Electrode sheet, battery, and electronic device

Abstract

The present application provides an electrode sheet, a battery, and an electronic device. The electrode sheet comprises a current collector and an active layer arranged on at least one side of the current collector. The active layer has L grooves extending in a first direction. In the first direction, each groove has N first recesses, a second recess is formed between every two adjacent first recesses, and the depth of the second recess is greater than that of the first recesses, wherein L≥1 and N≥2. When the electrode sheet is applied to a battery, the electrolyte infiltration rate and the electrolyte infiltration consistency of a battery cell can be improved, thereby avoiding lithium precipitation during a charge-discharge cycle of the battery, facilitating the diffusion of lithium ions, and improving the rate capability of the battery.

Description

An electrode, a battery, and an electronic device

[0001] This application claims priority to Chinese Patent Application No. 202422665268.9, filed on October 31, 2024, entitled “An Electrode, a Battery and an Electronic Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to an electrode, a battery, and an electronic device, belonging to the field of new energy technology. Background Technology

[0003] Figure 1 is a top view of a battery in the prior art, and Figure 2 is a side view of an electrode in the prior art. As shown in Figures 1 and 2, the battery mainly includes a positive electrode 1 and a negative electrode 2 stacked together. The electrode (positive electrode 1 or negative electrode 2) includes a current collector 4 and an active layer 3 located on at least one surface of the current collector 4. Currently, the battery capacity is mainly improved by increasing the size of the electrode and increasing the areal density of the active layer 3. However, with the increase of electrode size and areal density, on the one hand, the electrolyte wetting speed of the cell is easily reduced, and the electrolyte wetting consistency of the cell deteriorates. As a result, during the charge and discharge cycle of the battery, lithium plating is likely to occur in the middle position of the cell. On the other hand, it is not conducive to the diffusion of lithium ions, thus affecting the rate performance of the battery. Summary of the Invention

[0004] This application provides an electrode that, when applied to a battery, can improve the electrolyte wetting speed and consistency of the battery cell, prevent lithium deposition during charge-discharge cycles, and promote lithium ion diffusion, thereby improving the battery's cycle performance and rate performance.

[0005] This application provides a battery with excellent cycle performance and rate performance.

[0006] This application provides an electrical device whose driving source or energy storage source is the aforementioned battery. Therefore, the electronic device has excellent fast charging performance, battery life, and longevity, and has broad market application prospects.

[0007] This application provides an electrode, the electrode comprising a current collector and an active layer disposed on at least one side of the current collector;

[0008] The active layer has L grooves extending along a first direction. In the first direction, each groove has N first recesses, and a second recess is formed between two adjacent first recesses. The depth of the second recess is greater than the depth of the first recess, where L≥1 and N≥2.

[0009] The electrode as described above, wherein the dimension of the electrode in the first direction is ≥50mm.

[0010] The electrode as described above, wherein the ratio of the depth to the width of the first recess is ≥0.1.

[0011] As described above, in the first direction, the extension dimension L of the Mth first recess is... m The extension dimension L of the second recess between the (M+1)th first recess and the Mth first recess. m m+1 satisfy:

[0012] L m m+1 ≤0.2*L m M+1≤N.

[0013] The electrode as described above, wherein L m m+1 It ranges from 5μm to 1cm.

[0014] As described above, in the electrode, the depth h of the Mth first recess is... m The depth h of the second recess between the (M+1)th first recess and the Mth first recess m m+1 satisfy:

[0015] h m m+1 =1.4h m ~2.2h m M+1≤N.

[0016] In the electrode sheet described above, the ratio of the depth of the first recess to the thickness of the active layer is 1 / 9 to 1 / 2.

[0017] The electrode as described above, wherein the groove has a dimension of 1-200 μm in the second direction, and the second direction is perpendicular to the first direction; and / or,

[0018] When L > 1, the L grooves are parallel to each other, and in the second direction, the distance between two adjacent grooves is 80-5000 μm, and the second direction is perpendicular to the first direction.

