Battery activator and preparation method therefor, activation film, negative electrode sheet, battery, battery pack, and electric device

Abstract

Provided in the present application are a battery activator and a preparation method therefor, an activation film, a negative electrode sheet, a battery, a battery pack, and an electric device. The battery activator comprises a shell and a sustained-release material encapsulated in the shell, wherein the sustained-release material comprises an additive required for the formation an SEI film; and the shell comprises a first polymer layer close to the sustained-release material and a second polymer layer away from the sustained-release material, the first polymer layer comprises a plurality of first micropores, the second polymer layer comprises a plurality of second micropores, the second polymer layer comprises a cross-linked polymer formed by the cross-linking of a C-C unsaturated polymer, 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 the present application can continuously provide a battery cell with an additive required for the formation an SEI film, thereby ensuring the capacity utilization and cycling stability of a battery cell.

Description

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

[0001] The present application claims priority to the Chinese patent application No. 202411361895.1, filed on September 26, 2024, and entitled "A battery activator, a preparation method thereof, an activation film, a negative electrode sheet, a battery, a battery pack, and an electrical equipment", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, in particular to a battery activator, a preparation method thereof, an activation film, a negative electrode sheet, a battery, a battery pack, and an electrical equipment. BACKGROUND

[0003] The solid electrolyte interphase film (SEI film) is a key protective layer in lithium-ion batteries, usually formed between the negative electrode material (such as graphite) and the electrolyte. The stability and integrity of the SEI film are crucial to the performance and life of the battery. With the cycling of the battery, the SEI film may be damaged or decomposed, leading to a decrease in battery performance.

[0004] In order to form the SEI film, a specific additive such as vinylene carbonate (VC) is generally 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 the specific additive. However, too high a content of the specific additive will increase the viscosity of the electrolyte, leading to uneven lithium insertion in the battery and an increase in the internal resistance of the battery.

[0005] SUMMARY

[0006] The present application provides a battery activator which can continuously provide the required additive for forming the SEI film in the battery and can always maintain the concentration of the additive within a certain range, avoiding the phenomenon of difficult and uneven lithium ion diffusion caused by too high a content of the additive, thereby ensuring the capacity development and cycle stability of the battery.

[0007] The present application also provides a preparation method of the battery activator, which can prepare the battery activator and is simple to operate.

[0008] The present application also provides an activation film which can be combined with the negative electrode sheet, the separator, etc., thereby further improving the uniformity of the distribution of the additive required for forming the SEI film in the battery and ensuring that the battery has good capacity development while being long-cycled.

[0009] The application also provides a negative electrode sheet. Since the surface of the negative electrode sheet comprises the above-mentioned activation film, the negative electrode sheet can improve the uniformity of distribution of the additive required for forming the SEI film in the battery cell and maintain the stability of the SEI film, thereby ensuring long cycle and capacity of the battery cell.

[0010] The application also provides a separator. Since the separator comprises the above-mentioned activation film, it can improve the uniformity of distribution of the additive required for forming the SEI film in the battery cell and maintain the stability of the SEI film, thereby ensuring long cycle and capacity of the battery cell.

[0011] The application also provides a battery. Since the battery comprises the above-mentioned negative electrode sheet and / or the activation film, it has the advantages of long cycle, good capacity, etc.

[0012] The application also provides a battery pack. Since the battery pack comprises the above-mentioned battery, the battery pack has good electrical performance and stable cycle life.

[0013] The application also provides an electrical equipment. Since the electrical equipment comprises the above-mentioned solid-state battery or battery pack, the electrical equipment has good electrical performance and longer service life.

[0014] In detail, in a first aspect, the application provides a battery activator, comprising a shell and a sustained-release material encapsulated in the shell; the sustained-release material comprises an additive required for forming an SEI film; the shell comprises a first polymer layer close to the sustained-release material and a second polymer layer away from the sustained-release material, the first polymer layer comprises a plurality of first micropores, the second polymer layer comprises a plurality of second micropores, the second polymer layer comprises a crosslinked polymer crosslinked by a C-C unsaturated polymer, 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.

[0015] Further, the sustained-release material is in a semi-gel or gel state;

[0016] And / or, the pore size of the first micropores is 0.001 μm-0.2 μm, and the pore size of the second micropores is 0.5 μm-1 μm.

[0017] Further, the additive required for forming the SEI film comprises at least one of vinylene carbonate, propane sulfone lactone, methylene methane disulfate, vinyl ethylene carbonate, and fluoroethylene carbonate;

[0018] And / or, the additive accounts for 50%-70% of the weight of the sustained-release material.

[0019] Further, the first polymer layer comprises a polymer base material and a first additive, the polymer base material comprises at least one of polypropylene, polyethylene benzene, polycarbonate; the first additive comprises at least one of sulfonic acid-based polymer, phosphoric acid-based polymer, silicon-based-alkoxy polymer.

[0020] Further, the second polymer layer comprises the hydrophobic cross-linked polymer, a second additive and / or a third additive, the second additive comprises isocyanate-based polymer and / or epoxy ester-based polymer, and the third additive is silicon-based-alkoxy polymer.

