Battery pole piece suitable for large cylindrical battery and large cylindrical battery

Abstract

The invention discloses a battery pole piece suitable for a large cylindrical battery and the large cylindrical battery, the battery pole piece has a gradient porosity structure, and the porosity is gradually increased from one side close to a current collector to one side far away from the current collector; the micro-channel network is a conical micro-channel with the diameter of 5-30 microns and the depth of 10-50 microns formed on the surface of the pole piece by adopting a laser micromachining technology, the diameter of the channel is gradually increased from the outer side of the pole piece to the central area, and the density is gradually reduced from 15% to 5%. The capillary force driving mechanism is utilized, radial infiltration of the electrolyte is completed within 10 seconds, and the infiltration uniformity is gt; the formation of a dry region is eliminated, and meanwhile, only the energy density lt is reduced; the method is compatible with an existing production line, and the manufacturing cost is increased; 5%. According to the invention, the wettability of the electrolyte is improved by combining a multi-layer coating process and the cellulose ether polymer, so that the problem that the overlong pole piece is difficult to be uniformly wetted by the electrolyte due to the increase of the size of the large cylindrical battery is effectively solved, the formation of an internal dry area is avoided, and the capacity utilization rate is remarkably improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of batteries, in particular to a battery pole piece suitable for a large cylindrical battery and the large cylindrical battery. BACKGROUND

[0002] The large cylindrical battery has become an important development direction of the next generation of power batteries due to its high structural strength, large energy density, high group efficiency and low manufacturing cost. However, its large single size also brings new technical challenges:

[0003] 1. The electrolyte is difficult to uniformly infiltrate the super-long pole piece, and an internal dry area is easily formed, affecting the capacity and service life; 2. The ion migration path is significantly lengthened, resulting in increased internal resistance, decreased rate performance, and intensified polarization and heat generation during fast charging; 3. The heat conduction path from the center to the outside is lengthened, and local overheating is easily caused during fast charging or high rate, increasing the risk of thermal runaway; 4. Under the long-scale winding structure, the mechanical stress caused by the volume change of the active material is more concentrated, which may lead to pole piece deformation and active material peeling, threatening the structural stability and cycle life.

[0004] The traditional electrolyte infiltration method of the cylindrical battery is usually carried out under high pressure and vacuum environment, and then undergoes steps such as aging, pre-charging, aging and capacity distribution. This method has many problems for batteries with thick pole pieces: it is difficult to fully penetrate the interior of the pole piece, resulting in poor infiltration of the interior of the pole piece, and even "dry areas" that are not infiltrated, which not only reduces the capacity of the battery, but also may cause the internal resistance to increase, thereby causing the battery temperature to rise and further causing thermal runaway safety problems. In addition, when the electrolyte cannot fully infiltrate the pole piece, lithium ions are easily deposited on the surface of the negative electrode during charging to form lithium metal, thereby causing lithium deposition, which threatens the safety and stability of the battery.

[0005] In order to solve these problems, researchers have proposed various improvement schemes, such as surface treatment of the pole piece, optimization of the electrode structure, modification of the separator, and adjustment of the electrolyte infiltration path. However, these methods often have some limitations, such as being unable to simultaneously consider the energy density and infiltration efficiency of the battery, or requiring complex process flow and high cost. Therefore, developing a new technical solution that can effectively solve the problem of electrolyte infiltration difficulty while maintaining high energy density has become a key to the development of current lithium ion battery technology.

[0006] There are some invention patents that address the problem of electrolyte uniformity and infiltration rate. For example: CN114400301A discloses a high-performance lithium-ion battery thick electrode and its preparation method. The patent mixes lithium-ion battery positive / negative electrode materials with conductive agents, binders, additives, and solvents to prepare a slurry, and applies the slurry to the current collector for rolling to form a high-performance lithium-ion battery thick electrode with tree-shaped electrolyte channels. This method can ensure the full infiltration of electrolyte into the thick electrode, achieve faster liquid-phase transmission of lithium ions in the thick electrode pores, and simultaneously increase the electrolyte concentration, thereby improving the electrochemical performance of the thick electrode. However, the patent still has the problem of how to further optimize the double-coating structure to improve the electrochemical performance of the thick electrode.

