Electrode sheet structure of battery, battery, and preparation method for electrode sheet

Abstract

An electrode sheet of a battery. The electrode sheet comprises a metal layer (1), wherein an attenuated-transport layer (2) is provided at the edge of a first end of the metal layer (1); an active material layer (3) is provided on the surface of the attenuated-transport layer (2) away from the metal layer (1); and the resistivity of the attenuated-transport layer (2) is at least 1.1 to 2 times that of the active material layer (3). The attenuated-transport layer (2) disposed between the metal layer (1) and the active material layer (3) reduces the transport rate of electrons, suppresses the deintercalation rate of lithium ions, can solve safety problems such as lithium plating at the edge of the electrode sheet and excessive thickness at the head and tail of the electrode sheet, and ensures that lithium plating does not occur at the head and tail of the electrode sheet, thereby facilitating the improvement of the charging and discharging safety of a battery. In addition, further disclosed in the present invention are a preparation method for an electrode sheet, and a battery.

Description

A battery pole piece structure, battery and pole piece preparation method Technical Field

[0001] The present invention belongs to the technical field of batteries, and in particular relates to a battery pole piece structure, a battery and a method for preparing the pole piece. Background Art

[0002] Because the head and tail of existing lithium-ion batteries are close to the edge of the battery, when the battery kinetic window is insufficient or the process affects the interface between the cathode and anode and the separator, the edge effect of the battery will affect the rate of lithium ion insertion and extraction at the edge of the battery cell and the main part. As a result, lithium ions are easily deposited at the edge of the electrode, causing lithium deposition at the edge of the battery electrode, and causing the head and tail of the battery cell to be too thick, which in turn causes performance failure and safety risks of the battery cell. In the existing technology, there are currently no effective improvement measures in the industry for this anomaly. It can be seen that how to ensure that the battery electrode structure has sufficient safety has become one of the important difficulties in battery structure design. Therefore, it is urgent to propose a new technical solution to solve the above problems.

[0003] Summary of the Invention

[0004] One of the purposes of the present invention is to address the deficiencies in the prior art and provide a battery electrode structure that can effectively suppress the rate of lithium ion release from the edge of the electrode, thereby solving safety issues such as lithium deposition at the edge of the electrode and excessive thickness at the head and tail of the electrode, ensuring that lithium deposition will not occur at the head and tail of the electrode, and helping to improve the charge and discharge safety of the battery.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A battery pole piece structure includes a metal layer, a first end edge of the metal layer having a weakened transmission layer, a side of the weakened transmission layer away from the metal layer having an active material layer, and the resistivity of the weakened transmission layer is at least 1.1 to 2 times the resistivity of the active material layer.

[0007] As an improvement to the electrode structure of the battery described in the present invention, the active material layer covers the surface of the weakened transmission layer and the metal layer to ensure that the area of ​​the metal layer except the weakened transmission layer, that is, the main part of the metal layer, can quickly realize ion transmission.

[0008] As an improvement to the electrode structure of the battery of the present invention, the resistivity of the active material layer is 1.1×10 -2 Ω·m~1×10 2 Ω·m.

[0009] As an improvement to the electrode structure of the battery described in the present invention, the active material layer has a first part and a second part that are connected to each other, the first part and the weakened transmission layer are overlapped along the thickness direction of the electrode structure to form a first overlapping region, the second part and the first overlapping region are arranged in parallel on the metal layer, the thickness difference between the second part and the first overlapping region is H, the thickness of the weakened transmission layer is L1, and the H and the L1 satisfy the relationship: 0≤H / L1≤3. Within the above range, the thickness uniformity of the electrode can be guaranteed, thereby improving the charge and discharge uniformity of the battery.

[0010] As an improvement to the electrode structure of the battery described in the present invention, the width of the weakened transmission layer is W1, and the thickness of the weakened transmission layer is L1, which satisfies the relationship: 0.005≤L1 / W1≤0.025, 0.025≤L1 / W1≤0.05. Within this ratio range, the lithium ion escape rate can be best suppressed at the edge of the electrode, effectively overcoming the safety problem of lithium plating at the edge of the electrode, and improving the charging and discharging safety of the battery.

