Pole piece and battery

Abstract

The utility model relates to the field of energy storage batteries, in particular to a pole piece and a battery, which comprise a current collector and an active coating arranged on the single side surface of the current collector, the long axis of the pole piece extends in a first direction, and the short axis of the pole piece extends in a second direction; the active coating comprises a plurality of grooves; each groove extends in the first direction, and the multiple grooves are arranged in the second direction; in the second direction, the grooves have the groove width, a groove distance is formed between every two adjacent grooves, and the groove width and / or the groove distance are / is larger when the grooves are closer to the middle position. According to the utility model, the bending condition of the pole piece is improved, the lithium precipitation of the battery at the position of the pole piece is avoided, and the width and / or the distance between the grooves closer to the middle position are / is larger, so that the anti-curling effect is further improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of energy storage battery, in particular to a pole piece and battery. BACKGROUND

[0002] With the development of battery technology, consumers demand higher and higher charging speed and service life, and the laminated structure battery has more uniform current density, faster acceptable reaction rate and faster charging speed compared with the single pole ear winding structure battery, therefore, the laminated structure battery is more and more valued in the industry.

[0003] But in the process of manufacturing laminated battery core, due to the process requirement, the outermost current collector can only be single-sided coated with paste (i.e. single-sided active coating), and the single-sided paste coating will cause uneven stress distribution of the current collector of the pole piece, which is prone to curling, resulting in lithium precipitation of the corresponding outermost positive and negative pole pieces and reducing battery performance.

[0004] Therefore, how to avoid the curling of the single-sided paste-coated pole piece caused by stress concentration and further lithium precipitation is a problem to be solved by those skilled in the art. SUMMARY

[0005] The utility model aims to provide a pole piece and battery to solve the problem of lithium precipitation of the single-sided paste-coated pole piece caused by stress concentration in the prior art.

[0006] To solve the above technical problems, the utility model provides a pole piece, which comprises a current collector and an active coating arranged on a single side surface of the current collector.

[0007] The long axis of the pole piece extends in a first direction, and the short axis of the pole piece extends in a second direction.

[0008] The active coating comprises a plurality of grooves.

[0009] Each groove extends in the first direction, and the plurality of grooves are arranged in parallel along the second direction.

[0010] In the second direction, the groove has a groove width, and the adjacent grooves have a groove spacing.

[0011] The groove width gradually increases and then gradually decreases along the second direction.

[0012] And / or, the groove spacing gradually increases and then gradually decreases along the second direction.

[0013] Optionally, the pole piece has a first side edge and a second side edge arranged oppositely along the first direction, and the first side edge and the second side edge have a middle position.

[0014] In the second direction, the groove with the smallest distance from the middle position is the middle groove, which has the largest groove width and the largest groove spacing with the adjacent groove.

[0015] Optionally, in the electrode sheet, the groove is a continuous groove along the first direction;

[0016] And / or, the groove includes a plurality of spaced groove units in the first direction.

[0017] Optionally, in the electrode, the groove unit includes at least one of a rectangular groove unit and a circular groove unit.

[0018] Optionally, in the electrode sheet, the groove is an embossing roller groove.

[0019] Optionally, in the electrode, the groove has a first end and a second end disposed opposite to each other in the first direction;

[0020] The first end coincides with the first side;

[0021] And / or, the second end coincides with the second side.

[0022] Optionally, in the electrode, the groove has a first end and a second end disposed opposite to each other in the first direction;

[0023] There is a gap between the first end and the first side, and there is a gap between the second end and the second side.

[0024] Optionally, in the electrode, the electrode has a thickness H1 in the third direction, and the groove has a groove depth H2 in the third direction;

[0025] H1 and H2 satisfy: 1 / 3 ≤ H2 / H1 ≤ 1.

[0026] Optionally, in the electrode, the groove has a groove depth H2 in the third direction, and the active coating has an active layer thickness H3 in the third direction;

[0027] The bottom surface of the groove exposes the current collector, and H2 and H3 satisfy: H2>H3.

[0028] Optionally, in the electrode, the electrode has a width W1 in the second direction, and the sum of the groove widths W2 of the grooves. sum W1 satisfies: 0.05 ≤ W2 sum / W1≤0.10.

[0029] Optionally, in the electrode, the groove width W2 satisfies: 0.5mm ≤ W2 ≤ 1.0mm;

[0030] And / or, the groove spacing D1 satisfies: 0.5mm≤D1≤3.0mm.