[0007] CN114497436A proposes an electrode, its preparation method and a battery. The patent improves the transport dynamics of lithium-ion electrodes by setting an active material layer on the surface of the current collector, where capillary pores are formed between solid particles. This method can improve the porosity and liquid absorption time of the electrode, with a porosity increase of more than 10% and a liquid absorption time reduction of more than 10% compared to conventional electrodes. However, the patent still faces the problem of how to further optimize the formulation and preparation process of solid particles to improve the electrochemical performance and electrolyte infiltration of the electrode.

[0008] The existing technology has the following disadvantages:

[0009] 1. The traditional electrolyte infiltration method for large cylindrical batteries cannot fully penetrate the interior of the electrode, resulting in poor infiltration of the internal area of the electrode, and the formation of "dry areas" that are not infiltrated. This not only reduces the capacity of the battery, but also may cause the internal resistance to increase, leading to an increase in battery temperature and further causing a thermal runaway safety problem.

[0010] 2. In the existing technology, when the electrolyte cannot fully infiltrate the electrode, lithium ions may deposit on the negative electrode surface during charging, forming lithium metal and causing lithium deposition, which threatens the safety and stability of the battery.

[0011] 3. The current improvement scheme cannot simultaneously consider the energy density and infiltration efficiency of the battery, or requires complex process flow and high cost, limiting its application in large-scale production.

[0012] 4. In the existing technology, the porosity and infiltration of the electrode are difficult to effectively improve, resulting in a decrease in the transmission efficiency of the electrolyte in the interior of the electrode, affecting the overall performance of the battery.

[0013] 5. Although some improvement schemes can improve the infiltration of the electrode, they may adversely affect the mechanical strength of the electrode, making it difficult to balance the infiltration and mechanical strength. SUMMARY

[0014] To solve the above problems, the application provides a battery pole piece and a large cylindrical battery for optimizing electrolyte infiltration path and speed and electrolyte infiltration channel.

[0015] A battery pole piece suitable for a large cylindrical battery, comprising a current collector and an active material layer on the surface of the current collector, the battery pole piece having a gradient porosity structure gradually increasing from the side close to the current collector to the side away from the current collector; the active material layer is provided with an electrolyte transport channel.

[0016] Preferably, the gradient porosity gradually increases from 15-20% on the side close to the current collector to 35-42% on the side away from the current collector; the active material layer is formed by a multi-layer coating process to form 5-10 sub-coating layers, each sub-coating layer has a thickness of 10-20 μm, and the porosity of adjacent layers increases at a rate of 1-3%; a coating layer with multiple through holes is formed on both sides of the base layer by 3D printing technology.

[0017] Preferably, the electrolyte transport channel comprises multiple through holes formed on both sides of the base layer by 3D printing technology, and two sizes of micropores provided on the surface of the pole piece; the micropores include first micropores with a diameter of 50-80 μm and second micropores with a diameter of 60-110 μm, and the arrangement interval of the micropores is 170-240 μm.

[0018] Preferably, a radially gradient-distributed microchannel network is provided on the surface of the pole piece, the microchannel network is a tapered microchannel with a diameter of 5-30 μm and a depth of 10-50 μm formed on the surface of the pole piece by laser microprocessing technology, and the diameter of the microchannel gradually increases from the outer side to the central region of the pole piece, and the density decreases from 15% to 5%.

[0019] Preferably, the inner wall of the microchannel is treated by plasma to form a gradient lyophilicity with hydroxyl and carboxyl functional groups, so that the lyophilicity of the inner wall of the microchannel gradually increases from the outer side to the central region, and the contact angle decreases from 65° to 25°.

[0020] Preferably, a secondary capillary network with a diameter of 1-3 μm is provided between the main microchannels to form an interconnected three-dimensional liquid transport network.

[0021] Preferably, a radial-axial double gradient micropore network is provided on the surface of the pole piece: 1) radial gradient: the diameter of the micropore gradually increases from 5 μm to 30 μm from the outer layer to the inner layer of the pole piece, and the porosity increases from 15% to 35%, forming a gradient of electrolyte infiltration driving force; 2) axial gradient: a group of "trunk-branch" structure microchannels are arranged every 50 mm along the length direction of the pole piece, the width of the trunk channel is 40-60 μm, the width of the branch channel is 8-15 μm, and the depth of the channel is 60-80% of the thickness of the active material layer.

[0022] Preferably, the double-gradient micropore network is made by picosecond laser processing with the following parameters: power 0.5-2W, pulse width 10-30ps, scanning speed 200-500mm / s.

