Battery pole piece, battery and electric device

Abstract

The application discloses a battery pole piece, a battery and a power utilization device. The battery pole piece comprises a current collector and an electrode film layer arranged on at least one side of the current collector, wherein the electrode film layer comprises an electrode active material layer and a porous liquid absorbing material layer, the porous liquid absorbing material layer is arranged between the current collector and the electrode active material layer, and the porous liquid absorbing material layer comprises a porous material. The porous liquid absorbing material layer has liquid absorbing and liquid retaining capabilities, and is arranged between the current collector and the electrode active material layer, so that more electrolyte on the side of the electrode active material layer far from the current collector can permeate to the side close to the current collector, the electrolyte can be better immersed into the whole electrode active material layer, and thus the immersion performance of the whole battery pole piece is improved. The battery pole piece is used in a secondary battery, and the first coulomb efficiency of the battery can be significantly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and particularly relates to a battery pole piece, a battery and a power utilization device. BACKGROUND

[0002] In recent years, new energy vehicles have developed rapidly, and the battery driving system is a main factor affecting the performance and cost of new energy vehicles. Due to the characteristics of high energy density, low memory effect and high working voltage, the secondary battery has become the preferred solution for the power battery in the battery driving system of the current new energy vehicle.

[0003] The secondary battery cell generally includes a positive pole piece, a separator and a negative pole piece. When the compaction density of the pole piece is increased, the energy density of the material can be increased. However, under the condition of high compaction density of the pole piece, it is difficult for the electrolyte to penetrate, which hinders the ion transmission, thereby affecting the electrochemical performance of the battery. SUMMARY

[0004] In view of the above problems, the application provides a battery pole piece, a battery and a power utilization device, aiming to solve the technical problem of how to improve the overall electrolyte wettability of the battery pole piece.

[0005] In a first aspect, the application provides a battery pole piece, which includes a current collector and an electrode film layer arranged on at least one side of the current collector. The electrode film layer includes an electrode active material layer and a porous liquid-absorbing material layer. The porous liquid-absorbing material layer is located between the current collector and the electrode active material layer, and the porous liquid-absorbing material layer includes a porous material.

[0006] By arranging the porous liquid-absorbing material layer between the current collector and the electrode active material layer of the battery pole piece, the porous liquid-absorbing material layer has a liquid-absorbing function based on its porous structure, and the porous material therein has a liquid-retaining capacity. Therefore, by utilizing the liquid-absorbing and liquid-retaining capacity of the porous liquid-absorbing material layer, more electrolyte on the side of the electrode active material layer away from the current collector can be penetrated to the side close to the current collector, and the electrolyte can also be immersed in the entire film layer of the electrode active material layer under the condition of high compaction density, thereby improving the overall wettability of the battery pole piece. Therefore, the battery pole piece provided by the application has good wettability to the electrolyte, and can significantly improve the first coulomb efficiency of the battery when used in the secondary battery.

[0007] In some embodiments, the porosity of the porous liquid-absorbing material layer is greater than or equal to 5.6%; and optionally, the porosity of the porous liquid-absorbing material layer is 48.3% to 60.4%.

[0008] The porous liquid-absorbing material layer with the above porosity has better liquid-absorbing and liquid-retaining capacity, and can be arranged between the current collector and the electrode active material layer to further improve the wettability uniformity of the overall battery pole piece.

[0009] In some embodiments, the porous material includes at least one of an aerogel, a sponge, or a porous nanosheet.

[0010] The aerogel, the sponge, and the porous nanosheet are porous materials with good liquid absorption and retention capabilities. The electrolyte penetrates into the porous materials through the pores between the porous materials and is further absorbed, thereby improving the wettability of the electrolyte in the electrode active material layer far from the current collector to the side close to the current collector.

[0011] In some embodiments, the following (1) to (3) are included:

[0012] (1) The aerogel includes at least one of an organic aerogel, an inorganic aerogel, or an organic-inorganic hybrid aerogel;

[0013] (2) The sponge includes at least one of a melamine sponge, a carbon nanotube sponge, or a honeycomb porous graphene sponge;

[0014] (3) The porous nanosheet includes at least one of a porous carbon nanosheet, a porous boron nitride nanosheet, or a porous carbon nitride nanosheet.

[0015] The above-mentioned aerogel, sponge, and porous nanosheet all have good liquid absorption and retention capabilities, and can significantly improve the wettability of the battery electrode sheet as a whole to the electrolyte when used between the current collector and the electrode active material layer.

[0016] In some embodiments, the aerogel satisfies one or more of the following (1) to (5):

[0017] (1) The specific surface area is 780 to 950 m 2 / g;

[0018] (2) The electrical conductivity is 64 to 85 S / cm;

[0019] (3) The porosity is 90.4 to 96%;

[0020] (4) The pore size is 68 to 90 nm;

[0021] (5) The pore volume is 3.5 to 4.2 ml / g.

[0022] The aerogel in the above parameter range further improves the electrolyte wettability rate on the basis of improving the liquid absorption and retention capabilities of the battery electrode sheet.

[0023] In some embodiments, the sponge satisfies one or more of the following (1) to (5):

[0024] (1) The specific surface area is 2050 to 2350 m 2 / g;

[0025] (2) the electrical conductivity is 1550-1800 S / cm;

[0026] (3) the porosity is 97.8%-99.1%;

[0027] (4) the pore size is 86-92 um;

[0028] (5) the pore volume is 4.1-4.7 ml / g.

[0029] The sponge in the above parameter range further improves the electrolyte infiltration rate on the basis of improving the liquid absorption and retention capacity of the battery electrode sheet.

[0030] In some embodiments, the porous nanosheet satisfies one or more of the following (1)-(5):

[0031] (1) the specific surface area is 1200-1300 m 2 / g;

[0032] (2) the electrical conductivity is 778-850 S / cm;

[0033] (3) the porosity is 7.4-8.7%;

[0034] (4) the pore size is 400-450 nm;

[0035] (5) the pore volume is 1.5-2 ml / g.

[0036] The porous nanosheet in the above parameter range further improves the electrolyte infiltration rate on the basis of improving the liquid absorption and retention capacity of the battery electrode sheet.

[0037] In some embodiments, the porous material includes aerogel, sponge and porous nanosheet, and the mass ratio of the aerogel, sponge and porous nanosheet is (70-94):(3-15):(3-15); or (80-90):(5-10):(5-10).

[0038] The aerogel, sponge and porous nanosheet are used in the porous liquid absorption material layer in the above mass ratio, so that the pore network formed by the porous materials of multiple morphologies in the porous liquid absorption material layer can further improve the liquid absorption and retention capacity of the porous liquid absorption material layer. The porous liquid absorption material layer used between the current collector and the electrode active material layer can further significantly improve the electrolyte infiltration effect of the battery electrode sheet.

[0039] In some embodiments, the aerogel includes carbon aerogel and silicon aerogel, and the mass ratio of the carbon aerogel and the silicon aerogel is (11.2-20.5):1.

[0040] The carbon aerogel and the silicon aerogel not only have good liquid absorption and liquid retention capacity, but also have good ionic conductivity. Therefore, using more carbon aerogel in the porous liquid-absorbing material layer is beneficial to improving the ion transmission performance of the battery electrode sheet on the substrate for improving the electrolyte wetting performance.

[0041] In some embodiments, the thickness of the porous liquid-absorbing material layer is 1-20 μm; optionally 3-5 μm.

[0042] The liquid retention amount of the porous liquid-absorbing material layer in the above thickness range can enable the electrode active material close to the current collector side to be fully wetted, and has good volumetric energy density.

[0043] In some embodiments, the battery electrode sheet is a positive electrode sheet or a negative electrode sheet.

[0044] The porous liquid-absorbing material layer used in the positive electrode sheet or the negative electrode sheet can achieve the effect of high electrolyte wetting.

[0045] In a second aspect, the embodiments of the present application provide a battery including the battery electrode sheet provided by the first aspect of the embodiments of the present application.

