Current collector, negative pole piece, preparation method of negative pole piece, battery and electric equipment

Abstract

The invention discloses a current collector, a negative pole piece, a preparation method of the negative pole piece, a battery and electric equipment, the current collector comprises a substrate, a plurality of accommodating holes are formed in at least one side surface of the substrate in the thickness direction, the distance between two adjacent accommodating holes is x, the diameter of each accommodating hole is r, and the depth of each accommodating hole is h1; one part of the lithium supplementing piece covers the surface of the at least one side of the base body in the thickness direction to form a lithium supplementing layer, the other part of the lithium supplementing piece is filled into the multiple containing holes, the thickness of the lithium supplementing layer is h2, and h2, x, r and h1 meet the condition that r2 * (h1 + h2) is smaller than or equal to x2 * h2. According to the current collector, the lithium supplement effect is good, the bonding strength of the current collector and the active dressing is improved, and the use performance of the battery is improved.

Description

Current collectors, negative electrode sheets and their preparation methods, batteries and electrical devices Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a current collector, a negative electrode sheet and its preparation method, a battery and an electrical device. Background Technology

[0002] Common methods for lithium replenishment in anodes involve coating the surface of the anode active material with lithium powder or composite lithium foil. However, since the metallic lithium is directly exposed to the surface of the anode active material and comes into direct contact with oxygen and moisture in the environment, it not only leads to a significant loss of active lithium and prevents the specific capacity of the metallic lithium from being effectively utilized, but also causes significant heat generation when the metallic lithium is in contact with the environment for a long time. In addition, the spontaneous embedding of metallic lithium into the anode active material generates heat, resulting in significant heat generation during the entire lithium replenishment and assembly process, posing a great safety risk.

[0003] To improve lithium utilization efficiency and reduce heat generation, traditional technologies employ current collectors for lithium replenishment. However, metallic lithium easily embeds into the anode active material, causing the replenishment layer to disappear and resulting in a lack of effective adhesion between the current collector and the anode material layer. After repeated charge-discharge cycles, the anode active material can easily detach from the current collector surface, losing electrical contact. This leads to a sharp increase in battery impedance, a significant decrease in battery capacity, and a marked reduction in battery reliability and lifespan. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one object of this invention is to provide a current collector that, while providing good lithium replenishment, improves the adhesion strength between the current collector and the active coating, thereby enhancing battery performance.

[0005] The second objective of this invention is to provide a negative electrode sheet employing the aforementioned current collector.

[0006] The third objective of this invention is to provide a method for preparing a negative electrode sheet.

[0007] The fourth object of the present invention is to provide a battery using the above-mentioned current collector or negative electrode sheet.

[0008] A third objective of this invention is to provide an electrical device that uses the aforementioned battery.

[0009] According to a first aspect of the present invention, a current collector includes: a substrate having a plurality of receiving holes formed on at least one surface in the thickness direction of the substrate, the spacing between two adjacent receiving holes being x, the diameter of the receiving holes being r, and the depth of the receiving holes being h1; and a lithium replenishing element, a portion of which covers the at least one surface in the thickness direction of the substrate to form a lithium replenishing layer, and another portion of which fills the plurality of receiving holes, the thickness of the lithium replenishing layer being h2, wherein h2, x, r, and h1 satisfy: r 2 ×(h1+h2)≤x 2 ×h2.

[0010] According to the first aspect of the present invention, the current collector has a simple structure, high operability in preparation, relatively simple and reliable process, and low implementation difficulty. Furthermore, by setting h2, x, r, and h1, the following condition is met: r 2 ×(h1+h2)≤x 2 ×h2, all parameters are in optimal condition, and while the lithium replenishment effect is good, it does not affect the direct contact between the current collector and the anode active material, i.e., the active dressing. This avoids poor contact caused by weak contact between the current collector and the active dressing, as well as the problem of the active dressing easily falling off the surface of the current collector. This is conducive to the long-term use of the current collector and the negative electrode sheet, improves the performance and reliability, and extends the service life.

[0011] According to some embodiments of the present invention, x, r and h1 respectively satisfy: 20um≤x≤120um, 20um≤r≤50um, 2um≤h1≤6um.

[0012] According to some embodiments of the present invention, x, r and h1 further satisfy: 40um≤x≤90um, 30um≤r≤40um, 3um≤h1≤5um.

[0013] According to some embodiments of the present invention, h2 satisfies: 1um ≤ h2 ≤ 10um.

[0014] According to some embodiments of the present invention, h2 further satisfies: 2um ≤ h2 ≤ 8um.

[0015] According to some embodiments of the present invention, when the lithium replenishing element is provided on one side surface of the substrate in the thickness direction, the lithium replenishing areal density of the lithium replenishing element is ρ, wherein ρ satisfies: 0.3 g / m³ 2 ≤ρ≤2.0g / m 2 .

[0016] According to some embodiments of the present invention, the ρ further satisfies: 0.5 g / m 2 ≤ρ≤1.5g / m 2 .

[0017] According to some embodiments of the present invention, the lithium replenishing component includes a lithium replenishing agent and a conductive material, wherein the conductive material is coated on the outer peripheral surface of the lithium replenishing agent.

[0018] According to some embodiments of the present invention, the lithium replenishing agent comprises lithium powder; and / or, the particle size of the lithium replenishing element is D, wherein D satisfies: 20um≤D≤60um.

[0019] According to some embodiments of the present invention, D further satisfies: 30um ≤ D ≤ 50um.

[0020] According to some embodiments of the present invention, the conductive material includes at least one of polyaniline, polypyrrole, polydioxothiophene, poly(p-phenylene), polyphenylene sulfide, and polyphthalic acid compounds.

[0021] According to some embodiments of the present invention, the conductive material includes polyaniline.

