C1-C20 alkyl group with n greater than 0.

2. The battery activator according to claim 1, characterized in that, The sustained-release material is in a semi-gel or gel state; And / or, the pore size of the first micropore is 0.001µm-0.2µm, and the pore size of the second micropore is 0.5µm-1µm.

3. The battery activator according to claim 2, characterized in that, The additives required to form the SEI film include at least one of vinylene carbonate, propane sulpholactone, methyl methane disulfide, ethylene ethylene carbonate, and fluoroethylene carbonate.

4. The battery activator according to any one of claims 1-3, characterized in that, The second polymer layer comprises a hydrophobic crosslinked polymer formed by crosslinking of polyacrylate, a second additive, and / or a third additive, wherein the second additive is an isocyanate polymer and / or an epoxy ester polymer, and the third additive is a silicone-alkoxy polymer.

5. The battery activator according to claim 1, characterized in that, The first additive accounts for 2%-5% of the weight of the polymer substrate.

6. The battery activator according to claim 4, characterized in that, The second additive accounts for 2%-5% of the weight of the crosslinked polymer; And / or, the third additive accounts for 2%-5% of the weight of the crosslinked polymer.

7. A method for preparing a battery activator as described in any one of claims 1-6, characterized in that, Includes the following steps: 1) The additives and gelling agents required for forming the SEI film are mixed and treated to obtain a semi-gel or gel-state sustained-release material; 2) The sustained-release material is added to a dispersion comprising a polymer substrate, a first additive, a dispersant, and a solvent, and the mixture is subjected to a mixing process to obtain a mixed system. The solvent in the mixed system is then evaporated to obtain a sustained-release material encapsulating a first polymer layer. The solid content of the mixed system is 30%-40%. 3) The slow-release material encapsulating the first polymer layer is added to a dispersion comprising a crosslinked polymer formed by crosslinking polyacrylate, a second additive and / or a third additive, a crosslinking curing agent, and a solvent, and a crosslinking reaction is carried out at 50°C-70°C to obtain the battery activator.

8. An activated membrane formed from the battery activator according to any one of claims 1-6.

9. A negative electrode sheet, characterized in that, It includes a current collector and a negative electrode material layer and an activation film sequentially disposed on at least one surface of the current collector, wherein the activation film is the activation film according to claim 8, and the thickness of the activation film is 1µm~10µm.

10. A diaphragm, characterized in that, The separator is the activated membrane as described in claim 8; or, it includes a separator base layer and an activated membrane, wherein the activated membrane is disposed on the side of the separator base layer near the negative electrode sheet, and the activated membrane is the activated membrane as described in claim 8.

11. A battery, characterized in that, Includes the negative electrode sheet as described in claim 9; and / or the separator as described in claim 10.

12. A battery pack, characterized in that, Includes the battery as described in claim 11.

13. An electrical appliance, characterized in that, Includes the battery of claim 11 or the battery pack of claim 12.

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