[0011] As an improvement to the electrode structure of the battery described in the present invention, the resistivity of the weakened transmission layer is ρ1, the resistivity of the active material layer is ρ2, and the thickness of the active material layer located on the surface of the weakened transmission layer is L2, satisfying the relationship: 100≤(ρ1 / ρ2)×L2≤110. Within this ratio range, the lithium ion escape rate can be best suppressed at the edge of the electrode, effectively overcoming the safety problem of lithium plating at the edge of the electrode, and improving the charging and discharging safety of the battery.

[0012] As an improvement to the electrode structure of the battery described in the present invention, the ρ1 and the ρ2 satisfy the relationship: 2≤ρ1 / ρ2≤20; that is, 0.05≤ρ2 / ρ1≤0.5. Within this ratio range, effective regulation of the performance of reducing electron transmission can be achieved.

[0013] As an improvement to the electrode structure of the battery described in the present invention, the active material layer has active particles with an average particle size of d2, and the thickness of the weakened transmission layer is L1, satisfying the relationship: 0.1≤L1 / d2≤0.4. By limiting the thickness of the weakened transmission layer, effective regulation of the performance of reducing electron transmission can be achieved.

[0014] As an improvement to the electrode sheet structure of the battery according to the present invention, the thickness of the active material layer embedded in the weakening transmission layer is d, and d, L1, and d2 satisfy the relational expression: d < L1, 0.05 ≤ d / d2 ≤ 0.3. In this numerical range, it can prevent the thickness of the active material layer embedded in the weakening transmission layer from being excessive, so as to ensure that the active particles of the active material layer do not contact and scratch the metal layer. Moreover, it is also necessary to prevent the thickness of the active material layer embedded in the weakening transmission layer from being too small, so as to prevent the situation that the adhesion between the active material layer and the weakening transmission layer is poor and easy to delaminate.

[0015] As an improvement to the electrode sheet structure of the battery according to the present invention, the weakening transmission layer has granular bodies with an average particle size of d1, and d1, d, and L1 satisfy the relational expression: d < d1 < L1 or d1 < d < L1. Among them, the granular bodies can be ceramic particles. The ceramic particles can increase the resistance value of the weakening transmission layer. Moreover, the ceramic particles, as weakly conductive particles, have the effect of reducing electron transmission. The weakening transmission layer can be made by mixing a conductive agent and ceramic particles with an average particle size of d1.

[0016] As an improvement to the electrode sheet structure of the battery according to the present invention, when the active material layer is in a liquid state, the contact angle of θ° is formed with the surface of the solid weakening transmission layer. θ, d, and L1 satisfy the relational expression: 1 ≤ θ × d / L1 ≤ 15. Within the above range, it can ensure better adhesion between the active material layer and the weakening transmission layer and the appearance of the electrode sheet, and improve the charge-discharge safety of the battery.

[0017] As an improvement to the electrode sheet structure of the battery according to the present invention, d2 is 10um to 30um, d1 is 0.5um to 3um, d is 1um to 3um, L1 is 1um to 4um, d2 < L2, H is 0 to 10um, and θ is 1.1 to 20. Within these numerical ranges, it can ensure the best effect of suppressing the lithium ion extraction speed at the edge part of the electrode sheet, effectively overcome the safety problem of lithium deposition at the edge of the electrode sheet, and at the same time ensure the uniformity of the electrode sheet and improve the charge-discharge safety of the battery.

[0018] The second object of the present invention is to provide a battery including the electrode sheet structure as described above.

[0019] The third object of the present invention is to provide a method for preparing an electrode sheet, including the following steps:

[0020] S1. Prepare an active material layer with a resistivity of ρ2, and make the resistivity of the weakening transmission layer at least 1.1 to 2 times that of the active material layer, and prepare the required weakening transmission layer;

[0021] S2. Coating the weakened transmission layer of step S1 on the edge of the first end of the metal layer, and coating the active material layer of step S1 on the side of the weakened transmission layer away from the metal layer to obtain the required electrode.