[0046] Since the battery electrode sheet provided by the first aspect of the embodiments of the present application has good wetting effect on the electrolyte, the battery has good charge and discharge performance.

[0047] In a third aspect, the embodiments of the present application provide a power utilization device including the battery provided by the second aspect of the embodiments of the present application.

[0048] By using the battery provided by the second aspect of the embodiments of the present application, the power utilization device has good charge and discharge performance and can work more stably and for a long time.

[0049] The above description is only a summary of the technical solutions of the present application. In order to enable the technical means of the present application to be more clearly understood, and to be implemented according to the content of the description, and in order to enable the above and other purposes, characteristics and advantages of the present application to be more apparent and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0050] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of the preferred embodiments and are not meant to limit the present application. Moreover, the same reference numerals in the attached drawings indicate the same or similar elements. In the drawings:

[0051] Figure 1 is a structural schematic diagram of the battery electrode sheet of the embodiments of the present application;

[0052] Figure 2is a flowchart of a method for manufacturing a battery electrode sheet according to an embodiment of the present application.

[0053] Figure 3 is a structural diagram of an embodiment of a secondary battery according to an embodiment of the present application.

[0054] Figure 4 is Figure 3 is a structural diagram of an embodiment of a secondary battery according to an embodiment of the present application.

[0055] Figure 5 is a structural diagram of an embodiment of a battery module according to an embodiment of the present application.

[0056] Figure 6 is a structural diagram of an embodiment of a battery pack according to an embodiment of the present application.

[0057] Figure 7 is Figure 6 is a structural diagram of an embodiment of a battery pack according to an embodiment of the present application.

[0058] Figure 8 is a structural diagram of an embodiment of an electrical device including a battery according to an embodiment of the present application as a power source.

[0059] BRIEF DESCRIPTION OF DRAWINGS

[0060] 11 - current collector; 12 - electrode film layer; 121 - electrode active material layer; 122 - porous liquid absorbing material layer; 20 - battery cell; 21 - case; 22 - top cover assembly; 23 - electrode assembly; 30 - battery module; 40 - battery pack; 41 - upper case; 42 - lower case. DETAILED DESCRIPTION

[0061] The embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0063] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified.

[0064] Reference within this document to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. It is expressly understood that any of the embodiments described herein can be combined with any of the other embodiments unless explicitly stated otherwise.

[0065] In the description of the embodiments of the present application, the term "and / or" is merely used to describe associated objects, and can represent that three conditions can exist simultaneously, for example, A and / or B can represent that the three conditions of A alone, A and B, and B alone can exist. In addition, the character " / " in the present application is generally used to represent that the associated objects are in an "or" relationship.

[0066] In the description of the embodiments of the present application, the term "a plurality of" refers to two or more (including two), and similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of pieces" refers to two or more pieces (including two pieces). "At least one" refers to one or more (including one, two, three, etc.).

[0067] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application.

[0068] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "mounting", "connecting", "connecting", "fixing", and the like should be understood in a broad sense, for example, can be fixedly connected, or can be detachably connected, or can be integrated; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0069] With the decreasing of traditional energy resources, the development of new energy storage devices is getting more and more attention. Among them, secondary batteries are concerned because of their high energy density, high theoretical capacity, good cycle stability and environmental protection characteristics. Secondary batteries can not only be applied to energy storage power systems such as hydroelectric, thermal, wind and solar power stations, but also be widely used in electric bicycles, electric motorcycles, electric vehicles and other electric vehicles. With the continuous expansion of the application field of secondary batteries as power batteries, the market demand is also increasing, and the electrochemical performance requirements of secondary batteries are also getting higher and higher.

[0070] Energy density refers to how much energy can be stored per unit volume or weight. It can be said that energy density is the biggest bottleneck restricting the development of current secondary batteries. Therefore, in order to develop high specific energy density materials, it is generally necessary to improve the compaction. However, when the compaction density of the electrode sheet is too large, the porosity in the electrode sheet decreases, which is not conducive to the infiltration of the electrolyte into the electrode sheet. Under the condition of high compaction density, it is difficult for the electrolyte to penetrate into the interior of the electrode sheet, which easily leads to the difficulty of active metal ions such as lithium ions to effectively insert and extract, thereby hindering the transport of active metal ions, resulting in a decrease in ionic conductivity and poor electrochemical performance.

[0071] After the electrode assembly is injected, the side of the electrode active material layer far from the current collector has more electrolyte than the side relatively close to the current collector. Taking the positive electrode sheet as an example, some studies have simulated the electrolyte infiltration characteristics of positive electrode sheets with different compaction ratios (thickness reduction of positive electrode active material layer by 0%, 10%, 20%, 30%, 40%) by using LBM (lattice Boltzmann) model. After the positive electrode active material is formed without rolling (i.e. the thickness of the positive electrode active material layer is reduced by 0%), the electrolyte can basically diffuse to most of the gap positions in the positive electrode active material layer, and only a small amount of electrolyte is left in the gap of the positive electrode active material layer. When the compaction density of the battery electrode sheet is increased, such as the thickness of the positive electrode active material layer is reduced by 10%, the electrolyte diffused from the separator begins to have difficulty in diffusing to the bottom of the positive electrode sheet, that is, the electrolyte on the side of the positive electrode active material layer far from the current collector is blocked from penetrating to the side close to the current collector. With the continuous reduction of the thickness of the positive electrode active material layer, the diffusion of the electrolyte in the battery electrode sheet becomes more and more difficult.

[0072] That is to say, for the battery electrode sheet in the vertical direction of the surface, under the condition of the same compaction density, the electrolyte in the electrode active material layer appears to have a decrease in infiltration as the distance from the surface of the current collector becomes closer. And in the case of no rolling of the electrode active material layer, the trend of reduction is slow, and the infiltration of the electrolyte on the surface of the battery electrode sheet is good; while in the case of increasing the compaction density, the saturation of the electrolyte infiltration decreases very obviously. Therefore, the compaction density of the battery electrode sheet and the electrolyte infiltration are difficult to be achieved at the same time.

[0073] Based on the above considerations, in order to overcome the defects of the battery pole piece, the embodiments of the present application design a battery pole piece which can better penetrate the electrolyte on the side close to the current collector from the side far from the current collector of the electrode active material layer. Specifically, a porous liquid absorbing material layer is arranged between the current collector and the electrode active material layer of the battery pole piece. By using the liquid absorbing and liquid retaining capacity of the porous liquid absorbing material layer, the battery pole piece can have good wettability of the electrolyte under the condition of high compaction density. Therefore, the following technical solutions are proposed.

[0074] Battery pole piece

[0075] In a first aspect, the embodiments of the present application provide a battery pole piece, which comprises: (1) a current collector (2) an electrode film layer, the electrode film layer is arranged on at least one side of the current collector. That is, the electrode film layer is arranged on one side of the current collector, or the electrode film layer is arranged on both sides of the current collector. The electrode film layer can be understood as a film layer containing electrode active material arranged on the current collector.

[0076] As shown in Figure 1 The battery pole piece comprises a current collector 11 and an electrode film layer 12. The electrode film layer 12 comprises an electrode active material layer 121 and a porous liquid absorbing material layer 122. The porous liquid absorbing material layer 122 is arranged between the current collector 11 and the electrode active material layer 121.

[0077] The battery pole piece is the core component of the battery, mainly plays the role of conducting electricity and storing electric quantity, generally includes positive pole piece and negative pole piece.

[0078] The current collector 11 refers to a structure or part that collects current in the battery. The current collector 11 in the positive pole piece can be called a positive current collector, and the current collector 11 in the negative pole piece can be called a negative current collector.

[0079] The electrode active material layer 121 refers to a film layer containing electrode active material in the battery. The electrode active material in the positive pole piece can be called positive active material, and the electrode active material in the negative pole piece can be called negative active material. During the charging and discharging of the battery, the electrode active material in the electrode active material layer 121 can realize the embedding and extraction of active metal ions.