[0021] Further, the structure of the silicon-based-alkoxy polymer is shown in Formula 1:

[0022] wherein, R1 and R2 are each independently one of -OCH3, -N(CH3)CH3, -NH-R3, R3 is C1-C20 alkyl, and n is greater than 0.

[0023] Further, the first additive accounts for 2%-5% of the weight of the polymer base material.

[0024] Further, the second additive accounts for 2%-5% of the weight of the cross-linked polymer.

[0025] And / or, the third additive accounts for 2%-5% of the weight of the cross-linked polymer.

[0026] In a second aspect, the application provides a preparation method of the above battery activator, comprising the following steps:

[0027] 1) mixing the additives and gelling agents required for forming SEI film to obtain a semi-gel or gel state slow-release material;

[0028] 2) adding the slow-release material to a dispersion liquid comprising a polymer base material, a first additive, a dispersant, and a solvent, mixing to obtain a mixed system, evaporating the solvent of the mixed system to obtain a slow-release material wrapped with a first polymer layer; wherein the solid content of the mixed system is 30-40%, and the evaporation rate of the solvent is >2750 cm / h;

[0029] 3) adding the slow-release material wrapped with the first polymer layer to a dispersion liquid comprising C-C unsaturated polymer, a second additive and / or a third additive, a cross-linking curing agent, and a solvent, and performing cross-linking reaction at 50-70°C to obtain the battery activator.

[0030] In a third aspect, the application provides an activation film formed by the battery activator of the first aspect.

[0031] In a fourth aspect, the present application provides a negative electrode sheet, comprising a current collector, and a negative electrode material layer and an activation film arranged on at least one surface of the current collector in sequence, wherein the activation film is the activation film according to the third aspect.

[0032] In a fifth aspect, the present application provides a separator, which is the activation film according to the third aspect; or, comprises a separator base layer and an activation film arranged on one side of the separator base layer close to a negative electrode sheet, wherein the activation film is the activation film according to the third aspect.

[0033] In a sixth aspect, the present application provides a battery, comprising the negative electrode sheet according to the fourth aspect; and / or the separator according to the fifth aspect.

[0034] In a seventh aspect, the present application provides a battery pack, comprising the battery according to the sixth aspect.

[0035] In an eighth aspect, the present application provides an electrical equipment, comprising the battery according to the sixth aspect or the battery pack according to the seventh aspect.

[0036] The battery activator provided by the present application can continuously provide the additive required for forming SEI film for the battery cell, and can always keep the additive concentration in the electrolyte within a certain range, avoiding the phenomenon of difficult and uneven diffusion of lithium ions caused by too high additive content, so as to ensure the capacity development and cycle stability of the battery cell.

[0037] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments thereof, with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0038] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present application and serve to explain the principles of the present application.

[0039] FIG. 1 is a structural schematic diagram of a battery according to an embodiment of the present application;

[0040] FIG. 2 is an interface diagram of different battery cells, wherein a is an interface diagram of a battery cell prepared in a control application example 1, b is an interface diagram of a battery cell prepared in the application example 1 using the battery activator of the embodiment 1, c is an interface diagram of a battery cell prepared in the application example 2 using the battery activator of the embodiment 1, and d is an interface diagram of a battery cell prepared in the application example 3 using the battery activator of the embodiment 1.

[0041] FIG. 3 is a cycle comparison diagram of the battery cell prepared in the control application example 1, the battery cell prepared in the application example 1 using the battery activator of the embodiment 1, the battery cell prepared in the application example 2 using the battery activator of the embodiment 1, and the battery cell prepared in the application example 3 using the battery activator of the embodiment 1. DETAILED DESCRIPTION

[0042] In order for those skilled in the art to better understand the scheme of the present application, the present application is further described in detail below. The following specific embodiments are only used to describe the principles and characteristics of the present application, and the examples are used to explain the present application, but not to limit the scope of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0043] In a first aspect, the present application provides a battery activator, comprising a shell and a slow-release material encapsulated in the shell; the shell comprises a first polymer layer close to the slow-release material and a second polymer layer away from the slow-release material, the first polymer layer comprises a plurality of first micropores, the second polymer layer comprises a plurality of second micropores, the second polymer layer comprises a cross-linked polymer cross-linked by C-C unsaturated polymer, the pore size of the first micropore is not greater than 0.2 μm, and the pore size of the second micropore is not less than 0.5 μm.

[0044] The battery activator provided by the present application can continuously provide the additive required for the formation of SEI film for the battery cell, and can always keep the concentration of the additive within a certain range, avoiding the phenomenon of lithium ion diffusion difficulty and unevenness caused by high content of the additive, and the structure can ensure that there is uniform VC content at all positions on the surface of the pole piece, avoiding the accelerated attenuation of the battery cell caused by uneven VC, thereby ensuring the capacity development and cycle stability of the battery cell. The main reasons include: the slow-release material can provide the additive required for the formation of SEI film for the battery cell, the first polymer layer is the first barrier for slow release of the slow-release material, and the pore size only allows the additive in the slow-release material to enter and exit, while the molecules in the electrolyte exist in the form of macromolecules with solvation structure and cannot pass through the first polymer layer. The second polymer layer is the second barrier for slow release of the slow-release material, and the slow release of the slow-release material from the first polymer layer and then through the second polymer layer can achieve long-term slow release, so that the additive in the electrolyte always remains within a certain concentration range, avoiding the phenomenon of diffusion difficulty and unevenness caused by high content of the additive. In addition, the traditional additive is generally dispersed in the electrolyte, and the additive is most likely to be mainly distributed at the bottom of the battery cell or on the outermost aluminum plastic film of the pole core, and cannot diffuse to the middle of the pole piece, thereby causing uneven distribution of current in the battery cell and easy center cracking of the battery cell. However, the second polymer layer of the present application comprises a cross-linked polymer, so that the battery activator of the present application can be stretched into a film and directly used as a separator or adhered to the separator or the negative pole piece, thereby ensuring uniform distribution of the additive in the battery cell and further prolonging the service life of the battery.

