Battery pole piece, battery and electric equipment

Abstract

The utility model discloses a battery pole piece, a battery and electric equipment. The battery pole piece comprises a current collector, a first active material layer with first compaction density and a second active material layer with second compaction density, the battery pole piece is designed in a layered manner, the first active material layer and the second active material layer are arranged on the same side of the current collector in the thickness direction, and the first active material layer with high compaction density is arranged below the second active material layer with low compaction density in the gravity direction; through the arrangement, the first active material layer with high compaction density can improve the energy density of the battery; under the action of a gravity field, the first active material layer with high compaction density is in contact with the electrolyte enrichment layer, so that the mass transfer capability of the first active material layer is improved, the intrinsic mass transfer capability difference between the first active material layer and the second active material layer is reduced, the electrode internal resistance is reduced, and the battery performance is improved.

Description

Technical Field

[0001] The present application relates to the technical field of battery electrodes, and in particular to a battery electrode sheet, a battery and an electrical device. Background Art

[0002] In order to obtain higher energy density, it is necessary to increase the compaction density of the positive and negative electrodes of the battery. However, the increase in compaction density will lead to a decrease in the liquid phase mass transfer capacity of the electrode, resulting in a larger internal resistance, which restricts the working performance of the battery. Utility Model Content

[0003] The purpose of the present application is to provide a battery electrode, a battery and an electrical device to solve the problem of low mass transfer capacity caused by increased compaction density.

[0004] To achieve the purpose of this application, this application provides the following technical solutions:

[0005] In a first aspect, the utility model provides a battery pole piece, which includes a current collector, a first active material layer and a second active material layer; the first active material layer and the second active material layer are arranged on the same side of the current collector in a thickness direction, and the first active material layer has a first compaction density; the second active material layer has a second compaction density; the first compaction density is greater than the second compaction density, and in the direction of gravity, the second active material layer is arranged above the first active material layer.

[0006] In one embodiment, the first compaction density is 1.3 g / cm 3 -2.2g / cm 3 The second compacted density is 1.3 g / cm 3 -2.2g / cm 3 .

[0007] In one embodiment, the surface density of the first active material layer and the second active material layer is the same, and the surface density is 0.001 g / cm 2 -0.02g / cm 2 .

[0008] In one embodiment, the particle size D1 of the first active material layer is 5 μm-30 μm; and / or the particle size D2 of the second active material layer is 10 μm-50 μm; and / or the particle size D1 of the first active material layer and the particle size D2 of the second active material layer satisfy: D1 <D2。

[0009] In one embodiment, the first active material layer includes a first sublayer and a second sublayer, the compaction density of the first sublayer is greater than the compaction density of the second sublayer, the second active material layer includes a third sublayer and a fourth sublayer, the compaction density of the third sublayer is greater than the compaction density of the fourth sublayer, and the compaction density of the second sublayer is greater than the compaction density of the third sublayer; the fourth sublayer, the third sublayer, the second sublayer and the first sublayer are arranged in sequence.

[0010] In one embodiment, the battery electrode includes a third active material layer and a fourth active material layer; the third active material layer and the fourth active material layer are arranged on the same side in the thickness direction of the current collector; the third active material layer has a third compaction density; the fourth active material layer has a fourth compaction density; the third compaction density is greater than the fourth compaction density, and in the direction of gravity, the third active material layer is arranged below the fourth active material layer; the current collector includes a first side and a second side opposite to each other, the first active material layer is connected to the first side, and the fourth active material layer is connected to the second side.

[0011] In one embodiment, the battery electrode is a positive electrode or a negative electrode.

[0012] In a second aspect, the utility model provides a battery, comprising a housing and a battery pole piece as described in each embodiment of the first aspect, wherein the battery pole piece is accommodated inside the housing.

[0013] In one embodiment, the battery is a lithium ion battery or a sodium ion battery.

[0014] In a third aspect, the utility model provides an electrical device, comprising a battery and an electrical device as described in any one of the embodiments of the second aspect, wherein the battery supplies power to the electrical device.

[0015] The utility model provides a battery pole piece, which comprises a first active material layer with a first compaction density, a second active material layer with a second compaction density and a current collector. The battery pole piece is designed in layers, the first active material layer and the second active material layer are arranged on the same side in the thickness direction of the current collector, and the first active material layer with a large compaction density is arranged below the second active material layer with a small compaction density in the gravity direction; through the above arrangement, the first active material layer with a large compaction density can improve the energy density of the battery; under the action of the gravity field, the first active material layer with a large compaction density contacts with the electrolyte enrichment layer, so as to improve the mass transfer capacity of the first active material layer, reduce the difference in intrinsic mass transfer capacity between the first active material layer and the second active material layer, reduce the internal resistance of the electrode, and improve the battery performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 is a schematic diagram of an embodiment;

[0018] Figure 2 A schematic diagram of a multi-layer arrangement of an embodiment.

[0019] Description of reference numerals:

[0020] 1-first active material layer, 11-first sublayer, 12-second sublayer;

[0021] 2-second active material layer, 21-third sublayer, 22-fourth sublayer;

[0022] 3- third active material layer;

[0023] 4- fourth active material layer;

[0024] 5-Current collector. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there can be a central component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there can be a central component at the same time.

[0027] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in this application and in the specification are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this application includes any and all combinations of one or more of the related listed items.

[0028] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0029] The utility model provides a battery pole piece, which includes a first active material layer 1, a second active material layer 2 and a current collector 5; the first active material layer 1 has a first compaction density; the second active material layer 2 has a second compaction density; the first compaction density is greater than the second compaction density, the first active material layer 1 and the second active material layer 2 are arranged on the same side of the current collector 5 in the thickness direction, and in the gravity direction, the second active material layer 2 is arranged above the first active material layer 1.

