Pole piece, battery, battery pack and electric equipment

Abstract

The invention provides a pole piece, a battery, a battery pack and electric equipment. The pole piece comprises a current collector base material; the liquid absorption layer is positioned on at least one side of the current collector base material; the liquid absorption layer comprises a porous current collector and an adsorption material located in the porous current collector; the active material layer is located on the side, away from the current collector base material, of the liquid absorption layer, and the surface of the active material layer is provided with a concave part. The low-temperature charging and discharging efficiency and the low-temperature fast charging performance of the battery can be improved.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to an electrode, a battery, a battery pack, and an electrical device. Background Technology

[0002] Batteries are common electrochemical devices with wide applications, and electrodes are an important component that affects battery performance, including low-temperature performance. However, in current technologies, the lithium-ion transport capacity of electrodes is poor under low-temperature conditions, resulting in higher battery impedance. This leads to common defects in batteries, such as poor low-temperature charge-discharge efficiency and poor low-temperature fast-charging performance, which limit the application and efficiency of batteries under low-temperature conditions and urgently need to be addressed. Summary of the Invention

[0003] This invention provides an electrode, a battery, a battery pack, and an electrical device that can improve the low-temperature charging and discharging efficiency and low-temperature fast charging performance of the battery.

[0004] In one aspect, the present invention provides an electrode sheet comprising: a current collector substrate;

[0005] An absorbent layer is located on at least one side of the current collector substrate; the absorbent layer includes a porous current collector and an adsorbent material located in the porous current collector;

[0006] An active material layer is located on the side of the liquid-absorbing layer opposite to the current collector substrate, and the surface of the active material layer is provided with a recess.

[0007] According to one embodiment of the present invention, the adsorbent material includes one or more of carbon black, silicon dioxide, titanium dioxide, alumina, and zeolite;

[0008] And / or, the primary particle size of the adsorbent material is 2 to 50 nm.

[0009] According to one embodiment of the present invention, the adsorbent material comprises titanium suboxide.

[0010] According to one embodiment of the present invention, the porosity of the porous current collector is 20% to 60%;

[0011] And / or, the pore size range of the porous current collector is 5 to 100 nm.

[0012] According to one embodiment of the present invention, the depth of the recess is 10 to 50 μm;

[0013] And / or, the width of the recess is 70–110 μm;

[0014] And / or, the distance between two adjacent recesses is 200 to 800 μm.

[0015] According to one embodiment of the present invention, the porous current collector includes a first sub-hole, a second sub-hole, and a third sub-hole;

[0016] The aperture range of the first sub-hole is 5-20 nm, the aperture range of the second sub-hole is 25-60 nm, and the aperture range of the third sub-hole is 75-100 nm.

[0017] According to one embodiment of the present invention, the volume fraction of the first sub-pore in the pore is 0.05 to 0.25, the volume fraction of the second sub-pore in the pore is 0.3 to 0.55, and the volume fraction of the third sub-pore in the pore is 0.1 to 0.5.

[0018] According to one embodiment of the present invention, the thickness of the electrode is 100–160 μm;

[0019] And / or, the thickness of the current collector substrate is 49.5–149.5 μm;

[0020] And / or, the thickness of the absorbent layer is 0.1–0.5 μm;

[0021] And / or, the thickness of the active material layer is 79.5–151.9 μm.

[0022] According to one embodiment of the present invention, the electrode includes a positive electrode.

[0023] In another aspect, the present invention provides a method for preparing the above-mentioned electrode, comprising the following steps:

[0024] 1) The liquid-absorbing layer is formed on at least one side of the current collector substrate;

[0025] 2) The active material layer is formed on the side of the liquid-absorbing layer away from the current collector substrate, and a recess is formed on the surface of the active material layer to obtain the electrode.

[0026] According to one embodiment of the present invention, the process of forming the liquid-absorbing layer on at least one side of the current collector substrate includes the following steps:

[0027] A portion of the current collector precursor is perforated to form the porous current collector, and the remaining portion of the current collector precursor is the current collector substrate.

[0028] A first slurry containing adsorbent material is coated onto the porous current collector to form the liquid absorption layer.

[0029] According to one embodiment of the present invention, the first slurry further includes a first binder;

[0030] And / or, the solid content of the first slurry is 20% to 65%.

[0031] According to one embodiment of the present invention, the process of forming an active material layer on the side of the absorbent layer away from the current collector substrate includes: mixing an active substance and a second solvent to form a second slurry, and coating the second slurry onto the surface of the absorbent layer away from the current collector substrate, so as to form the active material layer on the side of the absorbent layer away from the current collector substrate.

[0032] And / or, the process of forming a recess on the surface of the active material layer includes: performing laser scribing on the active material layer to form the recess on the surface of the active material layer, thereby obtaining the electrode.

[0033] In another aspect, the present invention provides a battery comprising the electrode sheet described above or the electrode sheet prepared by the above preparation method.

[0034] In another aspect, the present invention provides a battery pack comprising at least the batteries described above that are interconnected.

[0035] In another aspect, the present invention provides an electrical device including the battery or battery pack described above.

[0036] This invention provides an electrode, a battery, a battery pack, and an electrical device. The electrode comprises a current collector substrate, an absorbent layer, and an active material layer stacked sequentially. The absorbent layer includes a porous current collector and an adsorbent material, and the surface of the active material layer has recesses. In the electrode system, the absorbent layer enhances the wettability and liquid retention capacity of the electrolyte, ensuring sufficient contact and wetting of the electrolyte at low temperatures and improving the low-temperature ion conductivity of the electrode. Simultaneously, the recesses on the surface of the active material layer increase the specific surface area of ​​the active material layer, accelerating the insertion and extraction of active ions, promoting ion transport, and reducing interfacial resistance, thereby improving both the low-temperature charge / discharge efficiency and low-temperature fast charging performance of the battery. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a liquid-absorbing layer formed on one side of a current collector substrate according to an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of the structure of the current collector precursor (including the current collector substrate and the perforated area stacked sequentially) in an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of the electrode structure in an embodiment of the present invention.

