Pole piece and battery

Abstract

The utility model discloses a pole piece and a battery. The pole piece comprises a current collector; the first active material layer is arranged on the first surface of the current collector, the first active material layer is provided with at least two convex regions and at least one concave region, and two ends of the concave region are respectively connected with the two convex regions; and the compaction density of the convex area is greater than that of the concave area. According to the pole piece, the diffusion speed of lithium ions can be improved, and the infiltration rate of the pole piece is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the battery field, concretely relates to pole piece and battery. BACKGROUND

[0002] The diffusion impedance of lithium ions between active substances is one of the important factors affecting the charging capacity of the battery. In a conventional lithium ion battery, the active substance layer is uniformly coated on the surface of the pole piece, and lithium ions need to diffuse from the surface to the interior. This process from the surface to the interior directly affects the charging speed. The speed of lithium ion insertion in the lower layer, i.e. the diffusion speed of lithium ions in the active substance, directly affects the improvement of the charging capacity of the battery. If the diffusion of lithium ions in the active substance is slow, the insertion speed of lithium ions during charging will slow down, thereby limiting the charging speed and charging efficiency of the battery.

[0003] At a high charging rate, the process of lithium ion insertion in the negative electrode becomes uneven, and lithium dendrites may gradually form on the negative electrode surface due to the inability to insert into the negative electrode graphite layer in time. The accumulation of lithium dendrites may pierce the separator, causing internal short circuit of the battery and leading to thermal runaway. At the same time, the growth of lithium dendrites consumes active lithium ions, resulting in a decrease in battery capacity and a decrease in battery service life. Therefore, optimizing the structure of the pole piece and improving the diffusion path and speed of lithium ions between active substances are crucial for improving the charging capacity of the battery.

[0004] In related technologies, the active substance layer on the surface of the pole piece is uniformly coated, the diffusion path of lithium ions in the lower layer is long, the diffusion speed is low, and the pole piece has low wettability, which affects the capacity and cycle stability of the battery. SUMMARY

[0005] The utility model aims at at least solves one of the technical problems existing in the prior art. To this end, the utility model provides a pole piece capable of improving the diffusion speed of lithium ions and the wettability of the pole piece.

[0006] The utility model further provides a battery.

[0007] The pole piece according to the first aspect of the utility model comprises:

[0008] a current collector;

[0009] a first active substance layer, the first active substance layer being arranged on a first surface of the current collector, the first active substance layer being provided with at least two protruding regions and at least one recessed region, both ends of the recessed region being connected to two protruding regions respectively;

[0010] The compaction density of the protruding region is greater than the compaction density of the recessed region.

[0011] According to the electrode plate provided by the embodiment of the present application, the diffusion speed of lithium ions can be improved, and the impregnation rate of the electrode plate can be improved.

[0012] According to some embodiments of the present application, the protruding areas and the recessed areas are both provided with a plurality of protruding areas and a plurality of recessed areas.

[0013] According to some embodiments of the present application, the cross section of the protruding area along the thickness direction of the first active material layer is shaped as a trapezoid, a rectangle, a triangle or a wave shape.

[0014] According to some embodiments of the present application, the protruding area has a first top surface away from the current collector, the distance between the first top surface and the first surface is H1, the recessed area has a lowest point away from the current collector, the distance between the lowest point and the first surface is H2, and H2 / H1<1.

[0015] According to some embodiments of the present application, the protruding areas and the recessed areas are both provided with a plurality of protruding areas and a plurality of recessed areas.

[0016] The first active material layer comprises a first region and a second region, in the first region, the distance between the lowest points of two adjacent recessed areas is D1, the distance between two adjacent first top surfaces is D2, and 0.2≤D2 / D1≤0.6.

[0017] According to some embodiments of the present application, D1≤5mm.

[0018] According to some embodiments of the present application, in the second region, the distance between two adjacent first top surfaces is D3, and D3 / D2≥1.1.

[0019] According to some embodiments of the present application, the compaction density of the raised area is PD1, the compaction density of the recessed area is PD2, and 0.6≤PD2 / PD1≤0.9.

[0020] According to some embodiments of the present application, the second active material layer is arranged on the second surface of the current collector opposite to the first surface.