[0019] In the electrode sheet described above, the opening end of the groove has a dimension of W in the second direction, and the bottom end opposite to the opening end has a dimension of W' in the second direction, where W ≥ W', and the second direction is perpendicular to the first direction; or,

[0020] On a cross-section extending along the second direction, the groove is V-shaped, and the second direction is perpendicular to the first direction.

[0021] In the electrode as described above, the volume of the groove accounts for 0.1-5% of the total volume of the active layer and the groove.

[0022] This application also provides a battery comprising the electrode sheet described in any of the above claims.

[0023] This application also provides an electrical device, wherein the driving source or energy storage source of the electrical device is the battery described above.

[0024] The electrode of this application has a special structure, which has excellent electrolyte wettability and lithium-ion diffusion performance. When applied to batteries, it can improve the cycle performance and rate performance of the batteries.

[0025] The battery of this application, due to including the aforementioned electrode, has excellent cycle performance and rate performance, and is suitable for widespread application.

[0026] This application provides an electrical device whose driving source or energy storage source is the aforementioned battery. Therefore, the electrical device has excellent fast charging performance, battery life, and longevity, and has broad market application prospects. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the accompanying drawings used in the description of the embodiments of this application or related technologies are briefly introduced below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 is a top view of a battery in the prior art;

[0029] Figure 2 is a side view of an electrode sheet in the prior art;

[0030] Figure 3 is a top view of the battery in some embodiments of this application;

[0031] Figure 4 is a top view of the battery in some other embodiments of this application;

[0032] Figure 5 is a side view of the electrode sheet in some embodiments of this application;

[0033] Figure 6 is a side view of the electrode sheet in another embodiment of this application;

[0034] Figure 7 is a top view of the groove in some embodiments of this application;

[0035] Figure 8 is a magnified view of a portion of Figure 7;

[0036] Figure 9 is a side view of the groove in some embodiments of this application.

[0037] Explanation of reference numerals in the attached drawings: 1: Positive electrode; 2: Negative electrode; 3: Active layer; 4: Current collector; 31: Groove; 311: First recess; 312: Second recess. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] Figure 3 is a top view of a battery in some embodiments of this application; Figure 4 is a top view of a battery in other embodiments of this application; Figure 5 is a side view of an electrode in some embodiments of this application; Figure 6 is a side view of an electrode in another embodiment of this application; Figure 7 is a top view of a groove in some embodiments of this application; Figure 8 is a partial enlarged view of Figure 7; Figure 9 is a side view of a groove in some embodiments of this application. As shown in Figures 3-9, a first aspect of this application provides an electrode, which includes a current collector 4 and an active layer 3 disposed on at least one side of the current collector 4;

[0040] The active layer 3 has L grooves 31 extending along a first direction. In the first direction, the grooves 31 have N first recesses 311. A second recess 312 is provided between two adjacent first recesses 311. The depth of the second recess is greater than the depth of the first recess, L≥1, N≥2.

[0041] It is understood that in this application, an active layer 3 can be formed on one surface of the current collector 4 to form an electrode, or an active layer 3 can be formed on both surfaces of the current collector 4 to form an electrode.

[0042] This application does not specifically limit the first direction; the first direction can be any direction. For example, the first direction can be the length direction of the current collector 4, the width direction of the current collector 4, or the diagonal direction of the current collector 4. As shown in Figure 3, the first direction is the width direction of the current collector 4, and the active layer 3 has L grooves 31 extending along the width direction of the current collector 4. As shown in Figures 4, 7, and 8, the first direction is the length direction of the current collector 4, and the active layer 3 has L grooves 31 extending along the length direction of the current collector 4. In this application, depth refers to the extension dimension of the first recess 311 or the second recess 312 in the thickness direction of the current collector 4 (the z-direction in the figures).