[0080] The battery pole piece of the embodiment of the present application sets a porous liquid-absorbing material layer 122 with good liquid-absorbing and liquid-retaining capacity between the current collector 11 and the electrode active material layer 121. The electrolyte penetrates into the porous liquid-absorbing material layer 122 through the pores, and is continuously absorbed like the capillary adsorption, and further reaches saturation. In this way, more electrolyte on the side of the electrode active material layer 121 away from the current collector 11 can be penetrated to the side close to the current collector 11, and the electrolyte can also be immersed in the whole layer of the electrode active material layer 121 under the condition of high compaction density, thereby improving the overall immersion performance of the battery pole piece. Therefore, the battery pole piece provided by the embodiment of the present application has good immersion effect on the electrolyte, and can significantly improve the charge and discharge performance of the battery when used in the secondary battery.

[0081] In some embodiments, the porous liquid-absorbing material layer 122 refers to a film layer including a porous material. The porous liquid-absorbing material layer 122 has a certain porosity based on the porous characteristics of the porous material, thereby having good liquid-absorbing and liquid-retaining capacity for liquid. The porosity of the porous liquid-absorbing material layer 122 is at least 5%, so that it has good liquid-absorbing and liquid-retaining capacity for electrolyte.

[0082] In some embodiments, the porosity of the porous liquid-absorbing material layer 122 is ≥5.6%; for example, 6%, 7%, 10%, 12%, 14%, 18%, 20%, 25%, 28%, 30%, 35%, 38%, 40%, 45%, 49.5%, 50%, 51%, 52%, 54%, 55.1%, 55.8%, 56%, 56.5%, 57%, 57.2%, 58%, 60%, 65%, 68%, etc. The porous liquid-absorbing material layer 122 with such porosity can have good liquid-absorbing and liquid-retaining capacity for electrolyte.

[0083] Further, the porosity of the porous liquid-absorbing material layer 122 is 48.3% to 60.4%. The porous liquid-absorbing material layer 122 corresponding to the porosity range of 48.3% to 60.4% not only has better liquid-absorbing and liquid-retaining capacity, but also can make the electrolyte immersed in the whole electrode film layer 12 more uniform when set between the current collector 11 and the electrode active material layer 121, thereby further improving the immersion uniformity of the electrode film layer 12.

[0084] In some embodiments, the porous liquid-absorbing material layer 122 of the battery pole piece includes a porous material, and the porous material includes at least one of aerogel, sponge and porous nanosheet.

[0085] Aerogel refers to a kind of nanoscale porous solid material formed by replacing the liquid phase in the gel with gas through drying. It is the solid with the smallest density known at present. Aerogel has special microstructure characteristics such as high specific surface area and high porosity, and thus is used in the porous liquid-absorbing material layer 122 between the current collector 11 and the electrode active material layer 121, has good liquid-absorbing and liquid-retaining capacity for electrolyte, and thus can improve the wettability of the battery electrode sheet.

[0086] Sponge is a kind of porous material, including natural sponge and synthetic sponge, has good liquid-absorbing property, and thus is used in the porous liquid-absorbing material layer 122 between the current collector 11 and the electrode active material layer 121, has good liquid-absorbing and liquid-retaining capacity for electrolyte, and thus can improve the wettability of the battery electrode sheet.

[0087] Porous nanosheet is a kind of nanoscale sheet material with porous morphology, has large specific surface area, and thus is used in the porous liquid-absorbing material layer 122 between the current collector 11 and the electrode active material layer 121, has good liquid-absorbing and liquid-retaining capacity for electrolyte, and thus can improve the wettability of the battery electrode sheet.

[0088] In summary, aerogel, sponge and porous nanosheet are porous materials with good liquid-absorbing and liquid-retaining capacity. Electrolyte penetrates into the porous materials through the pores of the porous materials and is further absorbed, thereby improving the wettability of the electrolyte on the side of the electrode active material layer 121 far from the current collector 11 to the side close to the current collector 11. At the same time, the porous liquid-absorbing material layer 122 formed by the porous materials such as aerogel, sponge and porous nanosheet still has certain conductivity, enabling the electrical connection between the electrode active material layer 121 and the current collector 11.

[0089] In some embodiments, the aerogel includes at least one of organic aerogel, inorganic aerogel and organic-inorganic hybrid aerogel. Inorganic aerogel is based on inorganic matter, including elemental aerogel (such as carbon aerogel, graphene aerogel, metal gold aerogel, etc.), oxide aerogel (such as silicon dioxide, aluminum sesquioxide, etc.) and sulfide aerogel, etc. Organic aerogel is based on organic matter, mainly including phenolic aerogel, cellulose aerogel, polyimide aerogel, polyurethane (polyurea) aerogel, chitosan aerogel and chitosan-cellulose aerogel, etc. Organic-inorganic hybrid aerogel utilizes the advantages of organic matter and inorganic matter to realize the functionalization of aerogel materials. The above-mentioned types of aerogel all have good liquid-absorbing and liquid-retaining capacity, and thus can significantly improve the wettability of the battery electrode sheet as a whole when used between the current collector 11 and the electrode active material layer 121.

[0090] In some embodiments, the aerogel comprises an inorganic aerogel, and the inorganic aerogel comprises at least one of carbon aerogel, silicon aerogel, gold aerogel, oxide aerogel, and sulfide aerogel. The above inorganic aerogels not only have good liquid absorption and retention capacity, but also have stable performance and high temperature resistance, thus having a good service life in the battery pole piece.

[0091] In some embodiments, the sponge comprises at least one of melamine sponge, carbon nanotube sponge, and honeycomb porous graphene sponge. The above sponges have good liquid absorption and retention capacity, and can significantly improve the overall wettability of the battery pole piece to the electrolyte when used between the current collector 11 and the electrode active material layer 121.

[0092] In some embodiments, the porous nanosheet comprises at least one of porous carbon nanosheet, porous boron nitride nanosheet, and porous carbon nitride nanosheet. The above porous nanosheets have good liquid absorption and retention capacity, and can significantly improve the overall wettability of the battery pole piece to the electrolyte when used between the current collector 11 and the electrode active material layer 121.

[0093] In some embodiments, the aerogel satisfies: the specific surface area can be 780-950 m 2 / g; for example, the specific surface area of the aerogel can be 780 m 2 / g, 800 m 2 / g, 900 m 2 / g, 920 m 2 / g, 940 m 2 / g, 950 m 2 / g, etc. The electrical conductivity of the aerogel can be 64-85 S / cm; for example, the electrical conductivity of the aerogel can be 64 S / cm, 70 S / cm, 75 S / cm, 80 S / cm, 85 S / cm, etc. The porosity of the aerogel can be 90.4-96%; for example, the porosity of the aerogel can be 91%, 92%, 94%, 95%, 96%, etc. The pore size of the aerogel can be 68-90 nm; for example, the pore size of the aerogel can be 68 nm, 70 nm, 75 nm, 80 nm, 86 nm, 88 nm, 90 nm, etc. The pore volume of the aerogel can be 3.5-4.2 ml / g; for example, the pore volume of the aerogel can be 3.5 ml / g, 3.8 ml / g, 4 ml / g, 4.2 ml / g, etc.

[0094] The electrical conductivity (total dissolved solids) is referred to as: T.D.S. The electrical conductivity is the ability of a material to conduct current. The basic unit of electrical conductivity is Siemens (S), and the unit electrical conductivity S / cm is used in standard measurement.

[0095] The specific surface area refers to the total area per unit mass of the material, and the unit is m 2 / g according to the national standard. For materials with holes or pores, there are external surface areas and internal surface areas, and thus the specific surface area of the embodiments of the present application includes the sum of the external surface area and the internal surface area of the porous material.