[0040] Explanation of reference numerals in the attached figures:

[0041] 1-Current collector substrate; 2-Liquid absorbent layer; 3-Perforated area; 4-Current collector precursor; 5-Recess; 6-Active material layer; 7-Electrode; 8-Liquid-retaining current collector. Detailed Implementation

[0042] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] In related technologies, the transport capacity of active ions in the electrode is poor under low temperature conditions, resulting in high battery impedance. Consequently, batteries generally suffer from defects such as poor low-temperature charge and discharge efficiency and poor low-temperature fast charging performance, which urgently need to be addressed.

[0044] Taking lithium-ion batteries as an example, their applications are becoming increasingly widespread in electric vehicles, seabed exploration, space exploration, and polar scientific research. This has led to higher demands on the low-temperature performance of lithium-ion batteries (including low-temperature charge-discharge efficiency and low-temperature fast-charging performance). The low-temperature performance of lithium-ion batteries is mainly related to the low-temperature conductivity of the electrolyte, the electrode interface, and the diffusion ability of lithium ions in the active materials. Currently, improving the low-temperature performance of lithium-ion batteries is primarily achieved through designing highly conductive electrolytes and low-impedance electrode interfaces.

[0045] According to the inventors' research, adding adsorbent materials that can adsorb electrolyte to the electrode can enhance the wettability of the electrolyte, improve the transport capacity of active ions, and reduce impedance, thereby effectively improving the low-temperature performance of the battery. However, the addition of adsorbent materials also changes the complexity and tortuosity of the pores or channels inside the electrode material, which to some extent limits the further improvement of the low-temperature performance of the battery.

[0046] In view of this, embodiments of the present invention provide an electrode, such as Figure 3 As shown, it includes: a current collector substrate 1; a liquid absorbent layer 2 located on the first surface of the current collector substrate 1, the liquid absorbent layer 2 including a porous current collector and an adsorbent material located in the porous current collector; and an active material layer 6 located on the side of the liquid absorbent layer 2 away from the current collector substrate 1, the surface of the active material layer 6 (i.e. the surface away from the current collector substrate) is provided with a recess 5.

[0047] The electrode comprises a current collector substrate, an absorbent layer, and an active material layer stacked sequentially. The surface of the active material layer has recesses, which significantly improves the battery's low-temperature charge-discharge performance and low-temperature fast-charging capability. This is because the absorbent layer includes a porous current collector and an adsorbent material. The porous structure of the current collector enhances the wettability and liquid retention capacity of the electrolyte, while the adsorbent material effectively absorbs and retains the electrolyte, ensuring sufficient contact and wetting of the electrolyte at low temperatures and improving the electrode's low-temperature ion conductivity. Simultaneously, the recesses on the surface of the active material layer increase its specific surface area, providing more reaction sites, accelerating the insertion and extraction of active ions, promoting ion transport, and reducing interfacial resistance, thereby improving the battery's low-temperature charge-discharge efficiency and low-temperature fast-charging capability.

[0048] Furthermore, the prepared porous current collector with liquid retention function is easy to mass-produce.

[0049] In this embodiment of the invention, the adsorbent material includes one or more of carbon black, silicon dioxide, titanium suboxide, aluminum oxide, and zeolite, which facilitates better absorption and retention of the electrolyte, ensuring sufficient contact and wetting of the electrolyte at low temperatures, thereby further improving the low-temperature charge and discharge efficiency and low-temperature fast charging performance of the battery.

[0050] In some embodiments, the primary particle size of the adsorbent material is 2-50 nm, which has a high specific surface area and adsorption capacity, thus helping to further improve the low-temperature charge and discharge efficiency and low-temperature fast charging performance of the battery.

[0051] For example, the primary particle size of the adsorbent material can be 2nm, 5nm, 10nm, 20nm, 30nm, 40nm or 50nm, etc.

[0052] In this embodiment of the invention, the primary particle size of the adsorbent material is measured using conventional methods in the art, such as a laser particle size analyzer. Specifically, the battery can be fully discharged (i.e., discharged to 0% state of charge (0% SOC)) to ensure operational safety. Then, the battery is disassembled, and the active material layer of the electrode is peeled from the liquid-retaining current collector (including the current collector substrate and the liquid-absorbing layer). The adsorbent material on the liquid-retaining current collector is then scraped off with a scraper to obtain the adsorbent material. This adsorbent material is then fully dispersed to ensure that the particles do not aggregate, and the primary particle size of the adsorbent material is measured using a laser particle size analyzer.

[0053] In some embodiments, the adsorbent material includes titanium suboxide, which is easily dispersed and has good conductivity. At the same time, the surface defects of titanium suboxide give it better liquid retention capacity, which is beneficial to further improve the low-temperature charge and discharge efficiency and low-temperature fast charging performance of the battery.

[0054] In this embodiment of the invention, the porosity of the porous current collector is 20% to 60%, which can improve the structural stability of the electrode, as well as the permeation and ion transport capabilities of the electrolyte in the electrode, thereby further improving the low-temperature charge and discharge efficiency and low-temperature fast charging performance of the battery, preferably 20% to 50%.

[0055] For example, the porosity of the porous current collector can be 20%, 30%, 40%, 50%, or 60%, etc.

[0056] In this embodiment of the invention, the porosity of a porous current collector can be measured by mercury intrusion porosimetry. Specifically, the porous current collector with perforations is used as a sample. After vacuum drying at 105°C, the sample tube is placed inside a mercury intrusion porosimetry device. The volume of mercury injected / removed is measured using a metal jacket and electrode cap. The test environment temperature is 20±5°C, and the test pressure range is 15-30000 pisa. Twenty data points are collected at each order of magnitude, and the average value is taken as the porosity of the porous current collector.

[0057] In some implementations, the porous current collector has a pore size range of 5–100 nm, which helps to better enhance ion transport and improve electrolyte wettability, thereby further improving the battery's low-temperature charge-discharge efficiency and low-temperature fast charging performance.

[0058] For example, the pore size of the porous current collector can be 5nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm or 100nm, etc.

[0059] In this embodiment of the invention, the pore size range of the porous current collector is obtained using the BET pore size distribution method. Specifically, the battery can be fully discharged (i.e., discharged to 0% state of charge (0% SOC)) to ensure operational safety. Then, the battery is disassembled, and the active material layer of the electrode is peeled off from the liquid-retaining current collector (including the current collector substrate and the liquid-absorbing layer). The adsorbed material on the liquid-retaining current collector is then scraped off with a scraper to obtain the porous current collector. The porous current collector is placed in a BET analyzer. The pore size distribution of the porous current collector is measured through processes such as nitrogen adsorption-desorption.