[0043] In this application, when the two surfaces of the current collector 4 are respectively provided with active layers 3, as shown in Figure 5, a groove 31 can be provided in one active layer 3, as shown in Figure 6, or grooves 31 can be provided in two active layers 3 respectively.

[0044] In this application, N first recesses and N-1 second recesses are alternately arranged to form a groove. The structure of the groove 31 is specifically described below, taking the length direction of the current collector 4 as an example (x-direction in the figures). As shown in Figures 7 and 8, in the first direction, the groove 31 includes N first recesses 311, and a second recess 312 is provided between any two adjacent first recesses 311, the depth of the second recess being greater than the depth of the first recess. For example, the tail of the first first recess 311 and the head of the second first recess 311 are connected by the second recess 312 to form a groove, the depth of the second recess 312 being greater than the depth of the first recess 311.

[0045] In the electrode of this application, the active layer 3 has grooves 31. These grooves 31 increase the porosity and reduce the tortuosity of the active layer 3. When applied to a battery, this electrode can more quickly and fully immerse itself in the electrolyte, promoting rapid lithium-ion transport and thus improving the battery's cycle performance and rate performance. Simultaneously, the grooves 31 of this application include N first recesses 311 connected sequentially by second recesses 312. These grooves 31 have excellent structural consistency, allowing the electrode to fully utilize their function when applied to a battery, resulting in superior cycle performance and rate performance. Furthermore, the depth of the second recesses 312 in this application is greater than the depth of the first recesses 311. The second recesses 312 can further store electrolyte and provide channels for lithium-ion transport, further improving the battery's cycle performance and rate performance.

[0046] This application does not limit the formation method of the groove 31. In some embodiments, the active layer 3 can be formed into the groove 31 by at least one of the following processing methods: mechanical mold processing, laser etching, and solvent etching. When using laser etching, this application forms a groove in which the area of ​​the subsequent laser processing overlaps with the area of ​​the previous laser processing, including the alternating arrangement of the first groove 311 and the second groove 312; wherein, the overlap between the area of ​​the subsequent laser processing and the area of ​​the previous laser processing forms the second groove 312, and the area of ​​the subsequent laser processing or the area of ​​the previous laser processing forms the first groove 311. Since the second groove 312 is formed by two laser processing operations, the depth of the second groove 312 is greater than the depth of the first groove 311. It is understood that, compared with other processing methods, laser etching equipment has greater controllability, lower maintenance frequency, and longer service life.

[0047] When the electrode is a large-sized electrode, for example, when the size of the electrode in the first direction is ≥50mm, the groove 31 can be set by laser. In this case, the processing yield is higher and it is more conducive to the industrial production of large electrodes.

[0048] To allow the electrolyte to wet the electrode plates more thoroughly and improve the battery's cycle performance and rate capability, the depth-to-width ratio of the first recess 311 can be controlled. Specifically, the depth-to-width ratio of the first recess 311 is ≥0.1. Further, the depth-to-width ratio of the first recess 311 is 0.2 to 0.5. Here, the width of the first recess 311 refers to its maximum dimension in the second direction.

[0049] The second direction is perpendicular to the first direction. It can be understood that when the first direction is the length direction of the current collector 4, the second direction is the width direction of the current collector 4; when the first direction is the width direction of the current collector 4, the second direction is the length direction of the current collector. As shown in Figures 7 and 9, the first direction is the length direction (x-direction) of the current collector 4, and the second direction is the width direction (y-direction) of the current collector 4.

[0050] In this application, the dimensions of the first recess 311 and the second recess 312 in the groove 31 can be further selected so that the first recess 311 and the second recess 312 can be better combined to form a groove 31 with a more stable structure, thereby improving the cycle performance and rate performance of the battery.

[0051] In some embodiments of this application, taking a 400mm*400mm processing area as an example, in the first direction, the extension dimension L of the Mth first recess 311 is... m The extension dimension L of the second recess 312 between the (M+1)th first recess 311 and the Mth first recess 311 m m+1 satisfy:

[0052] L m m+1 ≤0.2*L m M+1≤N.

