Battery and its preparation method and electrical equipment

Abstract

The present invention relates to the technical field of batteries, and discloses a battery, a preparation method thereof, and an electrical device. The battery includes a negative electrode and a positive electrode. It is characterized in that the negative electrode includes a negative electrode active material layer. In the negative electrode active material layer, the ratio of the sum of the volumes of pores with a size ≥ 1 μm to the pore volume of all pores is X, and the ratio of the lithium supplementation capacity of the battery to the capacity of the battery other than the lithium supplementation capacity is Y. X and Y satisfy: 0.2X < Y < 1.33X. The present invention cooperates the lithium supplementation amount with the pore characteristics of the negative electrode to compensate for the loss of active lithium during the operation of the battery, optimizes the lithium supplementation state under different pore distributions, and enables the battery to have excellent power performance, fast charging performance, and high and low temperature performance.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, in particular to the field of battery lithium supplementation technology, and specifically to a battery and a preparation method thereof and an electrical device. Background Art

[0002] Positive or negative electrode lithium replenishment technology is a battery technology currently being developed by most battery companies to improve energy density, cycle performance and other performance. The amount of lithium replenishment is usually set according to actual product needs. For example, to improve energy density, it is only necessary to replenish the lost capacity of the first cycle efficiency. If the purpose of long cycle is to be achieved, additional lithium must be pre-stored, and the amount of lithium replenishment must be greatly increased.

[0003] However, lithium supplementation affects the SEI impedance on the negative electrode side. Different amounts of lithium supplementation will lead to significant differences in the SEI impedance on the negative electrode side. Different amounts of lithium supplementation will also lead to significant differences in power performance. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problem that the existing lithium supplementation technology affects the negative electrode of the battery power performance, and to provide a battery and its preparation method and electrical equipment.

[0005] In order to achieve the above object, the present invention provides a battery in one aspect, which includes a negative electrode, wherein the negative electrode includes a negative electrode active material layer; in the negative electrode active material layer, the ratio of the sum of the volume of pores with a size of ≥1 μm to the pore volume of all pores is X, and the ratio of the lithium replenishment capacity of the battery to the capacity of the battery other than the lithium replenishment capacity is Y, and X and Y satisfy: 0.2X <Y<1.33X。

[0006] Optionally, 0.2X <Y<0.9X。

[0007] Optionally, X is 0.1% to 30%.

[0008] Optionally, X is 14% to 28%.

[0009] Optionally, X satisfies 16%≤X≤26%.

[0010] Optionally, 3% <Y<19.95%。

[0011] Optionally, Y is 5%-17%.

[0012] Optionally, the battery further comprises a positive electrode, and the positive electrode and / or the negative electrode comprises a self-supporting electrode membrane.

[0013] A second aspect of the present invention provides a method for preparing the battery described above, the method comprising:

[0014] Prepare the negative electrode so that the battery meets 0.2X <Y<1.33X;

[0015] Among them, the negative electrode includes a negative electrode active material layer, X is the ratio of the sum of the volumes of pores with a size ≥ 1 μm in the negative electrode active material layer to the total pore volume of all pores; Y is the ratio of the lithium supplement capacity of the battery to the capacity of the battery other than the lithium supplement capacity.

[0016] Optionally, 0.2X < Y < 0.9X, and X is 16% - 26%.

[0017] Optionally, the method for preparing the negative electrode includes mixing a negative electrode lithium supplement agent with a negative electrode active material, and / or

[0018] setting a negative electrode lithium supplement layer, and the negative electrode lithium supplement layer includes a negative electrode lithium supplement agent.

[0019] Optionally, the method for preparing the negative electrode includes: mixing a negative electrode active material, a binder, and a conductive agent, followed by rolling to obtain a self-supporting negative electrode membrane, and then laminating the negative electrode membrane with a negative electrode current collector; adding a negative electrode lithium supplement agent for lithium supplementation.

[0020] Optionally, based on the amount of the negative electrode active material, the amount of the binder is 0.5 wt% - 3 wt%, and the amount of the conductive agent is 0.2 wt% - 3 wt%. <​​​​​​​​​​​​​​​​​​​Optionally, the positive electrode lithium supplement includes at least one of lithium oxalate, Li2O, Li2O2, Li2S, Li3N, LiF, Li5FeO4, Li2CO3, Li2MoO4, Li6CoO4, and Li2NiO2.

[0028] Optionally, the positive electrode active material includes at least one of a metal oxide positive electrode active material, a phosphate-based positive electrode active material, and a metal sulfide positive electrode active material.

[0029] The third aspect of the present invention provides an electrical device, which includes the battery described above or the battery prepared by the method described above.

[0030] Compared with the prior art, the present invention has at least the following beneficial effects:

[0031] The inventors found through research that when a specific relationship is satisfied between the lithium supplementation amount of the battery and the pore size of the negative electrode, while compensating for the loss of active lithium during the operation of the battery, the lithium supplementation state under different pore distributions can be optimized, enabling the battery to have excellent power performance, fast charging performance, and high and low temperature performance. Detailed Description of the Specific Embodiments

[0032] The following provides a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not used to limit the present invention.

[0033] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0034] The first aspect of the present invention provides a battery, which includes a negative electrode. The negative electrode includes a negative electrode active material layer. In the negative electrode active material layer, the sum of the volumes of pores with a size ≥ 1 μm and the pore volume of all pores is X, and the ratio of the lithium supplementation capacity of the battery to the capacity of the battery other than the lithium supplementation capacity is Y (hereinafter referred to as the lithium supplementation capacity ratio). X and Y satisfy: 0.2X < Y < 1.33X. The lithium supplementation capacity of the battery can be understood as the capacity contributed by the lithium supplement during the normal use cycle of the battery (capacity attenuation less than 20%), and the capacity of the battery other than the lithium supplementation capacity refers to the remaining capacity other than the capacity contributed by the lithium supplement during the normal use cycle of the battery (capacity attenuation less than 20%).

[0035] In the negative electrode active material layer, the ratio of the sum of the volumes of pores with a size ≥ 1 μm to the pore volume of all pores is X. That is to say, for the negative electrode active material layer, its pore volume is V0, and the sum of the volumes of pores with a size ≥ 1 μm is V1, and X = V1 / V0.

[0036] The battery described in the present invention can be various common batteries in the art. Its composition can be the same as or different from that of common batteries in the art. In addition to including a negative electrode, it can also include a positive electrode, a separator, an electrolyte, and / or a solid electrolyte, etc. In some embodiments, in addition to the negative electrode active material layer, the negative electrode may further include a negative electrode current collector. The negative electrode current collector can be, for example, a carbon-coated copper foil or an uncoated copper foil, etc. The negative electrode active material layer can be disposed on one or both surfaces in the thickness direction of the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material; in some embodiments, the negative electrode active material layer includes a negative electrode active material, a binder, and a conductive agent; in some embodiments, the negative electrode active material layer further includes a lithium supplement agent. The lithium supplement agent in the negative electrode active material layer can exist in the form of being mixed with the negative electrode active material, and / or the lithium supplement agent in the negative electrode active material layer can exist in the form of a separate negative electrode lithium supplement layer.

[0037] The inventors of the present invention surprisingly found through research that a battery in which X and Y satisfy the above relationship can enable batteries with negative electrodes having different pore distributions to balance power performance, fast charging performance, and high and low temperature performance. Exemplarily, X and Y can satisfy: Y = 0.25X, Y = 0.3X, Y = 0.4X, Y = 0.5X, Y = 0.6X, Y = 0.7X, Y = 0.8X, Y = 0.9X, Y = X, Y = 1.1X, Y = 1.2X, or Y = 1.25X, etc.