[0096] The porosity refers to the percentage of the pore volume in the porous material to the total volume of the material in a natural state. The ratio of the total volume of the interconnected microvoids in the porous material to the external volume of the porous material is referred to as the effective porosity, and is denoted by ; the ratio of the total volume of all the interconnected and non-interconnected microvoids in the porous material to the external volume of the porous material is referred to as the absolute porosity or the total porosity, and is denoted by . The porosity of the present application refers to the effective porosity of the porous material

[0097] The bore diameter refers to the diameter of the hole on the surface of the material, and generally refers to the shape and size of the pore in the porous material. The hole is generally irregular, and thus it is generally regarded as a circle and the size of the hole is represented by the diameter.

[0098] The pore volume, also referred to as the pore volume, generally refers to the total pore volume per unit mass of the porous material, which is one of the adsorption characteristic values of the porous structural material.

[0099] Further, the conductivity of the porous material can be directly measured by using the two-probe method to measure the resistivity, and then converted into the conductivity. The specific surface area, porosity, pore diameter and pore volume of the porous material can be measured by using the nitrogen adsorption method.

[0100] The specific surface area, porosity, pore diameter and pore volume all reflect the liquid absorption rate of the porous material to the electrolyte to some extent, and appropriate parameter selection can shorten the time for the electrode active material to be soaked by the electrolyte, thereby improving the electrolyte soaking efficiency. By using porous materials with different porosities, specific surface areas, pore diameters and pore volumes in the porous liquid absorption material layer 122, the membrane layer has a certain porosity, which can affect the rate at which the electrolyte is soaked to the side of the electrode active material layer 121 close to the current collector 11, and the aerogels in the above parameter range of the embodiments of the present application further improve the electrolyte soaking rate on the basis of improving the liquid absorption and liquid retention capacity of the battery electrode sheet.

[0101] In some embodiments, the sponge satisfies: the specific surface area can be 2050-2350 m 2 / g; for example, the specific surface area of the sponge can be 2050 m 2 / g, 2060 m 2 / g, 2100 m 2 / g, 2200 m 2 / g, 2250 m 2 / g, 2300 m 2 / g, 2350 m 2 / g, etc. The sponge can have a conductivity of 1550-1800 S / cm; illustratively, the sponge can have a conductivity of 1550 S / cm, 1600 S / cm, 1650 S / cm, 1700 S / cm, 1750 S / cm, 1780 S / cm, 1800 S / cm, etc. The sponge can have a porosity of 97.8%-99.1%; illustratively, the sponge can have a porosity of 97.8%, 98%, 98.5%, 98.8%, 99%, 99.1%, etc. The sponge can have a pore size of 86 nm-92 um; illustratively, the sponge can have a pore size of 86 nm, 100 nm, 1 um, 5 um, 10 um, 20 um, 30 um, 50 um, 60 um, 70 um, 80 um, 92 um, etc. The sponge can have a pore volume of 4.1-4.7 ml / g; illustratively, the sponge can have a pore volume of 4.1 ml / g, 4.2 ml / g, 4.5 ml / g, 4.7 ml / g, etc. The sponge within the above parameter ranges further improves the electrolyte infiltration rate on the basis of improving the liquid absorption and retention capacity of the battery electrode sheet.

[0102] In some embodiments, the porous nanosheet satisfies: the specific surface area can be 1200-1300 m 2 / g; illustratively, the porous nanosheet can have a specific surface area of 1200 m 2 / g, 1250 m 2 / g, 1260 m 2 / g, 1280 m 2 / g, 1290 m 2 / g, 1300 m 2The conductivity of the porous nanosheet can be 778-850 S / cm; exemplary, the conductivity of the porous nanosheet can be 778 S / cm, 780 S / cm, 800 S / cm, 810 S / cm, 820 S / cm, 850 S / cm, etc. The porosity of the porous nanosheet can be 7.4-8.7%; exemplary, the porosity of the porous nanosheet can be 7.4%, 7.5%, 8%, 8.2%, 8.5%, 8.7%, etc. The pore size of the porous nanosheet can be 400-450 nm; exemplary, the pore size of the porous nanosheet can be 400 nm, 410 nm, 420 nm, 425 nm, 430 nm, 435 nm, 440 nm, 450 nm, etc. The pore volume of the porous nanosheet can be 1.5-2 ml / g; exemplary, the pore volume of the porous nanosheet can be 1.5 ml / g, 1.7 ml / g, 1.8 ml / g, 2 ml / g, etc. The porous nanosheet within the above parameter range can further improve the electrolyte infiltration rate on the basis of improving the liquid absorption and retention capacity of the battery electrode sheet.

[0103] In some embodiments, the porous material includes aerogel, sponge and porous nanosheet, and the mass ratio of the aerogel, sponge and porous nanosheet is (70-94):(3-15):(3-15). Exemplary, the mass ratio of the aerogel, sponge and porous nanosheet is 70:15:15, 75:10:15, 80:10:10, 85:7:8, 90:5:5, 94:3:3, etc. typical but non-limiting mass ratio.

[0104] The aerogel, sponge and porous nanosheet are used in the porous liquid absorption material layer 122 in the above mass ratio, so that the pore network formed by the porous materials with multiple morphologies in the porous liquid absorption material layer 122 can further improve the liquid absorption and retention capacity of the electrolyte of the porous liquid absorption material layer 122. Such a porous liquid absorption material layer 122 used between the current collector 11 and the electrode active material layer 121 can further significantly improve the infiltration effect of the electrolyte on the whole battery electrode sheet.

[0105] In some embodiments, the mass ratio of the aerogel, sponge and porous nanosheet is (80-90):(5-10):(5-10). The aerogel, sponge and porous nanosheet are used in the porous liquid absorption material layer 122 in the above mass ratio, so that the porous liquid absorption material layer 122 has better liquid absorption and retention capacity for the electrolyte.

[0106] In some embodiments, the aerogel includes carbon aerogel and silicon aerogel, and the mass ratio of the carbon aerogel and the silicon aerogel is (11.2-20.5):1. Exemplary, the mass ratio of the carbon aerogel and the silicon aerogel is 11.2:1, 12:1, 14:1, 16:1, 18:1, 20:1, etc. typical but non-limiting mass ratio.

[0107] Specifically, the mass ratio of the aerogel, the sponge and the porous nanosheet is (80-90):(5-10):(5-10), and the aerogel is composed of carbon aerogel and silicon aerogel with a mass ratio of (11.2-20.5):1. The carbon aerogel and the silicon aerogel not only have good liquid absorption and liquid retention capacity, but also have good ionic conductivity due to the carbon aerogel. Therefore, the use of more carbon aerogel in the porous liquid-absorbing material layer 122 is beneficial to improve the ion transmission performance of the battery electrode tab on the substrate with improved electrolyte wettability.

[0108] In some embodiments, the thickness of the porous liquid-absorbing material layer 122 is 1-20 μm. For example, the thickness of the porous liquid-absorbing material layer 122 can be 1 μm, 2 μm, 5 μm, 8 μm, 10 μm, 15 μm, 20 μm, etc. By arranging the porous liquid-absorbing material layer 122 with a certain thickness between the current collector 11 and the electrode active material layer 121, the total amount of electrolyte immersed into the porous liquid-absorbing material layer 122 is affected. If the thickness is too low, the improvement effect on the electrolyte immersion is limited, and if the thickness is too high, the volume energy density is affected. Therefore, the porous liquid-absorbing material layer 122 with a thickness in the range of 1-20 μm can make the electrode active material on the side close to the current collector 11 be fully immersed, while having a very good volume energy density. Moreover, the electrolyte on both surfaces of the electrode active material layer 121 has good immersion uniformity, and the electrolyte immersion effect on the upper and lower surfaces of the electrode active material layer 121 can be ensured to be consistent.

[0109] In some embodiments, the compacted density of the electrode active material layer 121 is 0.5-5 g / cm 3 . For example, the compacted density of the electrode active material layer can be 0.5 g / cm 3 , 1 g / cm 3 , 1.5 g / cm 3 , 2 g / cm 3 , 3 g / cm 3 , 4 g / cm 3 , 5 g / cm 3 , etc.