[0060] In some embodiments, adjusting the depth, width, and spacing between adjacent recesses increases the specific surface area of ​​the active material layer, providing more reaction sites and allowing the electrolyte to better penetrate the active material layer. Simultaneously, this recess design shortens the diffusion path of ions within the active material layer, reducing diffusion resistance and further improving the battery's low-temperature charge / discharge efficiency and low-temperature fast charging capability. In some embodiments, the recess depth is 10–50 μm, the recess width is 70–110 μm, and the spacing between adjacent recesses is 200–800 μm.

[0061] For example, the depth of the recess can be 10μm, 20μm, 30μm, 40μm or 50μm, etc.

[0062] For example, the width of the recess can be 70μm, 80μm, 90μm, 100μm or 110μm, etc.

[0063] For example, the distance between two adjacent recesses can be 200μm, 300μm, 400μm, 500μm, 600μm, 700μm or 800μm, etc.

[0064] In this embodiment of the invention, the porous current collector includes a first sub-pore, a second sub-pore, and a third sub-pore. The pore size of the first sub-pore ranges from 5 to 20 nm, the second sub-pore ranges from 25 to 60 nm, and the third sub-pore ranges from 75 to 100 nm. The first sub-pore provides a high specific surface area, increasing the contact area between the electrode material and the electrolyte; the second sub-pore helps optimize the permeability and ion transport efficiency of the electrolyte; and the third sub-pore mainly enhances the rapid penetration and distribution of the electrolyte. This multi-level porous structure provides multiple ion transport pathways through synergistic effects, reducing the diffusion distance and resistance of active ions in the electrode, and facilitating rapid and uniform wetting of the entire electrode material by the electrolyte, thereby further improving the low-temperature charge-discharge efficiency and low-temperature fast-charging performance of the battery.

[0065] For example, the aperture range of the first sub-aperture can be 5nm, 10nm, 15nm or 20nm, etc.

[0066] For example, the aperture range of the second sub-aperture can be 25nm, 30nm, 40nm, 50nm, 60nm, etc.

[0067] For example, the aperture range of the third sub-aperture can be 75nm, 80nm, 90nm or 100nm, etc.

[0068] In this embodiment of the invention, the volume fractions of the first, second, and third sub-pores of the porous current collector made by perforating aluminum foil can be measured using the BET pore size distribution method. Specifically, the battery can be fully discharged (i.e., discharged to 0% state of charge (0% SOC)) to ensure operational safety. The battery is then disassembled, and the active material layer of the electrode is peeled off from the liquid-retaining current collector (including the current collector substrate and the liquid-absorbing layer). The adsorbed material on the liquid-retaining current collector is then scraped off with a scraper to obtain the porous current collector. The porous current collector is placed in a BET analyzer. The volume fractions of the first, second, and third sub-pores of the porous current collector are measured through processes such as nitrogen adsorption-desorption.

[0069] In some embodiments, the volume fraction of the first sub-pore in the pore is 0.05 to 0.25, preferably 0.1 to 0.25; the volume fraction of the second sub-pore in the pore is 0.3 to 0.55, preferably 0.3 to 0.5; and the volume fraction of the third sub-pore in the pore is 0.1 to 0.5, preferably 0.1 to 0.3, which is beneficial to further improve the low-temperature charge and discharge efficiency and low-temperature fast charging performance of the battery.

[0070] In this embodiment of the invention, the volume fraction of the first sub-pore in the pore is = (volume of the first sub-pore / (volume of the first sub-pore + volume of the second sub-pore + volume of the third sub-pore)) × 100%; the volume fraction of the second sub-pore in the pore is = (volume of the second sub-pore / (volume of the first sub-pore + volume of the second sub-pore + volume of the third sub-pore)) × 100%; the volume fraction of the third sub-pore in the pore is = (volume of the third sub-pore / (volume of the first sub-pore + volume of the second sub-pore + volume of the third sub-pore)) × 100%.

[0071] For example, the volume fraction of the first sub-pore in the pore can be 0.05, 0.1, 0.15, 0.2 or 0.25, etc.

[0072] For example, the volume fraction of the second sub-pore in the pore can be 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, etc.

[0073] For example, the volume fraction of the third sub-pore in the pore can be 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45 or 0.5, etc.

[0074] In this embodiment of the invention, by adjusting the thickness of the electrode, the current collector substrate, the absorbent layer, and the active material layer, it is beneficial to shorten the ion diffusion path, improve the ion conduction rate at low temperatures, and reduce the interfacial impedance between the electrode and the electrolyte, thereby further improving the low-temperature charge-discharge efficiency and low-temperature fast-charging performance of the battery. In some embodiments, the electrode thickness is 100–160 μm, the current collector substrate thickness is 49.5–149.5 μm, the absorbent layer thickness is 0.1–0.5 μm, and the active material layer thickness is 79.5–151.9 μm.

[0075] For example, the thickness of the electrode can be 100μm, 110μm, 120μm, 130μm, 140μm, 150μm or 160μm, etc.

[0076] For example, the thickness of the current collector substrate can be 49.5 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm or 160 μm, etc.

[0077] For example, the thickness of the absorbent layer can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm or 0.5 μm, etc.

[0078] For example, the thickness of the active material layer can be 79.5 μm, 85 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm or 151.9 μm, etc.

[0079] This invention also provides a method for preparing the above-mentioned electrode, comprising the following steps: 1) forming an absorbent layer on one side of a current collector substrate; 2) forming an active material layer on the side of the absorbent layer away from the current collector substrate, and forming a recess on the surface of the active material layer to obtain the electrode. The above-mentioned electrode preparation method is simple to operate, easy to implement for large-scale production, and suitable for industrial applications.

[0080] In some embodiments, the process of forming an absorbent layer on at least one side of the current collector substrate includes the following steps: perforating a portion of the current collector precursor to form a porous current collector, wherein the remaining portion of the current collector precursor is the current collector substrate.