[0022] The beneficial effects of the present invention are: 1) the weakened transmission layer of the present invention is equivalent to coating a weak conductive coating on the foil at the head and tail edges of the battery cell. The weakened transmission layer arranged between the metal layer and the active material layer inhibits the release rate of lithium ions, improves and regulates the release rate of lithium ions in different areas of the electrode, and can significantly reduce the transmission rate of electrons at the edge of the electrode; 2) by inhibiting the release rate of lithium ions, the release rate of lithium ions at the edge of the electrode is reduced, which can effectively solve the safety problems such as lithium deposition at the edge of the electrode, easy lithium deposition at the edge of the battery cell, and excessive thickness of the head and tail of the electrode, and ensure that lithium deposition will not occur at the head and tail of the electrode; 3) since lithium deposition no longer occurs during charging and discharging of the battery, the charging and discharging safety of the battery can be greatly improved, thereby effectively overcoming the problem of unsafe charging and discharging of the battery, effectively and significantly enhancing the charging and discharging performance of the battery and extending the service life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Features, advantages, and technical effects of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.

[0024] FIG1 is a schematic diagram of the structure of the metal layer, the transmission weakening layer and the active material layer of the present invention.

[0025] FIG2 is a second schematic structural diagram of the metal layer, the transmission weakening layer and the active material layer of the present invention.

[0026] FIG3 is a schematic structural diagram of a pole piece of the present invention.

[0027] FIG. 4 is a schematic diagram showing the difference in ion transport between the transport layer and the active material layer according to the present invention.

[0028] Among them, the figure marks are explained as follows: 1-metal layer; 2-weakening transmission layer; 21-particle body; L1-thickness of weakening transmission layer; 3-active material layer; 3a-first part; 3b-second part; 31-active particles; L2-thickness of active material layer located on the surface of weakening transmission layer; d-thickness of active material layer embedded in weakening transmission layer; H-thickness difference between the second part of active material layer and the first overlapping area formed in pole piece structure; T-thickness direction of pole piece structure. DETAILED DESCRIPTION

[0029] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but rather use differences in the functions of the components as the criteria for distinction. For example, "including" mentioned throughout the specification and claims is an open term and should be interpreted as "including but not limited to". In addition, "substantially" means that within an acceptable error range, those skilled in the art can solve technical problems within a certain error range and basically achieve the desired technical effect.

[0030] The inventors have discovered that lithium deposition at the edges of the battery cell pole pieces poses a high safety risk to battery charging and discharging. Therefore, a new pole piece structure is needed to overcome the problem of lithium deposition at the edges of the pole pieces.

[0031] The present invention will be further described below in conjunction with Figures 1 to 4 , but they are not intended to limit the present invention.

[0032] A battery electrode structure, see Figures 1 to 3, includes a metal layer 1, a first end edge of the metal layer 1 having a weakened transmission layer 2, and a side of the weakened transmission layer 2 away from the metal layer 1 having an active material layer 3, and the resistivity of the weakened transmission layer 2 is at least 1.1 to 2 times the resistivity of the active material layer 3.

[0033] Preferably, the active material layer 3 covers the surface of the weakened transmission layer 2 and the metal layer 1, and the resistivity of the active material layer 3 is 1.1×10 -2 Ω·m~1×10 2 Ω·m.

[0034] Preferably, the resistivity of the weakened transmission layer 2 is ρ1, the resistivity of the active material layer 3 is ρ2, and the thickness of the active material layer 3 located on the surface of the weakened transmission layer 2 is L2, satisfying the relationship: 100≤(ρ1 / ρ2)×L2≤110, 0.05≤ρ2 / ρ1≤0.5.