[0022] According to some embodiments of the present invention, the receiving holes are formed on both sides of the thickness direction of the substrate, and the receiving holes on both sides of the substrate are staggered along the thickness direction of the substrate.

[0023] According to some embodiments of the present invention, the substrate includes copper foil, nickel foil, or stainless steel foil.

[0024] According to some embodiments of the present invention, the substrate is a copper foil, and the thickness of the substrate is d, wherein d satisfies: 6um ≤ d ≤ 8um.

[0025] A negative electrode includes a current collector as described in the first aspect embodiment above.

[0026] According to a third aspect of the present invention, the method for preparing the negative electrode sheet includes the following steps: forming a plurality of receiving holes on the surface of a substrate; coating a lithium replenishing element on one side surface of the substrate having the receiving holes, and then performing a rolling process; and covering the lithium replenishing element with an active coating to obtain the negative electrode sheet.

[0027] According to some embodiments of the present invention, forming a plurality of receiving holes on the surface of the substrate specifically includes: forming a plurality of receiving holes on the surface of the substrate by laser processing, wherein the pulse width of the laser processing is 1000ps to 1000000ps, the power of the laser processing is 250W to 1000W, the spot size of the laser processing is 5um to 300um, and the step size of the laser processing is 5um to 1000um.

[0028] According to some embodiments of the present invention, coating the lithium replenishing element on the side surface of the substrate having the receiving hole specifically includes: coating the lithium replenishing element on the side surface of the substrate having the receiving hole by a wet or dry method.

[0029] According to some embodiments of the present invention, the active dressing includes a carbon-based anode material, a silicon anode material, or a lithium-intercalated alloy material, wherein the carbon-based anode material includes at least one of natural graphite, artificial graphite, soft carbon, hard carbon, mesophase carbon microspheres, nano-carbon, and carbon fiber.

[0030] A battery according to a fourth aspect embodiment of the present invention includes a current collector according to the first aspect embodiment described above, or a negative electrode sheet according to the second aspect embodiment described above, or a negative electrode sheet prepared according to the preparation method described in the third aspect embodiment described above.

[0031] An electrical appliance according to a fifth aspect of the present invention includes a battery according to the fourth aspect of the present invention.

[0032] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0033] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments in conjunction with the following drawings, in which: FIG1 is a top view of a current collector according to an embodiment of the present invention, wherein the lithium supplement layer is not shown; FIG2 is a side view of a current collector according to an embodiment of the present invention, wherein the lithium supplement layer is not shown; FIG3 is a fluid microstructure diagram of a current collector according to an embodiment of the present invention; FIG4 is a schematic diagram of a current collector according to an embodiment of the present invention before lithium powder is coated on a substrate and rolled; FIG5 is a schematic diagram of a current collector according to an embodiment of the present invention after lithium powder is coated on a substrate and rolled; FIG6 is a schematic diagram of a negative electrode sheet according to an embodiment of the present invention.

[0034] Reference numerals: 100, current collector; 200, negative electrode sheet; 1, substrate; 11, receiving hole; 2, lithium replenishing component; 21, lithium replenishing agent; 22, conductive material; 201, active dressing. Detailed Implementation

[0035] The embodiments of the present invention will now be described in detail. The embodiments described with reference to the accompanying drawings are exemplary. The current collector 100 according to an embodiment of the first aspect of the present invention will now be described with reference to Figures 1-5. In the following description of this application, the current collector 100 will be used as a negative electrode current collector for illustrative purposes.

[0036] As shown in Figures 1 and 2, the current collector 100 according to a first aspect embodiment of the present invention includes a substrate 1 and a lithium replenishment element 2.

[0037] Specifically, a plurality of receiving holes 11 are formed on at least one surface of the substrate 1 in the thickness direction. The distance between two adjacent receiving holes 11 is x, the diameter of the receiving hole 11 is r, and the depth of the receiving hole 11 is h1. A portion of the lithium replenishing component 2 covers at least one surface of the substrate 1 in the thickness direction to form a lithium replenishing layer, and another portion of the lithium replenishing component 2 fills the plurality of receiving holes 11. The thickness of the lithium replenishing layer is h2, wherein h2, x, r, and h1 satisfy: r 2 ×(h1+h2)≤x 2 ×h2.

[0038] In other words, the substrate 1 can be roughly configured as a sheet-like structure with a certain thickness. A lithium replenishment layer is provided on one or both sides of the substrate 1 along its thickness direction. The portion of the lithium replenishment component 2 located on one side of the substrate 1 along its thickness direction constitutes the lithium replenishment layer, while the other portion of the lithium replenishment component 2 is located within a plurality of receiving holes 11. For example, in the example of Figure 1, the plurality of receiving holes 11 are arranged in an array, with a distance x between two adjacent receiving holes 11 along the length or width direction of the substrate 1, and the cross-sectional shape of the receiving holes 11 is circular.

[0039] When the current collector 100 is used in the negative electrode 200, the lithium replenishment layer of the current collector 100 is first rolled, and then an active coating 201 is applied to the surface of the lithium replenishment layer. The current collector 100 before and after the rolling process are shown in Figures 4 and 5. After the rolling process, the shape of the lithium replenishment component 2 located on the surface of the receiving hole 11 and the substrate 1 will change. The lithium replenishment component 2 includes a lithium replenishing agent 21, which can be lithium powder. For example, when r... 2 ×(h1+h2)>x 2 When the value is ×h2, it means that there is obvious overlap between the flattened lithium metal particles after rolling, the lithium replenishment surface density of the lithium replenishment layer on the surface of the substrate 1 is too high, or the thickness of the lithium replenishment layer is too small, and the spacing between the receiving holes 11 on the current collector 100 is too small. When the current collector 100 is used to make the negative electrode 200, the contact area between the active dressing 201 and the surface of the current collector 100 is reduced, which may lead to poor contact.