[0081] Specifically, when an absorbent layer is provided on one side of the current collector substrate, such as Figure 2 As shown, this portion (perforated area 3) is a partial area on one side of the current collector precursor 4, and the remaining portion of the current collector precursor 4 (i.e., the unperforated area) is the current collector substrate 1. When liquid-absorbing layers are provided on both sides of the current collector substrate, this portion (perforated area) includes a first perforated area on one side of the current collector precursor and a second perforated area on the other side of the current collector precursor, and the remaining unperforated area is the current collector substrate, which is located between the first and second perforated areas.

[0082] In some embodiments, the drilling process includes laser drilling, in which the current is 5-65 mA, the time is 50-250 μs, the frequency is 50-250 Hz, and the average speed is 0.3-2.5 m / min, which is beneficial for adjusting the pore size and distribution of the porous current collector.

[0083] In some implementations, the laser drilling process can be performed using conventional laser drilling instruments in the art, without any particular limitation, such as CO2 lasers, ultraviolet lasers, fiber lasers, etc.

[0084] In some embodiments, the current collector is a current collector conventionally used in the art, and there is no special limitation thereto; for example, it can be copper foil.

[0085] In some embodiments, the first adhesive may be a conventional adhesive material in the art. For example, the first adhesive may include one or more of polyvinylidene fluoride (PVDF), polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, etc.

[0086] In some embodiments, the first solvent includes N-methylpyrrolidone (NMP), which facilitates uniform mixing of the adsorbent material and the first binder.

[0087] In some embodiments, the process of coating the first slurry onto the surface of the porous current collector away from the current collector substrate to form an absorbent layer on at least one side of the current collector substrate further includes: coating the first slurry onto the surface of the porous current collector away from the current collector substrate, and drying it to form an absorbent layer on at least one side of the current collector substrate.

[0088] In some embodiments, the mass ratio of the first binder to the adsorbent material is 1:(0.3 to 0.7). The first binder is used to firmly fix the adsorbent material onto the porous current collector, ensuring the stability of the adsorbent material in the porous current collector, thereby further improving the charge and discharge efficiency and fast charging performance of the battery under low temperature conditions.

[0089] For example, the mass ratio of the first binder to the adsorbent material can be 1:0.3, 1:0.4, 1:0.5, 1:0.6 or 1:0.7, etc.

[0090] In this embodiment of the invention, the solid content of the first slurry is 20% to 65%, which is beneficial for the uniform distribution of the first slurry in the porous structure of the porous current collector and avoids clogging of the pores. Preferably, it is 20% to 50%.

[0091] For example, the solid content of the first slurry can be 20%, 30%, 40%, 50%, 60%, or 65%, etc.

[0092] In this embodiment of the invention, the process of forming an active material layer on the side of the absorbent layer away from the current collector substrate includes: mixing an active substance and a second solvent to form a second slurry, and coating the second slurry onto the surface of the absorbent layer away from the current collector substrate to form an active material layer on the side of the absorbent layer away from the current collector substrate.

[0093] In some embodiments, the process of forming an active material layer on the side of the absorbent layer away from the current collector substrate further includes: mixing an active substance, a second binder, a conductive agent, and a second solvent to form a second slurry; coating the second slurry onto the surface of the absorbent layer away from the current collector substrate; and drying the slurry to form an active material layer on the side of the absorbent layer away from the current collector substrate.

[0094] In this embodiment of the invention, the process of forming a recess on the surface of the active material layer includes: forming a recess on the surface of the active material layer using a laser.

[0095] In some embodiments, the process of forming a recess on the surface of the active material layer includes: laser scribing the active material layer to form a recess on the surface of the active material layer, thereby obtaining an electrode.

[0096] In some embodiments, the active material layer may contain 70% to 99% by mass, for example, 70%, 75%, 80%, 85%, 90%, 93%, 95%, 97%, 99%, or any combination thereof; the conductive agent may contain 0.5% to 15% by mass, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 8%, 10%, 13%, 15%, or any combination thereof; the second solvent may include, for example, N-methylpyrrolidone (NMP); and the second binder may contain 0.5% to 15% by mass, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 8%, 10%, 13%, 15%, or any combination thereof.

[0097] The embodiments of the present invention do not impose special limitations on the areal density of the electrode; for example, the areal density of the electrode can be 50–700 g / m³. 2 For example, 50g / m 2 100g / m 2 150g / m 2 200g / m 2 250g / m 2 300g / m 2 350g / m 2 400g / m 2 450g / m 2 500g / m 2 550g / m 2 600g / m 2 650g / m 2 700g / m 2 or a range consisting of any two of them.

[0098] In this embodiment of the invention, the test process for the areal density of the electrode is as follows: a circular sampler is used to sample the liquid-retaining current collector and the electrode to obtain a liquid-retaining current collector sample and an electrode (positive electrode or negative electrode) sample. The mass m1 of the electrode sample and the mass m2 of the liquid-retaining current collector are tested. The areal density of the electrode is calculated as (m1-m2) / S (where S is the area of ​​the original sampler).

[0099] The embodiments of the present invention do not impose special limitations on the compaction density of the electrode sheet; for example, the compaction density of the electrode sheet can be 2.1 g / m³. 3 ~3.1g / m 3 For example, 2.1g / m 3 2.3g / m 3 2.5g / m 3 2.7g / m 3 2.9g / m 3 3.1g / m 3 or a range consisting of any two of them.

[0100] In this embodiment of the invention, the electrode can be either a positive electrode or a negative electrode.

[0101] In detail, when the electrode is a positive electrode, the current collector substrate is a positive current collector substrate, the liquid absorption layer is a positive liquid absorption layer, and the active material layer is a positive active material layer. Specifically, the positive liquid absorption layer can be provided on one side surface of the positive current collector substrate in the thickness direction, and the positive active material layer can be provided on the side surface of the positive liquid absorption layer away from the positive current collector substrate.

[0102] The positive electrode active material layer may include a positive electrode active material, a conductive agent, and a binder. In the positive electrode active material layer, the mass percentage of the positive electrode active material may be 70% to 99%, for example, 70%, 75%, 80%, 85%, 90%, 93%, 95%, 97%, 99%, or any combination thereof. The mass fraction of the binder may be 0.5% to 15%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 8%, 10%, 13%, 15%, or any combination thereof.

[0103] The binder for the positive electrode active layer can be one or more of the following: composite polyvinylidene fluoride (PVDF), polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, etc.