[0030] Please refer to Figure 1 , the higher the compaction density of the battery pole piece, the higher the volume energy density of the battery, but the liquid phase mass transfer capacity of the electrode with high compaction density is worse. The utility model arranges the battery pole piece into a first active material layer 1 and a second active material layer 2; the first compaction density of the first active material layer 1 is greater than the second compaction density of the second active material layer 2; in the spatial arrangement of the first active material layer 1 and the second active material layer 2, the second active material layer 2 is arranged above the first active material layer 1 in the direction of gravity, and the first active material layer 1 and the second active material layer 2 are arranged on one side of the current collector 5. The compaction density of the first active material layer 1 at the bottom is large but the liquid phase mass transfer capacity is poor, and the compaction density of the second active material layer 2 at the top is small but the liquid phase mass transfer capacity is good. In a gravitational field, due to the action of gravity, the electrolyte molecules with higher density tend to move downward, resulting in uneven distribution inside the electrolyte. Therefore, in the vertical structure of the battery, the electrolyte concentration or density at a lower position will be relatively high, while the electrolyte concentration or density at a higher position will be relatively low. Through the above arrangement, the compaction density of the battery electrode can be improved, and the first active material layer 1 at the bottom contacts the electrolyte enrichment layer under the action of gravity, thereby improving the liquid phase mass transfer capacity of the first active material layer 1 during service, reducing the difference in intrinsic mass transfer capacity between the first active material layer 1 and the second active material layer 2, and reducing the total electrode internal resistance; at the same time, during the charging and discharging process of the battery, the positive and negative electrodes alternately expand and shrink in volume. Taking the negative electrode as an example, the volume expands during charging and the electrolyte is squeezed out, and the volume shrinks during discharging and the electrolyte flows back. The electrolyte reflux capacity of the first active material layer 1 is enhanced under the action of the gravitational field, and the problem of preferential liquid shortage of the first active material layer 1 during long-term cycle accumulation is alleviated.

[0031] In one embodiment, the first compaction density is 1.3 g / cm 3 -2.2g / cm 3 ; The second compaction density is 1.3g / cm 3 -2.2g / cm 3 .

[0032] The first compacted density may be, but is not limited to, 1.3 g / cm 3 , 1.5g / cm 3 , 1.7g / cm 3 , 1.9g / cm 3 , 2.1g / cm 3 , 2.2g / cm 3 . When the above-mentioned first compaction density range is met, the battery can store more energy per unit volume or unit weight. The energy density can be improved; the electronic conductivity inside the active material layer can be improved, the resistance can be reduced, and the electronic transmission efficiency of the battery can be improved; the diffusion rate of ions in the first active material layer 1 can be increased, and the diffusion path of ions in the material can be reduced, thereby accelerating the reaction rate of the battery. When the first compaction density is lower than the above-mentioned range, less active material is contained in the unit volume, resulting in a decrease in the energy density of the battery, that is, the battery can store less electrical energy at the same volume or weight; resulting in reduced contact between particles, decreased electronic conductivity inside the first active material layer 1, and increased resistance, thereby affecting the discharge efficiency and power output of the battery; slowing down the ion diffusion rate of the first active material layer 1, affecting the charge and discharge rate and overall electrochemical performance of the battery; resulting in insufficient mechanical strength of the pole piece, which is easy to cause damage to the material structure due to volume expansion and contraction during the charge and discharge cycle of the battery. When the first compaction density is higher than the above range, the ion transmission channel in the first active material layer 1 will be restricted, which will slow down the diffusion rate of ions during the charge and discharge process, thereby affecting the rapid charge and discharge capability and overall electrochemical performance of the battery; too high a compaction density may cause the internal stress in the first active material layer 1 to increase, causing poor contact between particles and rupture of the material microstructure, increasing resistance and reducing electronic conduction efficiency; during the battery charge and discharge process, the active material will expand and shrink in volume, and too high a compaction density will limit the volume change, resulting in excessive internal stress in the material, causing deformation or rupture of the battery shell. The second compaction density can be, but is not limited to, 1.3 g / cm 3 , 1.5g / cm 3 , 1.7g / cm 3 , 1.9g / cm 3 , 2.1g / cm 3 , 2.2g / cm 3 The reason for setting the second compaction density range is the same as that for the first compaction density range, so it will not be repeated here.

[0033] In one embodiment, the first active material layer 1 and the second active material layer 2 have the same surface density, which is 0.001 g / cm 2 -0.01g / cm 2 .

[0034] The same surface density of the first active material layer 1 and the second active material layer 2 can make the distribution of electrochemical reactions of the battery uniform during charging and discharging, which helps to improve the overall performance and life of the battery; the same surface density helps to maintain the consistency of current density when the battery is working, thereby reducing local overheating or uneven electrochemical reactions. The surface density can be but is not limited to 0.001g / cm 2 , 0.002g / cm 2 , 0.003g / cm 2 、0.004g / cm 2 , 0.005g / cm 2 , 0.006g / cm 2 , 0.007g / cm 2 , 0.008g / cm 2 , 0.009g / cm 2 , 0.01g / cm 2 , 0.02g / cm 2 When the above surface density range is met, the transmission rate of ions and electrons in the active material can be optimized, the reaction speed and power output of the battery can be accelerated; uniform electrochemical reaction can be achieved, polarization effect can be reduced, and the charge and discharge efficiency and cycle stability of the battery can be improved; the internal resistance of the battery can be reduced because the electronic conductivity and ion diffusion rate of the active material layer can be balanced, thereby improving the overall efficiency of the battery. When the surface density is less than 0.001g / cm 2 When the surface density is greater than 0.02 g / cm, the mass of active materials carried per unit area is less, resulting in a decrease in the energy density of the battery and affecting the discharge rate and power output of the battery; too low a surface density may cause the local electrochemical reaction of the active material layer to be too fast or too slow, making the electrochemical performance unstable; resulting in an increase in the internal resistance of the battery, affecting the discharge efficiency and overall performance of the battery. 2 When the surface density is too high, the ion transmission channels in the active material layer will be restricted, slowing down the diffusion rate of ions during the charge and discharge process, thereby affecting the charge and discharge capacity and overall electrochemical performance of the battery; too high a surface density may increase the internal stress of the material, causing poor contact between particles, which in turn increases resistance and reduces electronic conduction efficiency.

[0035] In one embodiment, the thickness H1 of the first active material layer 1 is 30 μm-300 μm; and / or the thickness H2 of the second active material layer 2 is 30 μm-300 μm; and / or the thickness H1 of the first active material layer 1 and the thickness H2 of the second active material layer 2 satisfy: 1≤H1 / H2≤3.