[0040] Therefore, by setting h2, x, r, and h1, the following condition is met: r 2 ×(h1+h2)≤x 2With parameters at their optimal levels (×h2), the lithium replenishment effect is good without affecting the direct contact between the current collector 100 and the anode active material, i.e., the active dressing 201. This avoids poor contact caused by weak contact between the current collector 100 and the active dressing 201, as well as the problem of the active dressing 201 easily detaching from the surface of the current collector 100. This is beneficial for the long-term use of the current collector 100 and the negative electrode sheet, improving performance and reliability, and extending service life. Furthermore, the current collector 100 has a simple structure, high operability in its preparation, and a relatively simple and reliable process with low implementation difficulty.

[0041] According to the first aspect of the present invention, the current collector 100 has a simple structure, high operability in preparation, relatively simple and reliable process, and low implementation difficulty. Furthermore, by setting h2, x, r, and h1, the following condition is met: r 2 ×(h1+h2)≤x 2 ×h2, all parameters are in optimal condition, and the lithium replenishment effect is good. At the same time, it does not affect the direct contact between the current collector 100 and the anode active material, i.e., the active dressing 201. This avoids poor contact caused by weak contact between the current collector 100 and the active dressing 201, as well as the problem that the active dressing 201 is easy to fall off from the surface of the current collector 100. This is conducive to the long-term use of the current collector 100 and the negative electrode sheet, improves the performance and reliability, and extends the service life.

[0042] According to some embodiments of the present invention, x, r, and h1 respectively satisfy: 20um ≤ x ≤ 120um, 20um ≤ r ≤ 50um, and 2um ≤ h1 ≤ 6um. This configuration results in a reasonable setting of the spacing between two adjacent receiving holes 11, the diameter of the receiving hole 11, and the depth of the receiving hole 11. This satisfies the above-mentioned formulas while facilitating the arrangement and formation of the receiving holes 11 on the surface of the substrate 1, thereby benefiting the preparation of the current collector 100. Preferably, x, r, and h1 further satisfy: 40um ≤ x ≤ 90um, 30um ≤ r ≤ 40um, and 3um ≤ h1 ≤ 5um. Therefore, the spacing between two adjacent receiving holes 11, the diameter of the receiving hole 11, and the depth of the receiving hole 11 are more reasonably set, further facilitating the production, processing, and use of the current collector 100.

[0043] According to some embodiments of the present invention, h2 satisfies: 1µm ≤ h2 ≤ 10µm. For example, when the thickness of the lithium replenishment layer is less than 1µm, the lithium replenishment layer is too thin, which is not conducive to the uniform coverage of the lithium replenishment layer on the surface of the substrate 1. Moreover, it also reduces the lithium replenishment effect of the negative electrode 200. When the thickness of the lithium replenishment layer is greater than 10µm, the thickness of the lithium replenishment layer is large, which increases the amount of material used and also increases the difficulty of delithiation of the lithium replenishment component 2, reduces the energy density of the battery, and at the same time, due to the large amount of lithium replenishment, the battery is prone to lithium plating. Therefore, by setting the thickness of the lithium replenishment layer to meet the above-mentioned limitations, the thickness setting of the lithium replenishment layer is reasonable, the lithium replenishment effect of the lithium replenishment component 2 is good, and the amount of material used in the lithium replenishment component 2 is reduced. Optionally, h2 further satisfies: 2µm ≤ h2 ≤ 8µm.

[0044] According to some embodiments of the present invention, when a lithium replenishing element 2 is provided on one side surface of the substrate 1 in the thickness direction, the lithium replenishing areal density of the lithium replenishing element 2 is ρ, wherein ρ satisfies: 0.3 g / m 2 ≤ρ≤2.0g / m 2 For example, the lithium replenishment areal density (ρ) refers to the mass of the lithium replenishing element 2, such as the lithium replenishing agent 21, per unit area on the surface of the substrate 1 of the current collector 100 (i.e., the mass per unit area of ​​the coated lithium powder). A reasonable range is when 0.3 g / m² ≤ ρ ≤ 2.0 g / m². If the lithium replenishment areal density is too low (less than 0.3 g / m²), it may not be able to effectively replenish enough lithium to compensate for losses during battery cycling. For example, after multiple charge-discharge cycles, the battery capacity will gradually decrease due to lithium consumption, and a low lithium replenishment areal density cannot effectively alleviate this capacity decay. Conversely, if the lithium replenishment areal density is too high (greater than 2.0 g / m²), excessive lithium replenishing agent 21 will lead to an increase in the areal density of the negative electrode active material, a decrease in battery energy density or NP ratio, and a risk of lithium plating. On the other hand, excessive lithium replenishing agent 21 may cause some abnormal chemical reactions inside the battery, such as excessive reaction with the electrolyte, producing gases or other harmful byproducts, thereby affecting the safety and stability of the battery.

[0045] Within the range of 0.3 g / m² ≤ ρ ≤ 2.0 g / m², lithium supplement 21 can effectively perform its lithium replenishment function, thus slowing down battery capacity decay. Taking lithium-ion batteries for electric vehicles as an example, within this lithium replenishment areal density range, the capacity retention rate of the battery can be significantly improved after multiple charge-discharge cycles. Simultaneously, this range also helps ensure battery safety and good electrochemical performance. At this density, lithium supplement 21 will not have an excessive impact on the battery's internal resistance, ensuring good power performance during charge and discharge. Moreover, an appropriate amount of lithium supplement 21 can reduce abnormal reactions with battery components such as the electrolyte, maintaining the stability of the battery's internal environment, thereby improving the overall performance and lifespan of the battery.

[0046] Preferably, ρ further satisfies: 0.5 g / m 2 ≤ρ≤1.5g / m 2 When the lithium replenishment areal density ρ is further restricted to the range of 0.5 g / m² ≤ ρ ≤ 1.5 g / m², the optimization of battery performance is more precise compared to the previous range of 0.3 g / m²-2.0 g / m². Within this range, lithium replenishment agent 21 can more accurately balance the lithium replenishment amount and the internal chemical reactions of the battery.