[0021] According to the battery of the second aspect of the present application, at least the following beneficial effects can be achieved: the diffusion speed of lithium ions can be improved, and the wettability of the electrode plate can be improved.

[0022] According to the battery of the second aspect of the present application, at least the following beneficial effects can be achieved: the diffusion speed of lithium ions can be improved, and the wettability of the electrode plate can be improved.

[0023] Additional aspects and advantages of the present application will be given in part in the following description, will become apparent from the following description, or will be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0024] The present application will be further described below in combination with the drawings and embodiments, in which:

[0025] Figure 1 FIG. 1 is a schematic view of an electrode plate according to a first embodiment of the present application;

[0026] Figure 2 FIG. 2 is a schematic view of an electrode plate according to a second embodiment of the present application;

[0027] Figure 3 FIG. 3 is a schematic view of an electrode plate according to a third embodiment of the present application;

[0028] Figure 4 FIG. 4 is a schematic view of an electrode plate according to a fourth embodiment of the present application;

[0029] Figure 5 FIG. 5 is a top view of a battery according to a fifth embodiment of the present application;

[0030] Figure 6 A plan view of the battery of the sixth embodiment of the present application.

[0031] Reference signs:

[0032] Current collector 100; first surface 101; second surface 102; first active material layer 200; protruding region 210; first top surface 211; recessed region 220; lowest point 221; second active material layer 300; first region A; second region B. DETAILED DESCRIPTION

[0033] Embodiments of the present application will be described in detail below, examples of which are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary and are only used to explain the present application and cannot be understood as a limitation of the present application.

[0034] In the description of the present application, it should be understood that the orientation description, such as the orientation or position relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as a limitation of the present application.

[0035] In the description of the present application, the meaning of several is more than one, the meaning of multiple is more than two, greater than, less than, more than, etc. are understood as not including the number, above, below, etc. are understood as including the number. If it is described as first, second, it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the order of indicated technical features.

[0036] In the description of the present application, unless otherwise explicitly limited, the words such as setting, installing, connecting, etc. should be broadly understood, and the skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0037] In the description of the utility model, the description of the reference terms "one embodiment", "some embodiments", "illustrative embodiment", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the utility model. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0038] With the widespread use of electric vehicles and electronic products, lithium ion batteries have become one of the important energy storage systems in modern society due to their high energy density, low self-discharge, long cycle life and environmental friendliness. The diffusion resistance of lithium ions between active materials is one of the important factors affecting the charging capacity of the battery. In conventional lithium ion batteries, the surface of the electrode sheet is uniformly coated, and lithium ions need to diffuse from the surface to the interior. This process from the surface to the interior directly affects the charging speed. The speed of lithium ion insertion into the lower layer, i.e. the diffusion speed of lithium ions in the active material, directly affects the improvement of the charging capacity of the battery. If the diffusion of lithium ions in the active material is slow, it will slow down the insertion of lithium ions during the charging process, thereby limiting the charging speed and charging efficiency of the battery.

[0039] At high charging rate, the process of lithium ion insertion into the negative electrode becomes uneven, and may deposit on the surface of the negative electrode due to the inability to insert into the negative electrode graphite layer in time, gradually forming lithium dendrites. The accumulation of lithium dendrites may pierce the separator, causing internal short circuit of the battery and leading to thermal runaway, while the growth of lithium dendrites consumes active lithium ions, leading to a decrease in battery capacity and reducing the service life of the battery. Therefore, optimizing the electrode sheet structure and improving the diffusion path and speed of lithium ions between active materials is crucial for improving the charging capacity of the battery.

[0040] In related technologies, the active material layer on the surface of the electrode sheet is uniformly coated, the diffusion path of lithium ions in the lower layer is long, the diffusion speed is low, and the electrode sheet wettability is low, which affects the capacity and cycle stability of the battery. In addition, in related technologies, some methods are to manufacture grooves on the surface of the electrode sheet through laser drilling process, so as to shorten the transmission path of lithium ions in the lower layer, but the laser drilling process needs to be cleaned in the later stage to remove residues, increasing the complexity and cost of battery production. During the cleaning process, part of the active material may be washed away, resulting in a decrease in material utilization and affecting the capacity and cycle stability of the battery, further leading to slow charging speed and short service life.