[0104] In some embodiments, the positive electrode active material may include LiCoO2, LiNiO2, or LiCo. x Ni 1-x O2 (0≤x≤1), LiCo x Ni 1-x-y Al y O2(0≤x≤1,0≤y≤1), LiMn2O4, LiFe x Mn y M zO4 (M is one or more of Al, Mg, Ga, Cr, Co, Ni, Cu, Zn or Mo, 0≤x≤1, 0≤y≤1, 0≤z≤1, x+y+z=1), Li 1+x L 1－y－z M y N z O2 (L, M, N are one or more of Li, Co, Mn, Ni, Fe, Al, Mg, Ga, Ti, Cr, Cu, Zn, Mo, F, I, S, B, -0.1≤x≤0.2, 0≤y≤1, 0≤z≤1, 0≤y+z≤1), LiFePO4, Li3V2(PO4)3, Li3V3(PO4)3, LiVPO4F, Li2CuO2, Li5FeO4, and metal sulfides and oxides (such as TiS2, V2S3, FeS, FeS2, LiMS) x (M is at least one of the transition metal elements such as Ti, Fe, Ni, Cu, Mo, etc., 1≤x≤2.5), TiO2, Cr3O8, V2O5, MnO2, etc.

[0105] The embodiments of the present invention may employ conventional positive current collector substrates in the art, such as copper foil.

[0106] In one specific embodiment, when the electrode is a negative electrode, the current collector substrate is a negative current collector substrate, the liquid absorption layer is a negative liquid absorption layer, and the active material layer is a negative active material layer. Specifically, the negative liquid absorption layer can be provided on one side surface of the negative current collector substrate in the thickness direction, and the negative active material layer can be provided on the side surface of the negative liquid absorption layer away from the negative current collector substrate.

[0107] The negative electrode active material layer may include a negative electrode active material, a conductive agent, and a binder, or the negative electrode active material layer may include a composite active material, a conductive agent, and a binder. The composite active material is obtained by coating the negative electrode active material with a coating material using chemical vapor deposition (CVD), resulting in a composite active material with a negative electrode active material core and an amorphous carbon coating layer. The coating material may be, for example, pitch. The negative electrode active material may be a conventional negative electrode active material in the art, such as one or more of graphite, hard carbon, soft carbon, and silicon carbide. The conductive agent may include one or more of conductive carbon black, carbon nanotubes (CNTs), acetylene black, graphene, Ketjen black, and carbon fiber. The binder can be a conventional bonding material in the art. For example, the binder in the negative electrode active material layer may include one or more of the following: styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, ethylene oxide-containing polymers, polyvinylpyrrolidone, and polyurethane. Generally, the mass percentage of the negative electrode active material in the negative electrode active material layer can be 80% to 100%, and the mass percentage of the negative electrode active material in the negative electrode active material layer can be, for example, 80%, 82%, 85%, 88%, 90%, 92%, 95%, 98%, 100%, or any combination thereof.

[0108] The embodiments of the present invention may employ conventional negative electrode current collector substrates in the art, for example, negative electrode current collector substrates include copper foil.

[0109] This invention also provides a battery, including an electrode sheet, which includes the electrode sheet described above. This battery has advantages corresponding to the electrode sheet described above, which will not be elaborated further.

[0110] In some embodiments, the battery described above may be a lithium-ion battery.

[0111] Generally, a battery includes an electrolyte, a battery cell, and a casing that encapsulates the battery cell. The electrolyte is injected into the battery cell inside the casing. The battery cell includes a positive electrode, a negative electrode, and a separator located between the positive and negative electrode. The battery cell can be a stacked cell, meaning it is composed of alternating layers of positive electrode, separator, and negative electrode; or it can be a wound cell, meaning it is composed of stacked positive electrode, separator, and negative electrode, which are then wound together.

[0112] The electrolyte in this embodiment of the invention can be a conventional electrolyte in the art. For example, the electrolyte is a non-aqueous electrolyte, which may specifically include organic solvents, additives, and electrolyte salts. Organic solvents include one or more of ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and propylene carbonate (PC). Additives include, for example, fluoroethylene carbonate (FEC), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and methyl methoxydisilane (MMDS). Electrolyte salts may include lithium salts, such as lithium hexafluorophosphate (LiPF6), but are not limited thereto.

[0113] In this embodiment of the invention, the separator is used to separate the positive electrode and the negative electrode to prevent the positive electrode and the negative electrode from short-circuiting due to contact. Conventional separators in the art can be used in this embodiment of the invention, and there are no special limitations on this.

[0114] In this embodiment of the invention, the battery cell can be packaged using conventional housing materials in the art, such as flexible packaging materials like aluminum-plastic film, but is not limited thereto.

[0115] In this embodiment of the invention, components such as positive electrode, separator and negative electrode can be assembled into a battery using conventional methods in the art. For example, positive electrode, separator and negative electrode can be stacked in an alternating manner to obtain a stacked cell (or wound into a wound cell); then the cell is placed in a casing (outer packaging) and after conventional processes such as electrolyte injection (i.e., injection of electrolyte) and encapsulation, a battery is obtained.

[0116] This invention also provides a battery pack comprising at least two batteries as described above that are interconnected. This battery pack has advantages corresponding to the batteries described above, which will not be elaborated further.

[0117] The battery pack includes multiple batteries as individual cells, which are connected to form the battery pack. These batteries can be electrically connected using methods conventional in the art, such as series connection, parallel connection, or a combination of these connection methods, without any particular limitation.

[0118] This invention also provides an electrical device, including the battery or battery pack described above. This electrical device has advantages corresponding to the battery described above, which will not be elaborated further.

[0119] The electrical equipment in the embodiments of the present invention can be conventional electrical equipment in the art, such as power equipment (e.g., electric vehicles, electric cars), electronic equipment (e.g., mobile phones, tablets, laptops, digital cameras, etc.), wearable devices (e.g., watches, bracelets, VR glasses, etc.), energy storage power stations, etc., and there are no particular limitations.

[0120] The present invention will be further described below through specific embodiments.