[0038] In specific embodiments, lithium can be supplemented to both the positive electrode and the negative electrode simultaneously, or lithium can be supplemented only to the positive electrode or the negative electrode. When there is no lithium supplementation to the positive electrode, Y is the proportion of the lithium supplementation capacity of the negative electrode; when there is no lithium supplementation to the negative electrode, Y is the proportion of the lithium supplementation capacity of the positive electrode; when both the positive electrode and the negative electrode are supplemented with lithium, Y is the sum of the proportion of the lithium supplementation capacity of the negative electrode and the proportion of the lithium supplementation capacity of the positive electrode.

[0039] In some embodiments, 0.2X < Y < 0.9X. Thus, the power performance, fast charging performance, and high and low temperature performance of the battery can be further improved. Exemplarily, X and Y can satisfy: Y = 0.25X, Y = 0.3X, Y = 0.35X, Y = 0.4X, Y = 0.45X, Y = 0.5X, Y = 0.55X, Y = 0.6X, Y = 0.65X, Y = 0.7X, Y = 0.75X, Y = 0.8X, or Y = 0.85X, etc.

[0040] In some embodiments, X can be 0.1% to 30%. When X is within the range of 0.1% to 30%, the negative electrode can have good structural stability, energy density, and rate performance. In a more specific embodiment, when X is 15%, that is, the ratio of the sum of the pore volumes of pores with a size of ≥1 μm in the negative electrode active material layer to the total pore volume of all pores is 15%, the lithium supplementation capacity ratio of the battery is 3% < Y < 19.95%. In some embodiments, X is 14% to 28%. Specifically, for example, X can be 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, or 28%. In some more preferred embodiments, X satisfies 16% ≤ X ≤ 26%.

[0041] In some embodiments, the battery further includes a positive electrode, and the positive electrode and / or the negative electrode includes a self-supporting electrode membrane. The self-supporting electrode membrane refers to an electrode membrane that can be independently formed without relying on a current collector for support.

[0042] In the present invention, the ratio of the sum of the pore volumes of pores with a size of ≥1 μm in the negative electrode active material layer to the total pore volume of all pores is X, which is obtained by testing and calculating through mercury intrusion porosimetry.

[0043] In the present invention, the detection method for the lithium supplementation capacity ratio is as follows:

[0044] (1) When the end product is a battery:

[0045] The detection method for the lithium supplementation capacity ratio of the positive electrode is as follows: First, adjust the SOC state of the battery to 0%, then disassemble the battery, and take out the complete positive electrode A1, negative electrode B1, and electrolyte.

[0046] [[ID=z18]]Assemble the positive electrode A1 and the negative electrode B1 into a battery, place the battery in an environment at 25°C for 10 h, and perform an electrochemical test of full charge (100% SOC) / full discharge (0% SOC) on the battery at a current of 0.1C, and the first-cycle discharge specific capacity obtained is C1. Assemble the positive electrode A1 and the non-lithium-supplemented and non-formed negative electrode B2 (except not using a lithium supplementing agent, the negative electrode B2 uses the same material composition and electrode structure as the negative electrode B1) into a battery, place the battery in an environment at 25°C for 10 h, charge the current to the full charge state (100% SOC) at a current of 0.1C, put it in an oven at 45°C for high-temperature storage for 24 h, then transfer it to an environment at 25°C to cool for 10 h. After the temperature inside and outside the battery returns to room temperature, discharge the battery completely at a current of 0.1C (0% SOC), and the first-cycle discharge specific capacity obtained is C2. The lithium supplementation capacity ratio of the positive electrode Y = (C1 - C2) / C2.

[0047] The detection method for the proportion of lithium compensation capacity in the negative electrode is as follows: adjust the SOC state of the lithium-compensated battery to 0%, then disassemble the battery and take out the complete positive electrode A3 and negative electrode B3.

[0048] Adjust the SOC state of the non-lithium-compensated battery (except for using the lithium compensator, the non-lithium-compensated battery uses the same material composition and structure as the lithium-compensated battery) to 0%, then disassemble the battery and take out the complete positive electrode A4 and negative electrode B4. Assemble the negative electrode B3 with lithium metal to form a battery, then place the battery in an environment at 25°C for 10 h, and perform a complete de-lithiation test with a current of 0.1C. The obtained specific capacity is C3. Assemble the negative electrode B4 with lithium metal to form a battery, then place the battery in an environment at 25°C for 10 h, and perform a complete de-lithiation test with a current of 0.1C. The obtained specific capacity is C4. Then the proportion of additional pre-stored lithium is Y 额外 =(C3 - C4) / C2;

[0049] Assemble the positive electrode A3 and the negative electrode B3 to form a battery, then place the battery in an environment at 25°C for 10 h, and perform an electrochemical test of full charge (100% SOC) / full discharge (0% SOC) on the battery with a current of 0.1C. The obtained discharge specific capacity is C5. Assemble the positive electrode A3 and the non-lithium-compensated and non-formed negative electrode B5 (except for not using the lithium compensator, the negative electrode B5 uses the same material composition and electrode structure as the negative electrode B3) to form a battery, and perform an electrochemical test of full charge (100% SOC) / full discharge (0% SOC). The obtained first-cycle discharge specific capacity is C6. Then the proportion of the consumed lithium compensation capacity in the negative electrode is Y 消耗 =(C5 - C6) / C6. So the total proportion of lithium compensation Y = Y 额外 + Y 消耗 .

[0050] The second aspect of the present invention provides a method for preparing the battery described above. The method includes: preparing a negative electrode to make the battery satisfy 0.2X < Y < 1.33X;

[0051] Wherein, the negative electrode includes a negative electrode active material layer, X is the ratio of the sum of the volumes of pores with a size ≥ 1 μm in the negative electrode active material layer to the total pore volume of all pores; Y is the ratio of the lithium compensation capacity of the battery to the capacity of the battery other than the lithium compensation capacity.

[0052] In the specific implementation manner, the negative electrode can be prepared first, so that the ratio of the sum of the volumes of pores with a size ≥ 1 μm in the negative electrode to the total pore volume is X. According to the relationship of 0.2X < Y < 1.33X, adjust and control the total proportion Y of the lithium compensation capacity of the battery, and then control the dosage of the lithium compensator. In the preferred implementation manner, 0.2X < Y < 0.9X, and X is 16% - 26%.

[0053] In the method described in the present invention, controlling the amount of the lithium supplement agent specifically refers to controlling the amount of the lithium supplement agent based on the amount of available active lithium that can actually be exerted in the lithium supplement agent. Generally, the theoretical active lithium of the lithium supplement agent is not the same as the amount of available active lithium that can actually be exerted. Different lithium supplement materials have different ratios of available active lithium. The amount of available active lithium for each lithium supplement material can be calculated according to the amount known to those skilled in the art or provided by the lithium supplement supplier.

[0054] In actual applications, the lithium supplement capacity is used to convert the amount of lithium supplement agent used. For the same lithium supplement capacity, the amount of lithium supplement agent used will be different when using different lithium supplement agents. It needs to be calculated based on the chemical formula of lithium supplement. Therefore, it is only necessary to emphasize the lithium supplement capacity to control the amount of lithium supplement agent used (there are many types of lithium supplement agents).

[0055] In a specific embodiment, the method for preparing the negative electrode includes mixing a negative electrode lithium supplement agent with a negative electrode active material.