[0041] Based on the above problems, the present application proposes a battery which aims to solve the problems existing in the related art to some extent.

[0042] With reference to Figures 1 to 6 , mainly with reference to Figure 1 According to the electrode piece of the first aspect of the present application, the electrode piece has at least the following beneficial effects: the diffusion speed of lithium ions can be improved, and the wettability of the electrode piece is improved.

[0043] According to the electrode piece of the first aspect of the present application, the electrode piece has at least the following beneficial effects: the diffusion speed of lithium ions can be improved, and the wettability of the electrode piece is improved.

[0044] Specifically, in the present application, the first active material layer 200 is provided with the raised area 210 and the recessed area 220, which can be directly formed on the current collector 100 by coating or the like. Compared with the conventional first active material of a planar shape without the raised area 210 and the recessed area 220, the diffusion path of lithium ions in the recessed area 220 is shorter, and the diffusion speed of lithium ions is improved. In addition, since the compaction density of the recessed area 220 of the electrode piece of the present application is less than that of the raised area 210, the compaction density of the active material layer changes in the horizontal direction. Since the compaction density of the recessed area 220 is low, the lithium intercalation resistance is small, and lithium ions preferentially intercalate into the recessed area 220 and then diffuse to both sides, further reducing the mass transfer resistance of lithium ions and improving the transmission efficiency of lithium ions in the lower layer area. Therefore, the electrode piece of the present application can improve the diffusion speed of the active material in the lower layer area and improve the wettability.

[0045] With reference to Figure 2In the specific process of achieving the compaction density of the raised area 210 being greater than the compaction density of the recessed area 220, after the first active material layer 200 is coated on the current collector 100, unlike the conventional coating to form a flat film surface, the present application first coats a uniform first active material layer 200 on the surface of the current collector 100. In the semi-dry state of the active material layer 200, a recess (punching) is formed by, for example, a gas blowing method such as a pulse gas pulse. The first active material layer 200 coated on the current collector 100 is uneven in thickness, so that the surface of the dried film forms a regular concave-convex appearance. Alternatively, the first active material layer 200 can also be coated on the surface of the current collector 100 in an uneven manner. Specifically, the first active material layer 200 is coated on the surface of the current collector 100 in a regular pattern, for example, in a wave shape, and the recessed area can be distributed in a point shape, a corrugated shape, a straight line shape, etc. After the first active material layer 200 is coated, the raised area 210 of the first active material layer 200 is rolled to make the compaction density of the raised area 210 greater than the compaction density of the recessed area 220, thereby forming the raised area 210 with a greater compaction density and the recessed area 220 with a smaller compaction density. After rolling, the upper surface of the raised area 210 is flat, thereby forming the raised area 210 and the recessed area 220 with different compaction densities (hereinafter also referred to as compaction). After rolling, the recessed area 220 has a smaller thickness and a lower compaction density than the raised area 210. The low-compaction-density area has a small lithium intercalation impedance, and lithium ions are preferentially intercalated into the low-compaction-density area and then diffuse to the low-compaction-density areas on both sides. Furthermore, the diffusion efficiency of lithium ions is improved, the wetting rate is improved, and the cycle stability and the charging capacity of the battery are improved.

[0046] Thus, by unevenly coating the first active material layer 200, the coated first active material layer 200 has the raised area 210 and the recessed area 220, and after rolling, the recessed area 220 has a small thickness and a low compaction density. Compared with the conventional pole piece formed by coating a flat active material layer on the current collector and then laser punching the flat active material layer, the subsequent cleaning step of the pole piece is not required, and the material input and process cost can be reduced.