[0121] Example 1

[0122] 1. Preparation of positive electrode sheet

[0123] 1) such as Figure 1 As shown, along the thickness direction of the current collector precursor (copper foil) 4, the current collector precursor (copper foil) 4 is divided into two regions, including an un-drilled region (i.e., current collector substrate 1) and a drilled region 3 stacked sequentially. The drilled region 3 is laser-drilled using a laser drilling machine to form a porous current collector on one side of the current collector substrate 1.

[0124] In the laser drilling process, the power is 30%, the frequency is 60kHz, the speed is 2000 mm / s, and the time is 45s.

[0125] The porous current collector has a porosity of 35%, and the pores include a first sub-pore (pore size range of 5-20 nm), a second sub-pore (pore size range of 20-60 nm), and a third sub-pore (pore size range of 60-100 nm). The volume fraction of the first sub-pore in the pores is 10%, the volume fraction of the second sub-pore in the pores is 45%, and the volume fraction of the third sub-pore in the pores is 35%.

[0126] 2) Mix carbon black (primary particle size of 30nm), styrene-butadiene rubber and NMP to form a first slurry with a solid content of 25%, wherein the mass ratio of carbon black to styrene-butadiene rubber is 1.5. Coat the first slurry on the surface of the porous current collector and dry it to obtain a liquid-retaining current collector 8 including current collector substrate 1 and liquid-absorbing layer 2.

[0127] 3) Lithium iron phosphate, polyvinylidene fluoride (PVDF), NMP, and conductive agents (including carbon nanotubes and carbon black, with a mass ratio of carbon nanotubes to carbon black of 0.5:1) are mixed to form a second slurry. The second slurry is coated onto the surface of the absorbent layer 2 away from the current collector substrate 1, dried at 110°C, cold-pressed, and die-cut to form an active material layer 6. The active material layer 6 is then laser-scribed to form recesses 5 on its surface, resulting in a positive electrode sheet 7.

[0128] The depth of the recess is 30 μm, the width of the recess is 90 μm, the spacing between adjacent recesses is 145 μm, and the areal density of the positive electrode is 450 g / m³. 2 The compaction density of the positive electrode is 2.53 g / m³. 3 .

[0129] 2. Preparation of electrolyte

[0130] The electrolyte was prepared in an argon-atmospheric glove box with a water content of <10 ppm. First, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were mixed in a certain mass ratio of 3:2:2. Then, lithium salts (containing lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI) in a mass ratio of 2:1) were added. Subsequently, additives (based on the mass of the electrolyte, the additives contained 10 wt% ethylene carbonate (VC), 2 wt% fluoroethylene carbonate (FEC), and 2 wt% vinyl methane disulfonate (MMDS)) were added and mixed evenly to obtain the electrolyte.

[0131] 3. Preparation of negative electrode sheet

[0132] Graphite was coated with asphalt using chemical vapor deposition (CVD) to obtain a composite active material with a graphite core and an amorphous carbon coating layer. The composite active material was dispersed using N-methylpyrrolidone (NMP) to obtain a negative electrode slurry. The negative electrode slurry was then sieved (through a 200-mesh sieve) and coated onto a negative electrode current collector (copper foil). After drying at 100°C, cold pressing, and die-cutting, a negative electrode sheet was obtained. The mass ratio of the composite active material, conductive agent (carbon black), and binder (CMC) in the negative electrode slurry was 100:1.5:3.4.

[0133] 4. Preparation of lithium-ion batteries

[0134] In an argon-filled glove box, the positive electrode, polypropylene (PP) separator, and negative electrode are stacked in sequence to obtain a battery cell. The separator must completely separate the positive and negative electrode cells. The stacked battery cell is then placed into an aluminum-plastic film soft package and injected with the electrolyte. After vacuum sealing, settling, formation, aging, capacity testing, cutting, and sealing, a lithium-ion battery is obtained.

[0135] Examples 2 to 22 differ from Example 1 in that the type of adsorbent material, the primary particle size r1 of the adsorbent material, the porosity p of the porous current collector, the pore size range r2 of the porous current collector, the depth h of the recess, the width L1 of the recess, the length L2 of the recess, the volume fraction x1 of the first sub-pore in the pore, the volume fraction x2 of the second sub-pore in the pore, the volume fraction x3 of the third sub-pore in the pore, the thickness d1 of the current collector, the thickness d2 of the current collector substrate, the thickness d3 of the liquid absorption layer, the thickness d4 of the active material layer, and the solid content s of the first slurry are all different. For details, please refer to Table 1. Except for the differences shown in Table 1, the remaining steps and conditions are the same as in Example 1.

[0136] Comparative Example 1

[0137] The difference between this comparative example and Example 1 is that: during the preparation of the positive electrode, the active material layer was not laser-scribed, and no recesses were formed on the surface of the active material layer. All other conditions and steps were the same as in Example 1, and the areal density of the positive electrode was 450 g / m³. 2 The compaction density of the positive electrode is 2.53 g / m³. 3 .

[0138] Comparative Example 2

[0139] The difference between this comparative example and Example 1 is that: in the preparation process of the positive electrode sheet, no liquid-absorbing layer was set on one side of the current collector substrate, and no recess was formed on the surface of the active material layer; the remaining conditions and steps are the same as in Example 1. The specific preparation process of the positive electrode sheet includes the following steps: using copper foil as the current collector, lithium iron phosphate, polyvinylidene phosphate (PVDF), NMP, and a conductive agent (including carbon nanotubes and carbon black, with a mass ratio of carbon nanotubes to carbon black of 0.5:1) are mixed to form a second slurry. The second slurry is coated onto the surface of the copper foil, dried at 110°C, cold-pressed, and die-cut to obtain the positive electrode sheet. The areal density of the positive electrode sheet is 450 g / m³. 2 The compaction density of the positive electrode is 2.53 g / m³. 3 .

[0140] 1) Primary particle size of the adsorbent material: The battery can be fully discharged (i.e., discharged to 0% state of charge (0% SOC)) to ensure operational safety. Then, the battery is disassembled, and the active material layer of the electrode is peeled off from the liquid-retaining current collector (including the current collector substrate and the liquid-absorbing layer). Then, the adsorbent material on the liquid-retaining current collector is scraped off with a scraper to obtain the adsorbent material. The above adsorbent material is fully dispersed to ensure that the particles do not aggregate. The primary particle size of the adsorbent material is then measured by a laser particle size analyzer.