[0031] Optionally, in the electrode sheet, the electrode sheet has a third side and a fourth side disposed opposite to each other along the second direction, and the groove closest to the third side and the groove closest to the fourth side are both edge grooves.

[0032] In the second direction, the intermediate groove has a width W2. mid The intermediate groove has a spacing D1 between it and the adjacent groove. mid The edge groove has a width W2 side The edge groove has a spacing D1 between it and the adjacent groove. side ;

[0033] W2 mid Satisfies: 0.1mm≤W2 mid ≤0.2mm;

[0034] And / or, W2 side Satisfies: 0.01mm≤W2 side ≤0.03mm;

[0035] And / or, D1 mid Satisfies: 1.0mm≤D1 mid ≤3.0mm;

[0036] And / or, D1 side Satisfies: 0.1mm≤D1 side ≤1.0mm.

[0037] Optionally, in the electrode, a void area is provided at each end along the second direction;

[0038] The empty region extends through the electrode sheet along the first direction;

[0039] The groove is not provided in the empty area.

[0040] A battery comprising any of the electrodes described above.

[0041] The electrode provided by this invention features grooves in the active coating, effectively pre-reserving space for stress release. This prevents localized deformation during stress release from compressing and deforming the electrode as a whole, significantly improving its bending performance and preventing lithium plating at the electrode location. Furthermore, since the center of the electrode is most prone to stress accumulation and bending during stress release, the wider grooves and the greater the groove spacing closer to the center, the better the electrode's anti-bending effect, ultimately improving battery performance. This invention also provides a battery with the aforementioned beneficial effects. Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 A top view of a specific embodiment of the electrode sheet provided by this utility model;

[0044] Figure 2 A top view of the marked middle position of a specific embodiment of the electrode sheet provided by this utility model;

[0045] Figure 3 A top view of the first and second sides of a specific embodiment of the electrode sheet provided by this utility model.

[0046] Figure 4 To and Figure 1 A front cross-sectional schematic diagram of a specific embodiment of the electrode sheet provided by this utility model;

[0047] Figure 5 A top view schematic diagram of a specific embodiment of the electrode sheet provided by this utility model, which includes only a groove composed of groove units;

[0048] Figure 6 A top view schematic diagram of a specific embodiment of the electrode sheet provided by this utility model, which has two types of grooves;

[0049] Figure 7 A top view schematic diagram of a specific embodiment of the electrode sheet with multiple grooves mixed according to the present utility model;

[0050] Figure 8A top view schematic diagram showing different positional relationships between the groove end face and the edge of the electrode sheet in one specific embodiment of the electrode sheet provided by this utility model;

[0051] Figure 9 A front cross-sectional schematic diagram of another specific embodiment of the electrode sheet provided by this utility model;

[0052] Figure 10 A top view of the third and fourth sides of a specific embodiment of the electrode sheet provided by this utility model.

[0053] Figure 11 A top view of a specific embodiment of the electrode sheet provided by this utility model, wherein the edge position does not have a groove.

[0054] The figure includes 01-first side, 02-second side, 03-third side, 04-fourth side, 10-active coating, 20-current collector, 30-groove, 30a-first end, 30b-second end, 30A-middle groove, 30B-edge groove, 31-circular groove unit, 32-rectangular groove unit, and 40-empty area. Detailed Implementation

[0055] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] The first direction of this application is the winding direction of the electrode, the third direction is the thickness direction of the electrode, and the second direction is perpendicular to the first direction and the third direction, that is, the width direction where the minor axis of the electrode is located.

[0057] The core of this utility model is to provide an electrode sheet, the structural schematic diagram of one specific embodiment of which is shown below. Figure 1 As shown, this is referred to as Specific Embodiment 1, which includes a current collector 20 and an active coating 10 disposed on one side surface of the current collector 20.

[0058] The long axis of the electrode extends in a first direction, and the short axis of the electrode extends in a second direction.

[0059] The active coating 10 includes a plurality of grooves 30;

[0060] A single groove 30 extends in the first direction, and a plurality of grooves 30 are arranged in parallel along the second direction;

[0061] In the second direction, the groove 30 has a groove width W2, and there is a groove spacing D1 between adjacent grooves 30;

[0062] The groove width W2 gradually increases and then gradually decreases along the second direction;

[0063] And / or, the groove spacing D1 gradually increases and then gradually decreases along the second direction.