[0035] Preferably, ρ1 and ρ2 satisfy the relationship: 2≤ρ1 / ρ2≤2.5, 2.5≤ρ1 / ρ2≤3, 3≤ρ1 / ρ2≤3.5, 3.5≤ρ1 / ρ2≤4, 4≤ρ1 / ρ2≤7.5, 7.5≤ρ1 / ρ2≤10.5, 10.5≤ρ1 / ρ2≤16.5 or 16.5≤ρ1 / ρ2≤20.

[0036] Preferably, the thickness of the embedded weakening transmission layer 2 for the active material layer 3 is d, and the active material layer 3 has active particles 31 with an average particle size of d2, satisfying the relationship: 0.05 ≤ d / d2 ≤ 0.1, 0.1 ≤ d / d2 ≤ 0.15, 0.15 ≤ d / d2 ≤ 0.2, 0.2 ≤ d / d2 ≤ 0.25, or 0.25 ≤ d / d2 ≤ 0.3.

[0037] Preferably, the width of the weakening transmission layer 2 is W1, and the thickness of the weakening transmission layer 2 is L1. W1 and L1 satisfy the relationship: 0.005 ≤ L1 / W1 ≤ 0.015, 0.015 ≤ L1 / W1 ≤ 0.025, 0.025 ≤ L1 / W1 ≤ 0.03, 0.03 ≤ L1 / W1 ≤ 0.035, 0.035 ≤ L1 / W1 ≤ 0.04, 0.04 ≤ L1 / W1 ≤ 0.045, or 0.045 ≤ L1 / W1 ≤ 0.05.

[0038] Preferably, the active material layer 3 has a first part 3a and a second part 3b connected to each other. The first part 3a and the weakening transmission layer 2 are overlapped along the thickness direction T of the electrode structure to form a first overlapping area. The second part 3b is arranged并列 to the first overlapping area on the metal layer 1. The thickness difference between the second part 3b of the active material layer 3 and the first overlapping area formed in the electrode structure is H, and the thickness value of the weakening transmission layer 2 is L1, satisfying the relationship: 0 ≤ H / L1 ≤ 1, 1 ≤ H / L1 ≤ 2, 2 ≤ H / L1 ≤ 3. H is the thickness difference between the first overlapping area on one side of the electrode and the second part 3b.

[0039] Preferably, L1, d, and d2 satisfy the relationship: d < L1, 0.1 ≤ L1 / d2 ≤ 0.4. Among them, L1 and d2 satisfy the relationship: 0.1 ≤ L1 / d2 ≤ 0.15, 0.15 ≤ L1 / d2 ≤ 0.17, 0.17 ≤ L1 / d2 ≤ 0.195, 0.195 ≤ L1 / d2 ≤ 0.25, 0.25 ≤ L1 / d2 ≤ 0.3, 0.3 ≤ L1L1 / d2 ≤ 0.35, or 0.35 ≤ L1 / d2 ≤ 0.4.

[0040] Preferably, the weakening transmission layer 2 has granular bodies 21 with an average particle size of d1. d1, d, and L1 satisfy the relationship: d < d1 < L1 or d1 < d < L1.

[0041] Preferably, when the active material layer 3 is in a liquid state, it forms a contact angle of θ° with the surface of the solid weakening transmission layer 2. That is, when the slurry of the active material layer 3 is dropped onto the surface of the weakening transmission layer 2, it forms a contact angle of θ°. This contact angle is formed by the contact of the liquid and the solid before drying. Actually, it is the interfacial angle formed when the active material layer 3 is in a liquid state and the weakening transmission layer 2 is in a solid state. The solid content of the liquid active material layer 3 is 45 - 55%; the weight loss rate of the solid weakening transmission layer 2 is ≤ 1%.

[0042] More preferably, θ, d and L1 satisfy the relationship: 1≤θ×d / L1≤5, 5≤θ×d / L1≤10, 10≤θ×d / L1≤15, wherein the contact angle can be in the range of 1.1° to 20°.

[0043] Preferably, the metal layer 1 has two opposite first end edges, and the two transmission-weakening layers 2 are relatively arranged on the same side of the metal layer 1. There are four transmission-weakening layers 2 on the front and back sides of the metal layer 1, and there is an active material layer 3 on the front and back sides of the metal layer 1 respectively.