[0047] According to some embodiments of the present invention, the lithium replenishing component 2 includes a lithium replenishing agent 21 and a conductive material 22, with the conductive material 22 covering the outer peripheral surface of the lithium replenishing agent 21. This configuration ensures the stability of the lithium replenishing agent 21 in air before rolling, preventing oxidation and failure. It also improves the utilization rate of the lithium replenishing agent 21 and reduces the risk of overheating and hardening / brittleness of the negative electrode 200. After rolling, the conductive material 22 covers a portion of the outer peripheral surface of the lithium replenishing agent 21, exposing part of the lithium replenishing agent 21. The remaining conductive material 22 can connect the current collector 100 and the active coating 201, assisting in improving the electrical contact between the current collector 100 and the active coating 201, preventing poor electrical contact after long-term charging and discharging of the battery. Furthermore, it avoids the material shedding problem associated with conventional current collector 100 lithium replenishment, which leads to a decrease in power performance. Furthermore, after the negative electrode 200 is formed, the cavities 11 created by embedding the lithium replenishing agent 21 into the anode active material can also serve as electrolyte storage sites, improving the ion transport capacity required for high-rate charge and discharge. Moreover, placing the lithium replenishing layer between the current collector 100 and the active coating 201 effectively avoids long-term direct contact between the lithium replenishing layer and the environment, reducing the loss of active lithium, improving the utilization rate of metallic lithium, and reducing heat generation. For example, a conductive material 22 can be coated onto the surface of the lithium replenishing agent 21 using a conventional lithium powder coating process. According to some embodiments of the present invention, the lithium replenishing agent 21 comprises lithium powder. And / or, the particle size of the lithium replenishing element 2 is D, where D satisfies: 20µm ≤ D ≤ 60µm.

[0048] For example, when lithium powder is used as lithium supplement 21, it possesses high chemical activity, enabling it to efficiently release lithium ions within the electrochemical environment of the battery. During battery charging and discharging, lithium powder can react with the electrolyte, rapidly replenishing lithium ions to the electrode materials. For instance, during the first charge of a lithium-ion battery, lithium powder can replenish lithium to the negative electrode through reaction, compensating for lithium consumed by processes such as the formation of the solid electrolyte interphase (SEI) film, thereby increasing the battery's initial capacity. Lithium is a light metal with a high energy density. As lithium supplement 21, lithium powder can provide a greater amount of lithium with relatively small mass and volume. This is highly advantageous for improving battery energy density, especially in applications with high energy density requirements, such as electric vehicles and portable electronic devices. For example, at the same lithium supplement areal density, lithium powder can more effectively enhance the battery's energy storage capacity than some other lithium supplement 21s. Furthermore, lithium itself is a good conductor, and lithium powder can play a certain conductive auxiliary role within the battery. It can improve the internal conductive pathways of the battery and reduce its internal resistance. For example, when lithium powder is uniformly distributed on the surface of current collector 100, it can form good electrical contact with the electrode material and current collector 100, making electron transport within the battery smoother and thus improving the battery's charge and discharge efficiency. When the particle size D of the lithium replenishment component 2 (lithium powder) is in the range of 20μm-60μm, the particle size affects its reactivity. Smaller lithium powder particles have a relatively larger specific surface area, meaning they have a larger contact area with the electrolyte and electrode material, thus enabling them to participate in the lithium replenishment reaction more quickly. For example, in the early stages of battery charging, smaller-sized lithium powder particles can quickly release lithium ions to replenish the electrode material, helping to improve the initial charging efficiency of the battery. However, the particle size cannot be too small, as this may cause the lithium powder reaction to be too vigorous and difficult to control. Within this particle size range, the diffusion performance of lithium powder within the battery is good. A moderate particle size is beneficial for the diffusion of lithium ions in the electrolyte. If the particle size is too large (over 60μm), the path for lithium ions to diffuse from the interior of the lithium powder to the surface and then into the electrolyte becomes longer, which may limit the rate of lithium replenishment. Conversely, excessively small particle sizes (less than 20 μm) can lead to lithium powder agglomeration, which also affects the normal diffusion of lithium ions. For example, during battery cycling, lithium powder with an appropriate particle size can ensure the stable diffusion of lithium ions into the electrode material, maintaining battery performance. Limiting the particle size range helps improve the uniformity of lithium replenishment. Lithium powder with a particle size between 20 μm and 60 μm is easier to distribute uniformly when coated on the surface of the current collector 100. This is because the particle size in this range is moderate, avoiding both localized accumulation due to excessively large particles and agglomeration due to excessively small particles. Uniform lithium replenishment can avoid performance differences caused by excessively high or low local lithium content within the battery, such as the risk of overcharging due to excessively high local capacity or the impact of excessively low local capacity on the overall battery capacity.Preferably, D further satisfies: 30um ≤ D ≤ 50um.

[0049] According to some embodiments of the present invention, the conductive material 22 includes at least one selected from polyaniline, polypyrrole, polydioxythiophene, poly(p-phenylene), polyphenylene sulfide, and polyphthalic acid compounds. This configuration, using the aforementioned conductive material 22, strengthens the connection between the current collector 100 and the active dressing 201, further enhancing the electrical contact between them, preventing poor electrical contact after prolonged charging and discharging, improving battery performance, and extending battery life.

[0050] According to some embodiments of the present invention, the conductive material 22 comprises polyaniline. Polyaniline possesses unique electrical conductivity and chemical stability. Polyaniline exhibits good resistance to chemicals in the environment. It can maintain relative stability of its structure and properties under various chemical environments. Furthermore, polyaniline can be processed and molded in various ways. It can be blended with other polymer materials to produce composite materials with conductive properties.