[0064] The electrode has a first side 01 and a second side 02 disposed opposite to each other along a first direction, and the first side 01 and the second side 02 have an intermediate position;

[0065] In the second direction, the groove 30 with the smallest distance from the middle position is the middle groove 30A. The middle groove 30A has the largest groove width and the largest groove spacing with the adjacent groove 30.

[0066] The distance from the first side 01 to the middle position is the same as the distance from the second side 02 to the middle position, which can be used as a reference. Figure 2 , Figure 2 If the distance from the first side 01 to point A is the same as the distance from the second side 02 to point A, both being W0, then point A is the intermediate position. Of course, there are also cases where there are two grooves 30 that are equidistant from the intermediate position in the second direction; in this case, both grooves 30 are the intermediate groove 30A (e.g., ...). Figure 1 , Figure 2 If a groove 30 exists at the intermediate position, it can be assumed that the distance between the groove 30 and the intermediate position in the second direction is 0, and the groove 30 is directly considered to be the intermediate groove 30A (refer to...). Figure 5 , Figure 6 Additionally, the first side 01 and the second side 02 are in... Figure 3 The area is outlined with a dashed line.

[0067] For ease of combination Figure 1 It is understood that the length of the electrode (i.e., the dimension along the first direction) can be L1, and the width of the electrode (i.e., the dimension along the second direction) can be W1, and L1 and W1 satisfy: L1>W1.

[0068] The groove width W2 and the corresponding spacing D1 of each groove 30 can be different, or they can be divided into several groups. The groove width W2 and spacing D1 of the same group are the same. However, in any case, the groove width W2 and the spacing D1 of the adjacent grooves 30 must gradually decrease from the middle to the two side edges. Figure 1 This is a top view of the electrode, showing the current collector 20 exposed at the bottom of the groove 30.Figure 9 for Figure 1 The corresponding cross-sectional view.

[0069] Please refer to Figure 1 , Figure 1 The markers indicate the first direction and the second direction, which are typically perpendicular to each other.

[0070] The groove 30 extends continuously along the first direction;

[0071] And / or the groove 30 includes a plurality of spaced groove units in the first direction.

[0072] Please refer to the following: Figure 1 , Figure 5 and Figure 6 , Figure 1 The grooves 30 on the corresponding electrode are continuous in the first direction. Figure 5 The corresponding groove 30 on the electrode sheet includes multiple spaced groove units in the first direction. Figure 6 The corresponding electrode includes the two types of grooves 30 mentioned above. The continuous grooves 30 in the first direction are easy to groove and are beneficial to improving production efficiency. The grooves 30, which include multiple spaced groove units, have low structural damage to the electrode itself and can further increase the surface area of ​​the active coating 10. While improving the yield of finished products, they further alleviate stress expansion.

[0073] Furthermore, the groove unit includes at least one of a rectangular groove unit 32 and a circular groove unit 31.

[0074] You can refer to this. Figure 7 , Figure 7 The electrode sheet includes a groove 30 composed only of the rectangular groove unit 32, a groove 30 composed only of the circular groove unit 31, and a groove 30 composed of both the circular groove unit 31 and the rectangular groove unit 32. The above two types of groove units are easy to open. Of course, other shapes of groove units can also be selected. This utility model will not be described in detail here.

[0075] In a preferred embodiment, the groove 30 is an embossed roller groove, which is formed on the active coating 10 using a special roller. A corresponding protrusion is formed on the back of the active coating 10, and the protrusion is positioned opposite to the groove 30. During the fabrication of the embossed roller groove, a force in the opposite direction is applied to the electrode sheet, releasing the internal stress of the electrode sheet in advance. This prevents subsequent bending of the electrode sheet due to stress concentration, further improving the electrode sheet's anti-curling properties and reducing the probability of lithium plating.

[0076] In one specific embodiment, the groove 30 has a first end 30a and a second end 30b disposed opposite to each other in the first direction;

[0077] The first end portion 30a coincides with the first side portion 01;

[0078] And / or, the second end 30b coincides with the second side 02.

[0079] In another specific embodiment, there is a gap between the first end 30a and the first side 01, and a gap between the second end 30b and the second side 02.