[0141] 2) Porosity of porous current collector: The porous current collector after drilling is used as a sample. After vacuum drying at 105℃, the sample tube is placed in the mercury intrusion porosimeter. The mercury injection / extraction volume is measured through the metal jacket and electrode cap. The test environment temperature is 20±5℃, the test pressure range is 15-30000 pisa, and twenty data points are collected for each order of magnitude. The average value is the porosity of the porous current collector.

[0142] 3) Pore size range of the porous current collector: The battery is fully discharged (i.e., discharged to 0% state of charge (0% SOC)) to ensure operational safety. The battery is then disassembled, and the active material layer of the electrode is peeled off from the liquid-retaining current collector (including the current collector substrate and the liquid-absorbing layer). The adsorbed material on the liquid-retaining current collector is then scraped off with a scraper to obtain the porous current collector. The porous current collector is placed in a BET analyzer. The pore size distribution of the porous current collector is measured through processes such as nitrogen adsorption-desorption.

[0143] 4) Pore diameter ranges of the first, second, and third sub-pores: The battery is fully discharged (i.e., discharged to 0% state of charge (0% SOC)) to ensure operational safety. The battery is then disassembled, and the active material layer of the electrode is peeled from the liquid-retaining current collector (including the current collector substrate and the liquid-absorbing layer). The adsorbed material on the liquid-retaining current collector is then scraped off with a scraper to obtain a porous current collector. The porous current collector is placed in a BET analyzer. Through nitrogen adsorption-desorption processes, the pore diameter ranges of the first, second, and third sub-pores of the porous current collector are measured.

[0144] 5) Volume fractions of the first, second, and third sub-pores in the pore structure: The battery is fully discharged (i.e., discharged to 0% state of charge (0% SOC)) to ensure operational safety. The battery is then disassembled, and the active material layer of the electrode is peeled from the liquid-retaining current collector (including the current collector substrate and the liquid-absorbing layer). The adsorbed material on the liquid-retaining current collector is then scraped off with a scraper to obtain a porous current collector. The porous current collector is placed in a BET analyzer. The volume fractions of the first, second, and third sub-pores of the porous current collector are measured through nitrogen adsorption-desorption processes.

[0145] Table 1 summarizes the following parameters in each embodiment and comparative example: type of adsorbent material, primary particle size r1 of adsorbent material, porosity p of porous current collector, pore size range r2 of porous current collector, depth h of recess, width L1 of recess, distance L2 between two adjacent recesses, volume fraction x1 of the first sub-pore in the pore, volume fraction x2 of the second sub-pore in the pore, volume fraction x3 of the third sub-pore in the pore, thickness d1 of electrode, thickness d2 of current collector substrate, thickness d3 of liquid absorption layer, thickness d4 of active material layer, and solid content s of first slurry. Except for the differences shown in Table 1, the other conditions are basically the same.

[0146] Table 1

[0147]

[0148]

[0149] The positive electrode and lithium-ion battery in the above embodiments and comparative examples were tested as follows:

[0150] 1) Positive electrode resistivity: A constant current is applied through the electrode under a certain pressure, and the resistivity is obtained by measuring the voltage drop. The test results include the resistance of the auxiliary material layer, the contact resistance between the auxiliary material layer and the current collector, and the contact resistance between the sample and the probe.

[0151] 2) Liquid-phase diffusion impedance of the positive electrode: When the charge transfer resistance (Rct) is extremely high, the impedance change of the electrode can be measured by applying a small-amplitude sinusoidal potential signal of a certain frequency, thereby eliminating the influence of charge transfer and solid-phase diffusion. The impedance of the electrode system is measured as a function of the sinusoidal frequency, and the spectrum is then analyzed and fitted to obtain information on electrode process kinetics and electrode interface structure. Generally, an equivalent circuit can be fitted to obtain the diffusion impedance value of lithium ions in the electrolyte, which is used to characterize the internal impedance of the battery. The liquid-phase diffusion impedance of the electrode can, to a certain extent, represent the lithium ion transport in the electrochemical system and can be reflected in the battery's kinetic performance.

[0152] The specific testing method is as follows: Assemble the two positive electrode plates and the separator in sequence to form the electrode core; place the electrode core in the outer packaging shell, bake it, inject electrolyte, and after encapsulation and wetting processes, obtain a liquid phase diffusion impedance battery. Perform liquid phase diffusion impedance testing using an electrochemical workstation within the frequency range of 300,000 Hz to 0.05 Hz.

[0153] 3) Peel force of the positive electrode: Measured using a tensile testing machine, the peel force characterizes the adhesion between the active material layer and the current collector; it is the force required to peel the active material layer from the current collector. Insufficient peel force may lead to poor contact between the active material layer and the current collector, increasing contact resistance and affecting the battery's low-temperature kinetic performance. Furthermore, it may cause the active material layer to detach during manufacturing or use, affecting the battery's stability.

[0154] 4) -10℃, 1 / 3C charging capacity ratio: Record the rated capacity C0 of the lithium-ion battery (the rated capacity of the lithium-ion battery under standard conditions (usually 25℃)). Place it in an environmental chamber and discharge it to full discharge at 25℃ with a constant current of 1 / 3C0. Then, keep the battery at -10℃ for 4 hours. Next, charge it to 3.6V with a constant current of 1 / 3C0, and record the charging capacity as C1. Calculate (C1 / C0)×100% to obtain the charging capacity ratio under -10℃, 1 / 3C conditions. The results are shown in Table 2.

[0155] 5) -10℃, 1 / 3C discharge capacity ratio: Record the calibrated capacity C0 of the lithium-ion battery, place it in an environmental chamber, and discharge it to full discharge at 25℃ with a constant current of 1 / 3C0. Then, keep the battery at -10℃ for 4 hours. Next, charge it to 2V with a constant current of 1 / 3C0, and record the discharge capacity as C2. Calculate (C2 / C0)×100% to obtain the discharge capacity ratio under the -10℃, 1 / 3C condition. The results are shown in Table 2.

[0156] 6) 1.5C discharge DC internal resistance: Adjust the battery to 50% state of charge (SOC), and discharge it at a constant current of 1.5C for 30s at -10℃ and -20℃ respectively. Record the voltage U1 before discharge and the voltage U2 after discharge. Calculate the 1.5C discharge DC internal resistance (DCIR) = (U1-U2) / discharge current × 1000. The results are shown in Table 2.