[0036] The thickness H1 of the first active material layer 1 may be, but is not limited to, 30 μm, 60 μm, 90 μm, 120 μm, 150 μm, 180 μm, 210 μm, 240 μm, 270 μm, or 300 μm. When the thickness H1 of the first active material layer 1 is within this range, the power density and energy density can be balanced, and the electrochemical performance can be optimized; the stress caused by volume change during the battery charge and discharge process can be resisted, thereby improving the long-term mechanical stability of the battery. When the thickness H1 of the first active material layer 1 is less than 30 μm, the total amount of active material stored in the first active material layer 1 is reduced, resulting in a decrease in the capacity of the battery; the transmission path of ions and electrons may become shorter, which may increase the internal resistance of the battery, reduce the power output and efficiency of the battery, and reduce the electrochemical performance; if the first active material layer 1 is too thin, it will be difficult to coat it evenly, especially in large-scale production, resulting in uneven distribution of active materials, thereby affecting the overall performance and life of the battery; if the first active material layer 1 is too thin, it will be affected by mechanical stress during the charge and discharge process of the battery, resulting in the rupture or shedding of the layered structure, which will shorten the cycle life of the battery; it cannot effectively disperse and absorb the heat generated by the battery during operation, which may cause local overheating and affect the safety and performance of the battery. When the thickness H1 of the first active material layer 1 is greater than 200 μm, the excessive thickness of the first active material layer 1 will increase the path length of ion transmission, resulting in an increase in the internal resistance of the battery, thereby reducing the power density and rapid charge and discharge capability of the battery; reducing the electronic conduction efficiency of the first active material layer 1, affecting the overall performance of the battery; an overly thick first active material layer 1 will increase the internal stress, causing the material to crack or fall off, thereby shortening the cycle life of the battery; it is not conducive to the dispersion of heat, resulting in an increase in the local temperature of the battery, affecting the thermal stability and safety of the battery; in a limited space, an overly thick pole piece will occupy more space, and the space utilization efficiency will decrease. The thickness H1 of the second active material layer 2 can be, but is not limited to, 30 μm, 60 μm, 90 μm, 120 μm, 150 μm, 180 μm, 210 μm, 240 μm, 270 μm, 300 μm. The reason why the thickness H2 of the second active material layer 2 is 30 μm-300 μm is the same as that of the first active material layer 1, and will not be repeated.

[0037] The ratio of the thickness H1 of the first active material layer 1 to the thickness H2 of the second active material layer 2 (H1 / H2) can be, but is not limited to, 1, 1.5, 2, 2.5, 3. The ratio of the thickness H1 of the first active material layer 1 to the thickness H2 of the second active material layer 2 is within this range, the thickness of the first active material layer 1 (H1) is greater than that of the second active material layer 2 (H2), and the thicker first active material layer 1 can store more active substances, thereby increasing the total energy storage capacity of the battery and improving the energy density; although the first active material layer 1 is thicker, the second active material layer 2 still maintains a certain thickness, so that a certain power output and charge and discharge rate can be maintained, while utilizing the capacity advantage of the first active material layer 1 to optimize the power output, while maintaining a higher energy density, maintaining better power output and cycle stability; the thicker first active material layer 1 can provide better mechanical support, which helps to reduce the stress caused by volume change during the charge and discharge process, thereby improving the long-term mechanical stability of the battery and improving safety performance. When the ratio of the thickness H1 of the first active material layer 1 to the thickness H2 of the second active material layer 2 is less than 1, the first active material layer 1 is thinner, resulting in less active material, which reduces the power output of the battery, affecting the overall performance and life of the battery; reduces the ion transmission efficiency, increases the internal resistance of the battery, and affects the efficiency and cycle performance of the battery; is more susceptible to mechanical stress during the charge and discharge process of the battery, resulting in rupture or shedding of the layered structure; is not conducive to the dispersion of heat, resulting in an increase in the local temperature of the battery. When the ratio of the thickness H1 of the first active material layer 1 to the thickness H2 of the second active material layer 2 is greater than 3, the first active material layer 1 is too thick, which will lead to a mismatch between the electrochemical reaction of the first active material layer 1 and the first active material layer 1 during the charge and discharge process, affecting the overall performance and life of the battery; increasing the path length of ion transmission, resulting in an increase in the internal resistance of the battery, affecting the power output and efficiency of the battery; reducing the electronic conduction efficiency, affecting the overall performance of the battery; during the charge and discharge process of the battery, the active material will expand and shrink in volume, and an overly thick first active material layer 1 will increase the internal stress, causing the material to crack or fall off, thereby shortening the cycle life of the battery; it is not conducive to the dispersion of heat, resulting in an increase in the local temperature of the battery, affecting the thermal stability and safety of the battery.

[0038] In one embodiment, the particle size D1 of the first active material layer 1 is 5 μm-30 μm; and / or the particle size D2 of the second active material layer 2 is 10 μm-50 μm; and / or the particle size D1 of the first active material layer 1 and the particle size D2 of the second active material layer 2 satisfy: D1 <D2。

[0039] The particle size D1 of the first active material layer 1 may be, but is not limited to, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, or 30 μm.

[0040] The particle size D1 of the first active material layer 1 is within this range, which can increase the specific surface area meeting the design conditions. This helps to increase the contact area between the active material and the electrolyte, improve the electrochemical activity, and enhance the overall performance of the battery; shorten the transmission distance of ions and electrons between active material particles, improve the electrical conductivity of the battery and reduce the internal resistance, and enhance the power density and fast charge-discharge ability of the battery; maintain the mechanical stability of the material and reduce structural damage during charge-discharge cycles; and facilitate quality control in large-scale production during the manufacturing process. When the particle size D1 of the first active material layer 1 is less than 5 μm, the too-small particle size of the first active material layer 1 will cause the electron transmission path to become longer, increase the internal resistance of the battery, thereby reducing the power density and charge-discharge efficiency of the battery; it may be difficult to distribute evenly during the coating and pressing processes, resulting in a decrease in the uniformity and compaction of the first active material layer 1, affecting the performance and lifespan of the battery; the too-small particle size causes particle rearrangement or the formation of voids during the pressing process, thereby reducing the compaction density of the first active material layer 1 and affecting the energy density of the battery; during the charge-discharge process, it is more likely to break or suffer structural damage due to volume changes, thereby reducing the mechanical stability of the battery. When the particle size D1 of the first active material layer 1 is greater than 30 μm, the too-large particle size D1 of the first active material layer 1 will have a lower specific surface area, reduce the contact area between the active material and the electrolyte, thereby reducing the electrochemical activity and causing the rate of the electrochemical reaction to slow down; the ion and electron transmission paths inside the large particles become longer, resulting in an increase in the internal resistance of the battery and affecting the power output and efficiency of the battery; it is difficult to achieve a high compaction density during the pressing process for the too-large particle size, affecting the volumetric energy density of the battery; during the charge-discharge process, the too-large particle size will be more likely to break or fall off due to volume changes, thereby affecting the long-term mechanical stability of the battery. The particle size D2 of the second active material layer 2 can be but is not limited to 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm. The reason for the particle size D2 of the second active material layer 2 being 10 μm - 50 μm is the same as that of the first active material layer 1 and will not be elaborated here. The particle size D1 of the first active material layer 1 and the particle size D2 of the second active material layer 2 satisfy the condition D1 < D2. Since the compaction density of the first active material layer 1 is greater than that of the second active material layer 2, the particle size D1 of the first active material layer 1 is less than the particle size D2 of the second active material layer 2. By controlling the particle sizes of the two layers of active materials, different electrochemical performances can be achieved in different regions of the battery electrode. The smaller D1 particle size can provide a higher energy density; while the larger D2 particle size can provide a higher electrochemical activity and power density.