[0023] Preferably, a "U"-shaped groove structure is formed by multi-layer coating, and the groove structure makes the porosity of the pole piece gradiently distributed; the surface of the pole piece is coated with a cellulose ether polymer, which forms pores in situ in the active material layer and is converted into a gel state.

[0024] Preferably, the pole piece further comprises a coating layer, wherein:

[0025] The current collector is an aluminum foil or an aluminum alloy foil with a thickness of 4-12μm; the active material layer is made of the following raw materials by weight:

[0026] Active material: 90-95 parts;

[0027] Conductive agent: 3-8 parts;

[0028] Binder: 10-15 parts;

[0029] Dispersant: 0.5-2 parts;

[0030] Solvent: the balance.

[0031] Among them, the active material is selected from one or more of LiCoO2, LiMn2O4, LiNiCoO2; the conductive agent is selected from one or more of carbon black, graphite, carbon nanotubes; the binder is selected from one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, polyvinylpyrrolidone homopolymer, polyethylene oxide; the dispersant is selected from one or more of polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol.

[0032] The active material layer is prepared by a multi-layer coating process, including the following steps:

[0033] 1) Mix the active material with the solvent, coat on the surface of the current collector, and the thickness is 10-20μm to form a first coating layer;

[0034] 2) Form a plurality of first micropores with a diameter of 50-80μm on the surface of the first coating layer by 3D printing technology, and the interval is 170-240μm;

[0035] 3) Form a second coating layer on the surface of the first micropore with a thickness of 10-20μm;

[0036] 4) Forming second micropores with a diameter of 60-110 μm on the first micropores on the surface of the second coating layer by 3D printing technology, the height difference between the first micropores and the second micropores being 10-20 μm;

[0037] 5) Repeating steps 3) and 4) until the required number of layers is reached.

[0038] The porosity between the coating layers changes in a gradient, and the porosity increment rate between adjacent coating layers is controlled at 1-3%. The porosity of the last coating layer is 35-42%.

[0039] The surface of the pole piece is also provided with third micropores with a diameter of 50-80 μm, which are prepared by laser micromachining technology and have a depth of 10-30 μm, and are used to form a rapid electrolyte diffusion channel.

[0040] The cellulose ether polymer is selected from one or more of polyvinyl alcohol, polyacrylic acid, and polyvinylpyrrolidone, and has a solid content of 15-25% and forms a porosity of 5-10% in situ in the active material layer.

[0041] During the electrolyte infiltration process, the micropores between the coating layers and the surface micropores form a rapid electrolyte permeation network, and the infiltration rate is controlled at 0.5-1.5 mm / s. After the pole piece is infiltrated, the electrolyte distribution uniformity reaches more than 95%, and the dry area is eliminated.

[0042] A large cylindrical battery includes the above-mentioned battery pole piece suitable for a large cylindrical battery.

[0043] The pole piece includes a current collector, an active material layer, and a coating layer, wherein:

[0044] Compared with the prior art, the present application provides a large cylindrical battery pole piece and a large cylindrical battery, which have the following beneficial effects:

[0045] 1. By adopting a gradient porosity pole piece microstructure to optimize the electrolyte infiltration channel design, combining a multi-layer coating process and a cellulose ether polymer to improve the electrolyte infiltration, the problem of electrolyte being difficult to uniformly infiltrate the super-long pole piece caused by the increase in the size of the large cylindrical battery is effectively solved, the electrolyte distribution uniformity is > 95%, the internal dry area is eliminated, and the capacity utilization is significantly improved;

[0046] 2, The application creates a tapered microchannel with a diameter of 5-30 μm and a depth of 10-50 μm on the surface of the pole piece by using laser microprocessing technology, the diameter of the channel gradually increases from the outside to the center area of the pole piece, and the density decreases from 15% to 5%, forming a radial gradient distribution; a secondary capillary network is designed between the main microchannels to form an interconnected three-dimensional liquid transport network. The structure utilizes the capillary force driving mechanism to achieve radial infiltration of the electrolyte within 10 seconds, with an infiltration uniformity of >98%, eliminating dry area formation, while only reducing the energy density by <2%, compatible with existing production lines, and increasing the manufacturing cost by <5%.