[0080] Please refer to Figure 8 , Figure 8 The electrode sheet includes the positional relationship between the end of the groove 30 and the first side 01 and the second side 02. Of the first end 30a and the second end 30b of the groove 30, only one may coincide with the corresponding side, both may coincide with the corresponding side, or neither may coincide with the corresponding side. When the first end 30a coincides with the first side 01 and the second end 30b coincides with the second side 02, the groove 30 penetrates the electrode sheet in the first direction (i.e., the length direction of the electrode sheet). Besides being simple to manufacture, the groove 30 penetrating the electrode sheet is itself a rigid strip structure, preventing the electrode sheet from curling in the length direction. Of course, the groove 30 may not penetrate the electrode sheet in the first direction; this can be chosen according to actual needs, and this invention does not limit this choice.

[0081] In one specific embodiment, the groove 30 has a groove depth H2 in the third direction, and the active coating 10 has an active layer thickness H3 in the third direction;

[0082] The bottom surface of the groove 30 exposes the current collector 20, and H2 and H3 satisfy: H2>H3.

[0083] The third direction is the thickness direction of the electrode sheet, and it is typically perpendicular to the plane formed by the first and second directions. In other words, the groove 30 is not merely a groove formed on the active coating 10, but rather a groove that completely penetrates the active coating 10 and also forms a recessed structure on the current collector 20. Please refer to [reference needed] for details. Figure 9 .

[0084] In one specific embodiment, the electrode has a thickness H1 in the third direction, and the groove 30 has a groove depth H2 in the third direction;

[0085] H1 and H2 satisfy: 1 / 3 ≤ H2 / H1 ≤ 1.

[0086] To achieve a good anti-curling effect, the groove depth H2 of the groove 30 needs to be at least 1 / 3 of the thickness H1 of the electrode sheet. Of course, in some cases, the groove 30 can also completely penetrate the electrode sheet. The depth of the groove 30 needs to be determined according to the actual needs.

[0087] In addition, the sum of the groove widths W2 of the grooves 30 on the electrode is W2 sum W1 satisfies: 0.05 ≤ W2 sum / W1≤0.10;

[0088] W2 sum Obtained through the following formula (1):

[0089] ; (1)

[0090] Among them, W2 i Let W2 be the groove width corresponding to the i-th groove 30. The electrode includes a total of n grooves 30.

[0091] The W2 sum The ratio to W1 can be any one of 0.050, 0.097, or 0.100.

[0092] In addition, the groove width W2 satisfies: 0.5mm≤W2≤1.0mm; that is, the groove width W2 of the groove 30 can be any one of 0.50 mm, 0.77 mm or 1.00 mm.

[0093] The groove spacing D1 satisfies: 0.5mm≤D1≤3.0mm; that is, the groove spacing D1 between adjacent grooves 30 can be any one of 0.50 mm, 2.33 mm or 3.00 mm.

[0094] The electrode has a third side 03 and a fourth side 04 arranged opposite to each other along the second direction. The groove 30 closest to the third side 03 and the groove 30 closest to the fourth side 04 are both edge grooves 30B.

[0095] In the second direction, the intermediate groove 30A has a width W2. mid The intermediate groove 30A and the adjacent groove 30 have a distance D1 between them. mid The edge groove 30B has a width W2 side The edge groove 30B has a spacing D1 with the adjacent groove 30. side ;

[0096] W2 midSatisfies: 0.1mm≤W2 mid ≤0.2mm; that is, the groove width W2 of the intermediate groove 30A can be any one of 0.10mm, 0.11mm or 0.20mm;

[0097] W2 side Satisfies: 0.01mm≤W2 side ≤0.03mm; that is, the groove width W2 of the edge groove 30B can be any one of 0.010mm, 0.021mm or 0.030mm;

[0098] D1 mid Satisfies: 1.0mm≤D1 mid ≤3.0mm; that is, the distance between the middle groove 30A and the adjacent groove 30 can be any one of 1.00mm, 1.94mm or 3.00mm;

[0099] D1 side Satisfies: 0.1mm≤D1 side ≤1.0mm; that is, the distance between the edge groove 30B and the adjacent groove 30 can be any one of 0.10mm, 0.81mm or 1.00mm.

[0100] Please refer to Figure 10 , Figure 10 The third side 03 and the fourth side 04 are outlined with dashed lines. It should be noted that... Figure 10 The grooves 30 of the electrode described in the text are distributed with... Figure 1 The same, having two of the aforementioned intermediate grooves 30A, if the grooves 30 are distributed as follows Figure 5 or Figure 6 As shown, there will then be only one intermediate groove 30A.