[0056] In another specific embodiment, the method for preparing the negative electrode includes providing a negative electrode lithium replenishing layer, wherein the negative electrode lithium replenishing layer includes a negative electrode lithium replenishing agent. For example, a negative electrode active material layer and a negative electrode lithium replenishing layer are stacked on a negative electrode current collector. In some embodiments, the negative electrode active material layer may include a negative electrode active material but not a negative electrode lithium replenishing agent, and the negative electrode lithium replenishing layer may include a negative electrode lithium replenishing agent but not a negative electrode active material; in some embodiments, the negative electrode active material layer may include a negative electrode active material and a negative electrode lithium replenishing agent, and the content of the negative electrode active material in the negative electrode active material layer is greater than the content of the negative electrode lithium replenishing agent, and / or the negative electrode lithium replenishing layer may include a negative electrode lithium replenishing agent and a negative electrode active material, and the content of the negative electrode lithium replenishing agent in the negative electrode lithium replenishing layer is greater than the content of the negative electrode active material.

[0057] In a specific embodiment, the negative electrode is prepared by a dry process. Specifically, the method for preparing the negative electrode by a dry process includes mixing and rolling the negative electrode active material, a binder and a conductive agent to obtain a self-supporting negative electrode membrane; then compounding the self-supporting negative electrode membrane with a negative electrode current collector; and adding a negative electrode lithium replenisher to replenish lithium. In some embodiments, compounding may include hot pressing and rolling. In a more specific embodiment, the method for preparing the negative electrode includes: grinding, mixing, rolling and calendering the negative electrode active material, a binder and a conductive agent in sequence to obtain a self-supporting negative electrode membrane; then hot pressing and rolling the self-supporting negative electrode membrane with a negative electrode current collector, and then adding a negative electrode lithium replenisher to replenish lithium. In a specific embodiment, based on the amount of the negative electrode active material, the amount of the binder is 0.5wt%-3wt%, and the amount of the conductive agent is 0.2wt%-3wt%.

[0058] In a preferred embodiment, the method for preparing the negative electrode comprises: premixing the negative electrode active material, binder, and conductive agent, then grinding and mixing the mixture, rolling the resulting ground mixture through a hot roller press to obtain a self-supporting negative electrode membrane, rolling the self-supporting negative electrode membrane through a calendering roller press to obtain a negative electrode membrane, laminating the negative electrode membrane with the negative electrode current collector through hot pressing and rolling, and then spraying lithium supplementation for lithium supplementation. The premixing can be performed in a mixer, and the grinding and mixing can be performed in a jet mill. The conditions for the hot roller press include: a rolling line pressure of 0.1-1 t / cm, a differential speed ratio of 1:1-3, and a temperature of 100-250°C. The conditions for the calendering roller press include: a rolling line pressure of 0.1-5 t / cm, a differential speed ratio of 1:1-3, and a temperature of 60-180°C.

[0059] In one embodiment, the negative electrode is prepared using a wet process. Specifically, the method for preparing the negative electrode includes: mixing a binder, a conductive agent, a solvent, and a negative electrode active material; applying the resulting slurry to a negative electrode current collector; rolling the mixture; and then adding a negative electrode lithium replenisher for lithium replenishment. The amounts of the binder and conductive agent can be determined according to conventional methods in the art. In a specific embodiment, the amount of the binder is 0.5-3wt%, and the amount of the conductive agent is 0.2-3wt%, based on the amount of the negative electrode active material.

[0060] In a preferred embodiment, the method for preparing the negative electrode comprises: mixing a binder, a conductive agent, and a solvent, then adding a negative electrode active material and continuing to mix to obtain a slurry; then sieving the slurry and spraying it on both sides of the negative electrode current collector; drying and rolling the slurry; and finally adding a negative electrode lithium replenisher for lithium replenishment. The mixing can be performed in a blender.

[0061] In a specific embodiment, the method for preparing the battery described above further includes preparing a positive electrode, and the method for preparing the positive electrode includes mixing a positive electrode lithium supplement with a positive electrode active material.

[0062] In another specific embodiment, the method for preparing the battery described above further includes preparing a positive electrode, wherein the method for preparing the positive electrode includes providing a positive electrode lithium replenishing layer, wherein the positive electrode lithium replenishing layer includes a positive electrode lithium replenishing agent. For example, a positive electrode active material layer and a positive electrode lithium replenishing layer are stacked on the positive electrode current collector. In some embodiments, the positive electrode active material layer may include a positive electrode active material but not a positive electrode lithium replenishing agent, and the positive electrode lithium replenishing layer may include a positive electrode lithium replenishing agent but not a positive electrode active material; in some embodiments, the positive electrode active material layer may include a positive electrode active material and a positive electrode lithium replenishing agent, wherein the content of the positive electrode active material in the positive electrode active material layer is greater than the content of the positive electrode lithium replenishing agent, and / or the positive electrode lithium replenishing layer may include a positive electrode lithium replenishing agent and a positive electrode active material, wherein the content of the positive electrode lithium replenishing agent in the positive electrode lithium replenishing layer is greater than the content of the positive electrode active material.

[0063] In a specific embodiment, the positive electrode is prepared by a dry process. Specifically, the method for preparing the positive electrode includes: mixing and rolling the positive electrode active material, the positive electrode lithium replenisher, the binder and the conductive agent to obtain a self-supporting positive electrode membrane, and compounding the self-supporting positive electrode membrane with the positive electrode current collector. In some embodiments, compounding may include hot pressing and rolling. In a more specific embodiment, the method for preparing the positive electrode includes: grinding, mixing, rolling and calendering the positive electrode active material, the positive electrode lithium replenisher, the binder and the conductive agent in sequence to obtain a self-supporting positive electrode membrane, and then hot pressing and rolling the self-supporting positive electrode membrane with the positive electrode current collector. The amount of the binder and the conductive agent can be determined according to conventional methods in the art. In a specific embodiment, based on the amount of the positive electrode active material, the amount of the binder is 0.5-3wt%, and the amount of the conductive agent is 0.2-3wt%.

[0064] In a preferred embodiment, the method for preparing the positive electrode comprises: premixing the positive electrode active material, a positive electrode lithium supplement, a binder, and a conductive agent, then grinding and mixing the mixture, rolling the resulting ground mixture through a hot roller press to obtain a self-supporting positive electrode membrane, rolling the self-supporting positive electrode membrane through a calendering roller press to obtain a positive electrode membrane, and hot pressing and rolling the positive electrode membrane and the positive electrode current collector. The premixing can be performed in a mixer; the grinding and mixing can be performed in a jet mill. The conditions for rolling on the hot roller press include: a rolling line pressure of 0.1-1 t / cm, a differential speed ratio of 1:1-3, and a temperature of 100-250°C. The conditions for rolling on the calendering roller press include: a rolling line pressure of 0.1-5 t / cm, a differential speed ratio of 1:1-3, and a temperature of 60-180°C.

[0065] In one embodiment, the positive electrode is prepared using a wet process. Specifically, the method for preparing the positive electrode includes: mixing a binder, a conductive agent, a solvent, a positive electrode active material, and a positive electrode lithium supplement; then applying the resulting slurry to a positive electrode current collector; and rolling the mixture. The amounts of the binder and conductive agent can be determined according to conventional methods in the art. In a specific embodiment, the amount of the binder is 0.5-3wt%, and the amount of the conductive agent is 0.2-3wt%, based on the amount of the positive electrode active material.

[0066] In a preferred embodiment, the method for preparing the positive electrode comprises: mixing a binder, a conductive agent, and a solvent, then adding a positive electrode active material and a positive electrode lithium supplement, and continuing to mix to obtain a slurry; then sieving the slurry, spraying it on both sides of the positive electrode current collector, drying it, and then rolling it. The mixing can be performed in a blender.

[0067] During the aforementioned process of preparing the negative and positive electrodes, the solvent can be any conventional solvent in the art. In specific embodiments, the solvent can be one or more of N-methylpyrrolidone (NMP) and deionized water (HO). The amount of the solvent used is not particularly limited, as long as the materials can be uniformly mixed to form a slurry. In specific embodiments, the viscosity of the slurry can be 2500-4300 mPa·s.