[0051] According to some embodiments of the present invention, referring to FIG. 2, receiving holes 11 are formed on both sides of the thickness direction of the substrate 1, and the receiving holes 11 on both sides of the substrate 1 are staggered along the thickness direction of the substrate 1. For example, multiple receiving holes 11 are formed on both sides of the substrate 1 in the thickness direction, and lithium replenishing elements 2 are provided on both sides of the substrate 1. Thus, by setting the receiving holes 11 on both sides to be staggered, the receiving holes 11 on both sides are less likely to interfere, and it is also beneficial to ensure the structural strength of the substrate 1, thereby facilitating the normal use of the current collector 100. It should be noted that when receiving holes 11 are formed on both sides of the thickness direction of the substrate 1, the lithium replenishing surface density of the lithium replenishing element 2 is ρ on one side and 2ρ on both sides. That is, 0.3 g / m² on one side. 2 ~2.0g / m 2 Double-sided, 0.6 g / m 2 ~4.0g / m 2 The preferred single-sided strength is 0.5 g / m. 2 ~1.5g / m 2 The preferred double-sided strength is 1.0 g / m 2 ~3.0g / m 2 .

[0052] According to some embodiments of the present invention, the substrate 1 comprises copper foil, nickel foil, or stainless steel foil. This configuration provides that copper foil exhibits high electrical conductivity, good processability, and relatively good chemical stability. Nickel foil demonstrates strong high-temperature resistance and good corrosion resistance. Stainless steel foil possesses excellent overall mechanical properties and outstanding corrosion resistance. Preferably, the substrate 1 is copper foil.

[0053] According to some embodiments of the present invention, the substrate 1 is a copper foil, and the thickness of the substrate 1 is d, wherein d satisfies: 6um≤d≤8um.

[0054] When the thickness d of the substrate 1 is in the range of 6μm-8μm, it provides a suitable electron conduction path. This thickness is neither too thick, leading to an excessively long electron transport path and increased resistance, nor too thin, preventing effective current carrying and conduction. For example, in the current collector 100 application of a battery, electrons need to be conducted from the electrode material through the substrate 1 to the external circuit. A suitable thickness ensures that electrons can be conducted quickly and smoothly, helping to reduce the battery's internal resistance and thus improve the battery's charge and discharge efficiency. Moreover, within this thickness range, good uniformity of conductivity can be achieved. A thicker substrate 1 may lead to differences in conductivity in different parts due to factors such as internal structure or impurity distribution. A thickness of 6μm-8μm is relatively thin, making the conductivity of the entire substrate 1 more uniform.

[0055] According to a second aspect embodiment of the present invention, the negative electrode 200, in conjunction with FIG6, includes the current collector 100 according to the first aspect embodiment described above.

[0056] According to an embodiment of the present invention, the negative electrode 200, by employing the aforementioned current collector 100, exhibits a high connection strength between the current collector 100 and the active coating 201 of the negative electrode 200. The active coating 201 is less prone to detachment, which is beneficial for the long-term stable use of the negative electrode 200 and extends its service life. Furthermore, the conductive material 22 on the surface of the lithium replenishment agent 21 can connect the current collector 100 and the active coating 201, thereby enhancing the electrical contact between them and preventing poor electrical contact after prolonged charging and discharging of the battery.

[0057] According to a third aspect embodiment of the present invention, the method for preparing the negative electrode 200 includes the following steps: forming a plurality of receiving holes 11 on the surface of a substrate 1; coating a lithium replenishing element 2 on one side of the substrate 1 having the receiving holes 11, and then performing a rolling process; covering the lithium replenishing element 2 with an active coating 201 to obtain the negative electrode 200.

[0058] For example, multiple receiving holes 11 can be formed on one or both surfaces of the substrate 1 in various ways according to usage requirements. The active coating 201 can be a negative electrode wet slurry or a negative electrode dry electrode. The preparation method can be either a wet process or a dry process. Correspondingly, the negative electrode wet slurry or negative electrode dry electrode can be coated or laminated onto the current collector 100 to form a negative electrode sheet 200. Thus, the preparation method is simple, highly operable, the process is relatively simple and reliable, the implementation difficulty is low, and the production efficiency is high.

[0059] According to some embodiments of the present invention, forming a plurality of receiving holes 11 on the surface of the substrate 1 specifically includes: forming a plurality of receiving holes 11 on the surface of the substrate 1 by laser processing, wherein the pulse width of the laser processing is 1000ps to 1000000ps, the power of the laser processing is 250W to 1000W, the spot size of the laser processing is 5um to 300um, and the step size of the laser processing is 5um to 1000um.

[0060] For example, the substrate 1 of the metal foil is obtained by laser drilling to form a substrate 1 with multiple accommodating holes 11. The micropores are fabricated by adjusting the laser power, spot size, etching time (pulse width), and spot step length. After ultrasonic cleaning, a current collector 100 with multiple accommodating holes 11 is formed. Furthermore, the fabrication technology of the current collector 100 with multiple accommodating holes 11 in this application is currently relatively mature. Only by changing conventional parameters such as laser power, spot size, etching time, and spot step length can the required diameter, depth, and spacing of the accommodating holes 11 be etched. This technology is relatively mature and reliable, and the above parameters are reasonably defined and easy to implement. At the same time, the morphology and particle size of the lithium powder are more suitable for mainstream products, and the coating density is more controllable.

[0061] According to some embodiments of the present invention, coating the lithium replenishing element 2 on one side surface of the substrate 1 having the receiving hole 11 specifically includes: coating the lithium replenishing element 2 on the one side surface of the substrate 1 having the receiving hole 11 by wet or dry method.