[0045] In an alternative embodiment, the testing method of the pore size of the first micropore and the pore size of the second micropore comprises: gas adsorption method + delamination test, specifically, after testing the overall pore size by BET, the outer layer buffer material is peeled off, and the inner and outer layer pore size distribution is obtained by static adsorption test again. Alternatively, longitudinal cutting + high-resolution imaging, specifically, the pore size distribution can be observed by longitudinally cutting the material and then testing under high-resolution imaging such as SEM.

[0046] In an alternative embodiment, the sustained-release material is in a semi-gel state or a gel state. The semi-gel state or gel state of the sustained-release material can serve as a third barrier for the sustained-release control of the sustained-release material, thereby further ensuring that the concentration of the additive is within a certain range and achieving long-acting sustained release of the additive.

[0047] The difference between the semi-gel state and the gel state of the sustained-release material can be judged from the aspects of appearance stability, limit value, mechanical property, and fluidity. Specifically, in terms of appearance, the gel state has a fixed shape and cannot flow spontaneously, and there is no change after being inverted or inclined; the semi-gel state has a weakly fixed shape, and slowly deforms and flows after being inverted or inclined. In terms of limit value, if the sustained-release material is inclined at 45°C and there is no deformation within 30 minutes, it is a gel; if there is obvious deformation, it is a semi-gel state; or, after stirring the sustained-release material for 30 minutes, if it returns to the original state, it is a gel state; if it does not return to the original state after more than 30 minutes, it is a semi-gel state; or, if the sustained-release material is placed on a horizontal plate, the gel state maintains a three-dimensional shape, and the semi-gel state appears "collapse" after 1 hour. In terms of mechanical property, the gel state is dominated by elasticity, and can fully return to the original state and support its own weight; the semi-gel state coexists with elasticity and viscosity, and can partially return after deformation, and is difficult to support its own weight. In terms of fluidity, the gel state hardly flows, and can return after external stirring; the semi-gel state easily flows after external stirring, and is prone to phenomena such as sticking to the cup.

[0048] In an alternative 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.

[0049] For example, the pore size of the first micropore is 0.001 μm, 0.002 μm, 0.005 μm, 0.007 μm, 0.01 μm, 0.02 μm, 0.03 μm, 0.04 μm, 0.05 μm, 0.06 μm, 0.07 μm, 0.08 μm, 0.09 μm, 0.1 μm, 0.12 μm, 0.15 μm, 0.16 μm, 0.17 μm, 0.18 μm, 0.19 μm, 0.2 μm, or any range formed by any two of them, and the pore size of the second micropore is 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, or any range formed by any two of them.

[0050] In an alternative embodiment, the additives required for forming the SEI film include at least one of vinylene carbonate (VC), propane sulfone (PS), methylene methanedisulfonate (MMDS), vinyl ethylene carbonate (VEC), fluoroethylene carbonate (FEC).

[0051] And / or, the additives account for 50%-70% of the weight of the sustained-release material.

[0052] In some embodiments, the sustained-release material is composed of additives required for forming the SEI film and a gelling agent, the gelling agent including at least one of vinyl carbonate, gelatin, agar, etc.

[0053] In an alternative embodiment, the first polymer layer includes a polymer base material and a first additive, the polymer base material including at least one of polypropylene, polystyrene, polycarbonate; the first additive including at least one of a sulfonic acid-based polymer, a phosphoric acid-based polymer, a silicon-based-alkoxy polymer.

[0054] Wherein, after the consumption of the additives in the sustained-release material, the first additive of the above-mentioned embodiments can continue to play the repairing function of the SEI film, because the sulfonic acid group and the phosphoric acid group of the sulfonic acid-based polymer and the phosphoric acid-based polymer can be reduced to form the SEI film, thereby repairing the SEI film. While the silicon-based-alkoxy polymer has a relatively high reduction potential, it does not directly reduce the main components of the SEI film in the presence of the sustained-release material, but it can reduce the rupture and regeneration of the SEI film on the negative material interface in the battery due to the water or acidity in the battery by adsorbing the water or acidity in the battery, thereby improving the cycle stability of the battery. And because the reduction potential of the sulfonic acid-based polymer, the phosphoric acid-based polymer and the silicon-based-alkoxy polymer is lower than that of the additives in the sustained-release material, they will not be reduced during the normal release of the sustained-release material and can exist stably.