[0157] 7) 0.3C discharge DC internal resistance: Adjust the battery to 50% state of charge (SOC), and discharge it at a constant current of 0.3C for 30s at -10℃ and -20℃ respectively. Record the voltage U1 before discharge and the voltage U2 after discharge. Calculate the 0.3C discharge DC internal resistance (DCIR) = (U1-U2) / discharge current × 1000. The results are shown in Table 2.

[0158] 8) Fast charging time from 10-80% SOC: Fast charging tests were conducted using the thickness inflection point method. The testing principle is as follows: when lithium deposition occurs on the negative electrode, its thickness increases significantly. This change can be used to determine the lithium deposition boundary during charging at different rates. The specific steps are as follows:

[0159] 1-1) Charging: Charge at 1 / 3C constant current to 3.8V, then let stand for 10 minutes;

[0160] 1-2) Discharge: Discharge at a constant current of 1C to 2.0V, let stand for 10 minutes, discharge at a constant current of 1 / 3C to 2.0V, let stand for 30 minutes;

[0161] 1-3) Continue repeating steps 1-2) to 1-2), with charging currents of 0.5C / 1C / 1.5C / 2C / 2.5C / 3C / 3.5C / 4C respectively. Record the battery thickness during testing using a sensor. After the test, perform a first-order derivative on the thickness change curve at each rate and find the inflection point of the derivative curve, which is the lithium plating boundary SOC at each rate. The results are shown in Table 2.

[0162] Table 2

[0163]

[0164]

[0165] Analysis of Table 2 shows that, comparing Examples 1-22 and Comparative Examples 1-2, the negative electrode composite material in Examples 1-22 exhibits superior low-temperature charge-discharge efficiency and low-temperature fast charging performance. This indicates that in the electrode composition system of the present invention, the absorbent layer effectively enhances the wettability and liquid retention capacity of the electrolyte, ensuring sufficient contact and wetting of the electrolyte at low temperatures and improving the low-temperature ion conductivity of the electrode. Simultaneously, the concave portions on the surface of the active material layer increase the specific surface area of ​​the active material layer, accelerating the insertion and extraction process of active ions, promoting ion transport, and reducing interfacial resistance, thereby simultaneously improving both the low-temperature charge-discharge efficiency and low-temperature fast charging performance of the battery.

[0166] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrode sheet, characterized in that, include: Current collector substrate; An absorbent layer is located on at least one side of the current collector substrate; The liquid absorption layer includes a porous current collector and an adsorbent material located in the porous current collector; An active material layer is located on the side of the liquid-absorbing layer opposite to the current collector substrate, and the surface of the active material layer is provided with a recess.

2. The electrode sheet according to claim 1, characterized in that, The adsorbent material includes one or more of carbon black, silicon dioxide, titanium suboxide, alumina, and zeolite; And / or, the primary particle size of the adsorbent material is 2 to 50 nm.

3. The electrode sheet according to claim 2, characterized in that, The adsorbent material includes titanium suboxide.

4. The electrode sheet according to any one of claims 1-3, characterized in that, The porosity of the porous current collector is 20% to 60%; And / or, the pore size range of the porous current collector is 5 to 100 nm.

5. The electrode sheet according to any one of claims 1-4, characterized in that, The depth of the recess is 10–50 μm; And / or, the width of the recess is 70–110 μm; And / or, the distance between two adjacent recesses is 200 to 800 μm.

6. The electrode sheet according to any one of claims 1-5, characterized in that, The porous current collector includes a first sub-hole, a second sub-hole, and a third sub-hole; The aperture range of the first sub-hole is 5-20 nm, the aperture range of the second sub-hole is 25-60 nm, and the aperture range of the third sub-hole is 75-100 nm.

7. The electrode sheet according to claim 6, characterized in that, The volume fraction of the first sub-pore in the pore is 0.05 to 0.25, the volume fraction of the second sub-pore in the pore is 0.3 to 0.55, and the volume fraction of the third sub-pore in the pore is 0.1 to 0.

5.

8. The electrode sheet according to any one of claims 1-7, characterized in that, The thickness of the electrode sheet is 100–160 μm; And / or, the thickness of the current collector substrate is 8–20 μm; And / or, the thickness of the absorbent layer is 0.1–0.5 μm; And / or, the thickness of the active material layer is 79.5–151.9 μm.

9. The electrode sheet according to any one of claims 1-8, characterized in that, The electrode includes a positive electrode.

10. A method for preparing an electrode according to any one of claims 1-9, characterized in that, Includes the following steps: 1) The liquid-absorbing layer is formed on at least one side of the current collector substrate; 2) The active material layer is formed on the side of the liquid-absorbing layer away from the current collector substrate, and a recess is formed on the surface of the active material layer to obtain the electrode.

11. The preparation method according to claim 10, characterized in that, The process of forming the liquid-absorbing layer on at least one side of the current collector substrate includes the following steps: A portion of the current collector precursor is perforated to form the porous current collector, and the remaining portion of the current collector precursor is the current collector substrate. A first slurry containing adsorbent material is coated onto the porous current collector to form the liquid absorption layer.

12. The preparation method according to claim 11, characterized in that, The first slurry also includes a first binder; And / or, the solid content of the first slurry is 20% to 65%.

13. The preparation method according to any one of claims 10-12, characterized in that, The process of forming an active material layer on the side of the absorbent layer away from the current collector substrate includes: mixing an active substance and a second solvent to form a second slurry, and coating the second slurry onto the surface of the absorbent layer away from the current collector substrate, so as to form the active material layer on the side of the absorbent layer away from the current collector substrate. And / or, the process of forming a recess on the surface of the active material layer includes: performing laser scribing on the active material layer to form the recess on the surface of the active material layer, thereby obtaining the electrode.

14. A battery, characterized in that, This includes the electrode sheet as described in any one of claims 1-9 or the electrode sheet prepared by the preparation method described in any one of claims 10-13.

15. A battery pack, characterized in that, It includes at least two batteries as described in claim 14 that are interconnected.

16. An electrical appliance, characterized in that, Includes the battery of claim 14 or the battery pack of claim 15.

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