[0062] For example, lithium powder coated with conductive material 22 is applied to the surface of the substrate 1 having multiple accommodating holes 11 using a wet or dry method. By adjusting the coating and rolling parameters, after rolling, some of the lithium powder coated on the surface of the current collector 100 fills the accommodating holes 11 of the porous current collector 100, while some lithium powder covers the surface of the current collector 100. The thickness of the lithium replenishment layer covering the surface of the current collector 100 is h2, and the above parameters satisfy the inequality: This forms the lithium replenishment current collector.

[0063] According to some embodiments of the present invention, the active dressing 201 includes a carbon-based anode material, a silicon anode material, or a lithium-intercalated alloy material. The carbon-based anode material includes at least one of natural graphite, artificial graphite, soft carbon, hard carbon, mesophase carbon microspheres, nano-carbon, and carbon fiber.

[0064] For example, the active dressing 201 can be laminated onto the lithium replenishment layer surface of the current collector 100 using either a dry or wet process. A dry process is preferred. For instance, the active dressing 201 can be a negative electrode wet slurry composed of a carbon-based negative electrode material, a silicon negative electrode material, or a lithium-intercalated alloy material as the negative electrode active material, a conductive agent, and a binder, using an organic system stable to lithium metal such as NMP (N-methylpyrrolidone), DMC (dimethyl carbonate), DEC (diethyl carbonate), or EMC (methyl ethyl carbonate) as the solvent. Alternatively, a negative electrode dry electrode composed of a negative electrode active material, a conductive agent, and PTFE (polytetrafluoroethylene) can be prepared by coating or laminating the active dressing 201 onto the current collector 100 to obtain the negative electrode sheet 200. The carbon-based negative electrode material is preferably graphite or graphite-doped silicon material, and the preparation method can be either a wet or dry process.

[0065] A battery according to a fourth aspect of the present invention includes a current collector 100 according to the first aspect of the present invention, or a negative electrode 200 according to the second aspect of the present invention, or a negative electrode 200 prepared according to the preparation method of the third aspect of the present invention.

[0066] According to the embodiments of the present invention, by employing the above-mentioned current collector 100 or negative electrode 200, the battery can be used stably for a long time, and the battery capacity is increased, thereby improving the battery's reliability and extending its service life.

[0067] According to some embodiments of the present invention, the effective active material of the positive electrode of the battery can be lithium iron phosphate (LiFePO4), lithium manganese iron phosphate (LiMnxFe1-xPO4), or a ternary layered positive electrode such as LiNi x Co y M(1-xy) (M is Mn, Al, etc.), one or more of the lithium-rich manganese-based materials Li2MnO3•LiMO2 (M is usually Ni, Co, Mn or Ni, Co, Mn binary or ternary layered materials), can be prepared by wet or dry methods.

[0068] The embodiments of the present invention are described in detail below. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In addition, unless otherwise specified, all reagents used in the following embodiments are commercially available or can be synthesized according to the methods described herein or known to others. For reaction conditions not listed, they are also readily available to those skilled in the art.

[0069] The battery of the present invention will be described by way of exemplary specific embodiments in conjunction with comparative examples. The following tests will examine the battery performance of the current collectors 100 used in the embodiments and comparative examples.

[0070] (1) Lithium efficiency determination: The negative electrode sheets of Examples 1-6 and Comparative Examples 1-5 were used to form 1+2 symmetrical cells (referring to a symmetrical cell consisting of a negative electrode sheet and a lithium sheet on each side) and the first lithium insertion / extraction test was performed on these symmetrical cells. The non-lithium-compensated electrode sheet of Comparative Example 6 was used to form 1+2 symmetrical cells (also called non-lithium-compensated cells) and the first lithium insertion / extraction test was performed on these symmetrical cells.

[0071] The test steps for symmetrical batteries are as follows: At room temperature (25 degrees Celsius), the above symmetrical batteries are tested as follows to calculate the delithiation capacity and lithium insertion capacity of different batteries. The test steps are as follows: ① Let stand for 180 minutes ② Reduce voltage from 0.01C to 0.005V, and record the capacity at this step as the lithium insertion capacity (C). 嵌 ③ Let stand for 10 minutes ④ Reduce from 0.01°C to 1.0°C, and record the capacity at this step as the delithiation capacity (C). 脱 Lithium-ionization specific capacity = Lithium-ionization capacity (C) 嵌 The specific capacity of lithium metal is calculated as follows: (Lithium-intercalated specific capacity of non-lithium-filled batteries - Lithium-intercalated specific capacity of lithium-filled batteries) × Electrode surface density / Lithium-filled surface density (g / m³) 2 It should be noted that the above-mentioned electrode surface density and lithium replenishment surface density (ρ) are both single-sided vertical or double-sided values.

[0072] (2) Determination of peel strength: A negative electrode sheet with a width of 25 mm was prepared, and the peel force between the anode active material and the current collector was tested using a universal tensile testing machine.

[0073] (3) After the impedance test and capacity assessment, the SOC state of the battery was adjusted to 20%, and the EIS was tested in constant voltage mode at room temperature of 25℃ and -10℃ respectively. The frequency range was 10000~0.05Hz and the amplitude was 5mV.

[0074] (4) Cycle life test: The formed battery is subjected to a cycle test at room temperature of 25 degrees Celsius. The test steps are as follows: 1) rest for 10 minutes; 2) 0.5C CC-CV to 4.3V 0.05C cutoff; 3) rest for 10 minutes; 4) 0.5C CC to 2.0V.

[0075] Repeat the above steps n times until the retention rate reaches 80%, and record the number of cycles.

[0076] Example 1: Positive and negative electrode sheets 200 were prepared and assembled into a battery according to the following steps: 1) Preparation of positive electrode sheet: 100 parts of lithium manganese iron phosphate, 1 part of conductive carbon black Super_Li, 1 part of conductive carbon nanotubes CNT430 and 2.2 parts of binder (PVDF_5130) were dissolved and mixed by NMP. This slurry was then coated on aluminum foil with a coating density of 220 g / m² on one side. 2 Double-sided 440g / m 2 After being dried in an oven, the material is rolled, slit, and die-cut into positive electrode sheets.