[0047] 3. By combining multi-layer coating process and 3D printing technology, the size, distribution and connectivity of each layer of micropores are ensured, forming a fast electrolyte transmission channel from the outside to the inside, optimizing the ion migration path, and significantly reducing the internal resistance;

[0048] 4. The cellulose ether polymer is used to form pores in situ in the active material layer of the pole piece, improving the porosity and electrolyte wettability, without changing the pole piece design or causing mechanical damage to the pole piece, effectively solving the problem of lithium metal deposition on the negative electrode surface caused by the inability of the electrolyte to fully infiltrate the pole piece in the traditional method;

[0049] 5. The application realizes fast and uniform electrolyte infiltration and ion transmission optimization through the synergistic effect of the double-gradient micro-pore network, tree-shaped micro-channels and surface modification. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 It is a structure schematic diagram of the battery pole piece suitable for large cylindrical batteries of embodiment 1 of the application.

[0051] Figure 2 It is a structure schematic diagram of the battery pole piece suitable for large cylindrical batteries of embodiment 3 of the application.

[0052] Figure 3 It is a structure schematic diagram of the battery pole piece suitable for large cylindrical batteries of embodiment 4 of the application.

[0053] Figure 4 It is a structure schematic diagram of the battery pole piece suitable for large cylindrical batteries of embodiment 5 of the application.

[0054] Figure 5 It is a structure schematic diagram of the battery pole piece suitable for large cylindrical batteries of embodiment 7 of the application.

[0055] Identified in the figure: (1) current collector, (2) active material layer, (3) microstructure, (4) tapered microchannel, (41) outer side area, (42) inner side area, (5) active material layer, (6) coating layer, (7) main channel, (8) branch channel. DETAILED DESCRIPTION

[0056] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. It can be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0057] Embodiment 1

[0058] Ternary positive electrode sheet suitable for 46140 battery

[0059] Sheet design: the current collector is aluminum foil, the active material layer is high-nickel ternary material, and the single-sided coating thickness is about 100 pm. The microstructure pattern adopts a sparse grid design of "longitudinal main groove + transverse auxiliary groove", the longitudinal groove depth is about 30 pm, the width is about 15 pm, and the pitch is 2 mm in the middle region of the sheet and 4 mm near the two side edge regions. The transverse groove depth is about 25 pm, the width is about 10 pm, and the pitch is 10 mm.

[0060] Preparation process: the positive electrode slurry is prepared according to the conventional process and coated on the aluminum foil. After drying and rolling, a continuous sheet blank is obtained. A high-power picosecond laser system (wavelength 1064 nm, average power 40 W) is used to scan the continuously advancing sheet blank at a scanning speed of 1500 mm / s to form the above-mentioned designed microstructure pattern. Finally, the processed sheet blank is cut according to the size, and the tabs are welded.

[0061] Effect: After being assembled into a 46140 battery, the infiltration time after liquid injection is shortened by more than 30% compared with the traditional sheet. In the 3C rate fast charging test, the temperature rise is reduced by about 5-8°C compared with the control group. After 1000 cycles, the capacity retention rate is increased by more than 15%, and the sheet is not deformed or dropped after disassembly.

[0062] Embodiment 2

[0063] Lithium iron phosphate positive electrode sheet suitable for 46140 battery

[0064] Sheet design: lithium iron phosphate (LFP) is used as the active material, and the microstructure pattern is a combination of high-density uniform dot array pits and shallow trenches. The dot array pit (diameter ~ 8 pm, depth ~ 15 pm, pitch ~ 20 pm) is used to increase the specific surface area and introduce oxygen vacancies; the shallow trench (width ~ 10 pm, depth ~ 12 pm) connects the main dot array to form an auxiliary flow network.

[0065] Preparation process: use a picosecond laser with a wavelength of 532 nm to scan the positive electrode blank after coating and rolling, laser power: 15 W, scanning speed: 2000 mm / s.

[0066] Effect: After assembling into 46140 batteries, the oxygen vacancies introduced by laser processing and the increased specific surface area significantly improve the reaction kinetics of LFP materials. The capacity retention rate of the assembled 4680 battery at 3C charge-discharge rate is increased by about 10%, and the thermal safety is significantly improved.

[0067] Comparative Example 1

[0068] The same basic formula and process as in the above examples are used to prepare the electrode sheet, but no final laser microstructure processing is performed, which is used as a comparative sample of a traditional electrode sheet.