[0110] The compacted density refers to the material density of the electrode active material layer on the surface of the current collector after pressing during the cell design process. The compacted density = areal density / thickness of the electrode active material layer, unit: g / cm 3 . The compacted density can be divided into negative electrode compacted density and positive electrode compacted density, respectively for negative electrode tab and positive electrode tab. During the manufacturing process of the lithium ion power battery, the compacted density has a great influence on the battery performance.

[0111] Too low compact density affects energy density, and too high compact density reduces the wettability of electrolyte. The electrode active material layer 121 of the embodiment of the present application has a compact density of 0.5-5 g / cm 3 under the above-mentioned compact density condition, and can improve the energy density of the electrode active material layer 121 while having good wettability to electrolyte. Thus, the charge and discharge performance of the battery can be further improved.

[0112] In some embodiments, the thickness of the porous liquid absorbing material layer 122 is 1-20 μm, and the compact density of the electrode active material layer 121 is 0.5-5 g / cm 3 The porous liquid absorbing material layer 122 having the above-mentioned thickness and the electrode active material layer 121 having the above-mentioned high compact density can further improve the charge and discharge performance of the battery and have better high-temperature aging resistance.

[0113] In some embodiments, the battery electrode sheet is a positive electrode sheet or a negative electrode sheet. The porous liquid absorbing material layer 122 used in the positive electrode sheet or the negative electrode sheet can achieve the effect of high wettability to electrolyte.

[0114] In an embodiment, the battery electrode sheet is a positive electrode sheet or a negative electrode sheet, and the corresponding current collector 11, also referred to as a positive current collector or a negative current collector, can be a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material base material such as a polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0115] In an embodiment, the battery electrode tab is a positive electrode tab, and the electrode active material layer 121 is a positive electrode active material layer, wherein the electrode active material contained therein is a positive electrode active material. Alternatively, the battery electrode tab is a negative electrode tab, and the electrode active material layer 121 is a negative electrode active material layer, wherein the electrode active material contained therein is a negative electrode active material. The positive electrode active material or the negative electrode active material is a conventional selection in the art, for example, the positive electrode active material in the positive electrode tab can be a lithium ion active material, such a positive electrode active material can be used in a lithium ion secondary battery, or the positive electrode active material can be a sodium ion active material, such a positive electrode active material can be used in a sodium ion secondary battery. Specifically, taking the lithium ion active material as an example, it can include lithium cobaltate (LCO), lithium manganate (LMO), lithium iron phosphate (LFP), ternary material (lithium nickel cobalt manganese oxide NCM or lithium nickel cobalt aluminum oxide NCA). Alternatively, as an example, the negative electrode active material in the negative electrode tab can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate, etc.

[0116] In an embodiment, the battery electrode tab is a positive electrode tab, and the positive electrode active material layer of the positive electrode tab further comprises a binder, which can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin. In some embodiments, the positive electrode active material layer further comprises a conductive agent, which can include at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0117] In an embodiment, the battery electrode tab is a negative electrode tab, and the negative electrode active material layer of the negative electrode tab further optionally comprises a binder. The binder can be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS). The negative electrode active material layer further optionally comprises a conductive agent. The conductive agent can be selected from at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the negative electrode active material layer further optionally comprises other auxiliary agents, such as dispersants, thickening agents (such as sodium carboxymethyl cellulose (CMC-Na)), etc.

[0118] Specifically, the preparation method of the battery electrode tab described above in the embodiments of the present application, as shown in Figure 2 includes the following steps:

[0119] S01: coating the slurry containing the porous material on the current collector, and then performing a drying process to obtain a porous liquid-absorbing material layer;

[0120] S02: preparing an electrode active material layer on the porous liquid-absorbing material layer.

[0121] The slurry containing the porous material prepared in the embodiment is coated on the current collector and dried to obtain the porous liquid-absorbing material layer, and then the electrode active material layer is prepared on the porous liquid-absorbing material layer. The porous liquid-absorbing material layer is sequentially prepared on the current collector and the electrode active material layer, so that a porous liquid-absorbing material layer with good liquid-absorbing and liquid-retaining capacity is formed between the current collector and the electrode active material layer. The preparation method is not only simple in process and easy to industrialize, but also the prepared battery pole piece can make the electrolyte on the side of the electrode active material layer away from the current collector penetrate to the side close to the current collector, and the electrolyte can also be immersed in the whole layer of the electrode active material layer under a high compaction density. Therefore, the prepared battery pole piece has good wettability to the electrolyte.

[0122] S01: preparing the slurry containing the porous material; the specific steps include dispersing the porous material raw material (see the above for specific types and parameters) in a certain aqueous solvent, and stirring to obtain a uniform slurry.

[0123] In some embodiments, the viscosity of the slurry containing the porous material under the condition of 20-25℃ is 2000-5000 mPa·s. Exemplarily, the viscosity can be 2000 mPa·s, 2500 mPa·s, 3000 mPa·s, 3500 mPa·s, 4000 mPa·s, etc. The viscosity under this condition can make the porous material disperse uniformly, and is also conducive to coating a film on the current collector.

[0124] In some embodiments, the temperature of the drying process is 50-80℃. Exemplarily, the drying temperature can be 50℃, 60℃, 70℃, 80℃, etc. The drying process under this temperature condition can make the solvent in the slurry containing the porous material volatilize sufficiently to form a desolvated porous liquid-absorbing material layer.

[0125] In some embodiments, the slurry containing the porous material can be coated on the current collector by a roll coating method at a speed of 5-50 m / min. After the final drying and desolvation, the thickness of the porous liquid-absorbing material layer can be 1-20 μm, and the porosity of the porous liquid-absorbing material layer is ≥5.6%, which has good electrolyte-absorbing and liquid-retaining capacity.

[0126] S02: electrode active material layer preparation.

[0127] Specifically, the electrode active material-containing electrode slurry is first prepared, and the electrode slurry is coated on the porous liquid-absorbing material layer by using a conventional coating process to form the electrode active material layer. The electrode active material, the conductive agent, and the binder contained in the electrode active material layer are described above and will not be repeated here.

[0128] Battery

[0129] In a second aspect, the embodiments of the present application provide a battery, which comprises the battery pole piece provided by the first aspect of the embodiments of the present application.

[0130] The battery provided by the embodiments of the present application uses the battery pole piece specific to the embodiments of the present application, and such a battery pole piece has a good wetting effect on electrolyte, so that the battery of the embodiments of the present application has good charge and discharge performance.

[0131] Specifically, the battery comprises a positive electrode, a negative electrode, and a separator film arranged between the positive electrode and the negative electrode, wherein the positive electrode and / or the negative electrode is the battery pole piece.

[0132] In an embodiment, the positive electrode is the positive pole piece of the embodiments of the present application, which comprises a positive electrode current collector and a positive electrode active material layer combined with the positive electrode current collector, and a porous liquid-absorbing material layer is arranged between the positive electrode current collector and the positive electrode active material layer. Alternatively, the negative electrode is the negative pole piece of the embodiments of the present application, which comprises a negative electrode current collector and a negative electrode active material layer combined with the negative electrode current collector, and a porous liquid-absorbing material layer is arranged between the negative electrode current collector and the negative electrode active material layer.

[0133] In an embodiment, the separator film can use materials commonly known in the art for battery separator films. As an example, the separator film substrate can include one or several of polyethylene, polypropylene, polyvinylidene fluoride.

[0134] In some embodiments, the battery of the embodiments of the present application can include a secondary battery, and specifically can include any one of a battery cell, a battery module, and a battery pack of a secondary battery.