[0053] For example, when M is 1, the extension dimension L of the second recess 312 between the second first recess 311 and the first first recess 311 in the first direction is... 12 ≤0.2L1. This application does not limit the dimensions of the first recesses 311 on both sides of the second recess 312; their dimensions or depths in the first direction may be different from or the same as each other. Further, L m m+1 ≤0.1*L m .

[0054] In one specific implementation, when L m m+1With a thickness of 5μm to 1cm, it can ensure higher energy density of the battery while improving its cycle performance and rate performance.

[0055] Furthermore, the depth h of the Mth first recess 311 m The depth h of the second recess 312 between the (M+1)th first recess 311 and the Mth first recess 311 m m+1 satisfy:

[0056] h m m+1 =1.4h m ~2.2h m M+1≤N.

[0057] For example, when M is 1, the depth h of the second recess 312 between the second first recess 311 and the first first recess 311 is... 12 =1.4h1~2.2h1.

[0058] In some embodiments of this application, when the ratio of the depth of the first recess 311 to the thickness of the active layer is 1 / 9 to 1 / 2, the electrolyte wetting performance and lithium-ion transport performance of the active layer 3 can be sufficiently improved while ensuring the energy density of the battery, thereby improving the cycle performance and rate performance of the battery. Further, the ratio of the depth of the first recess 311 to the thickness of the active layer is 1 / 4 to 1 / 2.

[0059] In some embodiments of this application, the groove 31 has a dimension of 1-200 μm in the second direction. Further, the groove 31 has a dimension of 30-180 μm in the second direction. As mentioned above, the second direction is perpendicular to the first direction.

[0060] In this application, the extension dimension of the groove 31 in the second direction refers to the maximum dimension W of the groove 31 extending in the second direction. When the extension dimension of the groove 31 in the second direction satisfies the above relationship, the electrolyte wettability and ion transport of the active layer 3 can be further improved without affecting the charge and discharge performance of the active layer 3, thus obtaining a battery with excellent capacity, cycle performance and rate performance.

[0061] Furthermore, as shown in Figure 7, when L > 1, the L grooves 31 are parallel to each other, and in the second direction perpendicular to the first direction, the distance between two adjacent grooves 31 is 80-5000 μm.

[0062] In this application, when the active layer 3 includes multiple grooves 31, the multiple grooves 31 are parallel to each other. The distance between two adjacent grooves refers to the distance d between the center lines of two adjacent grooves 31, where the direction of the extension of the center line is the direction in which the length of the groove 31 lies. When d meets the above-mentioned range, the grooves 31 on the active layer 3 can be more uniformly distributed, which can improve the cycle performance and rate performance of the battery while ensuring the battery capacity. Furthermore, when d is 500-3000 μm, the cycle performance and rate performance of the battery are even better.

[0063] As shown in Figure 9, in some embodiments of this application, the bottom of the groove 31 has a dimension of W' in the second direction, and the opening end of the groove 31 has a dimension of W in the second direction, wherein the second direction is perpendicular to the first direction, and W ≥ W'.

[0064] That is, the shape of the groove 31 is such that the opening end is larger than the bottom end, or the opening end and the bottom end are the same size.

[0065] In some embodiments of this application, the groove 31 is V-shaped in cross-section extending along the second direction, wherein the second direction is perpendicular to the first direction. That is, the opening end of the groove 31 is larger than the bottom end, and the groove 31 is V-shaped.

[0066] In this application, when the groove 31 is shaped with a larger top and a smaller bottom, or when the top and bottom are the same size, it can absorb electrolyte more quickly, improve the electrolyte wettability and ion transport performance of the active layer 3, and thus improve the cycle performance and rate performance of the battery.