[0055] In an alternative embodiment, the second polymer layer includes the hydrophobic cross-linked polymer, a second additive and / or a third additive, the second additive including an isocyanate-based polymer and / or an epoxy ester-based polymer, and the third additive being a silicon-based-alkoxy polymer.

[0056] Wherein, the hydrophobic cross-linked polymer can make the battery activator of the above-mentioned 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 battery, and the third additive can continue to play the repairing function of the SEI film after the consumption of the additives in the sustained-release material.

[0057] In an alternative embodiment, the structure of the silicon-based-alkoxy polymer is as shown in Formula 1:

[0058] wherein R1 and R2 are each independently one of -OCH3, -N(CH3)CH3, -NH-R3, R3 is C1-C20 alkyl, and n is greater than 0.

[0059] In some embodiments, n is any value from 1-200, any value from 2-100, any value from 5-50, 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.

[0060] In some embodiments, the method of preparing the silicon-based alkoxy polymer comprises the following process:

[0061] In a vacuum or atmosphere of rare gas, polydimethylsiloxane, tetramethoxysilane, monomethylamine, etc. are mixed in a mass ratio of 1:1.5, reacted at about 100°C, and after stirring for 30 min under vacuum, water is added, the upper layer product is obtained after stirring and layering, which is the silicon-based alkoxy polymer.

[0062] In an alternative embodiment, the first additive accounts for 5%-8% of the weight of the polymer matrix.

[0063] In an alternative embodiment, the second additive accounts for 3%-5% of the weight of the cross-linked polymer; and / or, the third additive accounts for 2%-5% of the weight of the cross-linked polymer.

[0064] The second additive has the effect of adsorbing moisture and acidity; however, its content should not be too high, otherwise it may reduce the content of cross-linked structures and destroy the pore structure of the activator in the later cycle.

[0065] In some embodiments, the degree of cross-linking of the C-C unsaturated polymer is >80%; and / or, the release rate of the above battery activator is 1-1000 μg / day.

[0066] The release rate can meet the continuous repair of VC to the SEI film in the cycle process. The degree of cross-linking of the C-C unsaturated polymer can be obtained by calculation, for example: degree of cross-linking = m (mass of cross-linking agent + additive after cross-linking) / m (amount of cross-linking agent + additive).

[0067] In a first aspect, the present application provides a method for preparing the above-mentioned battery activator, comprising the following steps:

[0068] 1) The additives and gelling agents required for forming the SEI film are mixed to obtain a semi-gel or gel state release material;

[0069] 2) adding the slow-release material into a dispersion liquid comprising a polymer base material, a first additive, a dispersant, a solvent, mixing to obtain a mixed system, and evaporating the solvent of the mixed system to obtain the slow-release material wrapped by the first polymer layer; wherein the solid content of the mixed system is 30-40%, and the evaporation rate of the solvent is >2750 cm / h;

[0070] 3) adding the slow-release material wrapped by the first polymer layer into a dispersion liquid comprising a C-C unsaturated polymer, a second additive and / or a first additive cross-linking curing agent, and a solvent, and performing cross-linking reaction at 50-70°C to obtain the battery activator.

[0071] In some embodiments, the evaporation rate of the solvent is 2800-3000 cm / h (vacuum evaporation rate).

[0072] In some embodiments, the content of the first additive is 1-3%, which can assist the pore formation of the first polymer layer.

[0073] Exemplarily, the gelling agent can be any substance that can make the additive become 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 phosphoric acid, sodium dodecyl sulfate, etc.; the solvent in step 2) and step 3) can be the same or different, and is preferably an easily volatile solvent, including but not limited to: dichloromethane, ethanol, etc.; the cross-linking curing agent is any curing agent that can accelerate the cross-linking of the C-C unsaturated polymer, including but not limited to: polyamide cross-linking curing agent, aliphatic amine cross-linking curing agent, aromatic amine cross-linking curing agent, etc.

[0074] The time of the cross-linking reaction is not particularly limited in the present application, and can be adjusted by the skilled person according to the degree of cross-linking, for example, when the mass of the C-C unsaturated polymer is 100 g, the temperature of the cross-linking reaction is 50-70°C, and the time is 48 h.

[0075] The amount of the cross-linking curing agent added is not particularly limited in the present application, and can be adjusted by the skilled person according to the required rate of cross-linking, for example, the mass ratio of the cross-linking curing agent to the C-C unsaturated polymer is 20%-40%.

[0076] In a third aspect, the present application provides an activation film formed by the battery activator of the first aspect.

[0077] In some embodiments, the activation film is prepared by the following process:

[0078] The appropriate amount of the battery activator is added into a high-speed mixer for stirring treatment, and the obtained material is subjected to calendering treatment by an electric heating roll press to obtain the activation film.

[0079] Exemplarily, the high-speed mixing is at a speed of 200-1000 r / min, and the mixing time is 1-5 h; in the calendering process, the gap width between the two hot calender rollers is 1-500 μm, the roller speed is 1.0-5 m / min, and the roller temperature is 40-80 °C.

[0080] In addition, the thickness of the activated film can be adjusted by adjusting the parameters of the calendering process. In one specific embodiment, the thickness of the activated film is 100-150 μm.