[0047] Further, according to some embodiments of the present application, the plurality of protruding regions 210 are arranged at the same interval, and the plurality of recessed regions 220 are arranged at the same interval. Specifically, the plurality of protruding regions 210 and the plurality of recessed regions 220 can be evenly distributed, and the plurality of protruding regions 210 and the plurality of recessed regions 220 are alternately connected. The distance between each adjacent protruding region 210 is the same, and the distance between each adjacent recessed region 220 is the same. It should be noted that the distance between adjacent protruding regions 210 and the distance between adjacent recessed regions 220 can be different. By arranging the plurality of protruding regions 210 and the plurality of recessed regions 220 at the same interval on the pole piece, the surface area of the pole piece can be increased, thereby increasing the contact area of the pole piece and the electrolyte, improving the wettability of the electrolyte, optimizing the transmission path of lithium ions, and shortening the transmission distance of ions in the active material. At the same time, the tortuosity is reduced, thereby improving the rate performance of the battery and the utilization rate of the active material.

[0048] In addition, this structure can also reduce the polarization phenomenon of the battery during charging and discharging, improve the energy density, reduce the risk of thermal runaway, thereby enhancing the safety and stability of the battery. By arranging the interval of each adjacent protruding region 210 to be the same, and arranging the interval of each adjacent recessed region 220 to be the same, the lithium ion insertion process on the negative electrode becomes uniform, and the lithium ion cannot be inserted in time to deposit and gradually form lithium dendrites.

[0049] Further, with reference to Figures 2 to 5 According to some embodiments of the present application, the cross section of the protruding region 210 along the thickness direction of the first active material layer 200 is shaped as a trapezoidal, rectangular, triangular or wave-shaped shape. The pattern formed by the interconnection of the protruding region 210 and the recessed region 220 can be any shape, and the recessed region 220 can be distributed on the surface of the pole piece in the form of dots, corrugations, straight lines, etc. as long as the shape conforms to the periodic variation rule. Thus, the surface area containing the same number of recessed regions 220 and protruding regions 210 can maintain a consistent surface density.

[0050] Further, according to some embodiments of the present application, the protruding region 210 has a first top surface 211 away from the current collector 100, and the distance between the first top surface 211 and the first surface 101 is H1. The recessed region 220 has a lowest point 221 away from the current collector 100, and the distance between the lowest point 221 and the first surface 101 is H2, and H2 / H1<1. In this application, with reference to Figure 1, the protruding area 210 can be shaped as a trapezoidal shape along the cross section of the first active material layer 200 in the thickness direction, and the recessed area 220 is shaped as a triangular shape. At this time, the protruding area 210 has a first top surface 211 on the surface of the first active material layer 200, and the recessed area 220 has a lowest point 221 on the surface of the first active material layer 200. Along the thickness direction of the first active material layer 200, the distance between the first top surface 211 and the first surface 101 of the current collector 100 is H1, and the distance between the lowest point 221 and the first surface 101 of the current collector 100 is H2. In the present application, H2 / H1 < 1, for example, the relationship between H2 and H1 can satisfy H2 / H1 = 0.8, H2 / H1 = 0.6, and H2 / H1 = 0.4, etc., that is, the depth of the recessed area 220 is less than the depth of the protruding area 210, so as to further ensure that the diffusion path of lithium ions in the recessed area 220 is short, the diffusion speed of lithium ions is improved, and the wettability of the pole piece is improved, the cycle stability of the battery is improved, and the charging capacity is improved.

[0051] It should be noted that in the present application, if the pole piece is provided as Figure 4 the structure shown in the figure, the lowest point 221 of the recessed area 220 refers to the center point of the bottom surface of the recessed area 220 away from the current collector 100.

[0052] Further, according to some embodiments of the present application, a plurality of protruding areas 210 and recessed areas 220 are provided, the protruding area 210 has a first top surface 211 away from the current collector 100, and the recessed area 220 has a lowest point 221 away from the current collector 100. The first active material layer 200 includes a first area A (refer to the area surrounded by the left dashed box in Figure 5 Fig. 2) and a second area B (refer to the area surrounded by the right dashed box in Figure 5 Fig. 2), in the first area A, the distance between the lowest points 221 of two adjacent recessed areas 220 is D1, and the distance between two adjacent first top surfaces 211 is D2, 0.2≤D2 / D1≤0.6. Specifically, D1 and D2 need to satisfy a proper proportional relationship, so that the transition of the protruding area 210 and the recessed area 220 is smooth, and the size difference between the protruding area 210 or the recessed area 220 will not be too large. Therefore, the stress concentration inside the battery can be reduced, and the mechanical stability and cycle life of the battery can be improved. At the same time, it can also help the uniform distribution and wettability of the electrolyte on the pole piece, and improve the charging and discharging efficiency and performance of the battery. In the present application, D1 and D2 satisfy: 0.2≤D2 / D1≤0.6, further, D2 / D1 = 0.3, D2 / D1 = 0.4, D2 / D1 = 0.5.