[0067] In some embodiments of this application, when the volume of the groove accounts for 0.1-5% of the total volume of the active layer and the groove, the active layer has more suitable porosity and tortuosity. When this electrode is applied to a battery, it can be more quickly and fully immersed in the electrolyte, promoting rapid lithium-ion transport and thus improving the battery's cycle performance and rate performance. Further, the volume of the groove accounts for 0.5-5% of the total volume of the active layer and the groove, and even more specifically, 1-5%.

[0068] The electrode in this application can be either a positive electrode or a negative electrode.

[0069] When the electrode is a positive electrode, the positive electrode 1 includes a positive current collector and a positive active layer located on at least one surface of the positive current collector.

[0070] This application does not specifically limit the positive electrode current collector, and it can be any positive electrode current collector commonly used in the art. For example, the positive electrode current collector can be aluminum foil. The positive electrode active layer includes a positive electrode active material, a conductive agent, and a binder. This application does not specifically limit the positive electrode active material, and it can be any positive electrode active material commonly used in the art. For example, the positive electrode active material can be LiFePO4, Li3V2(PO4)3, LiMn2O4, LiMnO2, LiNiO2, LiCoO2, LiVPO4F, LiFeO2, etc. Meanwhile, the conductive agent and binder can also be materials commonly used in the art. For example, the conductive agent can be selected from at least one of acetylene black, conductive carbon black, and conductive graphite, and the binder can be selected from at least one of fluorinated resins or polyolefin compounds, such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and styrene-butadiene rubber (SBR). Based on the mass of the positive electrode active material, the content of the conductive agent is 0.5-15 wt%, further 1-10 wt%, and the content of the binder is 0.01-10 wt%, further 0.02-5 wt%.

[0071] In some embodiments, a positive electrode active material, a conductive agent, and a binder can be formed into a positive electrode slurry. The positive electrode slurry is then coated onto at least one surface of an aluminum foil, and the foil is baked and rolled to form a positive electrode sheet roll with a certain compaction density. The positive electrode active layer is then processed to form a groove 31 to obtain the positive electrode sheet 1.

[0072] Among them, a groove 31 can be formed on the positive electrode active layer by laser etching. By controlling the laser energy, pulse width, dust removal wind speed and processing frequency, the positive electrode active layer is formed into the groove 31. The laser performs synchronous processing with the winding and unwinding speed of the positive electrode roll, and a positive electrode sheet 1 including the groove 31 is obtained. During the formation of the groove 31, dust can be removed by a dust removal fan.

[0073] When the electrode is a negative electrode 2, the negative electrode 2 includes a negative current collector and a negative active layer located on at least one surface of the negative current collector.

[0074] This application does not specifically limit the negative electrode current collector, and it can be any negative electrode current collector commonly used in the art. For example, the negative electrode current collector can be copper foil. The negative electrode active layer of this application includes a negative electrode active material, a conductive agent, and a binder. This application does not specifically limit the negative electrode active material, and it can be any negative electrode active material commonly used in the art. For example, the negative electrode active material can be at least one of artificial graphite, natural graphite, mesophase carbon microspheres, hard carbon, soft carbon, silicon, silicon oxide, silicon carbon, and silicon alloys, wherein the particle size of the negative electrode active material is 5μm-50μm. Simultaneously, the conductive agent and binder can also be materials commonly used in the art. For example, the conductive agent can be selected from at least one of conductive carbon black, nickel powder, copper powder, etc., and the binder can be selected from at least one of polyvinyl fluoride, polyvinyl chloride, or styrene-butadiene rubber. Based on the mass of the negative electrode active material, the content of the conductive agent is 1-4wt%, and the content of the binder is 2-6wt%. Furthermore, the negative electrode active layer may also include a pore-forming agent. In some embodiments, when the negative electrode active material is a graphite system (artificial graphite and / or natural graphite), the porosity of the negative electrode active layer without grooves can be 20-40%; when the negative electrode active material is a silicon negative electrode system (at least one of silicon, silicon oxide, silicon carbon, and silicon alloy), the porosity of the negative electrode active layer without grooves can be 60-70%.