[0081] In a fourth aspect, the application provides a negative electrode sheet, comprising a current collector, and a negative electrode material layer and an activated film arranged in sequence on at least one surface of the current collector, wherein the activated film is the activated film of the first aspect.

[0082] Exemplarily, the thickness of the activated film can be 1-3 μm. If the thickness is too large, the impedance of the battery cell will increase, and if the thickness is too small, the internal semi-permeable membrane structure of the crosslinked structure will be excessively compressed and deformed, and even the permeation rate will increase.

[0083] It can be understood that the negative electrode material layer further comprises a negative electrode active material and optionally a binder, wherein the negative electrode active material is various lithium-embeddable and -extractable negative electrode active materials commonly used by those skilled in the art, for example, can be selected from one or more of carbon materials, tin alloys, silicon alloys, silicon, tin, and germanium; the carbon material can be one or more of non-graphitized carbon, graphite, or carbon obtained by high-temperature oxidation of polyacetylene-based polymer materials or pyrolytic carbon, coke, organic polymer sinter, activated carbon, etc.; when the negative electrode active material is a silicon-based material, the negative electrode coating further comprises a conductive agent, which is a material commonly used by those skilled in the art that can enhance electron transport, for example, can be selected from at least one of natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fibers, carbon nanotubes, metal powder, graphene, etc.; the binder can be at least one of polyvinylidene fluoride, vinylidene-hexafluoropropylene copolymer, polytetrafluoroethylene, polyacrylonitrile, polypropylene carbonate, butadiene-styrene rubber, butyronitrile rubber, sodium carboxymethyl cellulose, polyethylene oxide, and ethylene oxide-propylene oxide copolymer.

[0084] In a fifth aspect, the application provides a separator, which is the activated film of the third aspect; or, comprises a separator base layer and an activated film, wherein the activated film is arranged on one side of the separator base layer close to the negative electrode sheet, and the activated film is the activated film of the first aspect.

[0085] Exemplarily, when the activated film is directly used as a separator, the thickness of the activated film can be 1-15 μm. If too thick, it can cause the impedance of the battery to increase, and if too thin, it can cause the semi-permeable membrane structure inside the cross-linked structure to be excessively compressed and deformed, and even cause the permeation rate to increase; when the activated film and the traditional separator are stacked, the thickness of the activated film can be 1-5 μm; if too thick, it will cause the impedance of the battery to increase, and if too thin, it can cause the semi-permeable membrane structure inside the cross-linked structure to be excessively compressed and deformed, and even cause the permeation rate to increase.

[0086] The above-mentioned separator base layer is not particularly limited in the present application, and any known porous structure separator base layer with electrochemical stability and chemical stability can be selected, for example, it can be at least one of glass fiber, non-woven fabric, polyethylene, polypropylene or polyvinylidene fluoride.

[0087] In a sixth aspect, the present application provides a battery comprising the negative electrode sheet of the fourth aspect or the separator of the fifth aspect.

[0088] It should be noted that the above-mentioned battery can include but is not limited to single battery, battery module, battery pack, etc., i.e. the actual application form of the battery provided by the present application can be but is not limited to the listed products, and can also be other application forms, when the battery is a single battery, it includes at least one of cylindrical battery, square battery, etc.

[0089] In some embodiments, the battery comprises a positive electrode sheet, a negative electrode sheet and a separator of the fifth aspect, and the structural schematic diagram is shown in FIG. 1.

[0090] It can be understood that the above-mentioned positive electrode sheet comprises a current collector and a positive electrode material layer sequentially arranged on at least one surface of the current collector, the positive electrode material layer comprises a positive electrode active material, a conductive agent and optionally a binder, the positive electrode active material is selected from lithium cobaltate (LiCoO2), lithium nickelate (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(wherein, A is selected from one of Co, Mn, 0 (1-m-n)at least one of O2(wherein, B, C are independently selected from at least one of Co, Al, Mn, and B and C are not the same, 0 < m < 1, 0 < n < 1); the conductive agent is a material commonly used by those skilled in the art which can play a role in enhancing electron transport, for example, can be selected from at least one of natural graphite, artificial graphite, carbon black, acetylene black, graphene, carbon fiber, carbon nanotube, and Ketjen black; the at least one of polyvinylidene fluoride, vinylidene-hexafluoropropylene copolymer, polytetrafluoroethylene, polyacrylonitrile, polypropylene carbonate, styrene butadiene rubber, nitrile butadiene rubber, sodium carboxymethyl cellulose, polyethylene oxide, ethylene oxide-propylene oxide copolymer, polyethylene, polypropylene, polyamide imide, polyvinyl alcohol, and sodium polyacrylate.

[0091] The thickness and the area density of the above-mentioned positive electrode sheet and negative electrode sheet are not specifically limited in the present application, but 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 area 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 2 , 8.5 mg / cm 2 , 9 mg / cm 2 , 9.5 mg / cm 2 mg / cm 2 , 10 mg / cm 2 , 10.5 mg / cm 2 , 11 mg / cm 2 , 11.5 mg / cm 2 , 12 mg / cm 2 , 12.5 mg / cm 2 , 13 mg / cm 2 , 13.5 mg / cm 2 , 14 mg / cm 2 , 14.5 mg / cm 2 , 15 mg / cm 2 , 16 mg / cm2 17 mg / cm 2 18 mg / cm 2 18 mg / cm 2 19 mg / cm 2 20 mg / cm 2 21 mg / cm 2 22 mg / cm 2 23 mg / cm 2 24 mg / cm 2 25 mg / cm 2 and so on.