[0068] In the present invention, the positive and negative electrode lithium replenishers can be various options known in the art, as long as they can replenish lithium for the battery. In a specific embodiment, the negative electrode lithium replenisher can be selected from one or more of lithium powder, lithium silicide powder, lithium foil, and lithium ribbon. The positive electrode lithium replenisher can be selected from one or more of lithium oxalate, Li2O, Li2O2, Li2S, Li3N, LiF, Li5FeO4, Li2CO3, Li2MoO4, Li6CoO4, and Li2NiO2.

[0069] In the present invention, the negative electrode active material can be various choices well known in the art. For example, the negative electrode active material can be selected from one or more of carbon-based negative electrode materials, silicon-based negative electrode materials, tin-based negative electrode materials, titanium-based negative electrode materials, iron-based negative electrode materials, lithium negative electrode materials, sodium negative electrode materials, potassium negative electrode materials, magnesium negative electrode materials, zinc negative electrode materials, aluminum negative electrode materials, and antimony negative electrode materials. In a specific embodiment, the carbon-based negative electrode material can be one or more of graphite, hard carbon, soft carbon, and graphene. In a specific embodiment, the silicon-based negative electrode material can be selected from one or more of silicon, silicon-carbon, silicon-oxygen, and silicon-metal compounds. In a specific embodiment, the tin-based negative electrode material can be selected from one or more of tin, tin-carbon, tin-oxygen, and tin-metal compounds. In a specific embodiment, the lithium negative electrode material, the sodium negative electrode material, the potassium negative electrode material, the magnesium negative electrode material, the zinc negative electrode material, the aluminum negative electrode material, and the antimony negative electrode material can be lithium metal, sodium metal, potassium metal, magnesium metal, zinc metal, aluminum metal, and antimony metal. In a more specific embodiment, the negative electrode active material is selected from one or more of natural graphite, artificial graphite, hard carbon, soft carbon, lithium titanate, iron oxide, lithium titanium phosphate, titanium dioxide, silicon, silicon oxide, aluminum, tin and antimony.

[0070] In the present invention, the positive electrode active material is selected from one or more of metal oxide positive electrode active materials, phosphate positive electrode active materials and metal sulfide positive electrode active materials. The metal oxide positive electrode active materials, phosphate positive electrode active materials and metal sulfide positive electrode active materials can be conventionally selected in the art. In some specific embodiments, the metal oxide positive electrode active material is selected from LiCoO2, LiNiO2, LiCo x Ni 1-x O2(0≤x≤1), LiCo x Ni 1-x-y Mn y O2(0≤x≤1,0≤y≤1), LiCo x Ni 1-x-y Al y O2(0≤x≤1,0≤y≤1), LiMn2O4, LiFe x Mn y M z O4 (M is at least one of Al, Mg, Ga, Cr, Co, Ni, Cu, Zn and Mo, 0≤x≤1, 0≤y≤1, 0≤z≤1, x+y+z=1), Li 1+x L 1－y－z M y N zO2 (L, M, N are each independently at least one of Li, Co, Mn, Ni, Fe, Al, Mg, Ga, Ti, Cr, Cu, Zn, Mo, F, I, S and B, -0.1≤x≤0.2, 0≤y≤1, 0≤z≤1, 0≤y+z≤1), one or more of Li2CuO2, Li5FeO4, TiO2, Cr3O8, V2O5 and MnO2. In some specific embodiments, the phosphate-based positive electrode active material is selected from one or more of LiFePO4, Li3V2(PO4)3, Li3V3(PO4)3 and LiVPO4F. In some specific embodiments, the metal sulfide is selected from TiS2, V2S3, FeS, FeS2 and LiMS x (M is at least one transition metal element such as Ti, Fe, Ni, Cu, Mo, etc., 1≤x≤2.5) one or more.

[0071] In the present invention, the conductive agent can be a conventional choice in the art. In a specific embodiment, the conductive agent is selected from one or more of acetylene black, Ketjen black, Super-P, carbon nanotubes, carbon nanofibers, activated carbon and graphene.

[0072] In the present invention, the binding agent can be the conventional selection of this area.In a specific embodiment, the binding agent can be selected from tetrafluoroethylene and copolymer thereof, polyvinylidene fluoride and copolymer thereof, polyolefin and copolymer thereof, polyether and copolymer thereof, polyphenylene oxide and copolymer thereof, polysiloxane and copolymer thereof, polyester and copolymer thereof, polyethylene oxide, polyethylene-polyethylene glycol block copolymer, polydimethylsiloxane, poly (dimethylsiloxane-to-alkyl methyl siloxane), acrylonitrile-butadiene rubber, polyvinyl ester, polyvinyl acetate and polyacrylate one or more.In a more specific embodiment, the polyolefin includes one or more in polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinylidene fluoride copolymer and propylene-vinylidene fluoride copolymer. In a more specific embodiment, the polytetrafluoroethylene and its copolymers can be one or more of tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-propylene copolymer, tetrafluoroethylene-vinylidene fluoride copolymer, tetrafluoroethylene-ether copolymer, tetrafluoroethylene-siloxane copolymer, tetrafluoroethylene-branched polyether copolymer, tetrafluoroethylene-vinyl ether copolymer and tetrafluoroethylene-branched polyether-vinyl ether copolymer.

[0073] In some specific embodiments, the substrate used to prepare the negative electrode may be copper foil, and the substrate used to prepare the positive electrode may be aluminum foil.

[0074] A third aspect of the present invention provides an electrical device, which includes the battery described above or a battery prepared by the method described above.

[0075] The present invention will be described in detail below through examples, but the protection scope of the present invention is not limited thereto.

[0076] Example 1

[0077] In this embodiment, the negative electrode and the positive electrode are prepared by a dry method, and the negative electrode is supplemented with lithium.

[0078] S1. Pre-preparation of target negative electrode

[0079] S11, premixing 4000 g of negative electrode active material (graphite), 120 g of binder (tetrafluoroethylene-ethylene copolymer), and 40 g of conductive agent (Super-P) in a V-type mixer;

[0080] S12, grinding and mixing the mixture obtained in step S11 in a jet mill at a crushing pressure of 0.45 MPa;

[0081] S13, rolling the ground mixture obtained in step S12 into a self-supporting negative electrode membrane by a hot roller press, with a rolling line pressure of 0.8 t / cm, a differential speed ratio of 1:2, and a temperature of 160° C.;

[0082] S14, the self-supporting negative electrode membrane is subjected to two-stage calendering by a calendering roller press to obtain a plurality of thinned negative electrode membranes, the calendering line pressure is 0.8 t / cm, the differential speed ratio (i.e., the roller speed ratio) is 1:1.5, and the temperature is 130° C.;

[0083] S15. Hot-press the two thinned negative electrode films onto both sides of the copper foil with primer, and then roll-press with a linear pressure of 1.5 t / cm. The target negative electrode thickness is 140 μm.

[0084] After testing, the proportion M of the negative electrode pore size ≥1μm is 25.3%.

[0085] S2. Preparation of dry cathode

[0086] S21, placing 4000 g of positive electrode active material (LiFePO4), 100 g of binder (polytetrafluoroethylene) and 40 g of conductive agent (carbon nanotube) into a V-type mixer for premixing;

[0087] S22, grinding and mixing the mixture obtained in step S21 in a jet mill at a crushing pressure of 0.6 MPa;

[0088] S23, rolling the ground mixture obtained in step S22 into a self-supporting positive electrode membrane through a hot roller press, with a rolling line pressure of 1 t / cm, a differential speed ratio (i.e., roller speed ratio) of 1:2.5, and a temperature of 180° C.;

[0089] S24, the self-supporting positive electrode membrane is subjected to two-stage calendering by a calendering roller press to obtain a thinned positive electrode membrane, the calendering line pressure is 1.2 t / cm, the differential speed ratio is 1:2, and the temperature is 160° C.;

[0090] S25. The two thinned positive electrode films were hot-pressed and laminated on both sides of the aluminum foil with primer, and then rolled with a linear pressure of 2 t / cm. The thickness of the obtained positive electrode was 190 μm.