[0041] In one embodiment, the first active material layer 1 includes a first sublayer 11 and a second sublayer 12, the compaction density of the first sublayer 11 is greater than the compaction density of the second sublayer 12, the second active material layer 2 includes a third sublayer 21 and a fourth sublayer 22, the compaction density of the third sublayer 21 is greater than the compaction density of the fourth sublayer 22, and the compaction density of the second sublayer 12 is greater than the compaction density of the third sublayer 21; the first sublayer 11, the second sublayer 12, the third sublayer 21 and the fourth sublayer 22 are on one side of the current collector 5, and the fourth sublayer 22, the third sublayer 21, the second sublayer 12 and the first sublayer 11 are arranged in sequence.

[0042] Please refer to Figure 2 , the fourth sublayer 22, the third sublayer 21, the second sublayer 12 and the first sublayer 11 are arranged in sequence from top to bottom along the direction of gravity, and the compaction density gradually increases; the sublayer with high compaction density is arranged at the lower position, and the sublayer with high compaction density contacts the electrolyte enrichment layer under the action of gravity. By gradually increasing the compaction density from top to bottom, different electrochemical properties can be achieved in different areas of the battery pole piece. The upper sublayer with lower compaction density can provide better ion transport performance, while the lower sublayer with higher compaction density may provide higher electron transport performance. The sublayer with high compaction density contacts the electrolyte enrichment layer under the action of gravity, which helps to improve the utilization efficiency of the electrolyte and thus improve the performance of the battery. By realizing the compaction density stratification of different sublayers in the battery pole piece, different mechanical stabilities can be achieved in different areas. The sublayer with high compaction density provides better mechanical support and structural integrity, while the sublayer with low compaction density can reduce structural damage during charging and discharging.

[0043] In one embodiment, the battery electrode includes a current collector 5, a third active material layer 3 and a fourth active material layer 4; the current collector 5 includes a first surface and a second surface opposite to each other in the direction of gravity; the third active material layer 3 has a third compaction density; the fourth active material layer 4 has a fourth compaction density; the third compaction density is greater than the fourth compaction density, and in the direction of gravity, the third active material layer 3 is arranged below the fourth active material layer 4; the first active material layer 1 is connected to the first surface, and the fourth active material layer 4 is connected to the second surface.

[0044] Please refer to Figure 1, the second active material layer 2, the first active material layer 1, the current collector 5, the fourth active material layer 4 and the third active material layer 3 are arranged in order from top to bottom along the gravity direction, and different electrochemical properties can be achieved in different areas of the battery pole piece. The compaction density of the second active material layer 2 and the fourth active material layer 4 is low, which can provide better ion transmission performance; the compaction density of the first active material layer 1 and the third active material layer 3 is high, which can provide better energy density; the first active material layer 1 is arranged on the first surface of the current collector 5, and the fourth active material layer 4 is arranged on the second surface; both surfaces can participate in the electrochemical reaction, improving the overall energy density and power density of the battery; it can provide better mechanical stability, the first active material layer 1 and the third active material layer 3 can independently bear mechanical stress, reduce the damage of the overall structure, and improve the long-term stability and cycle life of the battery.

[0045] In one embodiment, the battery electrode is a positive electrode or a negative electrode.

[0046] When the battery pole piece is a positive pole piece, the active material in the active material layer can be at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese oxide, lithium vanadium oxide, lithium nickel manganese cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese aluminum oxide and lithium nickel cobalt manganese aluminum oxide; when the battery pole piece is a negative pole piece, the active material in the active material layer can be at least one of graphite, hard carbon, silicon, tin, lithium metal, lithium alloy and metal sulfide.

[0047] The utility model provides a battery, comprising a housing and a battery pole piece according to any one of the above embodiments, wherein the battery pole piece is accommodated inside the housing. The battery pole piece is in contact with the electrolyte inside the battery, and the layered battery pole piece and the electrolyte are subjected to the gravity field to improve the liquid phase mass transfer capacity of the high-density layer during service, reduce the internal resistance of the electrode, and improve the battery performance.

[0048] The utility model provides an electric device, including a battery and an electric device as described in any one of the above embodiments, wherein the battery supplies power to the electric device, which may be, but is not limited to, an electric energy storage device, an electric car, a smart phone, and a laptop computer.

[0049] In one embodiment, the utility model further provides a method for manufacturing a battery electrode sheet, wherein the electrode sheet is a negative electrode sheet, and the manufacturing method comprises the following steps:

[0050] S1, mixing the negative electrode active material, the binder, the solvent, and the conductive agent to prepare slurry A; mixing the negative electrode active material, the binder, the solvent, and the conductive agent to prepare slurry B.

[0051] S2, coating slurry A on copper foil, coating slurry B on slurry A, and preparing a negative electrode sheet through baking and rolling.

[0052] In one embodiment, the utility model further provides a method for manufacturing a battery electrode sheet, wherein the electrode sheet is a positive electrode sheet, and the manufacturing method comprises the following steps:

[0053] S3, mixing the positive electrode active material, the conductive agent, the binder and the solvent to prepare slurry C; mixing the positive electrode active material, the conductive agent, the binder and the solvent to prepare slurry D.

[0054] S4, coating slurry C on aluminum foil, coating slurry D on slurry C, and preparing a positive electrode through baking and rolling;

[0055] The technical solution of the utility model is described in detail below through specific embodiments.

[0056] Example 1

[0057] This embodiment provides a negative electrode sheet, which includes, from top to bottom in the gravity direction, a second active material layer, a first active material layer, a current collector, a fourth active material layer, and a third active material layer.

[0058] Among them, the negative electrode active materials are all graphite, and the compaction density of the first active material layer is 1.7g / cm 3 The compaction density of the second active material layer is 1.5 g / cm 3 The compaction density of the third active material layer is 1.7 g / cm 3 The compaction density of the fourth active material layer is 1.5 g / cm 3 The surface density of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer is 0.0075 g / cm 2 The particle sizes of the first active material layer and the third active material layer are both 10 μm, and the particle sizes of the second active material layer and the fourth active material layer are both 15 μm.