[0053] Table 1:

[0054]

[0055] From the above Table 1, it can be seen that when D1 and D2 are set to satisfy 0.2≤D2 / D1≤0.6, the degree of lithium precipitation is the lightest, and in particular, when D2 / D1 is set to be equal to 0.4, lithium precipitation does not occur in the three cases.

[0056] In addition, the first area A forms a flat part of the winding structure after the pole piece is wound into the battery cell, the second area B forms a curved part of the winding structure after the pole piece is wound into the battery cell, by setting the distance between the adjacent two first top surfaces 211 in the first area A and the second area B to be different, the specific situation can be set according to the specific situation of each part, the material utilization rate is improved, and the lithium precipitation at the corner is improved (for details, see the description below).

[0057] According to some embodiments of the present application, D1≤5mm. In a lithium ion battery, if the convex area 210 (high pressure dense area, i.e. the area with high lithium ion concentration in the battery) is too wide, it may cause a bottleneck problem of local ion diffusion, thereby affecting the charging efficiency of the battery. Specifically, if the high pressure dense area is too wide, it may cause the diffusion speed of lithium ions in this area to slow down, forming a local ion transmission short board, which means that during the charging process, the lithium ions in this area cannot participate in the electrochemical reaction quickly, so that the battery cannot fully utilize the charging window, thereby affecting the charging performance and efficiency of the battery. In the present application, by setting D1 to be less than or equal to 5mm, for example, it can be 4mm, 3mm, etc., the local ion diffusion speed can be avoided, and the charging efficiency of the battery can be improved.

[0058] Further, with reference to Figure 6 , according to some embodiments of the present application, in the second area B, the distance between the adjacent two first top surfaces 211 is D3, and D3 / D2≥1.1. The first area A forms a flat part of the winding structure after the pole piece is wound into the battery cell, and the second area B forms a curved part of the winding structure after the pole piece is wound into the battery cell. Since lithium precipitation is prone to occur in the curved part of the battery cell (i.e. the corner area of the battery cell), the width of the recessed area 220 can be appropriately increased, i.e. in the subsequent second area B forming the curved part, the distance D3 between the adjacent two first top surfaces 211 can be set to be greater than D2, and in the present application, D3 / D2≥1.1. Of course, D3 / D2 can also be 1.2, D3 / D2 can also be 1.3, etc., as long as the lithium precipitation phenomenon in the corner area of the battery cell can be improved as much as possible.

[0059] According to some embodiments of the present application, the compaction density of the raised area 210 is PD1, the compaction density of the recessed area 220 is PD2, and 0.6≤PD2 / PD1≤0.9. Specifically, a ratio between a lower compaction density area (the recessed area 220) and a higher compaction density area (the raised area 210) that is too large or too small will adversely affect the performance of the battery. If the ratio of the compaction densities of the recessed area 220 and the raised area 210 is too large, it may result in a too high porosity in the low compaction density area, affecting electrolyte infiltration and lithium ion transport, and reducing the charge and discharge performance. On the contrary, a too small ratio of the compaction densities may result in a too low porosity in the high compaction density area, increasing the internal resistance of the battery, and affecting the charge and discharge efficiency. In addition, uneven distribution of the compaction density may also result in increased battery polarization, decreased cycle stability, increased safety risk, and mismatched energy density and power density, thereby affecting the overall performance and service life of the battery. Therefore, in the present application, the compaction density of the raised area 210 is PD1 and the compaction density of the recessed area 220 is PD2, satisfying: 0.6≤PD2 / PD1≤0.9. Further, the relationship between PD2 and PD1 can be PD2 / PD1=0.7 or PD2 / PD1=0.8, etc.