[0091] S3. Preparation of negative electrode lithium supplementation plate

[0092] S31, spray lithium powder on the surface of the negative electrode obtained in S15, the amount of lithium powder is 2.8 mg / m 2 .

[0093] After testing, the proportion of pore size ≥1μm in the negative electrode lithium replenishment plate is X, which is 23.3%, and the proportion of lithium replenishment capacity is Y, which is 10%. It can be seen that Y=0.43X, and X and Y meet 0.2X <Y<1.33X。

[0094] Example 2

[0095] In this embodiment, the negative electrode and the positive electrode are prepared by a dry method, and the positive electrode is supplemented with lithium.

[0096] S1. Pre-preparation of target negative electrode

[0097] S11, premixing 4000 g of negative electrode active material (graphite), 120 g of binder (tetrafluoroethylene-ethylene copolymer), and 40 g of conductive agent (Super-P) in a V-type mixer;

[0098] S12, grinding and mixing the mixture obtained in step S11 in a jet mill at a crushing pressure of 0.45 MPa;

[0099] S13, rolling the ground mixture obtained in step S12 into a self-supporting negative electrode membrane on a hot roller press, with a rolling line pressure of 0.8 t / cm, a differential speed ratio (i.e., roller speed ratio) of 1:2, and a temperature of 160° C.;

[0100] S14, the self-supporting negative electrode membrane is subjected to two-stage calendering by a calendering roller press to obtain a plurality of thinned negative electrode membranes, the calendering line pressure is 0.8 t / cm, the differential speed ratio (i.e., the roller speed ratio) is 1:1.5, and the temperature is 130° C.;

[0101] S15. Hot-press the two thinned negative electrode films onto both sides of the copper foil with primer, and then roll-press with a linear pressure of 1.5 t / cm. The target negative electrode thickness obtained by rolling is 140 μm.

[0102] After testing, the proportion M of the negative electrode pore size ≥1μm is 25.3%.

[0103] S2. Preparation of lithium-supplemented dry cathode

[0104] S21, 4000g of positive electrode active material (LiFePO4), 100g of binder (polytetrafluoroethylene), 40g of conductive agent (carbon nanotubes) and 80g of Li5FeO4 were placed in a V-type mixer for premixing;

[0105] S22, grinding and mixing the mixture obtained in step S21 in a jet mill at a crushing pressure of 0.6 MPa;

[0106] S23, rolling the ground mixture obtained in step S22 into a self-supporting positive electrode membrane through a hot roller press, with a rolling line pressure of 1 t / cm, a differential speed ratio (i.e., roller speed ratio) of 1:2.5, and a temperature of 180° C.;

[0107] S24, the self-supporting positive electrode membrane is subjected to two-stage calendering by a calendering roller press to obtain a plurality of thinned positive electrode membranes, the calendering line pressure is 1.2 t / cm, the differential speed ratio (i.e., the roller speed ratio) is 1:2, and the temperature is 160° C.;

[0108] S25. The two thinned positive electrode films are respectively hot-pressed and laminated on both sides of the aluminum foil with the primer, and the thickness of the obtained positive electrode is 190 μm.

[0109] Since the negative electrode is not replenished with lithium, the proportion X of the pores with a size of ≥1 μm in the negative electrode is the same as M, that is, 25.3%.

[0110] After testing, the lithium replenishment capacity of the positive electrode accounts for 8% Y. It can be seen that Y = 0.32X, X and Y satisfy 0.2X <Y<1.33X。

[0111] Example 3

[0112] In this embodiment, the negative electrode and the positive electrode are prepared by a wet method, and the negative electrode is supplemented with lithium.

[0113] S1. Pre-preparation of target wet-process negative electrode

[0114] S11, 100 g of a binder (polyvinylidene fluoride), 40 g of a conductive agent (Super-P) and 3500 g of NMP were mixed and stirred in a blender;

[0115] S12, adding 4000 g of negative electrode active material (graphite) to the mixture obtained in step S11, and continuing to stir and mix uniformly;

[0116] S13. The slurry obtained in step S12 is sieved and then sprayed on both sides of a copper foil, dried at a drying temperature of 125° C., and then roll-pressed to obtain a target negative electrode with a thickness of 140 μm.

[0117] After testing, the proportion M of the negative electrode pore size ≥1μm is 23.8%.

[0118] S2. Preparation of wet cathode

[0119] S21, 100 g of a binder (polyvinylidene fluoride), 40 g of a conductive agent (carbon nanotubes), and 2300 g of NMP were mixed and stirred in a blender;

[0120] S22, adding 4000g of positive electrode active material (LiFePO4) to the mixture obtained in step S31, and continuing to stir and mix uniformly;

[0121] S23. The slurry obtained in step S22 is sieved and then sprayed on both sides of aluminum foil, dried at a drying temperature of 125° C., and then rolled to obtain a positive electrode with a thickness of 190 μm.

[0122] S3. Preparation of negative electrode lithium supplementation plate

[0123] S31, spray lithium powder on the surface of the negative electrode obtained in S13, the amount of lithium powder is 2.1mg / m 2 .

[0124] After testing, the proportion of pore size ≥1μm in the negative electrode lithium replenishment plate is X, which is 21.5%, and the proportion of lithium replenishment capacity is Y, which is 8%. It can be seen that Y=0.37X, and X and Y meet 0.2X <Y<1.33X

[0125] Example 4

[0126] In this embodiment, the negative electrode and the positive electrode are prepared by a wet method, and the positive electrode is supplemented with lithium.

[0127] S1. Pre-preparation of target wet-process negative electrode

[0128] S11, 100 g of a binder (polyvinylidene fluoride), 40 g of a conductive agent (Super-P) and 3500 g of NMP were mixed and stirred in a blender;

[0129] S12, adding 4000 g of negative electrode active material (graphite) to the mixture obtained in step S11, and continuing to stir and mix uniformly;

[0130] S13. The slurry obtained in step S12 is sieved and then sprayed on both sides of a copper foil, dried at a drying temperature of 125° C., and then roll-pressed to obtain a target negative electrode with a thickness of 140 μm.

[0131] After testing, the proportion M of the negative electrode pore size ≥1μm is 23.8%.

[0132] S2. Preparation of lithium-supplemented wet-process positive electrode

[0133] S21, 100 g of a binder (polyvinylidene fluoride), 40 g of a conductive agent (carbon nanotubes), 60 g of Li5FeO4, and 2300 g of NMP were mixed and stirred in a blender;

[0134] S22, adding 4000 g of positive electrode active material (LiFePO4) to the mixture obtained in step S31 and continuing to stir and mix evenly;

[0135] S23. The slurry obtained in step S22 is sieved and then sprayed on both sides of aluminum foil, dried at a drying temperature of 125° C., and then rolled to obtain a positive electrode with a thickness of 190 μm.

[0136] Since the negative electrode is not replenished with lithium, the proportion X of the pores with a size of ≥1 μm in the negative electrode is the same as M, that is, 23.8%.