[0059] The method for making the negative electrode sheet of this embodiment is as follows:

[0060] 1) Artificial graphite, a binder, N-methyl-2-pyrrolidone solvent (NMP) and a conductive agent are mixed to prepare slurry A; natural graphite, a binder, NMP and a conductive agent are mixed to prepare slurry B.

[0061] 2) Slurry B is coated on a current collector and dried to obtain a first active material layer.

[0062] 3) Slurry A is coated on the first active material layer and dried to obtain a second active material layer.

[0063] 4) Slurry A is coated on the current collector and dried to obtain the fourth active material layer.

[0064] 5) Slurry B is coated on the fourth active material layer and dried to obtain the third active material layer.

[0065] 6) Baking and rolling to prepare the negative electrode sheet.

[0066] Example 2

[0067] This embodiment provides a negative electrode sheet, which includes, from top to bottom in the gravity direction, a second active material layer, a first active material layer, a current collector, a fourth active material layer, and a third active material layer.

[0068] Among them, the negative electrode active materials are all graphite, and the compaction density of the first active material layer is 1.7g / cm 3 The compaction density of the second active material layer is 1.2 g / cm 3 The compaction density of the third active material layer is 1.7 g / cm 3 The compaction density of the fourth active material layer is 1.2 g / cm 3 The surface density of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer is 0.0075 g / cm 2 The particle sizes of the first active material layer and the third active material layer are both 10 μm, and the particle sizes of the second active material layer and the fourth active material layer are both 15 μm.

[0069] The difference between Example 2 and Example 1 is that the compaction density of the second active material layer and the fourth active material layer is changed, and the compaction density of the second active material layer and the fourth active material layer is lower than the set standard.

[0070] The method for making the negative electrode sheet in Example 2 is the same as that in Example 1.

[0071] Example 3

[0072] This embodiment provides a negative electrode sheet, which includes, from top to bottom in the gravity direction, a second active material layer, a first active material layer, a current collector, a fourth active material layer, and a third active material layer.

[0073] Among them, the negative electrode active materials are all graphite, and the compaction density of the first active material layer is 1.2g / cm 3 The compaction density of the second active material layer is 1.1 g / cm 3 The compaction density of the third active material layer is 1.2 g / cm 3 The compaction density of the fourth active material layer is 1.1 g / cm 3 The surface density of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer is 0.0075 g / cm 2The particle sizes of the first active material layer and the third active material layer are both 10 μm, and the particle sizes of the second active material layer and the fourth active material layer are both 15 μm.

[0074] The difference between Example 3 and Example 1 is that the compaction density of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer is changed, and the compaction density of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer is lower than the set standard.

[0075] The method for making the negative electrode sheet in Example 3 is the same as that in Example 1.

[0076] Example 4

[0077] This embodiment provides a negative electrode sheet, which includes, from top to bottom in the gravity direction, a second active material layer, a first active material layer, a current collector, a fourth active material layer, and a third active material layer.

[0078] Among them, the negative electrode active materials are all graphite, and the compaction density of the first active material layer is 2g / cm 3 The compaction density of the second active material layer is 1.5 g / cm 3 The compaction density of the third active material layer is 2 g / cm 3 The compaction density of the fourth active material layer is 1.5 g / cm 3 The surface density of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer is 0.0075 g / cm 2 The particle sizes of the first active material layer and the third active material layer are both 10 μm, and the particle sizes of the second active material layer and the fourth active material layer are both 15 μm.

[0079] The difference between Example 4 and Example 1 is that the compaction densities of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer are changed, and the compaction densities of the first active material layer and the third active material layer are both higher than the set standard.

[0080] The method for making the negative electrode sheet in Example 4 is the same as that in Example 1.

[0081] Example 5

[0082] This embodiment provides a negative electrode sheet, which includes, from top to bottom in the gravity direction, a second active material layer, a first active material layer, a current collector, a fourth active material layer, and a third active material layer.

[0083] Among them, the negative electrode active materials are all graphite, and the compaction density of the first active material layer is 2g / cm 3The compaction density of the second active material layer is 1.8 g / cm 3 The compaction density of the third active material layer is 2 g / cm 3 The compaction density of the fourth active material layer is 1.8 g / cm 3 The surface density of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer is 0.0075 g / cm 2 The particle sizes of the first active material layer and the third active material layer are both 10 μm, and the particle sizes of the second active material layer and the fourth active material layer are both 15 μm.

[0084] The difference between Example 5 and Example 1 is that the compaction density of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer is changed, and the compaction density of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer is higher than the set standard.

[0085] The method for making the negative electrode sheet in Example 5 is the same as that in Example 1.

[0086] Example 6

[0087] This embodiment provides a negative electrode sheet, which includes, from top to bottom in the gravity direction, a second active material layer, a first active material layer, a current collector, a fourth active material layer, and a third active material layer.

[0088] Among them, the negative electrode active materials are all graphite, and the compaction density of the first active material layer is 2g / cm 3 The compaction density of the second active material layer is 1.2 g / cm 3 The compaction density of the third active material layer is 2 g / cm 3 The compaction density of the fourth active material layer is 1.2 g / cm 3 The surface density of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer is 0.0075 g / cm 2 The particle sizes of the first active material layer and the third active material layer are both 10 μm, and the particle sizes of the second active material layer and the fourth active material layer are both 15 μm.

[0089] The difference between Example 6 and Example 1 is that the compaction densities of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer are changed, and the compaction densities of the first active material layer and the third active material layer are both higher than the set standard, and the compaction densities of the second active material layer and the fourth active material layer are both lower than the set standard.

[0090] The method for making the negative electrode sheet in Example 6 is the same as that in Example 1.

[0091] Example 7

[0092] This embodiment provides a negative electrode sheet, which includes, from top to bottom in the gravity direction, a second active material layer, a first active material layer, a current collector, a fourth active material layer, and a third active material layer.

[0093] Among them, the negative electrode active materials are all graphite, and the compaction density of the first active material layer is 1.7g / cm 3 The compaction density of the second active material layer is 1.5 g / cm 3 The compaction density of the third active material layer is 1.7 g / cm 3 The compaction density of the fourth active material layer is 1.5 g / cm 3 The surface density of the first active material layer and the third active material layer is 0.005 g / cm 2 The surface density of the second active material layer and the fourth active material layer is 0.01 g / cm 2 The particle sizes of the first active material layer and the third active material layer are both 10 μm, and the particle sizes of the second active material layer and the fourth active material layer are both 15 μm.