[0075] In some embodiments, a negative electrode active material, a conductive agent, and a binder can be formed into a negative electrode slurry. The negative electrode slurry is then coated onto at least one surface of a copper foil, and the negative electrode sheet roll is formed by baking and rolling to form a negative electrode active layer with a certain compaction density. The negative electrode active layer is then processed to form a groove 31 to obtain a negative electrode sheet 2.

[0076] Among them, grooves 31 can be formed on the negative electrode active layer by laser etching. By controlling the laser energy, pulse width, dust removal wind speed and processing frequency, grooves 31 are formed on the negative and positive electrode active layers. The laser performs synchronous processing with the winding and unwinding speed of the positive electrode roll, and a negative electrode sheet 2 including the grooves 31 is obtained. During the formation of grooves 31, dust can be removed by a dust removal fan.

[0077] A second aspect of this application provides a battery, wherein the electrode of the first aspect is included.

[0078] It is understood that in the battery of this application, at least one of the positive electrode 1 and the negative electrode 2 is the electrode of the first aspect. The battery of this application also includes an electrolyte, a separator, and an outer packaging. In this application, the positive electrode 1, the separator, and the negative electrode 2 can be stacked to form a cell with a stacked structure, and then the cell is placed in an outer packaging, electrolyte is injected into the outer packaging, and after sealing and formation, a battery is formed; alternatively, the positive electrode 1, the separator, and the negative electrode 2 can be stacked and then wound to form a cell with a wound structure, and then the cell is placed in an outer packaging, electrolyte is injected into the outer packaging, and after sealing and formation, a battery is formed.

[0079] In some implementations, hot pressing at 90°C can be performed during the formation of the battery cell.

[0080] The electrolyte is a mixed solution of lithium electrolyte and organic solvent. This application does not specifically limit the electrolyte; it can be any electrolyte commonly used in the art. In some embodiments, the lithium electrolyte is selected from one or more of lithium hexafluorophosphate (LiPF6), lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium halides, lithium chloroaluminate, and lithium fluorocarbon sulfonate. The organic solvent is a mixed solution of chain esters and cyclic esters. The chain ester can be at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), methyl propyl carbonate (MPC), dipropyl carbonate (DPC), and other fluorine-containing, sulfur-containing, or unsaturated chain organic esters. The cyclic ester can be at least one of ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), γ-butyrolactone (γ-BL), sulpholactone, and other fluorine-containing, sulfur-containing, or unsaturated cyclic organic esters. The injection volume of electrolyte is generally 1.5-4.9 g / Ah, and the concentration of electrolyte is generally 0.1-2.0 mol / L.

[0081] The battery of this application has excellent capacity, cycle performance and rate performance because at least one of the positive electrode 1 and the negative electrode 2 is a first-side electrode.

[0082] A third aspect of this application provides an electrical device, wherein the driving source or energy storage source of the electrical device is the battery of the second aspect.

[0083] In some implementations, the electrical device can be any device that uses a secondary battery as a power source or energy storage source, such as a mobile phone, a navigator, a drone, or an electric vehicle.

[0084] Since the power source or energy storage source of the electrical device in this application is a battery, the electronic device has excellent fast charging performance and battery life, and has broad market application prospects.

[0085] The solution of this application will be described in detail below through specific embodiments.

[0086] Example 1

[0087] The battery in this embodiment is prepared by a method including the following steps:

[0088] 1) Preparation of positive electrode sheet

[0089] The positive electrode includes an aluminum foil and a positive electrode active layer located on two surfaces of the aluminum foil, each with a thickness of 12 μm.

[0090] The positive electrode active layer comprises lithium iron phosphate as the positive electrode active material, conductive carbon black as the conductive agent, and polyvinylidene fluoride as the binder, with a mass ratio of 100:5:3.5; the thickness of the positive electrode active layer is 80 μm.