[0137] After testing, the lithium replenishment capacity of the positive electrode accounts for Y of 6%. It can be seen that Y = 0.25X, X and Y meet 0.2X <Y<1.33X。

[0138] Example 5

[0139] This embodiment adopts dry method to prepare negative electrode, wet method to prepare positive electrode, and lithium supplementation to negative electrode

[0140] S1. Pre-preparation of target negative electrode

[0141] S11, premixing 4000 g of negative electrode active material (graphite), 120 g of binder (tetrafluoroethylene-ethylene copolymer), and 40 g of conductive agent (Super-P) in a V-type mixer;

[0142] S12, grinding and mixing the mixture obtained in step S11 in a jet mill at a crushing pressure of 0.45 MPa;

[0143] S13, rolling the ground mixture obtained in step S12 into a self-supporting negative electrode membrane on a hot roller press, with a rolling line pressure of 0.8 t / cm, a differential speed ratio (i.e., roller speed ratio) of 1:2, and a temperature of 160° C.;

[0144] S14, the self-supporting negative electrode membrane is subjected to two-stage calendering by a calendering roller press to obtain a plurality of thinned negative electrode membranes, the calendering line pressure is 0.8 t / cm, the differential speed ratio (i.e., the roller speed ratio) is 1:1.5, and the temperature is 130° C.;

[0145] S15. Hot-press the two thinned negative electrode films onto both sides of the copper foil with primer, and then roll-press with a linear pressure of 2 t / cm. The target negative electrode thickness is 140 μm.

[0146] After testing, the proportion M of the negative electrode pore size ≥1μm is 20.3%.

[0147] S2. Preparation of wet cathode

[0148] S21, 100 g of a binder (polyvinylidene fluoride), 40 g of a conductive agent (carbon nanotubes), and 2300 g of NMP were mixed and stirred in a blender;

[0149] S22, adding 4000g of positive electrode active material (LiFePO4) to the mixture obtained in step S31, and continuing to stir and mix uniformly;

[0150] S23. The slurry obtained in step S22 is sieved and then sprayed on both sides of aluminum foil, dried at a drying temperature of 125° C., and then rolled to obtain a positive electrode with a thickness of 190 μm.

[0151] S3. Preparation of negative electrode lithium supplementation plate

[0152] S31, spray lithium powder on the surface of the negative electrode obtained in S15, the amount of lithium powder is 2.3mg / m 2 .

[0153] After testing, the proportion of pore size ≥1μm in the negative electrode lithium replenishment plate is X, which is 23.3%, and the proportion of lithium replenishment capacity is Y, which is 8.2%. It can be seen that Y=0.35X, and X and Y meet 0.2X <Y<1.33X。

[0154] Example 6

[0155] This embodiment uses a wet method to prepare the negative electrode and a dry method to prepare the positive electrode, and the negative electrode is lithium supplemented.

[0156] S1. Pre-preparation of target wet-process negative electrode

[0157] S11, 100 g of a binder (polyvinylidene fluoride), 40 g of a conductive agent (Super-P) and 3500 g of NMP were mixed and stirred in a blender;

[0158] S12, adding 4000 g of negative electrode active material (graphite) to the mixture obtained in step S11, and continuing to stir and mix uniformly;

[0159] S13. The slurry obtained in step S12 is sieved and then sprayed on both sides of a copper foil, dried at a drying temperature of 125° C., and then roll-pressed to obtain a target negative electrode with a thickness of 140 μm.

[0160] After testing, the proportion of the negative electrode pore size ≥ 1μm is 23.8%

[0161] S2. Preparation of dry cathode

[0162] S21, placing 4000 g of positive electrode active material (LiFePO4), 100 g of binder (polytetrafluoroethylene) and 40 g of conductive agent (carbon nanotube) into a V-type mixer for premixing;

[0163] S22, grinding and mixing the mixture obtained in step S21 in a jet mill at a crushing pressure of 0.6 MPa;

[0164] S23, rolling the ground mixture obtained in step S22 into a self-supporting positive electrode membrane through a hot roller press, with a rolling line pressure of 1 t / cm, a differential speed ratio (i.e., roller speed ratio) of 1:2.5, and a temperature of 180° C.;

[0165] S24, the self-supporting positive electrode membrane is subjected to two-stage calendering by a calendering roller press to obtain a plurality of thinned positive electrode membranes, the calendering line pressure is 1.2 t / cm, the differential speed ratio (i.e., the roller speed ratio) is 1:2, and the temperature is 160° C.;

[0166] S25. The two thinned positive electrode films were hot-pressed and laminated on both sides of the aluminum foil with primer, and then rolled with a linear pressure of 2 t / cm. The thickness of the obtained positive electrode was 190 μm.

[0167] S3. Preparation of negative electrode lithium supplementation plate

[0168] S31, spray lithium powder on the surface of the negative electrode obtained in S13, the amount of lithium powder is 2.1mg / m 2 .

[0169] After testing, the proportion of pore size ≥1μm in the negative electrode lithium replenishment plate is X, which is 22.3%, and the proportion of lithium replenishment capacity is Y, which is 8%. It can be seen that Y=0.36X, and X and Y meet 0.2X <Y<1.33X。

[0170] Example 7

[0171] In this comparative example, the negative electrode and the positive electrode were prepared by a wet method, and the negative electrode was supplemented with lithium.

[0172] S1. Pre-preparation of target wet-process negative electrode

[0173] S11, 100 g of a binder (polyvinylidene fluoride), 40 g of a conductive agent (Super-P) and 3500 g of NMP were mixed and stirred in a blender;

[0174] S12, adding 4000 g of negative electrode active material (graphite) to the mixture obtained in step S11, and continuing to stir and mix uniformly;

[0175] S13. The slurry obtained in step S12 is sieved and then sprayed on both sides of a copper foil, dried at a drying temperature of 125° C., and then roll-pressed to obtain a target negative electrode with a thickness of 140 μm.

[0176] After testing, the proportion M of the negative electrode pore size ≥1μm is 23.8%.

[0177] S2. Preparation of wet cathode

[0178] S21, 100 g of a binder (polyvinylidene fluoride), 40 g of a conductive agent (carbon nanotubes), and 2300 g of NMP were mixed and stirred in a blender;

[0179] S22, adding 4000g of positive electrode active material (LiFePO4) to the mixture obtained in step S31, and continuing to stir and mix uniformly;

[0180] S23. The slurry obtained in step S22 is sieved and then sprayed on both sides of aluminum foil, dried at a drying temperature of 125° C., and then rolled to obtain a positive electrode with a thickness of 190 μm.

[0181] S3. Preparation of negative electrode lithium supplementation plate

[0182] S31, spray lithium powder on the surface of the negative electrode obtained in S13, the amount of lithium powder is 1.4 mg / m 2 .

[0183] After testing, the proportion of pore size ≥1μm in the negative electrode lithium replenishment plate is X, which is 21.1%, and the proportion of lithium replenishment capacity is Y, which is 5.4%, Y=0.26X. It can be seen that X and Y meet 0.2X <Y<1.33X。

[0184] Example 8

[0185] In this comparative example, the negative electrode and the positive electrode were prepared by a wet method, and the negative electrode was supplemented with lithium.

[0186] S1. Pre-preparation of target wet-process negative electrode

[0187] S11, 100 g of a binder (polyvinylidene fluoride), 40 g of a conductive agent (Super-P) and 3500 g of NMP were mixed and stirred in a blender;

[0188] S12, adding 4000 g of negative electrode active material (graphite) to the mixture obtained in step S11, and continuing to stir and mix uniformly;

[0189] S13. The slurry obtained in step S12 is sieved and then sprayed on both sides of a copper foil, dried at a drying temperature of 125° C., and then roll-pressed to obtain a target negative electrode with a thickness of 140 μm.

[0190] After testing, the proportion M of the negative electrode pore size ≥1μm is 23.8%.