[0135] The battery cell refers to a battery cell body and an electric core packaged in the battery cell body. The shape of the battery cell is not particularly limited, and it can be cylindrical, square, or any other shape. As shown in the square structure of the battery cell 20. Figure 3

[0136] In some embodiments, as shown in FIG. 1, the battery 1 can include a battery cell 20, a battery module 30, and a battery pack 40. Figure 4 ​As shown, the outer package of the battery cell 20 can include a case 21 and a top cover assembly 22. The case 21 can include a bottom plate and side plates connected to the bottom plate, which enclose a receiving cavity. The case 21 has an opening communicating with the receiving cavity, and the top cover assembly 22 is used to cover the opening to seal the receiving cavity. The positive electrode, the separator and the negative electrode sheet contained in the secondary battery according to the embodiments of the present application can be formed into an electrode assembly 23 through a winding process and / or a stacking process. The electrode assembly 23 is packaged in the receiving cavity. The electrolyte is impregnated in the electrode assembly 23. The number of the electrode assembly 23 contained in the battery cell 20 can be one or more, which can be adjusted according to actual needs.

[0137] The preparation method of the battery cell 20 is known. In some embodiments, the positive electrode, the separator and the negative electrode sheet and the electrolyte can be assembled to form the battery cell 20. As an example, the positive electrode, the separator and the negative electrode sheet can be formed into the electrode assembly 23 through a winding process or a stacking process, the electrode assembly 23 is placed in the outer package, the electrolyte is injected after drying, and the battery cell 20 is obtained through processes such as vacuum packaging, standing, formation, shaping, etc.

[0138] The battery module refers to the assembly of the battery cell 20, that is, it can contain a plurality of battery cells 20, and the specific number can be adjusted according to the application and capacity of the battery module.

[0139] In some embodiments, Figure 5 is a schematic view of the battery module 30 as an example. As shown, Figure 5 In the battery module 30, a plurality of battery cells 20 can be arranged in sequence along the length direction of the battery module 30. Of course, they can also be arranged in other arbitrary ways. Further, the plurality of battery cells 20 can be fixed by fasteners.

[0140] Optionally, the battery module 30 can also include a housing having a receiving space, and the plurality of battery cells 20 are received in the receiving space.

[0141] The battery pack refers to the assembly of the battery cell 20 described above, that is, it can contain a plurality of battery cells 20, wherein the plurality of battery cells 20 can be assembled into the battery module 30 described above. The specific number of battery cells 20 or battery modules 30 contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0142] As in the embodiments, Figure 6 and Figure 7 is a schematic view of the battery pack 40 as an example. The battery pack 40 can include a battery box and a plurality of battery modules 30 arranged in the battery box. The battery box includes an upper box body 41 and a lower box body 42, the upper box body 41 is used to cover the lower box body 42 and forms a closed space for receiving the battery modules 30. The plurality of battery modules 30 can be arranged in the battery box in any arbitrary way.

[0143] Electric device

[0144] In a third aspect, the embodiments of the present application further provide an electric device, which comprises the battery of the above embodiments of the present application. The battery can be used as a power supply of the electric device, or can be used as an energy storage unit of the electric device. Therefore, the electric device of the embodiments of the present application has good charging and discharging performance, and can work more stably and for a long time.

[0145] The electric device can be, but is not limited to, a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc. The electric device can select a secondary battery, a battery module or a battery pack according to its use requirements.

[0146] Figure 8 FIG. 1 is a schematic diagram of an electric device as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirements of high power and high energy density of the electric device, a battery pack or a battery module can be used.

[0147] The electric device as another example can be a mobile phone, a tablet computer, a notebook computer, etc. The electric device usually requires thinning, and a secondary battery can be used as a power supply.

[0148] Embodiments

[0149] Hereinafter, the embodiments of the present application are described. The embodiments described below are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application. If a specific technology or condition is not specified in the embodiments, the technology or condition described in the literature in the art or according to the product instruction is used. If the reagent or instrument used is not specified by the manufacturer, it is a conventional product that can be obtained by purchase.

[0150] 1. Positive electrode sheet and preparation method thereof

[0151] Embodiment A1

[0152] Preparation of positive electrode sheet:

[0153] (1) Preparation of porous liquid absorbing material layer: 100 g of porous material (carbon aerogel, porous boron nitride nanosheet, superhydrophobic melamine sponge and silicon aerogel material, which are composed of a mass ratio of 82:8:6:4) is dispersed in 100 ml of aqueous solvent, and the rotation speed is controlled at 2000 rpm to obtain a uniform slurry with a viscosity of 4000 mPa·s.

[0154] The specific surface area of the carbon aerogel is 950 m2 / g; conductivity of 75 S / cm; porosity of 93.4%; pore size of 78 nm; pore volume of 3.8 ml / g; specific surface area of porous boron nitride nanosheet of 1300 m 2 / g; conductivity of 85 S / cm; porosity of 96%; pore size of 90 nm; pore volume of 4.2 ml / g. 2 / g; conductivity of 1800 S / cm; porosity of 99.1%; pore size of 92 nm; pore volume of 4.7 ml / g; specific surface area of silicon aerogel material of 850 m 2 / g; conductivity of 85 S / cm; porosity of 96%; pore size of 90 nm; pore volume of 4.2 ml / g.

[0155] The slurry containing the porous material prepared above was coated on a 13 um aluminum foil by a roll coating process of microgravure at a speed of 50 m / min, with a coating thickness of 3 um, and after baking at 50°C, a porous liquid-absorbing material layer was formed.

[0156] (2) Positive electrode active material layer preparation: LFP (lithium iron phosphate) with a Dv 50 50 um was dispersed in N-methylpyrrolidone solvent at a mass ratio of 96:2:2 to obtain a positive electrode slurry with a solid content of 40%, which was coated on the porous liquid-absorbing material layer and dried, and then pressed to control the compaction of the positive electrode active material layer of the positive electrode sheet to 2.6 g / cm 3 .

[0157] Example A2

[0158] Positive electrode sheet preparation:

[0159] The thickness of the porous liquid-absorbing material layer was adjusted to 5 um, and the others were the same as in Example A1.

[0160] Example A3

[0161] Positive electrode sheet preparation:

[0162] The thickness of the porous liquid-absorbing material layer was adjusted to 1 um, and the others were the same as in Example A1.

[0163] Example A4

[0164] Positive electrode sheet preparation:

[0165] The thickness of the porous liquid-absorbing material layer was adjusted to 20 um, and the others were the same as in Example A1.

[0166] Example A5

[0167] Positive electrode sheet preparation:

[0168] The thickness of the porous absorbent material layer was adjusted to 0.5 pm, and the others were the same as in Example Al.

[0169] Example A6

[0170] Preparation of the positive electrode sheet:

[0171] The thickness of the porous absorbent material layer was adjusted to 21 pm, and the others were the same as in Example Al.

[0172] Example A7

[0173] Preparation of the positive electrode sheet:

[0174] The mass ratio of carbon aerogel, porous boron nitride nanosheet, superhydrophobic melamine sponge and silicon aerogel material in the porous material was adjusted to 75:10:10:5, and the others were the same as in Example Al.

[0175] Example A8

[0176] Preparation of the positive electrode sheet:

[0177] The mass ratio of carbon aerogel, porous boron nitride nanosheet, superhydrophobic melamine sponge and silicon aerogel material in the porous material was adjusted to 84:5:5:6, and the others were the same as in Example Al.

[0178] Example A9

[0179] Preparation of the positive electrode sheet:

[0180] The mass ratio of carbon aerogel, porous boron nitride nanosheet, superhydrophobic melamine sponge and silicon aerogel material in the porous material was adjusted to 87:3:3:7, and the others were the same as in Example Al.

[0181] Example A10

[0182] Preparation of the positive electrode sheet:

[0183] The mass ratio of carbon aerogel, porous boron nitride nanosheet, superhydrophobic melamine sponge and silicon aerogel material in the porous material was adjusted to 66:15:15:4, and the others were the same as in Example Al.

[0184] Example A11

[0185] Preparation of the positive electrode sheet:

[0186] The mass ratio of carbon aerogel, porous boron nitride nanosheet, superhydrophobic melamine sponge and silicon aerogel material in the porous material was adjusted to 74:16:6:4, and the others were the same as in Example Al.