[0044] Among them, the resistance value of the coating can be tested by the four-probe method; the contact angle is tested by the sessile drop method, and the test is completed using an optical contact angle meter.

[0045] Specifically, the preparation method of the electrode of the present invention includes the following steps: preparing an active material layer 3 with a resistivity of ρ2, so that the resistivity of the weakened transmission layer 2 is at least 1.1 to 2 times the resistivity of the active material layer 3, preparing the required weakened transmission layer 2, coating the weakened transmission layer 2 in step S1 on the edge of the first end of the metal layer 1, and coating the active material layer 3 in step S1 on the side of the weakened transmission layer 2 away from the metal layer 1 to obtain the required electrode.

[0046] Furthermore, the present invention also provides a battery comprising a positive electrode sheet, a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet, wherein the positive electrode sheet of the battery is the electrode sheet structure comprising the metal layer 1, the reduced transmission layer 2, and the active material layer 3, and the battery can be used in vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, and electric tools, etc. Among them, the vehicle can be a fuel vehicle, a gas vehicle, or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle, etc.; the spacecraft includes airplanes, rockets, space shuttles, and spacecraft, etc.; the electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc.; the electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc.

[0047] Preferably, the battery can be a lithium ion battery, a sodium ion battery, a magnesium ion battery, etc.

[0048] To make the technical solutions and advantages of the present invention more clear, the present invention and its beneficial effects are further described in detail below in conjunction with specific implementation methods, but the implementation methods of the present invention are not limited thereto.

[0049] Example 1

[0050] Positive electrode sheet: See Figures 1 to 3, comprising a metal layer 1, a weakened transport layer 2 and an active material layer 3, the metal layer 1 is an aluminum current collector, first coated with a weak conductive material on the aluminum current collector, the weak conductive material can be made by mixing a conductive agent and ceramic particles with an average particle size of d1, d1 is 1.5um, the weak conductive material is coated at the position corresponding to the head and tail of the battery cell, that is, the weakened transport layer 2 is coated on the edge of the first end of the metal layer 1 to obtain a weak conductive current collector, and then the positive electrode active material, conductive agent acetylene black, conductive carbon nanotubes, and binder polyvinylidene fluoride (PVDF) are fully dispersed in an N-methylpyrrolidone solvent system in a weight ratio of 97.8:0.6:0.4:1.2 to obtain a positive electrode active material slurry, the positive electrode active material slurry is the active material layer 3, wherein the positive electrode active material can be LiCoO2, LiNiO2, LiVO2, LiCrO2, LiMn2O4, LiCoMnO4, Li2NiMn3O8, LiNi 0.5 Mn 1.5 One or more of O4, LiCoPO4, LiMnPO4, LiFePO4, LiNiPO4, LiCoFSO4, CuS2, FeS2, MoS2, NiS, and TiS2; the active particles 31 are a mixture of positive electrode active material, conductive agent acetylene black, and conductive carbon nanotubes; and finally, the positive electrode active material slurry is coated on the weakly conductive current collector; the portion of the positive electrode active material slurry superimposed on the weakened transmission layer 2 is the first portion 3a, and the portion of the positive electrode active material slurry not superimposed on the weakened transmission layer 2 is the second portion 3b; and then the positive electrode sheet is obtained by cold pressing and stripping.

[0051] Negative electrode sheet: The negative electrode active material, sodium carboxymethyl cellulose, and styrene-butadiene rubber (SBR) emulsion are mixed in a weight ratio of 97.4:1.3:1.3 to prepare a negative electrode active material slurry. The negative electrode active material can be a silicon-carbon material; the active material slurry is coated on a copper current collector to obtain an active material layer, and then cold pressed and slit to obtain a negative electrode sheet.

[0052] Isolation film: The PE surface is coated with a ceramic mixture as an isolation film.

[0053] Electrolyte: Ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), and propyl propionate (PP) are mixed in a volume ratio of 1:1:4:4, and then fully dried lithium salt LiPF6 is dissolved in a mixed organic solvent at a ratio of 1 mol / L to prepare an electrolyte.