[0094] The difference between Example 7 and Example 1 is that the surface density of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer is changed, and the surface density of the first active material layer and the third active material layer is different from the surface density of the second active material layer and the fourth active material layer.

[0095] The method for preparing the negative electrode sheet in Example 7 is the same as that in Example 1.

[0096] Example 8

[0097] This embodiment provides a negative electrode sheet, which includes, from top to bottom in the gravity direction, a second active material layer, a first active material layer, a current collector, a fourth active material layer, and a third active material layer.

[0098] Among them, the negative electrode active materials are all graphite, and the compaction density of the first active material layer is 1.7g / cm 3 The compaction density of the second active material layer is 1.5 g / cm 3 The compaction density of the third active material layer is 1.7 g / cm 3 The compaction density of the fourth active material layer is 1.5 g / cm 3 The surface density of the first active material layer and the third active material layer is 0.01g / cm 2 The surface density of the second active material layer and the fourth active material layer is 0.005 g / cm 2The particle sizes of the first active material layer and the third active material layer are both 10 μm, and the particle sizes of the second active material layer and the fourth active material layer are both 15 μm.

[0099] The difference between Example 8 and Example 1 is that the surface density of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer is changed, and the surface density of the first active material layer and the third active material layer is different from the surface density of the second active material layer and the fourth active material layer.

[0100] The method for preparing the negative electrode sheet in Example 8 is the same as that in Example 1.

[0101] Example 9

[0102] This embodiment provides a negative electrode sheet, which includes, from top to bottom in the gravity direction, a second active material layer, a first active material layer, a current collector, a fourth active material layer, and a third active material layer.

[0103] Among them, the negative electrode active materials are all graphite, and the compaction density of the first active material layer is 1.7g / cm 3 The compaction density of the second active material layer is 1.5 g / cm 3 The compaction density of the third active material layer is 1.7 g / cm 3 The compaction density of the fourth active material layer is 1.5 g / cm 3 The surface density of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer is 0.0075 g / cm 2 The particle sizes of the first active material layer and the third active material layer are both 15 μm, and the particle sizes of the second active material layer and the fourth active material layer are both 10 μm.

[0104] The difference between Example 9 and Example 1 is that the particle size of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer changes, and the particle size of the first active material layer and the third active material layer is larger than the particle size of the second active material layer and the fourth active material layer.

[0105] The method for making the negative electrode sheet in Example 9 is the same as that in Example 1.

[0106] Example 10

[0107] This embodiment provides a negative electrode sheet, which includes, from top to bottom in the gravity direction, a second active material layer, a first active material layer, and a current collector.

[0108] Among them, the negative electrode active materials are all graphite, and the compaction density of the first active material layer is 1.7g / cm 3The compaction density of the second active material layer is 1.5 g / cm 3 The surface density of the first active material layer and the second active material layer is 0.0075 g / cm 2 The particle size of the first active material layer is 10 μm, and the particle size of the second active material layer is 15 μm.

[0109] The difference between Example 10 and Example 1 is that only the first active material layer and the second active material layer are provided.

[0110] The method for preparing the negative electrode sheet in Example 10 is the same as that in Example 1.

[0111] Embodiment 11

[0112] This embodiment provides a positive electrode sheet, which includes, from top to bottom in the gravity direction, a second active material layer, a first active material layer, a current collector, a fourth active material layer, and a third active material layer.

[0113] Among them, the positive electrode active materials are all lithium iron phosphate, and the compaction density of the first active material layer is 2.75g / cm 3 The compaction density of the second active material layer is 2.45 g / cm 3 The compaction density of the third active material layer is 2.75 g / cm 3 The compaction density of the fourth active material layer is 2.45 g / cm 3 The surface density of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer is 0.015 g / cm 2 The particle sizes of the first active material layer and the third active material layer are both 10 μm, and the particle sizes of the second active material layer and the fourth active material layer are both 15 μm.

[0114] The method for making the positive electrode sheet of this embodiment is as follows:

[0115] 1) lithium iron phosphate, a binder, NMP and a conductive agent are mixed to prepare slurry C; lithium iron phosphate, a binder, NMP and a conductive agent are mixed to prepare slurry D.

[0116] 2) The slurry C is coated on the current collector and dried to obtain the first active material layer.

[0117] 3) Slurry D is coated on the first active material layer and dried to obtain a second active material layer.

[0118] 4) The slurry D is coated on the current collector and dried to obtain the fourth active material layer.

[0119] 5) Slurry C is coated on the fourth active material layer and dried to obtain the third active material layer.

[0120] 6) Baking and rolling to prepare the positive electrode sheet.

[0121] Comparative Example 1

[0122] This comparative example provides a negative electrode sheet, which includes, from top to bottom in the gravity direction, a second active material layer, a first active material layer, a current collector, a fourth active material layer, and a third active material layer.

[0123] Among them, the negative electrode active materials are all graphite, and the compaction density of the active material layer is 1.6g / cm 3 ; The surface density of each active material layer is 0.0075g / cm 2 ; The particle size of the active material layer is 12μm.

[0124] The difference between Comparative Example 1 and Example 1 is that the compaction density of the first active material layer is the same as that of the second active material layer, and the density of the third active material layer is the same as that of the fourth active material layer.

[0125] The method for preparing the negative electrode sheet in Comparative Example 1 is the same as that in Example 1.

[0126] Comparative Example 2

[0127] This embodiment provides a negative electrode sheet, which includes, from top to bottom in the gravity direction, a first active material layer, a second active material layer, a current collector, a fourth active material layer, and a third active material layer.

[0128] Among them, the negative electrode active materials are all graphite, and the compaction density of the first active material layer is 1.7g / cm 3 The compaction density of the second active material layer is 1.5 g / cm 3 The compaction density of the third active material layer is 1.7 g / cm 3 The compaction density of the fourth active material layer is 1.5 g / cm 3 The surface density of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer is 0.0075 g / cm 2 The particle sizes of the first active material layer and the third active material layer are both 10 μm, and the particle sizes of the second active material layer and the fourth active material layer are both 15 μm. The negative electrode sheet is composed of the first active material layer, the second active material layer, the current collector, the fourth active material layer and the third active material layer from top to bottom in the gravity direction.

[0129] The difference between Comparative Example 2 and Example 1 is that the first active material layer is below the second active material layer in the gravity direction.

[0130] The method for preparing the negative electrode sheet in Comparative Example 2 is the same as that in Example 1.