[0092] In a seventh aspect, the present application provides a battery pack comprising the solid-state battery of the sixth aspect.

[0093] In an eighth aspect, the present application provides an electrical device comprising the battery of the sixth aspect or the battery pack of the seventh aspect.

[0094] It should be noted that the above-mentioned electronic device can be any conventional device requiring electricity, for example, can include but is not limited to computers, electric vehicles, air conditioners, refrigerators, washing machines, microwave ovens, printers, fax machines, etc.

[0095] The present application will be further described below in conjunction with specific embodiments:

[0096] The following test sets and some raw material sources are shown in Table 1:

[0097] Table 1:

[0098] In Table 1, "-" represents that this parameter is not recorded.

[0099] Example 1

[0100] This example provides a battery activator comprising a shell and a slow-release material encapsulated in the shell; the shell comprises a first polymer layer close to the slow-release material and a second polymer layer away from the slow-release material, the first polymer layer comprises a plurality of first micropores, the pore size of the first micropores is about 0.1 μm; the first polymer layer comprises polypropylene and polyphosphate, wherein the mass ratio of polyphosphate to polypropylene is 3%;

[0101] The second polymer layer comprises a plurality of second micropores with a pore size of about 0.5 μm; the second polymer layer comprises, in terms of mass percentage, a cross-linked polymer (cross-linking degree > 80%) cross-linked by C-C unsaturated polymer polyacrylate, hexamethylene diisocyanate and a silicon-based-alkoxy polymer; the mass ratio of hexamethylene diisocyanate to the cross-linked polymer is 5%, and the mass ratio of the silicon-based-alkoxy polymer to the cross-linked polymer is 3%; the structure of the silicon-based-alkoxy polymer is shown in Formula 1, wherein R1 is -OCH3, R2 is -N(CH3)CH3, and n is 2.

[0102] The sustained-release material is in a semi-gel state and comprises, in terms of mass fraction, 75 parts of vinylene carbonate (VC) and 25 parts of ethylene carbonate (EC).

[0103] The preparation method comprises the following steps:

[0104] 1) In a nitrogen atmosphere, dimethylsiloxane and monomethylamine are reacted at a molar ratio of 1:1.5 at 100°C, vacuum stirring is performed for 30 min, water is added, stirring and layer separation are performed, and then the upper layer product is taken as the silicon-based-alkoxy polymer for standby;

[0105] 2) The 75 g of vinylene carbonate and 25 g of vinylene carbonate are stirred at a rotation speed of 300 rpm / s for 1 h to obtain a semi-gel state sustained-release material;

[0106] 3) 20 g of polypropylene, 5 g of polyphosphate, 10 g of divinyltriamine and 65 g of dichloromethane are mixed, the sustained-release material is added to the mixed system to make the solid content of the mixed system 30-40%, stirring is performed at 40°C for 3 h, the volatilization rate of dichloromethane is 2800-2900 cm / h, after dichloromethane is volatilized, alcohol is used to clean the residual vinylene carbonate on the surface, and the sustained-release material wrapped with the first polymer layer is obtained;

[0107] 4) The sustained-release material wrapped with the first polymer layer obtained in step 3) is added to a dispersion liquid comprising 30 g of polyacrylate, 5 g of m-phenylenediamine, 60 g of dimethyl carbonate, 3 g of hexamethylene diisocyanate and 2 g of the silicon-based-alkoxy polymer, and stirring is performed at 60°C for 12 h to perform a cross-linking reaction, after the reaction, the solvent is removed, alcohol is used to clean the residual polyacrylate on the surface, and the battery activator is obtained.

[0108] Example 2

[0109] 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; the preparation is referred to Example 1, and the pore size of the first micropore is 1 nm-10 nm.

[0110] Example 3

[0111] This example provides a battery activator substantially identical to Example 1, except that the second polymer layer does not contain hexamethylene diisocyanate; and it is prepared according to Reference Example 1.

[0112] Example 4

[0113] This example provides a battery activator substantially identical to Example 1, except that the second polymer layer does not contain a silicon-based alkoxy polymer; and it is prepared according to Reference Example 1.

[0114] Example 5

[0115] This example provides a battery activator substantially identical to Example 1, except that the slow-release material is in a gel state; and it is prepared according to Reference Example 1, except that in Step 2), 75 g of vinylene carbonate, 25 g of EC, and 10 g of vinyltriamine are mixed, and stirred at a rotation speed of 300 rpm / s for 1 h to obtain the slow-release material in a gel state.

[0116] Comparative Example 1

[0117] This example provides a battery activator including a housing and a slow-release material encapsulated in the housing; the housing is polystyrene, and the slow-release material is the same as in Example 1.