[0054] Preparation of a full battery: The positive electrode sheet, separator, and negative electrode sheet are wound or stacked to produce a bare cell, which is then encapsulated and injected with electrolyte to produce a finished lithium-ion battery.

[0055] Among them, the resistivity ρ1 of the weakened transmission layer 2 in the positive electrode plate is 0.4Ω·m, the resistivity ρ2 of the active material layer 3 is 0.16Ω·m, the thickness d of the first part 3a of the active material layer 3 embedded in the weakened transmission layer 2 is 2.1um, the thickness L1 of the weakened transmission layer 2 is 2.7um, the thickness L2 of the first part 3a of the active material layer 3 is 43um, and the average particle size d2 of the active particles 31 is 27um. The first overlapping area formed by the overlapping of the weakened transmission layer 2 and the first part 3a of the active material layer 3 in the electrode structure and the second part 3b of the adjacent active material layer 3 form a thickness difference H of 4.6um. The slurry of the active material layer 3 drips onto the surface of the weakened transmission layer 2 to form a contact angle of θ°=5°. By adjusting ρ1, ρ2, d, L1, L2 and d2, the following Examples 2 to 3 and Comparative Examples 1 to 5 are obtained, and the specific parameters are as shown in Table 1. Moreover, H, θ, ρ1, L1, d and d2 are the same in Example 1 and Comparative Examples 1 and 4, and only ρ2 and L2 are different; H, θ, ρ1, ρ2, L1 and d2 are the same in Example 1 and Comparative Example 2, and only d and L2 are different; H and θ are the same in Example 1 and Example 2; d2 is the same in Example 2 and Comparative Example 3, and H, θ, ρ1, L1 and d in Comparative Example 3 are all 0; H, θ, d and d2 are the same in Example 2 and Comparative Example 5, and only ρ1, ρ2, L1 and L2 are different; H, θ and L1 are the same in Example 1, Example 3 and Comparative Example 5.

[0056] Table 1

[0057] Performance testing was conducted on Examples 1-3 and Comparative Examples 1-5. The charging window is the maximum rate at which lithium deposition does not occur when the battery cell is directly charged to the cutoff voltage after disassembly of the cell interface at 3.0C, 3.5C, 4.0C, 4.5C, 5.0C, and 5.5C. The charging time is the time corresponding to a full charge under 5C and 3C cycle conditions. The lithium deposition windows for Examples 1-3 and Comparative Examples 1-5 were obtained as shown in Table 2 below.

[0058] Table 2

[0059] When there is no weak conductive layer or when the active material layer particles pierce the weak conductive layer and directly contact the foil, the electron transmission rate cannot be effectively suppressed, resulting in an accelerated lithium ion extraction rate, and thus the phenomenon of lithium precipitation occurs. Referring to Figure 4, the weakened transport layer 2 effectively reduces the electron transmission rate and suppresses the lithium ion extraction rate. It can be seen from the above table that when the resistivity ratio of the weak conductive coating to the resistivity of the active material layer does not match the thickness of the electrode, it significantly affects the performance of the battery cell. For example, when (ρ1 / ρ2)×L2 is less than 100, the electron transmission rate cannot be effectively suppressed, resulting in an accelerated lithium ion extraction rate, and thus the phenomenon of lithium precipitation occurs; when (ρ1 / ρ2)×L2 is greater than 110, the lithium ion extraction and insertion rate is too slow, and the charging time is increased.