[0191] S2. Preparation of wet cathode

[0192] S21, 100 g of a binder (polyvinylidene fluoride), 40 g of a conductive agent (carbon nanotubes), and 2300 g of NMP were mixed and stirred in a blender;

[0193] S22, adding 4000g of positive electrode active material (LiFePO4) to the mixture obtained in step S31, and continuing to stir and mix uniformly;

[0194] S23. The slurry obtained in step S22 is sieved and then sprayed on both sides of aluminum foil, dried at a drying temperature of 125° C., and then rolled to obtain a positive electrode with a thickness of 190 μm.

[0195] S3. Preparation of negative electrode lithium supplementation plate

[0196] S31, spray lithium powder on the surface of the negative electrode obtained in S13, the amount of lithium powder is 4.5 mg / m 2 .

[0197] After testing, the proportion of pore size ≥1μm in the negative electrode lithium replenishment plate is X, which is 19.2%, and the proportion of lithium replenishment capacity is Y, which is 16.6%, Y=0.86X. It can be seen that X and Y meet 0.2X <Y<1.33X。

[0198] Example 9

[0199] In this embodiment, the negative electrode and the positive electrode are prepared by a dry method, and the negative electrode is supplemented with lithium.

[0200] S1. Pre-preparation of target negative electrode

[0201] S11, premixing 4000 g of negative electrode active material (graphite), 120 g of binder (tetrafluoroethylene-ethylene copolymer), and 40 g of conductive agent (Super-P) in a V-type mixer;

[0202] S12, grinding and mixing the mixture obtained in step S11 in a jet mill at a crushing pressure of 0.45 MPa;

[0203] S13, rolling the ground mixture obtained in step S12 into a self-supporting negative electrode membrane by a hot roller press, with a rolling line pressure of 0.8 t / cm, a differential speed ratio of 1:2, and a temperature of 160° C.;

[0204] S14, the self-supporting negative electrode membrane is subjected to two-stage calendering by a calendering roller press to obtain a plurality of thinned negative electrode membranes, the calendering line pressure is 0.8 t / cm, the differential speed ratio (i.e., roller speed ratio) is 1:1.5, and the temperature is 130° C.;

[0205] S15. Hot-press the two thinned negative electrode films onto both sides of the copper foil with primer, and then roll-press with a linear pressure of 3 t / cm. The target negative electrode thickness is 135 μm.

[0206] After testing, the proportion M of the negative electrode pore size ≥1μm is 15.6%.

[0207] S2. Preparation of dry cathode

[0208] S21, placing 4000 g of positive electrode active material (LiFePO4), 100 g of binder (polytetrafluoroethylene) and 40 g of conductive agent (carbon nanotube) into a V-type mixer for premixing;

[0209] S22, grinding and mixing the mixture obtained in step S21 in a jet mill at a crushing pressure of 0.6 MPa;

[0210] S23, rolling the ground mixture obtained in step S22 into a self-supporting positive electrode membrane through a hot roller press, with a rolling line pressure of 1 t / cm, a differential speed ratio (i.e., roller speed ratio) of 1:2.5, and a temperature of 180° C.;

[0211] S24, the self-supporting positive electrode membrane is subjected to two-stage calendering by a calendering roller press to obtain a thinned positive electrode membrane, the calendering line pressure is 1.2 t / cm, the differential speed ratio (i.e., roller speed ratio) is 1:2, and the temperature is 160° C.;

[0212] S25. The two thinned positive electrode films were hot-pressed and laminated on both sides of the aluminum foil with primer, and then rolled with a linear pressure of 2 t / cm. The thickness of the obtained positive electrode was 190 μm.

[0213] S3. Preparation of negative electrode lithium supplementation plate

[0214] S31, spray lithium powder on the surface of the negative electrode obtained in S15, the amount of lithium powder is 1.9 mg / m 2 .

[0215] After testing, the proportion of pore size ≥1μm in the negative electrode lithium replenishment plate is X, which is 14.8%, and the proportion of lithium replenishment capacity is Y, which is 6.7%. It can be seen that Y=0.45X, and X and Y meet 0.2X <Y<1.33X。

[0216] Comparative Example 1

[0217] In this comparative example, the negative electrode and the positive electrode were prepared by a wet method, and the negative electrode was supplemented with lithium.

[0218] S1. Pre-preparation of target wet-process negative electrode

[0219] S11, 100 g of a binder (polyvinylidene fluoride), 40 g of a conductive agent (Super-P) and 3500 g of NMP were mixed and stirred in a blender;

[0220] S12, adding 4000 g of negative electrode active material (graphite) to the mixture obtained in step S11, and continuing to stir and mix uniformly;

[0221] S13. The slurry obtained in step S12 is sieved and then sprayed on both sides of a copper foil, dried at a drying temperature of 125° C., and then roll-pressed to obtain a target negative electrode with a thickness of 140 μm.

[0222] After testing, the proportion M of the negative electrode pore size ≥1μm is 23.8%.

[0223] S2. Preparation of wet cathode

[0224] S21, 100 g of a binder (polyvinylidene fluoride), 40 g of a conductive agent (carbon nanotubes), and 2300 g of NMP were mixed and stirred in a blender;

[0225] S22, adding 4000g of positive electrode active material (LiFePO4) to the mixture obtained in step S31, and continuing to stir and mix uniformly;

[0226] S23. The slurry obtained in step S22 is sieved and then sprayed on both sides of aluminum foil, dried at a drying temperature of 125° C., and then rolled to obtain a positive electrode with a thickness of 190 μm.

[0227] S3. Preparation of negative electrode lithium supplementation plate

[0228] S31, spray lithium powder on the surface of the negative electrode obtained in S13, the amount of lithium powder is 1.1 mg / m 2 .

[0229] After testing, the proportion of pore size ≥1μm in the negative electrode lithium replenishment plate is X, which is 21.5%, and the proportion of lithium replenishment capacity is Y, which is 4%, Y=0.19X. It can be seen that X and Y do not meet 0.2X. <Y<1.33X。

[0230] Comparative Example 2

[0231] In this comparative example, the negative electrode and the positive electrode were prepared by a wet method, and lithium supplementation was not performed.

[0232] S1. Pre-preparation of target wet-process negative electrode

[0233] S11, 100 g of a binder (polyvinylidene fluoride), 40 g of a conductive agent (Super-P) and 3500 g of NMP were mixed and stirred in a blender;

[0234] S12, adding 4000 g of negative electrode active material (graphite) to the mixture obtained in step S11, and continuing to stir and mix uniformly;

[0235] S13. The slurry obtained in step S12 is sieved and then sprayed on both sides of a copper foil, dried at a drying temperature of 125° C., and then roll-pressed to obtain a target negative electrode with a thickness of 140 μm.

[0236] After testing, the proportion M of the negative electrode pore size ≥1μm is 23.8%.

[0237] S2. Preparation of wet cathode

[0238] S21, 100 g of a binder (polyvinylidene fluoride), 40 g of a conductive agent (carbon nanotubes), and 2300 g of NMP were mixed and stirred in a blender;

[0239] S22, adding 4000g of positive electrode active material (LiFePO4) to the mixture obtained in step S31, and continuing to stir and mix uniformly;

[0240] S23. The slurry obtained in step S22 is sieved and then sprayed on both sides of aluminum foil, dried at a drying temperature of 125° C., and then rolled to obtain a positive electrode with a thickness of 190 μm.

[0241] Batteries were assembled using the positive and negative electrodes prepared in the Examples and Comparative Examples, along with a separator (polyethylene / polypropylene composite film) and an electrolyte (the electrolyte was a 1.2 mol / L LiPF6 solution, and the solvent was a mixed solvent of ethylene carbonate:ethyl methyl carbonate:dimethyl carbonate:diethyl carbonate:fluoroethylene carbonate in a mass ratio of 23:25:24:28:15). The batteries were then formed and tested for fast charge performance, cycle stability, and rate discharge capability. For each performance in each Example and Comparative Example, at least three parallel samples were run, and the results were averaged, as shown in Tables 1 and 2.