[0118] The preparation method includes the following steps:

[0119] Polystyrene (PS) is dissolved in dichloromethane (DCM) to prepare a dispersion (a) of 25 mL. In addition, an aqueous solution (b) of 250 mL is prepared, which includes 5 wt% of vinylidene chloride (VC) and 0.5 wt% of gelatin as a stabilizer, and the dispersion (a) is added to the aqueous solution (b) to form an oil / water emulsion. Then, the DCM is evaporated to obtain capsules containing VC, and the capsules thus obtained are washed several times with distilled water to prepare a battery activator.

[0120] Comparative Example 2

[0121] The difference from Example 1 is only that the second polymer layer is not included.

[0122] Test Example 1

[0123] An activation film is prepared using the battery activator of each of the above examples and comparative examples, including the following steps:

[0124] The battery activator is dispersed in dimethyl carbonate to obtain a slurry, the slurry is extruded at a high temperature of 70°C, and a thick sheet of a certain thickness is formed by rolling, and the thick sheet is sequentially stretched in the longitudinal direction or the transverse direction to an activation film of a desired thickness.

[0125] The tensile strength of the activated film of 3 μm thickness was ≥ 1500 kgf.

[0126] Example 1

[0127] A series of negative electrode sheets were provided, which included a current collector and, in order, a negative electrode material layer and an activated film provided on at least one surface of the current collector, the activated film being the activated film prepared in Test Example 1 and having a thickness of 1 μm.

[0128] The preparation of the above negative electrode sheet included the following steps:

[0129] In 100 g of artificial graphite, 100 g of an aqueous solution of sodium carboxymethyl cellulose (sodium carboxymethyl cellulose:deionized water = 2 wt%) was added, and the mixture was stirred in a vacuum stirrer until the mixture became a slurry having uniform fluidity. Then, 3 g of a styrene-butadiene latex was added, and the mixture was stirred in the vacuum stirrer until the mixture became a negative electrode slurry having uniform fluidity. The negative electrode slurry was uniformly coated on both surfaces of an aluminum foil having a thickness of 8 μm. The coated aluminum foil was baked in an oven having different temperature gradients, and then dried in an oven at 120°C for 8 h. Then, the negative electrode sheet was obtained by rolling and slitting. The single surface area density of the negative electrode sheet was 220 mg / cm 2 , and the compacted density was 1.5 g / cm 3 . The above activated film was uniformly stacked on the negative electrode sheet in a lamination manner and slightly rolled (the upper and lower pressing plate hot pressing pressure was set to a range of 8900 kgf ± 100 kgf).

[0130] A series of battery cells were also provided in this example.

[0131] 1) Preparation of a positive electrode sheet: LiFeP04, 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 in a vacuum stirrer until the mixture became a positive electrode slurry having uniform fluidity. The positive electrode slurry was uniformly coated on an aluminum foil having a thickness of 13 μm. The coated aluminum foil was baked in an oven having different temperature gradients, and then dried in an oven at 120°C for 8 h. Then, the positive electrode sheet was obtained by rolling and slitting. The single surface area density of the positive electrode sheet was 400 mg / cm 2 , and the compacted density was 2.4 g / cm 3 ;

[0132] 2) Preparation of an electrolyte solution: after mixing ethylene carbonate, dimethyl carbonate, and methyl ethyl carbonate in a mass ratio of 2:2:3, 5% of vinylene carbonate (VC) based on the total mass of the electrolyte solution and 13% of lithium hexafluorophosphate (LiPF6) based on the total mass of the electrolyte solution were added, and the mixture was stirred to obtain the electrolyte solution.

[0133] 3) Each battery is composed of one pole core, each pole core is composed of 7 positive electrode sheets prepared above, 8 negative electrode sheets prepared above and 16 separators (ion exchange membrane).

[0134] Application Example 2

[0135] This example provides a series of separators, including a 12 μm separator base layer and a 2 μm activation film, the activation film is set on the side of the separator base layer close to the negative electrode sheet, the activation film is the activation film of Test Example 1 (see Table 2 for details).

[0136] The battery is prepared using the above-mentioned separator, including the following steps:

[0137] Preparation of negative electrode sheet: 100 g of artificial graphite is added to 100 g of carboxymethyl cellulose sodium aqueous solution (carboxymethyl cellulose sodium accounts for 2 wt% of deionized water), and stirred under the action of a vacuum stirrer until the mixed system becomes a uniform slurry. Then 3 g of butadiene-styrene latex is added and stirred under the action of a vacuum stirrer until the mixed system becomes a uniform negative electrode slurry. The negative electrode slurry is uniformly coated on the upper and lower surfaces of an aluminum foil with a thickness of 8 μm. The coated aluminum foil is baked in an oven with different temperature gradients, and then dried in an oven at 120°C for 8 h. Then it is rolled and cut to obtain the negative electrode sheet. The single-sided area density of the negative electrode sheet is 220 mg / cm 2 , and the compacted density is 1.5 g / cm 3 ;

[0138] The positive electrode sheet and the electrolyte are the same as in Application Example 1;

[0139] Each battery is composed of one pole core, each pole core is composed of 7 positive electrode sheets prepared above, 8 negative electrode sheets prepared above and 16 separators (the separator is composed of a 12 μm ion exchange film and a 2 μm activation film, the activation film is set on the side of the ion exchange film close to the negative electrode sheet).