[0131] Comparative Example 3

[0132] This embodiment provides a negative electrode sheet, which includes a current collector (copper foil), a first active material layer, and a second active material layer. The negative electrode active materials are all graphite, and the compaction density of the first active material layer is 1.7 g / cm 3 The compaction density of the second active material layer is 1.5 g / cm 3 The surface density of the first active material layer and the second active material layer is 0.0075 g / cm 2 The particle size of the first active material layer is 10 μm, and the particle size of the second active material layer is 15 μm. The negative electrode sheet is composed of the first active material layer, the second active material layer and the current collector from top to bottom in the gravity direction.

[0133] The difference between Comparative Example 3 and Example 10 is that only the first active material layer and the second active material layer are provided in both, but the first active material layer is provided above the second active material layer.

[0134] The method for preparing the negative electrode sheet in Comparative Example 3 is the same as that in Example 1.

[0135] Comparative Example 4

[0136] This embodiment provides a positive electrode sheet, and the negative electrode sheet includes a first active material layer, a second active material layer, a current collector, a third active material layer, and a fourth active material layer from top to bottom in the gravity direction.

[0137] Among them, the positive electrode active materials are all lithium iron phosphate, and the compaction density of the first active material layer is 2.6g / cm 3 The compaction density of the second active material layer is 2.6 g / cm 3 The compaction density of the third active material layer is 2.6 g / cm 3 The compaction density of the fourth active material layer is 2.6 g / cm 3 The surface density of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer is 0.015 g / cm 2 The particle sizes of the first active material layer and the third active material layer are both 10 μm, and the particle sizes of the second active material layer and the fourth active material layer are both 15 μm.

[0138] The difference between Comparative Example 4 and Example 11 is that the compaction densities of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer are the same.

[0139] The method for preparing the positive electrode sheet in Comparative Example 4 is the same as that in Example 11.

[0140] The negative electrode sheets provided in Examples 1-10 and Comparative Examples 1-3 were assembled with the positive electrode sheets to form soft-pack batteries, wherein the positive electrode sheets were lithium iron phosphate positive electrode sheets. The positive electrode sheets provided in Example 11 and Comparative Example 4 were assembled with the negative electrode sheets to form soft-pack batteries, wherein the negative electrode sheets were graphite negative electrode sheets.

[0141] Test method:

[0142] (1) -10℃ continuous discharge capability test

[0143] The soft pack battery after the capacity division is adjusted to 50% SOC, and then according to the above different placement requirements, the battery is left at room temperature for 1 month and then the continuous discharge capacity at low temperature is tested. The test process is as follows: ① Recalibrate the battery capacity, fully charge with 1 / 3C constant current and constant voltage (calculate the charging current based on the nominal capacity), the upper limit voltage is 3.8V, the cut-off current of the constant voltage section is 0.05C, and then discharge with 1 / 3C constant current to 2.0V, and repeat this for 3 cycles. The discharge capacity of the third cycle is recorded as the recalibrated capacity C0. ② Fully charge with 1 / 3C0 constant current and constant voltage at 25℃ in the environmental chamber, and then keep it at -10℃ for 4h, and then discharge with 1 / 3C0 constant current to 2.0V. The discharge capacity is recorded as C1, and C1 / C0*100% is calculated as the discharge capacity ratio at -10℃@1 / 3C. The results are shown in Table 1.

[0144] (2) Testing of battery DC internal resistance at different temperatures

[0145] The battery was discharged at 1 / 3C constant current to 2.0V at room temperature, and charged at 1 / 3C constant current to 50% SOC. It was discharged at 1.5C constant current for 30s at 25℃ and -10℃ respectively, and the voltage before and after discharge was recorded. The discharge DCIR (mΩ) was calculated as (pre-discharge voltage - post-discharge voltage) / discharge current * 1000. The results are shown in Table 1.

[0146] Table 1

[0147]

[0148]

[0149] As shown in Table 1, by comparing Example 1 with Example 2, the sustained discharge capacity ratio of Example 2 is lower than that of Example 1, and the DC internal resistance at 25°C and -10°C is higher than that of Example 1. The compaction density of the second active material layer and the fourth active material layer of Example 2 is lower than the set standard, resulting in reduced contact between the particles of the second active material layer and the fourth active material layer, decreased electronic conductivity, and increased resistance, thereby affecting the discharge efficiency of the battery.

[0150] As shown in Table 1, by comparing Example 1 with Example 3, the sustained discharge capacity ratio of Example 3 is lower than that of Example 1, and the DC internal resistance at 25°C and -10°C is higher than that of Example 1. The compaction density of the active material layer of Example 3 is lower than the set standard, resulting in reduced contact between particles of the active material layer, decreased electronic conductivity, and increased resistance, thereby affecting the discharge efficiency of the battery.

[0151] As shown in Table 1, by comparing Example 1 with Example 4, the sustained discharge capacity ratio of Example 4 is lower than that of Example 1, and the DC internal resistance at 25°C and -10°C is higher than that of Example 1. The compaction density of the first active material layer and the third active material layer of Example 4 is higher than the set standard. High compaction density can increase energy density, but too high compaction density may increase internal stress in the high compaction layer, causing poor contact between particles and rupture of the material microstructure, reducing electronic conduction efficiency, and increasing resistance.

[0152] As shown in Table 1, by comparing Example 1 with Example 5, the sustained discharge capacity ratio of Example 5 is lower than that of Example 1, and the DC internal resistance at 25°C and -10°C is higher than that of Example 1. The compaction density of the active material layer of Example 5 is higher than the set standard. A high compaction density can increase the energy density, but an excessively high compaction density may increase the internal stress in the low compaction layer and the high compaction layer, causing poor contact between particles and rupture of the material microstructure, reducing the electronic conduction efficiency, and increasing the resistance.

[0153] As shown in Table 1, by comparing Example 1 with Example 6, the sustained discharge capacity ratio of Example 6 is lower than that of Example 1, and the DC internal resistance at 25°C and -10°C is higher than that of Example 1. The compaction density of the second active material layer and the fourth active material layer of Example 6 is lower than the set standard, and the compaction density of the first active material layer and the third active material layer of Example 6 is higher than the set standard. The difference in compaction density between the active material layers is too large, and the electrochemical properties at the interface are not matched, resulting in a large difference in intrinsic mass transfer capacity, reduced electronic conduction efficiency, and increased resistance.

[0154] As shown in Table 1, by comparing Example 1 with Example 7, the sustained discharge capacity ratio of Example 7 is lower than that of Example 1, and the DC internal resistance at 25°C and -10°C is higher than that of Example 1. In Example 7, the surface density of the second active material layer and the fourth active material layer is greater than the surface density of the first active material layer and the third active material layer, resulting in an imbalance in the electronic conductivity and ion diffusion rate of the active material layer, thereby increasing the internal resistance.