[0187] Example A12

[0188] Preparation of the positive electrode sheet:

[0189] The mass ratio of the porous materials of carbon aerogel, porous boron nitride nanosheets, superhydrophobic melamine sponge, and silicon aerogel material was adjusted to 72:8:16:4, and the others were the same as in Example Al.

[0190] Example A13

[0191] Positive electrode tab preparation:

[0192] The mass ratio of the porous materials of carbon aerogel, porous boron nitride nanosheets, superhydrophobic melamine sponge, and silicon aerogel material was adjusted to 79:8:6:7, and the others were the same as in Example Al.

[0193] Example A14

[0194] Positive electrode tab preparation:

[0195] The mass ratio of the porous materials of carbon aerogel, porous boron nitride nanosheets, superhydrophobic melamine sponge, and silicon aerogel material was adjusted to 78:8:6:8, and the others were the same as in Example Al.

[0196] Example A15

[0197] Positive electrode tab preparation:

[0198] The mass ratio of the porous materials of carbon aerogel, porous boron nitride nanosheets, superhydrophobic melamine sponge, and silicon aerogel material was adjusted to 83:8:6:3, and the others were the same as in Example Al.

[0199] Example A16

[0200] Positive electrode tab preparation:

[0201] Only carbon aerogel was used in the porous materials (i.e., the mass ratio of carbon aerogel, porous boron nitride nanosheets, superhydrophobic melamine sponge, and silicon aerogel material was 100:0:0:0), and the others were the same as in Example Al.

[0202] Example A17

[0203] Positive electrode tab preparation:

[0204] Only porous boron nitride nanosheets were used in the porous materials (i.e., the mass ratio of carbon aerogel, porous boron nitride nanosheets, superhydrophobic melamine sponge, and silicon aerogel material was 0:100:0:0), and the others were the same as in Example Al.

[0205] Example A18

[0206] Positive electrode tab preparation:

[0207] The porous material is only super-hydrophobic melamine sponge (i.e. the mass ratio of carbon aerogel, porous boron nitride nanosheet, super-hydrophobic melamine sponge and silica aerogel material is 0:0:100:0), and the others are the same as example A1.

[0208] Example A19

[0209] Preparation of positive electrode sheet:

[0210] The types and proportions of porous materials are the same as example A1, but the porous material parameters are different; wherein, the specific surface area of carbon aerogel is 900 m 2 / g; the electrical conductivity is 68 S / cm; the porosity is 91.2%; the pore size is 72 nm; the pore volume is 3.5 ml / g; the specific surface area of porous boron nitride nanosheet is 1250 m 2 / g; the electrical conductivity is 800 / cm; the porosity is 7.8%; the pore size is 420 nm; the pore volume is 1.8 ml / g; the specific surface area of super-hydrophobic melamine sponge is 2100 m 2 / g; the electrical conductivity is 1700 S / cm; the porosity is 98.5%; the pore size is 90 nm; the pore volume is 4.4 ml / g; the specific surface area of silica aerogel material is 810 m 2 / g; the electrical conductivity is 82 S / cm; the porosity is 95.3%; the pore size is 86 nm; the pore volume is 3.8 ml / g.

[0211] Example A20

[0212] Preparation of positive electrode sheet:

[0213] The types and proportions of porous materials are the same as example A1, but the porous material parameters are different; wherein, the specific surface area of carbon aerogel is 887 m 2 / g; the electrical conductivity is 64 S / cm; the porosity is 90.4%; the pore size is 68 nm; the pore volume is 3.4 ml / g; the specific surface area of porous boron nitride nanosheet is 1200 m 2 / g; the electrical conductivity is 778 S / cm; the porosity is 7.4%; the pore size is 400 nm; the pore volume is 1.5 ml / g; the specific surface area of super-hydrophobic melamine sponge is 2050 m 2 / g; the electrical conductivity is 1550 S / cm; the porosity is 97.8%; the pore size is 86 nm; the pore volume is 4.1 ml / g; the specific surface area of silica aerogel material is 780 m 2 / g; the electrical conductivity is 76 S / cm; the porosity is 94.8%; the pore size is 85 nm; the pore volume is 3.5 ml / g.

[0214] Example A21

[0215] Preparation of positive electrode sheet:

[0216] The kind and proportion of the porous material were the same as in Example Al, but the parameters of the carbon aerogel were different; specifically, in this example, the specific surface area of the carbon aerogel was 900 m 2 / g; the electrical conductivity was 68 S / cm; the porosity was 91.2%; the pore size was 72 nm; and the pore volume was 3.5 ml / g.

[0217] Example A22

[0218] Preparation of the positive electrode sheet:

[0219] The kind and proportion of the porous material were the same as in Example Al, but the parameters of the silicon aerogel were different; specifically, the specific surface area of the silicon aerogel material was 810 m 2 / g; the electrical conductivity was 82 S / cm; the porosity was 95.3%; the pore size was 86 nm; and the pore volume was 3.8 ml / g.

[0220] Comparative Example Al

[0221] Preparation of the positive electrode sheet: no porous liquid-absorbing material layer was prepared, and the positive electrode active material layer was the same as in Example Al.

[0222] Comparative Example A2

[0223] Preparation of the positive electrode sheet: no porous liquid-absorbing material layer was prepared, and the positive electrode active material layer was prepared by dispersing carbon aerogel (specific surface area 950 m 2 / g; electrical conductivity 75 S / cm; porosity 93.4%; pore size 78 nm; pore volume 3.8 ml / g), lithium iron phosphate (Dv 50 0.5 um), conductive carbon black, and polyvinylidene fluoride in a mass ratio of 1.44, 94.56:2:2 in N-methylpyrrolidone solvent, and the other conditions were the same as in Example Al.

[0224] Comparative Example A3

[0225] Preparation of the positive electrode sheet: no porous liquid-absorbing material layer was prepared, and the positive electrode active material layer was prepared by dispersing porous boron nitride nanosheets (specific surface area 1300 m 2 / g; electrical conductivity 850 S / cm; porosity 8.7%; pore size 450 nm; pore volume 2 ml / g), lithium iron phosphate (Dv 50 0.5 um), conductive carbon black, and polyvinylidene fluoride in a mass ratio of 1.44, 94.56:2:2 in N-methylpyrrolidone solvent, and the other conditions were the same as in Example Al.

[0226] 2. Secondary battery cell examples

[0227] Examples B1 to B22 and Comparative Examples B1 to B3;

[0228] The examples B1 to B22 and the comparative examples B1 to B3 each provide a secondary battery cell, each of which includes a bare cell formed of a positive electrode sheet, a separator, and a negative electrode sheet, and further includes an electrolyte. The positive electrode sheet of each of the examples B1 to B22 and the comparative examples B1 to B3 corresponds to the positive electrode sheet provided in the examples A1 to A22 and the comparative examples A1 to A3, respectively. The positive electrode sheet in the example A1 above is used as the positive electrode sheet in the secondary battery example B1 cell, the positive electrode sheet in the example A2 is used as the positive electrode sheet in the secondary battery example B2 cell, and so on, and the positive electrode sheet in the comparative example A3 is used as the positive electrode sheet in the secondary battery comparative example B3 cell.

[0229] The method for preparing the secondary battery cell includes:

[0230] Preparation of the positive electrode sheet: The positive electrode sheet provided in the examples A1 to A22 and the comparative examples A1 to A3 is used.

[0231] Preparation of the negative electrode sheet: The negative electrode active material artificial graphite, the conductive agent carbon black, the binder styrene-butadiene rubber (SBR), and the thickening agent sodium hydroxymethyl cellulose (CMC) are dissolved in a solvent in a weight ratio of 97.2:0.8:0.8:1.2, and the mixture is uniformly prepared into a negative electrode slurry. The negative electrode slurry is uniformly coated on a negative electrode current collector copper foil, and the negative electrode sheet is obtained through drying, cold pressing, and slitting.

[0232] The electrolyte: In an argon atmosphere glove box (H2O <0.1 ppm, O2 <0.1 ppm), organic solvents ethylene carbonate (EC) / ethyl methyl carbonate (EMC) are uniformly mixed in a volume ratio of 3 / 7, and LiPF6 lithium salt is dissolved in the organic solvents in a solid content of 12.5%, and the mixture is uniformly stirred to obtain the electrolyte.