[0101] The electrode provided by this utility model has grooves 30 on the active coating 10, which is equivalent to reserving space for stress release in advance. This avoids the pressure deformation of the electrode as a whole caused by local deformation during the stress release process, which greatly improves the bending of the electrode and avoids lithium deposition at the electrode position. Since the middle position of the electrode is most likely to accumulate stress and cause the electrode to bend during the stress release process, the groove width W2 and groove spacing D1 closer to the middle position are larger, which can further improve the anti-curling effect of the electrode and ultimately improve the battery performance.

[0102] Based on the first specific embodiment, the location of the groove 30 is further defined to obtain the second specific embodiment, the structural diagram of which is shown below. Figure 11 As shown, it includes a current collector 20 and an active coating 10 disposed on one side surface of the current collector 20.

[0103] The long axis of the electrode extends in a first direction, and the short axis of the electrode extends in a second direction.

[0104] The active coating 10 includes a plurality of grooves 30;

[0105] A single groove 30 extends in the first direction, and a plurality of grooves 30 are arranged in parallel along the second direction;

[0106] In the second direction, the groove 30 has a groove width W2, and there is a groove spacing D1 between adjacent grooves 30;

[0107] The groove width W2 gradually increases and then gradually decreases along the second direction;

[0108] And / or, the groove spacing D1 gradually increases and then gradually decreases along the second direction.

[0109] The electrode has a void region 40 at each end along the second direction;

[0110] The empty region 40 penetrates the electrode sheet along the first direction;

[0111] No groove 30 is provided in the empty area 40.

[0112] The difference between this specific embodiment and the above specific embodiment is that, in this specific embodiment, the groove 30 is not provided in the empty area 40 at both ends of the electrode in the second direction. The rest of the structure is the same as the above specific embodiment, and will not be described again here.

[0113] In this preferred embodiment, the groove 30 is only provided in the middle region of W1, while the groove 30 is not provided in the edge regions at both ends in the second direction (that is, the groove 30 is not provided in the empty area 40). As mentioned above, the main location where stress concentration causes the electrode sheet to curl is located in the middle region of the electrode sheet. Therefore, only the groove 30 needs to be provided in the middle region to have a certain anti-curling effect, and it can greatly simplify the production process and improve production efficiency. The empty area 40 has a width W3 in the second direction. Figure 11 The empty area 40 is outlined with a dashed line and marked with W3. The value of W3 needs to be determined according to the width of the electrode, such as 1 / 4 or 1 / 5 of W1, etc. It can be limited according to the actual situation, which will not be elaborated here.

[0114] This utility model also provides a battery, which includes an electrode sheet as described above. For specific technical details, please refer to the preceding description of the electrode sheet; these details will not be repeated here. This utility model creates grooves 30 on the active coating 10, effectively reserving space for stress release, thereby significantly improving the bending performance of the electrode sheet and preventing lithium deposition at the electrode location. Furthermore, since the center of the electrode sheet is most prone to stress accumulation and bending during stress release, the groove width W2 and groove spacing D1 are larger closer to the center, further enhancing the electrode sheet's anti-bending effect and ultimately improving battery performance.

[0115] The following describes the manufacturing processes of several battery cells, including:

[0116] Example 1

[0117] (1) Prepare positive electrode slurry with positive electrode active material lithium cobalt oxide: Prepare positive electrode slurry according to a certain batching process with a ratio of 96% positive electrode active material, 2.5% conductive agent and 1.5% binder. The slurry viscosity is 2000-7000 mPa.s and the solid content is 70%-80%.

[0118] (2) A negative electrode slurry is prepared using graphite as the active material. The negative electrode slurry is prepared according to a certain batching process with a ratio of 96.8% of negative electrode active material, 1.2% of conductive agent and 2% of binder. The slurry viscosity is 2000-5000 mPa.s and the solid content is 40%-50%.