[0060] Therefore, the key to the present invention is to control the relationship between the thickness of the weak conductive coating and the average particle size of the active material layer, as well as the relationship between the resistivity of the weak conductive coating and the resistivity and thickness of the active material layer, that is, to control the resistivity ρ1 of the weakened transmission layer 2 in the pole piece, the resistivity ρ2 of the active material layer 3, the thickness d of the active material layer 3 embedded in the weakened transmission layer 2, the thickness L1 of the weakened transmission layer 2, the thickness L2 of the active material layer 3 located on the surface of the weakened transmission layer 2, and the average particle size d2 of the active particles 31, so that 100≤(ρ1 / ρ2)×L2≤110, 2ρ2≤ρ1≤20ρ2, 0.05d2≤d≤0.3d2, 0.1d2≤L1≤0.4d2 and d<L1; d is 1um~3um; L1 is 1um~4um; d2 is 10um~30um; under these conditions, the weakly conductive coating reduces the transmission rate of electrons, suppresses the escape rate of lithium ions, and ensures that the particles of the active material layer will not pierce the weakly conductive layer, so as not to directly contact the foil and cause the effect of reducing the transmission rate of electrons to fail.

[0061] On the other hand, the present invention also obtains Examples 4 to 6 by only changing the value of θ on the basis of Examples 1 to 3, and obtains Comparative Examples 6 to 9 by only changing θ on the basis of Comparative Examples 1 to 4, obtains Comparative Example 10 by only changing the value of d on the basis of Example 4, and obtains Comparative Example 11 by only changing the value of L1 on the basis of Example 4, to explore the relationship between the degree of contact angle, the thickness L1 of the weakened transport layer 2, and the thickness d of the active material layer 3 embedded in the weakened transport layer 2 to obtain the design parameters in Table 3 and the difference in Poweloss under the 4C cycle conditions in Table 4.

[0062] Table 3

[0063] Powerloss refers to the difference between the capacity ratio of the standard charge and discharge per 100-cycle node and the capacity ratio of the standard charge and discharge per adjacent cycle. It is used to indicate the polarization of the battery cell. The greater the powerloss, the greater the polarization of the battery cell, and vice versa. The following results were obtained by comparing Examples 4-6 and Comparative Examples 6-11.

[0064] Table 4

[0065] It can be seen from the table that when the ratio of the thickness d of the active material layer 3 embedded in the weak conductive coating to the thickness L1 of the weakened transmission layer 2 shows an incompatible relationship with the contact angle of the surface formation value θ° when the active material layer 3 slurry is dropped onto the weakened transmission layer 2, that is, θ×d / L1 is too large or too small, it obviously affects the performance of the battery cell. When 1≤θ×d / L1≤15, there is a better bonding effect and electrode appearance between the active material layer 3 and the weakened transmission layer 2. As the cycle proceeds, the electrode is in a stable state and the polarization grows slowly. When θ×d / L1<1 or 15<θ×d / L1, the bonding effect between the active material layer 3 and the weakened transmission layer 2 is weak. As the cycle proceeds, the active material layer 3 and the weakened transmission layer 2 begin to separate, resulting in a significant increase in the polarization of the battery cell, affecting the cycle performance of the battery cell.

[0066] Finally, the present invention also demonstrates the effect of such a pole piece structure on charge and discharge uniformity by changing only the value of H based on Example 1 to obtain Example 7, and by changing only H and L1 based on Example 7 to obtain Examples 8-9 and Comparative Examples 12-14. That is, the relationship between H and the thickness value L1 of the weakened transmission layer 2 is further explored to obtain the design parameters in Table 5, and the difference in capacity retention under the 5C cycle standard conditions in Table 6 is obtained based on these parameters. At the same time, such a test can meet the single variable principle. Compared with Example 1 in Table 1, the variables in Examples 8-9 and Comparative Examples 12-14 are only H and L1.

[0067] Table 5

[0068] The following results were obtained by comparing Examples 7 to 9 with Comparative Examples 12 to 14.

[0069] Table 6

[0070] The table shows that when H and the thickness of the weakened transport layer 2, L1, do not match, the cell performance is significantly affected. When 3 ≤ H / L1, the electrode thickness uniformity is poor, resulting in localized polarization inconsistencies, leading to poor charge and discharge uniformity, which in turn affects the cycle retention rate. It can be seen that when H and the thickness of the weakened transport layer 2, L1, satisfy the relationship of 0 ≤ H / L1 ≤ 3, within the above range, the electrode charge and discharge uniformity can be guaranteed, thereby improving the corresponding electrical performance of the battery.