[0091] The positive electrode active layer has 800 grooves extending along the width direction of the positive electrode current collector. The 800 grooves are parallel to each other. In the width direction of the positive electrode current collector, each groove has 3 first recesses and a second recess between two adjacent first recesses.

[0092] Other parameters of the positive electrode active layer are shown in Table 1. In Table 1, L1 is the dimension of each first recess in the length direction, L... 12 Let h1 be the dimension of each second recess in the length direction, and h1 be the depth of each first recess. 12 The depth of each first recess, d is the dimension of two adjacent recesses in the width direction, W is the dimension of the opening end of the recess in the second direction, W' is the dimension of the bottom end of the recess in the second direction, and V% is the percentage of the volume of the recess in the total volume of the active layer and the recess.

[0093] 2) Preparation of negative electrode sheet

[0094] The negative electrode sheet includes a copper foil and negative electrode active layers located on two surfaces of the copper foil, each with a thickness of 6 μm.

[0095] The negative electrode active layer comprises graphite, conductive carbon black, carboxymethyl cellulose, styrene-butadiene rubber, and pore-forming agent azodicarbonamide, with a mass ratio of 100:2:2:4:3; the thickness of the negative electrode active layer is 70 μm.

[0096] 3) Battery manufacturing

[0097] In a glove box, positive electrode, separator and negative electrode are stacked to obtain electrode assembly. The electrode assembly is placed in aluminum-plastic film, electrolyte is injected into aluminum-plastic film, and after sealing and formation, battery is obtained.

[0098] Examples 2 to 5

[0099] Examples 2 to 5 are basically the same as Example 1, with the differences shown in Table 1.

[0100] Example 6

[0101] The battery in this embodiment is prepared by a method including the following steps:

[0102] 1) Preparation of negative electrode sheet

[0103] The negative electrode sheet includes a copper foil and negative electrode active layers located on two surfaces of the copper foil, each with a thickness of 6 μm.

[0104] The negative electrode active layer comprises graphite, conductive carbon black, carboxymethyl cellulose, styrene-butadiene rubber, and pore-forming agent azodicarbonamide, with a mass ratio of 100:2:2:4:3; the thickness of the negative electrode active layer is 70 μm.

[0105] The positive electrode active layer is processed by laser etching, so that the negative electrode active layer has 800 grooves extending along the width direction of the negative electrode current collector. The 800 grooves are parallel to each other. In the width direction of the negative electrode current collector, the groove has 3 first recesses and a second recess between two adjacent first recesses.

[0106] Other parameters of the negative electrode active layer are shown in Table 1.

[0107] 2) Preparation of positive electrode sheet

[0108] The positive electrode includes an aluminum foil and a positive electrode active layer located on two surfaces of the aluminum foil, each with a thickness of 12 μm.

[0109] The positive electrode active layer includes lithium iron phosphate as the positive electrode active material, conductive carbon black as the conductive agent, and polyvinylidene fluoride as the binder, with a mass ratio of 100:5:3.5; the thickness of the positive electrode active layer is 80μm.

[0110] 3) Battery manufacturing

[0111] In a glove box, positive electrode, separator and negative electrode are stacked to obtain electrode assembly. The electrode assembly is placed in aluminum-plastic film, electrolyte is injected into aluminum-plastic film, and after sealing and formation, battery is obtained.

[0112] Examples 7 to 8

[0113] Examples 7 and 8 are basically the same as Example 6, with the differences shown in Table 1.

[0114] Example 9

[0115] Example 9 is basically the same as Example 5, with the differences shown in Table 1.

[0116] Examples 10-13

[0117] Examples 10-13 are basically the same as Example 8, with the differences shown in Table 1.

[0118] Example 14

[0119] Example 14 is basically the same as Example 1, with the differences shown in Table 1.

[0120] Comparative Example 1

[0121] The preparation method of the battery in this comparative example is basically the same as that in Example 1, except that the positive electrode does not have a groove.