[0119] (3) Coat the slurry prepared in (1) onto the positive electrode current collector 20. Dry the resulting slurry. The outermost electrode is etched using laser etching. The slurry on the positive electrode is etched to a depth of 1 / 3 of the electrode width, a width of 0.01 mm, and a spacing of 0.1 mm near the left edge of the electrode (i.e., the left edge groove in Table 1). The middle part of the electrode (i.e., the middle groove in Table 1) is etched to a depth of 1 / 3 of the electrode width, a width of 0.1 μm, and a spacing of 1 mm. The right edge of the electrode (i.e., the right edge groove in Table 1) is etched to a depth of 1 / 3 of the electrode width, a width of 0.01 mm, and a spacing of 0.1 mm. The main electrode is not etched. It should be noted that the left and right sides of the electrode are the two sides at both ends of the second direction, namely the third side 03 and the fourth side 04. Of course, which of the third side 03 and the fourth side 04 is the left and which is the right can be determined according to the actual situation, and this utility model does not limit it here.

[0120] After the positive and negative electrode sheets obtained above are rolled, die-cut and slit, they are assembled into cores by stacking. After passing the short-circuit test, they are packaged with aluminum-plastic film, baked in an oven to remove moisture until the moisture content reaches the required level for electrolyte injection, and then injected with electrolyte. After aging for 24-48 hours, the first charge is completed by hot pressing to obtain the activated battery cell.

[0121] Examples 2-3

[0122] Examples 2 and 3 were carried out in accordance with Example 1, except that the etching width and spacing at the edges and in the middle were different, as detailed in Table 1.

[0123] Comparative Example 1

[0124] Comparative Example 1 is a blank control group, that is, the electrode is not etched and there are no grooves on the electrode.

[0125] Comparative Example 2

[0126] Comparative Example 2 is carried out with reference to Example 1, except that the width of the edge groove and the middle groove are fixed values, and the distance between the edge groove and the adjacent groove, and the distance between the middle groove and the adjacent groove are also fixed values.

[0127] Comparative Example 3

[0128] Comparative Example 3 was carried out in accordance with Example 1, except that the groove width and groove spacing gradually increase from left to right along the second direction.

[0129] Comparative Example 4

[0130] Comparative Example 4 was carried out in accordance with Example 1, except that the groove width and groove spacing gradually decrease from left to right along the second direction.

[0131] The battery cells prepared in the above embodiments and comparative examples were charged at a 3C rate and discharged at a 1C rate for 800 cycles. After the cycles, they were dissected to observe the electrode curling and lithium deposition. The results are shown in Table 1.

[0132] Table 1

[0133] left side edge groove width W2 side ]]> Left side edge groove spacing D1 side ]]> intermediate groove width W2 mid ]]> Intermediate groove spacing D1 mid ]]> Right side edge groove width W2 side ]]> Right side edge groove interval D1 side ]] Whether or not curled Whether or not lithiumizes Example 1 0.01 mm 0.1 mm 0.1 mm 1 mm 0.01 mm 0.1 mm Not curled Does not lithiumize Example 2 0.03 mm 1 mm 0.2 mm 3 mm 0.03 mm 1 mm Not curled Does not lithiumize Example 3 0.02 mm 0.5 mm 0.15 mm 2 mm 0.02 mm 0.5 mm Not curled Does not lithiumize Comparative Example 1 / / / / / / Generally curled Severely lithiumizes Comparative Example 2 0.15 mm 0.1 mm 0.15 mm 0.1 mm 0.15 mm 0.1 mm Slightly curled Slightly lithiumizes Comparative Example 3 0.01 mm 0.1 mm 0.05 mm 0.5 mm 0.15 mm 1 mm Severely curled Severely lithiumizes Comparative Example 4 0.2 mm 3 mm 0.1 mm 1.5 mm 0.01 mm 0.5 mm Severely curled Severely lithiumizes

[0134] As can be seen from Comparative Examples 1-2, when grooves are made on the active layer of the positive electrode, the bending degree and lithium plating degree of the electrode can be alleviated. This is because making grooves on the active layer reserves space for stress release in advance, thereby avoiding the pressure deformation of the electrode as a whole caused by local deformation during the stress release process.

[0135] As can be seen from Comparative Examples 3-4 and 2, the groove width / groove spacing gradually increases / decreases from left to right. This leads to severe curling and lithium plating on the electrode. This is because the unidirectional change in groove width and groove spacing disrupts the symmetry of the electrode itself, further damaging the uniformity of stress distribution on the electrode surface, and causing more severe curling and lithium plating.