[0077] 2) Preparation of substrate 1: The laser emitter power is set to 300W, the laser spot size is 25um, the laser etching time is 10000ps, and the laser stepping distance is 75um. A porous copper foil with a diameter r=35um, a depth h1=4um, and a spacing x=65um between two adjacent holes 11 is etched on both sides of a double-sided copper foil with a thickness of 8um. The holes 11 on both sides of the copper foil are staggered. After the micropores are prepared, ultrasonic cleaning is used for 10 minutes to remove impurities generated during the hole formation.

[0078] 3) Preparation of current collector 100: Lithium powder with a particle size D of 25 μm was coated onto the surface of the porous copper foil using a dry process, with a single-sided surface density of 1.2 g / m². 2 The areal density of both sides is 2.4 g / m³. 2 Adjust the roller press pressure to 0.6 MPa and the roller gap size to 60 μm to control the thickness of the lithium-filled layer after single-sided roller pressing to h2=2 μm.

[0079] 4) Preparation of negative electrode sheet 200: 100 parts graphite, 1 part conductive agent (Super_Li) and 4 parts PTFE (Daikin F104) were dry-mixed and extruded to form a self-supporting film with an areal density of 112 g / m² on one side. 2 Double-sided 224g / m 2 When combined with current collector 100, it forms a negative lithium supplement electrode (i.e., negative electrode 200).

[0080] 5) Die-cutting and stacking of positive and negative electrode sheets: After die-cutting the positive and negative electrode sheets, they are stacked with the separator to form a 7+8 layer soft-pack small cell. After being packaged in an aluminum shell or aluminum-plastic film, it is made into a battery. After electrolyte injection, it is charged and discharged for the first time. The battery is designed to have a capacity of 1900mAh.

[0081] 6) The battery electrolyte injection formation tank is used to form the battery after electrolyte injection by charging at a constant current of 0.05C for 2 hours and at a constant current of 0.2C for 3 hours.

[0082] 7) After the batteries are vacuumed, sealed and aged for 24 hours, they are subjected to capacity testing. The capacity testing steps are: charge at 1 / 3C constant current and constant voltage to 4.3V, let stand for 10 minutes, and discharge at 1 / 3C constant current to 2.0V. Record the discharge capacity at this time as C0.

[0083] Example 2 differs from Example 1 in that the stepping distance of the laser emitter is changed so that x = 70 μm, while the rest are the same.

[0084] Example 3 differs from Example 1 in that the stepping stroke of the laser emitter is changed so that x=55um, and the pressure or gap of the roller press after lithium powder coating is changed so that the single-sided thickness h2 of the lithium layer after roller pressing is 3um. All other aspects are the same.

[0085] Example 4 differs from Example 1 in that the stepping stroke of the laser emitter is changed so that x=60um, and the pressure or gap of the roller press after lithium powder coating is changed so that the single-sided thickness h2 of the lithium layer after rolling is 3um. All other aspects are the same.

[0086] Example 5 differs from Example 1 in that the stepping stroke of the laser emitter is changed to make x=50um, and the pressure or gap of the roller press after lithium powder coating is changed to make the single-sided thickness h2 of the lithium layer after roller pressing be 4um. All other aspects are the same.

[0087] Example 6 differs from Example 1 in that the stepping stroke of the laser emitter is changed to make x=55um, and the pressure or gap of the roller press after lithium powder coating is changed to make the single-sided thickness h2 of the lithium layer after roller pressing be 4um. All other aspects are the same.

[0088] Comparative Example 1 differs from Example 1 in that the step length of the laser emitter is changed so that x = 60 μm, while the rest are the same.

[0089] The difference between Comparative Example 2 and Example 1 is that the stepping stroke of the laser emitter is changed so that x=50um, and the pressure or gap of the roller press after lithium powder coating is changed so that the single-sided thickness of the lithium layer after rolling is h2=3um. All other aspects are the same.

[0090] Comparative Example 3 differs from Example 1 in that the step size of the laser emitter is changed so that x = 45 μm, while the rest are the same.

[0091] The difference between Comparative Example 4 and Example 1 is that the lithium replenishment site is located on the surface of the active dressing 201, while the rest are the same.

[0092] The difference between Comparative Example 5 and Example 1 is that the foil used is a double-sided glossy foil, and the foil is not pre-drilled. All other aspects are the same.

[0093] Comparative Example 6 differs from Example 1 in that it does not have a lithium replenishment element 21, but is otherwise identical (i.e., this example is the non-lithium replenishment electrode mentioned above).

[0094] The current collector 100 of the above embodiments and comparative examples is used to make a negative electrode 200, which is then combined with a separator by winding or stacking to form a secondary battery. After liquid injection and aging, the secondary battery is charged and discharged to allow the metallic lithium on the substrate 1 to be fully embedded in the active coating 201, forming a pre-lithiated negative electrode 200.

[0095] The parameter settings for the above embodiments and comparative examples are shown in the table below:

[0096] The performance test results of the above embodiments and comparative examples are shown in the table below:

[0097] As shown in the table above, the peel strength of Examples 1-6 is higher than that of the comparative example, indicating that the bonding strength between the current collector 100 and the active coating 201 is increased in the batteries prepared using the current collector 100 of this application. Furthermore, the specific capacity of Examples 1-6 is significantly higher than that of the comparative example, indicating that the loss of metallic lithium is significantly reduced in the batteries prepared using the lithium-replenishing current collector 100 of this application, resulting in improved specific capacity of metallic lithium with the same areal density, and full utilization of metallic lithium. In addition, the room temperature and low temperature impedance of Examples 1-6 are significantly lower than those of the comparative example, indicating that the metallic lithium in the batteries prepared using the lithium-replenishing current collector 100 of this application improves the composition of the SEI film by embedding it into the active material. The residual conductive polymer acts as a connector between the current collector 100 and the active material, enhancing the adhesion between the current collector 100 and the active material, thus significantly reducing the battery impedance. The battery capacity and cycle number of Examples 1-6 are significantly higher than those of the comparative example, indicating that the battery prepared using the lithium replenishing current collector 100 of this application has a significantly improved utilization rate of metallic lithium. The metallic lithium not only compensates for the loss of the SEI film, but also some metallic lithium is pre-stored in the negative electrode active material, which compensates for the continuous loss of active lithium during cycling. Therefore, the battery capacity and cycle number are significantly improved.