[0155] As shown in Table 1, by comparing Example 1 with Example 8, the sustained discharge capacity ratio of Example 8 is lower than that of Example 1, and the DC internal resistance at 25°C and -10°C is higher than that of Example 1. In Example 8, the surface density of the second active material layer and the fourth active material layer is less than that of the first active material layer and the third active material layer, resulting in an imbalance in the electronic conductivity and ion diffusion rate of the low compaction layer and the high compaction layer, thereby increasing the internal resistance.

[0156] As shown in Table 1, by comparing Example 1 with Example 9, the continuous discharge capacity ratio of Example 9 is lower than that of Example 1, and the DC internal resistance at 25°C and -10°C is higher than that of Example 1. The particle sizes of the first active material layer, the second active material layer, the third active material layer and the fourth active material layer have changed, and the particle sizes of the first active material layer and the third active material layer are larger than those of the second active material layer and the fourth active material layer. This causes the electron transmission path to become longer, increases the internal resistance of the battery, and thus reduces the power density and charge and discharge efficiency of the battery.

[0157] As shown in Table 1, by comparing Example 1 with Example 10, the continuous discharge capacity ratio and the DC internal resistance at 25°C and -10°C of Example 10 are not much different from those of Example 1. This indicates that the battery electrode is suitable for positive or negative electrodes.

[0158] As shown in Table 1, by comparing Example 1 with Comparative Example 1, the sustained discharge capacity ratio of Comparative Example 1 is lower than that of Example 1, and the DC internal resistance at 25°C and -10°C are both higher than that of Example 1. Compared with the single-layer setting of Comparative Example 1, the double-layer setting of Example 1 has the first active material layer and the third active material layer at the bottom contacting the electrolyte enrichment layer under the action of gravity, which improves the liquid phase mass transfer capacity of the first active material layer and the third active material layer during service, and reduces the difference in intrinsic mass transfer capacity between the first active material layer and the third active material layer and the second active material layer and the fourth active material layer, thereby reducing the total electrode internal resistance and affecting the power density and charge and discharge efficiency of the battery.

[0159] As shown in Table 1, by comparing Example 1 with Comparative Example 2, the sustained discharge capacity ratio of Comparative Example 2 is lower than that of Example 1, and the DC internal resistance at 25°C and -10°C is higher than that of Example 1. The design of Comparative Example 2 is set so that the first active material layer is above the second active material layer, resulting in the first active material layer being unable to contact the electrolyte enrichment layer under the action of gravity, thereby failing to reduce the total electrode internal resistance, affecting the power density and charge and discharge efficiency of the battery.

[0160] As shown in Table 1, by comparing Example 10 with Comparative Example 3, the sustained discharge capacity ratio of Comparative Example 3 is lower than that of Example 10, and the DC internal resistance at 25°C and -10°C is higher than that of Example 10. The first active material layer of Comparative Example 3 is not below the gravity direction, resulting in the first active material layer being unable to contact the electrolyte enrichment layer under the gravity, thereby failing to reduce the total electrode internal resistance, affecting the power density and charge and discharge efficiency of the battery.

[0161] As can be seen from Table 1, by comparing Example 11 with Comparative Example 4, the sustained discharge capacity ratio of Comparative Example 4 is lower than that of Example 11, and the DC internal resistance at 25°C and -10°C is higher than that of Example 11. The compaction density of the active material layers of Comparative Example 4 is the same, while the first active material layer and the third active material layer of Example 11 can contact the electrolyte enrichment layer under the action of gravity, thereby reducing the total electrode internal resistance and affecting the power density and charge and discharge efficiency of the battery.

[0162] In the description of the embodiments of the present application, it should be noted that the orientation or positional relationship of terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside" and "outside" are based on the orientation or positional relationship described in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0163] What is disclosed above is only a preferred embodiment of the present application, and it certainly cannot be used to limit the scope of rights of the present application. A person skilled in the art can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present application are still within the scope covered by the present application.

Claims

1. A battery pole piece, characterized in that: include: current collector; a first active material layer having a first compacted density; a second active material layer having a second compacted density; The first active material layer and the second active material layer are arranged on the same side in the thickness direction of the current collector, the first compaction density is greater than the second compaction density, and in the gravity direction, the second active material layer is arranged above the first active material layer.

2. The battery electrode according to claim 1, characterized in that: The first compacted density is 1.3 g / cm 3 -2.2g / cm 3 The second compacted density is 1.3 g / cm 3 -2.2g / cm 3 .

3. The battery pole piece according to claim 1, characterized in that: The surface density of the first active material layer and the second active material layer is the same, and the surface density is 0.001 g / cm 2 -0.02g / cm 2 .

4. The battery pole piece according to claim 1, characterized in that: The particle size D1 of the first active material layer is 5 μm-30 μm; and / or The particle size D2 of the second active material layer is 10 μm-50 μm; and / or The particle size D1 of the first active material layer and the particle size D2 of the second active material layer satisfy: D1 <D2。 5. The battery pole piece according to claim 1, characterized in that: The first active material layer includes a first sublayer and a second sublayer, the compaction density of the first sublayer is greater than the compaction density of the second sublayer, the second active material layer includes a third sublayer and a fourth sublayer, the compaction density of the third sublayer is greater than the compaction density of the fourth sublayer, and the compaction density of the second sublayer is greater than the compaction density of the third sublayer; the fourth sublayer, the third sublayer, the second sublayer and the first sublayer are arranged in sequence along the thickness direction of the current collector.

6. The battery pole piece according to claim 1, characterized in that: The battery pole piece comprises: a third active material layer having a third compacted density; a fourth active material layer having a fourth compaction density; The third active material layer and the fourth active material layer are arranged on the same side in the thickness direction of the current collector, the third compaction density is greater than the fourth compaction density, and in the gravity direction, the third active material layer is arranged below the fourth active material layer; The current collector includes a first surface and a second surface opposite to each other, the first active material layer is connected to the first surface, and the fourth active material layer is connected to the second surface.

7. The battery pole piece according to claim 1, characterized in that: The battery pole piece is a positive pole piece or a negative pole piece.

8. A battery, characterized in that: It comprises a shell and a battery pole piece as claimed in any one of claims 1 to 7, wherein the battery pole piece is accommodated inside the shell.

9. The battery according to claim 8, characterized in that The battery is a lithium ion battery or a sodium ion battery.

10. An electrical device, characterized in that: The invention comprises a battery as claimed in any one of claims 8 to 9 and an electrical device, wherein the battery supplies power to the electrical device.

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