[0060] Table 2:

[0061]

[0062] From the above Table 2, it can be seen that when PD1 and PD2 are set to satisfy: 0.6≤PD2 / PD1≤0.9, the degree of lithium precipitation is the lightest, and in particular when PD2 / PD1 is set to equal 0.7 or 0.9, lithium precipitation does not occur in the three cases.

[0063] According to some embodiments of the present application, the battery further comprises a second active material layer 300, which is arranged on the second surface 102 of the current collector 100 opposite to the first surface 101. The second active material layer 300 is arranged in the same manner as the first active material layer 200, and can refer to the structure of the first active material layer 200 for arrangement, which will not be described here.

[0064] According to the battery of the second aspect of the present application, the battery comprises any one of the above.

[0065] According to the battery of the second aspect of the present application, the battery has at least the following beneficial effects: it can improve the diffusion speed of lithium ions and improve the infiltration rate of the current collector. Specifically, in the present application, the first active material layer 200 is provided with a raised area 210 and a recessed area 220, which can be directly formed on the current collector 100 by coating or the like. Compared with the traditional first active material of a planar shape without the raised area 210 and the recessed area 220, the diffusion path of lithium ions in the recessed area 220 is shorter, and the diffusion speed of lithium ions is improved.

[0066] In addition, since the compaction density of the recessed area 220 of the tab of the present application is less than the compaction density of the raised area 210, the compaction density of the active material layer changes in the horizontal direction, and since the compaction density of the recessed area 220 is lower, its lithium insertion resistance is small, lithium ions preferentially insert into the recessed area 220, and then diffuse to both sides, further reducing the mass transfer resistance of lithium ions, and improving the transport efficiency of lithium ions in the lower layer area.

[0067] Therefore, the battery including the above-mentioned tab can also improve the diffusion speed of the active material in the lower layer area, improve the wettability of the tab, and further improve the cycle stability of the battery and the battery performance.

[0068] The embodiments of the utility model are explained in detail above in combination with the drawings, but the utility model is not limited to the above-mentioned embodiments, and within the knowledge range possessed by the ordinary skilled in the art, various changes can be made without departing from the purpose of the utility model.In addition, the embodiments of the utility model and the features in the embodiments can be combined with each other without conflict.

Claims

1. An electrode, characterized in that, include: current collector; A first active material layer is disposed on the first surface of the current collector. The first active material layer is provided with at least two raised areas and at least one recessed area, and the two ends of the recessed area are respectively connected to the two raised areas. The compaction density of the raised area is greater than that of the recessed area.

2. The electrode sheet according to claim 1, characterized in that, Multiple raised areas and multiple recessed areas are provided, with the raised areas and the recessed areas separated by the same spacing.

3. The electrode sheet according to claim 2, characterized in that, The protruding area is shaped into a trapezoidal, rectangular, triangular, or wave-shaped section along the thickness direction of the first active material layer.

4. The electrode sheet according to claim 1, characterized in that, The raised area has a first top surface away from the current collector, the distance between the first top surface and the first surface is H1, and the recessed area has a lowest point away from the current collector, the distance between the lowest point and the first surface is H2, H2 / H1<1.

5. The electrode sheet according to claim 1, characterized in that, Multiple protruding areas and multiple recessed areas are provided. The protruding areas have a first top surface away from the current collector, and the recessed areas have a lowest point away from the current collector. The first active material layer includes a first region and a second region. In the first region, the distance between the lowest points of two adjacent recessed regions is D1, and the distance between two adjacent first top surfaces is D2, where 0.2 ≤ D2 / D1 ≤ 0.

6.

6. The electrode sheet according to claim 5, characterized in that, D1≤5mm.

7. The electrode sheet according to claim 5, characterized in that, In the second region, the distance between two adjacent first top surfaces is D3, and D3 / D2 ≥ 1.

1.

8. The electrode sheet according to claim 1, characterized in that, The compaction density of the raised area is PD1, and the compaction density of the recessed area is PD2, where 0.6 ≤ PD2 / PD1 ≤ 0.

9.

9. The electrode sheet according to claim 1, characterized in that, It also includes a second active material layer, which is disposed on the second surface of the current collector opposite to the first surface.

10. A battery, characterized in that, The electrode includes any one of claims 1 to 9.

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