[0122] Table 1

[0123] Performance testing

[0124] The following performance tests were performed on the batteries in the examples and comparative examples respectively, and the changes of the other examples and comparative examples relative to comparative example 1 were calculated based on the test results of comparative example 1. The results are shown in Table 2.

[0125] 1. Liquid-phase diffusion impedance (Impedance measurement: an electrochemical measurement method that applies a sinusoidal AC signal to the electrodes of a lithium-ion battery electrolyte and uses impedance spectroscopy analysis to infer the battery's electrical characteristics. Accurate values ​​are obtained through multiple impedance measurements within a specific frequency range.)

[0126] 2. DCIR (Measurement method: Battery at 50% SOC, discharged at 1.5C for 30s, calculate R = ΔV / I)

[0127] 3. 10C Rate Discharge Capacity Ratio (The ratio of the actual capacity discharged by the battery under a 10C high-rate discharge condition to the battery's rated capacity. Connect the battery to a discharge tester, set the discharge rate to 10C, start the discharge test, record parameters such as voltage, current, and temperature during the discharge process, and calculate the capacity. Battery capacity = discharge current * discharge time)

[0128] Table 2

[0129] As shown in Table 2, the electrode in this application helps to improve the cycle performance and rate performance of the battery.

[0130] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An electrode sheet, characterized in that, The electrode includes a current collector (4) and an active layer (3) disposed on at least one side of the current collector (4); The active layer (3) has L grooves (31) extending along a first direction. In the first direction, the grooves (31) have N first recesses (311), and there is a second recess (312) between two adjacent first recesses (311). The depth of the second recess (312) is greater than the depth of the first recess (311), L≥1, N≥2.

2. The electrode sheet according to claim 1, characterized in that, The electrode sheet has a dimension ≥ 50 mm in the first direction.

3. The electrode sheet according to claim 1 or 2, characterized in that, The ratio of the depth to the width of the first recess (311) is ≥0.

1.

4. The electrode sheet according to claim 1 or 2, characterized in that, In the first direction, the extension dimension L of the Mth first recess (311) m The extension dimension L of the second recess (312) between the (M+1)th first recess (311) and the Mth first recess (311) mm+1 Satisfy: L mm+1 ≤0.2*L m M+1≤N.

5. The electrode sheet according to claim 4, characterized in that, L mm+1 It ranges from 5μm to 1cm.

6. The electrode sheet according to claim 1 or 2, characterized in that, The depth h of the Mth first recess (311) m The depth h of the second recess (312) between the (M+1)th first recess (311) and the Mth first recess (311) mm+1 Satisfy: h mm+1 =1.4h m ~2.2h m M+1≤N.

7. The electrode sheet according to claim 1 or 2, characterized in that, The ratio of the depth of the first recess (311) to the thickness of the active layer (3) is 1 / 9 to 1 / 2.

8. The electrode sheet according to claim 1 or 2, characterized in that, The groove (31) has a dimension of 1-200 μm in the second direction, which is perpendicular to the first direction; and / or, When L > 1, the L grooves (31) are parallel to each other, and in the second direction, the distance between two adjacent grooves (31) is 80-5000 μm, and the second direction is perpendicular to the first direction.

9. The electrode sheet according to claim 1 or 2, characterized in that, The opening end of the groove (31) has a dimension of W in the second direction, and the bottom end opposite to the opening end has a dimension of W' in the second direction, wherein W ≥ W', and the second direction is perpendicular to the first direction; or, On a cross section extending along the second direction, the groove (31) is V-shaped, and the second direction is perpendicular to the first direction.

10. The electrode sheet according to claim 1 or 2, characterized in that, The volume of the groove (31) accounts for 0.1-5% of the total volume of the active layer (3) and the groove (31).

11. A battery, characterized in that, Includes the electrode sheet as described in any one of claims 1-10.

12. An electrical appliance, characterized in that, The power source or energy storage source of the electrical equipment is the battery as described in claim 11.

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