[0136] The test results of Examples 1-3 and Comparative Examples 2-4 show that when the groove width and groove spacing on the positive electrode sheet meet the arrangement characteristics of "larger in the middle and smaller at both ends", the electrode sheet curling and lithium plating can be effectively avoided. This is because the middle position of the electrode sheet is the easiest place to accumulate stress and cause the electrode sheet to bend. The groove width and groove spacing of this invention meet the arrangement characteristics of "larger in the middle and smaller at both ends", which does not affect the uniformity of stress distribution on the electrode sheet surface, and at the same time provides additional space for stress release, effectively avoiding local deformation of the electrode sheet. In terms of effect, better anti-curling and anti-lithium plating effects can be obtained.

[0137] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0138] It should be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0139] The electrodes and battery provided by this utility model have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this utility model. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this utility model. It should be noted that those skilled in the art can make several improvements and modifications to this utility model without departing from the principles of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

Claims

1. A pole piece characterized by, The electrode plate comprises a current collector and an active coating layer disposed on a single side surface of the current collector; The long axis of the electrode plate extends in a first direction, and the short axis of the electrode plate extends in a second direction; The active coating layer comprises a plurality of grooves; The single groove extends in the first direction, and the plurality of grooves are arranged in parallel along the second direction; In the second direction, the groove has a groove width, and the adjacent grooves have a groove spacing; The groove width gradually increases and then gradually decreases along the second direction; And / or, the groove spacing gradually increases and then gradually decreases along the second direction.

2. The pole piece of claim 1, wherein The electrode plate has a first side edge and a second side edge arranged oppositely in the first direction, and the first side edge and the second side edge have a middle position; In the second direction, the groove closest to the middle position is a middle groove, the middle groove has the largest groove width, and the groove spacing between adjacent grooves is the largest.

3. The pole piece of claim 1, wherein The groove is a continuous groove in the first direction; And / or, the groove comprises a plurality of groove units arranged at intervals in the first direction.

4. The pole piece of claim 3, wherein The groove unit comprises at least one of a rectangular groove unit and a circular groove unit.

5. The pole piece of claim 1, wherein The groove is an embossing roller groove.

6. The pole piece of claim 2, wherein The groove has a first end and a second end arranged oppositely in the first direction; The first end coincides with the first side edge; And / or, the second end coincides with the second side edge.

7. The pole piece of claim 2, wherein The groove has a first end and a second end arranged oppositely in the first direction; The first end has a gap with the first side edge, and the second end has a gap with the second side edge.

8. The pole piece of claim 1, wherein The electrode plate has a thickness H1 in a third direction, and the groove has a groove depth H2 in the third direction; H1 and H2 satisfy: 1 / 3≤H2 / H1≤1.

9. The pole piece of claim 1, wherein The groove has a groove depth H2 in the third direction, and the active coating layer has an active layer thickness H3 in the third direction; The bottom surface of the groove exposes the current collector, and H2 and H3 satisfy: H2>H3.

10. The pole piece of claim 1, wherein The pole piece has a width W1 in the second direction, and the sum W2 of the slot widths of the slots sum W1 satisfies: 0.05 ≤ W2 sum / W1 ≤ 0.

10.

11. The pole piece of claim 1, wherein The groove width W2 satisfies: 0.5mm≤W2≤1.0mm; and / or, the groove spacing D1 satisfies: 0.5mm≤D1≤3.0mm.

12. The pole piece of claim 2, wherein The electrode plate has a third side edge and a fourth side edge arranged oppositely in the second direction, and the groove closest to the third side edge and the groove closest to the fourth side edge are both edge grooves; In the second direction, the intermediate grooves have a width W2 mid , the intermediate grooves have a spacing D1 mid between adjacent grooves, the edge grooves have a width W2 side , the edge grooves have a spacing D1 side between adjacent grooves; W2 mid satisfies: 0.1 mm ≤ W2 mid ≤ 0.2 mm; and / or, W2 side satisfies: 0.01 mm ≤ W2 side ≤ 0.03 mm; and / or, D1 mid satisfies: 1.0 mm ≤ D1 mid ≤ 3.0 mm; and / or, D1 side satisfies: 0.1 mm ≤ D1 side ≤ 1.0 mm.

13. The pole piece of any one of claims 1 to 12, wherein, The electrode plate is provided with an empty area at each end in the second direction; The empty area penetrates the electrode plate in the first direction; The groove is not arranged in the empty area.

14. A battery, characterized by The battery comprises the electrode plate according to any one of claims 1 to 13.

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