[0242] The test method is:

[0243] 1. Fast charging capability test: The expansion thickness of the battery cell at different charging rates is evaluated using an in-situ expansion analyzer. This can determine the lithium deposition voltage and SOC window of the battery cell at different charging rates. It is a non-destructive lithium deposition detection method. Specifically, the SOC window at the thickness inflection point during the charging rate (7C, 6.5C, 6C, 5.5C, 5C, 4.5C, 4C, 3.5C, 3C, 2.5C, 2C, 1.5C, 1C, 0.5C, 0.33C) is calculated. Push forward 20% as the SOC at which lithium deposition begins at this rate; the fast charging process starts charging at a high rate (such as 7C). When the SOC at which lithium deposition begins is reached, jump to the next rate (such as 6.5C) to continue charging at the SOC at which lithium deposition begins, then jump to the next rate (such as 5.5C) to continue charging at the SOC at which lithium deposition begins until the battery is charged to 80% SOC. The sum of the charging time at each rate is calculated as the battery's 0-80% SOC fast charging time. Comparing the time required for the battery to charge from 10% SOC to 80% SOC is used as a parameter to measure fast charging capability.

[0244] 2. Cycle performance: At 25°C, charge each battery at 1C to an upper voltage of 3.8V, then discharge at 1C to a lower voltage of 2.0V. This cycle is counted as one. Repeat this cycle for 1000 cycles. Record the discharge capacity at the 1000th cycle. Calculate the residual capacity after 1000 cycles of 1C charge and 1C discharge: residual capacity = discharge capacity at the 1000th cycle / discharge capacity at the first cycle.

[0245] 3. Room temperature rate discharge capacity: At 25°C, the battery is fully charged to 100% SOC at a current of 0.33C, and discharged to 0% SOC at a current of 0.33C. The capacity at this time is C1. The battery is then fully charged to 100% SOC at a current of 0.33C, and discharged to 0% SOC at a rate of 3C. The capacity at this time is C2. The room temperature 3C rate discharge capacity is C2 / C1.

[0246] 4. Low temperature (10°C) rate discharge capacity: At 25°C, the battery is fully charged to 100% SOC at a current of 0.33C, and discharged to 0% SOC at a current of 0.33C. The capacity at this time is calculated as C1. The battery is then fully charged to 100% SOC at a current of 0.33C, placed at low temperature (10°C) for 8 hours to make the internal and external temperatures of the battery cell consistent, and discharged to 0% SOC at a rate of 3C. The capacity at this time is calculated as C3, and the low temperature 3C rate discharge capacity is C3 / C1.

[0247] Table 1

[0248] serial number Fast charging capacity (min) Capacity remaining rate after 1000 cycles Example 1 13.6 97.7％ Example 2 14.5 97.5％ Example 3 20.5 94.6％ Example 4 20.8 93.8％ Example 5 18.6 96.3％ Example 6 17.8 96.5％ Example 7 21.3 94.6 Example 8 22.4 95.8％ Example 9 19.2 93.1％ Comparative Example 1 23.7 91.8％ Comparative Example 2 25.1 90％

[0249] Table 2

[0250]

[0251]

[0252] It can be seen from Table 1 and Table 2 that the batteries prepared using the positive and negative electrodes in the embodiments of the present invention have significantly better fast charging performance, cycle stability, room temperature rate discharge capacity and low temperature rate discharge capacity than the comparative examples.

[0253] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A battery comprising a negative electrode, characterized in that: The negative electrode includes a negative electrode active material layer; in the negative electrode active material layer, the ratio of the sum of the volumes of pores with a size of 1 μm or larger to the pore volume of all pores is X, the ratio of the lithium replenishment capacity of the battery to the capacity of the battery other than the lithium replenishment capacity is Y, and X and Y satisfy: 14%≤X≤26%, 5%≤Y≤17%, and 0.2X<Y≤0.9X.

2. The battery according to claim 1, characterized in that The battery further comprises a positive electrode, wherein the positive electrode and / or the negative electrode comprises a self-supporting electrode membrane.

3. A method for preparing the battery according to claim 1 or 2, characterized in that: The method comprises: preparing a negative electrode so that the battery satisfies the following conditions: 14%≤X≤26%, 5%≤Y≤17%, and 0.2X<Y≤0.9X; The negative electrode includes a negative electrode active material layer; X is the ratio of the sum of the volumes of pores with a size ≥1 μm to the pore volume of all pores in the negative electrode active material layer; and Y is the ratio of the lithium replenishment capacity of the battery to the capacity of the battery other than the lithium replenishment capacity.

4. The method according to claim 3, characterized in that The method for preparing the negative electrode comprises mixing a negative electrode lithium supplement with a negative electrode active material, and / or A negative electrode lithium replenishing layer is provided, and the negative electrode lithium replenishing layer includes a negative electrode lithium replenishing agent.

5. The method according to claim 3, characterized in that The method for preparing the negative electrode comprises: mixing and rolling a negative electrode active material, a binder and a conductive agent to obtain a self-supporting negative electrode film; then compounding the self-supporting negative electrode film with a negative electrode current collector; and adding a negative electrode lithium replenisher to replenish lithium.

6. The method according to claim 5, characterized in that Based on the amount of the negative electrode active material, the amount of the binder is 0.5wt%-3wt%, and the amount of the conductive agent is 0.2wt%-3wt%.

7. The method according to claim 3, characterized in that The method further comprises preparing a positive electrode, wherein the method comprises mixing a positive electrode lithium supplement with a positive electrode active material, and / or A positive electrode lithium replenishing layer is provided, and the positive electrode lithium replenishing layer includes a positive electrode lithium replenishing agent.

8. The method according to claim 3, characterized in that The method further includes preparing a positive electrode, and the method for preparing the positive electrode includes: mixing and rolling a positive electrode active material, a positive electrode lithium supplement, a binder and a conductive agent to obtain a self-supporting positive electrode membrane, and compounding the positive electrode membrane with a positive electrode current collector.

9. The method according to claim 8, characterized in that Based on the amount of the positive electrode active material, the amount of the binder is 0.5wt%-3wt%, and the amount of the conductive agent is 0.2wt%-3wt%.

10. The method according to claim 4 or 5, characterized in that The negative electrode lithium supplement comprises at least one of lithium powder, lithium silicide powder, lithium foil and lithium ribbon.

11. The method according to claim 4 or 5, characterized in that The negative electrode active material includes at least one of a carbon-based negative electrode material, a silicon-based negative electrode material, a tin-based negative electrode material, a titanium-based negative electrode material, an iron-based negative electrode material, a lithium negative electrode material, a sodium negative electrode material, a potassium negative electrode material, a magnesium negative electrode material, a zinc negative electrode material, an aluminum negative electrode material and an antimony negative electrode material.

12. The method according to claim 7 or 8, characterized in that The positive electrode lithium supplement includes at least one of lithium oxalate, Li2O, Li2O2, Li2S, Li3N, LiF, Li5FeO4, Li2CO3, Li2MoO4, Li6CoO4 and Li2NiO2.

13. The method according to claim 7 or 8, characterized in that The positive electrode active material includes at least one of a metal oxide positive electrode active material, a phosphate-based positive electrode active material, and a metal sulfide positive electrode active material.

14. An electrical device, characterized in that: The electrical device comprises the battery according to claim 1 or 2 or a battery prepared by the method according to any one of claims 3 to 13.

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