[0098] An electrical appliance according to a fifth aspect of the present invention includes a battery according to the fourth aspect of the present invention.

[0099] According to embodiments of the present invention, the performance of electrical devices is improved by employing the aforementioned batteries. Examples of such electrical devices include vehicles, aircraft, ships, computers, energy storage cabinets, etc.

[0100] Other configurations and operations of the current collector 100, electrode sheet, and electrical device according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

[0101] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0102] In the description of this invention, "a plurality of" means two or more.

[0103] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0104] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A current collector, characterized in that, include: A substrate, wherein a plurality of receiving holes are formed on at least one surface in the thickness direction of the substrate, the spacing between two adjacent receiving holes is x, the diameter of the receiving hole is r, and the depth of the receiving hole is h1; a lithium replenishing component, wherein a portion of the lithium replenishing component covers the at least one surface in the thickness direction of the substrate to form a lithium replenishing layer, and another portion of the lithium replenishing component fills the plurality of receiving holes, the thickness of the lithium replenishing layer being h2, wherein h2, x, r, and h1 satisfy: r 2 ×(h1+h2)≤x 2 ×h2.

2. The current collector according to claim 1, characterized in that, The x, r, and h1 satisfy the following conditions: 20um≤x≤120um, 20um≤r≤50um, and 2um≤h1≤6um, respectively.

3. The current collector according to claim 2, characterized in that, The x, r, and h1 further satisfy: 40um≤x≤90um, 30um≤r≤40um, and 3um≤h1≤5um.

4. The current collector according to claim 1, characterized in that, The h2 satisfies: 1um ≤ h2 ≤ 10um.

5. The current collector according to claim 4, characterized in that, The h2 further satisfies: 2um ≤ h2 ≤ 8um.

6. The current collector according to claim 1, characterized in that, When the lithium replenishing element is provided on one side surface of the substrate in the thickness direction, the lithium replenishing areal density of the lithium replenishing element is ρ, wherein ρ satisfies: 0.3 g / m³ 2 ≤ρ≤2.0g / m 2 .

7. The current collector according to claim 6, characterized in that, The ρ further satisfies: 0.5 g / m 2 ≤ρ≤1.5g / m 2 .

8. The current collector according to claim 1, characterized in that, The lithium replenishing component includes a lithium replenishing agent and a conductive material, wherein the conductive material is coated on the outer peripheral surface of the lithium replenishing agent.

9. The current collector according to claim 8, characterized in that, The lithium replenishing agent includes lithium powder; and / or the particle size of the lithium replenishing element is D, wherein D satisfies: 20um≤D≤60um.

10. The current collector according to claim 9, characterized in that, The D further satisfies: 30um ≤ D ≤ 50um.

11. The current collector according to claim 8, characterized in that, The conductive material includes at least one of polyaniline, polypyrrole, polydioxythiophene, poly(p-phenylene), polyphenylene sulfide, and polyphthalic acid compounds.

12. The current collector according to claim 11, characterized in that, The conductive material includes polyaniline.

13. The current collector according to claim 1, characterized in that, The receiving holes are formed on both sides of the thickness direction of the substrate, and the receiving holes on both sides of the substrate are staggered along the thickness direction of the substrate.

14. The current collector according to any one of claims 1-13, characterized in that, The substrate includes copper foil, nickel foil, or stainless steel foil.

15. The current collector according to claim 14, characterized in that, The substrate is a copper foil, and the thickness of the substrate is d, wherein d satisfies: 6um ≤ d ≤ 8um.

16. A negative electrode sheet, characterized in that, Includes the current collector according to any one of claims 1-15.

17. The method for preparing the negative electrode sheet according to claim 16, comprising the following steps: Multiple receiving holes are formed on the surface of the substrate; a lithium supplement is coated on the side surface of the substrate with the receiving holes, and then a roll forming process is performed; An active dressing is applied to the lithium replenishment component to obtain the negative electrode sheet.

18. The preparation method according to claim 17, characterized in that, The process of forming multiple receiving holes on the surface of the substrate specifically includes: forming multiple receiving holes on the surface of the substrate by laser processing, wherein the pulse width of the laser processing is 1000ps to 1000000ps, the power of the laser processing is 250W to 1000W, the spot size of the laser processing is 5um to 300um, and the step size of the laser processing is 5um to 1000um.

19. The preparation method according to claim 17, characterized in that, The process of coating the lithium replenishing element on the side surface of the substrate having the receiving hole specifically includes: coating the lithium replenishing element on the side surface of the substrate having the receiving hole by wet or dry methods.

20. The preparation method according to claim 17, characterized in that, The active dressing includes carbon-based anode materials, silicon anode materials, or lithium-intercalated alloy materials. The carbon-based anode materials include at least one of natural graphite, artificial graphite, soft carbon, hard carbon, mesophase carbon microspheres, nano-carbon, and carbon fiber.

21. A battery, characterized in that, It includes the current collector according to any one of claims 1-15, or the negative electrode sheet according to claim 16, or the negative electrode sheet prepared by the preparation method according to any one of claims 17-20.

22. An electrical appliance, characterized in that, Includes the battery according to claim 21.

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