[0071] Based on the disclosure and teachings of the above description, those skilled in the art will be able to make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the above specific embodiments. Any obvious improvements, substitutions, or modifications made by those skilled in the art based on the present invention fall within the scope of protection of the present invention. In addition, although certain specific terms are used in this description, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. A battery pole piece structure, characterized in that: Comprising: A metal layer (1), the first end edge of the metal layer (1) having a weakened transmission layer (2); One side of the weakened transmission layer (2) away from the metal layer (1) has an active material layer (3); The resistivity of the weakened transmission layer (2) is at least 1.1 to 2 times the resistivity of the active material layer (3).

2. The battery electrode structure according to claim 1, wherein: The active material layer (3) covers the surface of the transmission weakening layer (2) and the metal layer (1), and the resistivity of the active material layer (3) is 1.1×10 -2 Ω·m~1×10 2 Ω·m.

3. The battery electrode structure according to claim 1 or 2, characterized in that: The active material layer (3) has a first part (3a) and a second part (3b) connected to each other. The first part (3a) and the weakened transmission layer (2) are stacked in the thickness direction of the electrode structure to form a first stacked area. The second part (3b) is arranged side by side with the first stacked area on the metal layer (1). The thickness difference between the second part (3b) and the first stacked area is H, and the thickness of the weakened transmission layer (2) is L1. The H and the L1 satisfy the relationship: 0 ≤ H / L1 ≤ 3.

4. The battery electrode structure according to claim 1 or 2, characterized in that: The width of the weakened transmission layer (2) is W1, and the thickness of the weakened transmission layer (2) is L1, satisfying the relationship: 0.005 ≤ L1 / W1 ≤ 0.

05.

5. The battery electrode structure according to claim 1 or 2, characterized in that: The resistivity of the weakened transmission layer (2) is ρ1, the resistivity of the active material layer (3) is ρ2, and the thickness of the active material layer (3) on the surface of the weakened transmission layer (2) is L2, satisfying the relationship: 100 ≤ (ρ1 / ρ2) × L2 ≤ 110.

6. The battery electrode structure according to claim 5, characterized in that: The ρ1 and the ρ2 satisfy the relationship: 2 ≤ ρ1 / ρ2 ≤ 20.

7. The battery electrode structure according to claim 1 or 2, characterized in that: The active material layer (3) has active particles (31) with an average particle size of d2, and the thickness of the weakened transmission layer (2) is L1, satisfying the relationship: 0.1 ≤ L1 / d2 ≤ 0.

4.

8. The battery electrode structure according to claim 7, characterized in that: The thickness of the active material layer (3) embedded in the weakened transmission layer (2) is d. The d, the L1, and the d2 satisfy the relationship: d < L1, 0.05 ≤ d / d2 ≤ 0.

3.

9. The battery electrode structure according to claim 8, characterized in that: The weakened transmission layer (2) has particulate bodies (21) with an average particle size of d1. The d1, the d, and the L1 satisfy the relationship: d < d1 < L1 or d1 < d < L1.

10. The battery electrode structure according to claim 8, wherein: When the active material layer (3) is in a liquid state, it forms a contact angle of θ° with the surface of the solid weakened transmission layer (2). The θ, the d, and the L1 satisfy the relationship: 1 ≤ θ × d / L1 ≤ 15.

11. A battery, characterized in that: Including the electrode structure according to any one of claims 1 to 10.

12. A method for preparing a pole piece, characterized in that: Including the following steps: S1. Prepare an active material layer (3) with a resistivity of ρ2, making the resistivity of the weakened transmission layer (2) at least 1.1 to 2 times the resistivity of the active material layer (3), and prepare the required weakened transmission layer (2); S2. Coat the weakened transmission layer (2) in step S1 on the first end edge of the metal layer (1), and coat the active material layer (3) in step S1 on the side of the weakened transmission layer (2) away from the metal layer (1) to obtain the required electrode.

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