[0233] The separator is a polypropylene porous separator.

[0234] The electrolyte: lithium hexafluorophosphate with a concentration of 1M, and the organic solvents are a mixed solvent of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate in a mass ratio of 1:1:1.

[0235] Assembly of the secondary battery: The prepared negative electrode sheet, positive electrode sheet, and polypropylene porous separator are sequentially stacked, and a bare cell with a theoretical capacity of 280 Ah is obtained through a winding process. The bare cell is then encapsulated, liquid injected, formed, sorted, and the like to obtain a cylindrical lithium ion secondary battery, which is the secondary battery cell.

[0236] Performance test

[0237] The positive electrode sheet and the secondary battery cell of the above examples and comparative examples are each tested.

[0238] (1) Positive electrode sheet electrolyte infiltration rate: Capillary pipette method was used to test electrolyte absorption time and absorption rate.

[0239] The specific steps include: S1) measuring the thickness of the sheet; S2) fixing a 5*5 cm sheet to the sample table; S3) using a capillary to draw 2 mm of electrolyte; S4) contacting the capillary with the sheet and recording the time it takes for the electrolyte to be completely absorbed; S5) using the volume of electrolyte and the time it takes for the electrolyte to be completely absorbed: unit, seconds (s), to calculate the absorption rate of a single sheet = mass of electrolyte / absorption time, then the average absorption rate of multiple sheets can be calculated.

[0240] (2) Porous absorption material layer porosity test:

[0241] In Examples A1-19, the porosity of the porous absorption material layer was tested after the porous absorption material layer was prepared on the surface of the positive electrode sheet. The specific steps include: S1) immersing the sheet coated with the porous absorption material layer in electrolyte and recording the change in mass before and after the sheet is immersed in electrolyte to calculate the volume porosity V 孔 of the film; S2) using the density of the raw material of the porous absorption material layer and the dry film weight to calculate V 膜骨架 ; S3) the porosity of the film layer ε = V 孔 / V 膜外观 = V 孔 / (V 孔 + V 膜骨架 ).

[0242] The test results are shown in Table 1.

[0243] Table 1

[0244]

[0245]

[0246] Note: The electrolyte formula tested in Table 1 is the same as the electrolyte formula in the secondary battery cell described above, the solvent is a mixed solvent of ethylene carbonate (EC) / methyl ethyl carbonate (EMC) in a volume ratio of 3 / 7, and the electrolyte is a lithium salt of LiPF6 with a solid content of 12.5%.

[0247] (3) First coulombic efficiency test of the secondary battery cell:

[0248] The first coulombic efficiency test steps are shown in Table 2: where Rest represents static treatment, DP (Constant Power Charge) represents constant power charging, CP (Constant Power Discharge) represents constant power discharging, and P represents the power of the battery charging and discharging, for example, 0.5P represents the battery charging and discharging at a power of 0.5P.

[0249] Table 2

[0250]

[0251]

[0252] The test results are shown in Table 3.

[0253] Table 3

[0254] Embodiment First coulombic efficiency (%) Comparative Example B1 81.15％ Comparative Example B2 82.32％ Comparative Example B3 82.04％ Example B1 92.40％ Example B2 91.73％ Example B3 90.96％ Example B4 90.98％ Example B5 84.03％ Example B6 89.10％ Example B7 92.36％ Example B8 92.33％ Example B9 92.28％ Example B10 92.24％ Example B11 92.20％ Example B12 92.18％ Example B13 92.38％ Example B14 92.35％ Example B15 92.35％ Example B16 91.82％ Example B17 87.30％ Example B18 91.45％ Example B19 92.20％ Example B20 92.10％ Example B21 91.50％ Example B22 91.30％

[0255] From the above Table 1 and Table 2 data: relative to the comparative example, the application example sets a layer of porous liquid absorbing material layer between the current collector and the electrode active material layer, which can improve the overall wettability of the battery electrode, thereby improving the first coulomb efficiency of the battery. The test data of examples B1-B6 proves that the porous liquid absorbing material layer with a thickness of 1-20 μm makes the battery have better first coulomb efficiency. The test data of examples B1, B7-B12 proves that the porous liquid absorbing material layer with a mass ratio of aerogel, sponge and porous nanosheet of (70-94):(3-15):(3-15) has better effect on the first coulomb efficiency performance of the battery, and further, the mass ratio of (80-90):(5-10):(5-10) has the best effect. The test data of examples B1, B13-B15 proves that the mass ratio of carbon aerogel and silicon aerogel of (11.2-20.5):1 has better effect. The test data of examples 1B, 16B-18B proves that the mixed ratio of aerogel, porous nanosheet and sponge three kinds of porous materials has better effect than using single porous material. The test data of examples B1, 18B-22B proves that by adjusting the parameter characteristics of the porous material, the porous liquid absorbing material layer can form appropriate porosity, which can improve the first coulomb efficiency of the battery.

[0256] 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, and they should be covered in the scope of the claims and the description of the present application. Especially, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery electrode sheet comprising a current collector and an electrode film layer disposed on at least one side of the current collector, characterized in that, The electrode film layer comprises an electrode active material layer and a porous liquid-absorbing material layer between the current collector and the electrode active material layer, the porous liquid-absorbing material layer comprising a porous material; the porosity of the porous liquid-absorbing material layer is 48.3% to 60.4%, and the porous material comprises aerogel, sponge and porous nanosheet, and the mass ratio of the aerogel, the sponge and the porous nanosheet is (80-90):(5-10):(5-10).

2. The battery pole piece of claim 1, wherein, The aerogel comprises at least one of organic aerogel, inorganic aerogel or organic-inorganic hybrid aerogel; Alternatively, the sponge comprises at least one of melamine sponge, carbon nanotube sponge or honeycomb porous graphene sponge; Alternatively, the porous nanosheet comprises at least one of porous carbon nanosheet, porous boron nitride nanosheet or porous carbon nitride nanosheet.

3. The battery pole piece of claim 1 or 2, wherein, The aerogel satisfies one or more of the following (1)-(5): (1) a specific surface area of 780 to 950 m 2 / g; (2) the electrical conductivity is 64-85 S / cm; (3) the porosity is 90.4-96%; (4) the pore size is 68-90 nm; (5) the pore volume is 3.4-4.2 ml / g.

4. The battery pole piece of claim 1 or 2, wherein, The sponge satisfies one or more of the following (1)-(5): (1) a specific surface area of 2050 to 2350 m2 / g 2 / g; (2) the electrical conductivity is 1550-1800 S / cm; (3) the porosity is 97.8%-99.1%; (4) the pore size is 86-92 um; (5) the pore volume is 4.1-4.7 ml / g.

5. The battery pole piece of claim 1 or 2, wherein, The porous nanosheet satisfies one or more of the following (1)-(5): (1) a specific surface area of 1200 to 1300 m2 / g 2 / g; (2) the electrical conductivity is 778-850 S / cm; (3) the porosity is 7.4-8.7%; (4) the pore size is 400-450 nm; (5) the pore volume is 1.5-2 ml / g.

6. The battery pole piece of claim 1 or 2, wherein, The aerogel comprises carbon aerogel and silicon aerogel, and the mass ratio of the carbon aerogel and the silicon aerogel is (11.2-20.5):

1.

7. The battery pole piece of claim 1 or 2, wherein, The thickness of the porous liquid-absorbing material layer is 1-20 um.

8. The battery pole piece of claim 7, wherein, The thickness of the porous liquid-absorbing material layer is 3-5 um.

9. The battery pole piece of claim 1 or 2, wherein, The battery pole piece is a positive pole piece or a negative pole piece.

10. A battery, characterized by The battery pole piece comprises the battery pole piece of any one of claims 1-9.

11. An electrical device, characterized by The battery comprises the battery of claim 10.

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