[0140] Application Example 3

[0141] The battery activator of Example 1 and Comparative Example 1 is directly added to the electrolyte, and the negative electrode sheet and the separator do not include the battery activator. The process of preparing the battery is described in Application Example 1.

[0142] Control Application Example 1

[0143] The negative electrode sheet and the separator do not include the activation film, and the battery is prepared according to the process of Application Example 1.

[0144] Related tests:

[0145] The DCIR and cycle performance of the batteries of Application Examples 1-3 and Control Application Example 1 are tested, and the results are shown in Table 2. The test includes the following processes:

[0146] 50% SOC DC internal resistance test method: at room temperature 25±3℃, 1 / 3C constant current charging to 3.7V, 50% SOC, cell 1 / 3C constant current discharging to 50% SOC, standing for 30min; 3C constant current discharging for 10s, limiting the cell to 2.2V, detecting 50% SOC DC internal resistance.

[0147] 100% DOD 45℃ cycle test method: 1C-100% DOD charge-discharge, i.e. test step is 1C constant current constant voltage charging to 3.7V, standing for 10min, 1C discharging to 2.2V, cycling 2000 times.

[0148] Table 2:

[0149] As can be seen from Table 2, compared with the comparative examples or the control group, the battery activator prepared by the battery activator of the examples can be used for the cell, which can significantly reduce the DCIR of the cell, and the cycle stability of the cell is better

[0150] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery activator, characterized by, The battery activator comprises a shell and a sustained-release material encapsulated in the shell; the sustained-release material comprises an additive required for forming SEI film; the shell comprises a first polymer layer close to the sustained-release material and a second polymer layer away from the sustained-release material, the first polymer layer comprises a plurality of first micropores, the second polymer layer comprises a plurality of second micropores, the second polymer layer comprises a crosslinked polymer crosslinked by C-C unsaturated polymer, the first micropores have a pore size of no more than 0.2 μm, and the second micropores have a pore size of no less than 0.5 μm.

2. The battery activator of claim 1, wherein, The sustained-release material is in a semi-gel state or a gel state. The first micropores have a pore size of 0.001 μm to 0.2 μm, and the second micropores have a pore size of 0.5 μm to 1 μm.

3. The battery activator of claim 2, wherein, The additive required for forming SEI film comprises at least one of vinylene carbonate, propane sulfolactone, methylene methanedithiosulfate, vinyl ethylene carbonate, and fluoroethylene carbonate.

4. The battery activator of any one of claims 1-3, wherein, The first polymer layer comprises a polymer base material and a first additive, the polymer base material comprises at least one of polypropylene, polyvinylbenzene, and polycarbonate, and the first additive comprises at least one of sulfonic acid-based polymer, phosphoric acid-based polymer, and silicon-based-alkoxy polymer.

5. The battery activator of any one of claims 1-3, wherein, The second polymer layer comprises the crosslinked polymer, a second additive, and / or a third additive, the second additive is isocyanate-based polymer and / or epoxy ester-based polymer, and the third additive is silicon-based-alkoxy polymer.

6. The battery activator of claim 4 or 5, wherein, The structure of the silicon-based-alkoxyl polymer is as Formula 1: R1 and R2 are each independently one of -OCH3, -N(CH3)CH3, and -NH-R3, R3 is C1-C20 alkyl, and n is greater than 0.

7. The battery activator of claim 4, wherein, The first additive accounts for 2% to 5% of the weight of the polymer base material.

8. The battery activator of claim 5, wherein, The second additive accounts for 2% to 5% of the weight of the crosslinked polymer. The third additive accounts for 2% to 5% of the weight of the crosslinked polymer.

9. A method of preparing a battery activator as claimed in any one of claims 1 to 8, characterised in that, The method comprises the following steps: 1) mixing the additive required for forming SEI film and gelling agent to obtain a sustained-release material in a semi-gel state or a gel state; 2) adding the sustained-release material to a dispersion liquid comprising a polymer base material, a first additive, a dispersant, and a solvent, mixing to obtain a mixed system, volatilizing the solvent of the mixed system to obtain the sustained-release material wrapped by the first polymer layer, wherein the solid content of the mixed system is 30% to 40%, and the volatilization rate of the solvent is >2750 cm / h; 3) adding the sustained-release material wrapped by the first polymer layer to a dispersion liquid comprising C-C unsaturated polymer, a second additive and / or a third additive, a crosslinking curing agent, and a solvent, and performing crosslinking reaction at 50°C to 70°C to obtain the battery activator.

10. An activation film formed by the battery activator of any one of claims 1 to 8.

11. A negative electrode sheet characterized by comprising: The battery comprises a current collector, a negative electrode material layer arranged on at least one surface of the current collector, and an activation film, the activation film is the activation film of claim 10, and the thickness of the activation film is 1 μm to 10 μm.

12. A diaphragm characterized by, The separator is the activated film of claim 10; or, comprises a separator base layer and an activated film, the activated film is arranged on one side of the separator base layer close to the negative electrode sheet, and the activated film is the activated film of claim 10.

13. A battery, characterized by Comprises the negative electrode sheet of claim 11; and / or, the separator of claim 12.

14. A battery pack, characterized by Comprises the battery of claim 13.

15. An electrical device, characterized by Comprises the battery of claim 13 or the battery pack of claim 14.

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