[0069] Performance summary

[0070] The electrode sheets prepared in each example and comparative example are assembled into large cylindrical batteries for testing, and the results show that: 1. In terms of electrolyte infiltration speed, all examples are significantly ahead of the comparative example; 2. In terms of fast charge rate performance and cycle life, the example batteries all show significant advantages; 3. In terms of thermal management, the temperature rise of the example batteries in high rate testing is significantly lower than that of the comparative example.

[0071] In summary, the present application constructs microstructures on the battery electrode sheet through laser processing technology, which ingeniously solves multiple technical problems and provides an effective and industrialized technical path for the development of high-performance large cylindrical batteries.

[0072] Example 3

[0073] The present application optimizes the electrolyte infiltration path, and adopts a variable porosity structure in which the porosity of the active material layer of the electrode sheet gradually increases (20% to 42%) from the side close to the current collector to the side away from the current collector, with a thickness of about 10 μm per layer, and the porosity increment rate of adjacent layers is 2%. A coating layer with multiple through holes is formed on both sides of the current collector through 3D printing technology, achieving an electrolyte distribution uniformity of >95%. At the same time, first micropores with a diameter of 50-80 μm and second micropores with a diameter of 60-110 μm are arranged with a spacing of 170-240 μm on the surface of the electrode sheet, forming an electrolyte rapid diffusion channel. This structure effectively reduces the surface polarization of the electrode sheet and improves the performance of the battery under high current and low temperature conditions, increases the electrolyte infiltration rate to 0.5-1.5 mm / s^-0.5, eliminates dry area formation, and improves capacity utilization.

[0074] The application optimizes the pole piece structure to improve the battery performance, improve the electrolyte infiltration effect, and improve the performance of the battery under large current and low temperature. The porosity gradually increases from 20% near the current collector side to 42% away from the current collector side. The thickness of each layer is about 10μm, and the porosity of adjacent layers increases at a rate of 2%, guiding the efficient penetration of electrolyte from the outside to the inside.

[0075] On both sides of the base layer, a coating layer with multiple through holes is formed by 3D printing technology. The 3D printing technology forms through holes and micropores on the coating layer. The uniformity of electrolyte distribution is improved to >95%, avoiding local insufficient infiltration.

[0076] The multi-layer coating process is combined with the 3D printing technology. The active material layer is formed by the multi-layer coating process, and the micropore structure of each layer is precisely controlled by the 3D printing technology, ensuring uniform pore distribution and good structural integrity, solving the problem that the traditional single-layer pole piece porosity and mechanical strength are difficult to balance.

[0077] The application sets two sizes of micropores: the first micropore diameter is 50-80μm, and the second micropore diameter is 60-110μm; the micropore spacing is 170-240μm, forming a "surface channel" for rapid diffusion of electrolyte.

[0078] The electrolyte infiltration rate of the application reaches 0.5-1.5mm / s^-0.5, greatly shortening the infiltration time; completely eliminating the "dry area" of the pole piece, improving the capacity utilization; at the same time, reducing the surface polarization of the pole piece, significantly improving the stability and performance of the battery under large current discharge and low temperature environment.

[0079] Since large cylindrical batteries need to maintain high energy density while solving the problem of electrolyte difficult to uniformly infiltrate the super-long pole piece, both the electrolyte distribution uniformity >95% and the energy density cannot be significantly reduced and the manufacturing complexity cannot be increased; therefore, as shown in Figure 2 The application creates a radially gradient distributed microchannel network on the surface of the pole piece:

[0080] 1) Microchannel structure design: laser micromachining technology is used to create a tapered microchannel 4 with a diameter of 5-30μm and a depth of 10-50μm on the surface of the pole piece. From the outside of the pole piece to the center area, the channel diameter gradually increases, and the pole piece density decreases from 15% to 5%, forming a radially gradient distribution;

[0081] 2) Surface modification treatment: a coating layer 6 with hydroxyl and carboxyl functional groups is introduced to the inner wall of the microchannel through plasma treatment, so that the liquid affinity of the inner wall of the channel gradually increases from the outside to the center area (the contact angle decreases from 65° to 25°);

[0082] 3) Multi-level capillary structure: A secondary capillary network 5 (1-3 μm in diameter) is provided between the primary microchannels, forming an interconnected three-dimensional liquid transport network. This structure utilizes the capillary force driving mechanism to achieve radial infiltration of the electrolyte within 10 seconds, with uniformity > 98%, eliminating dry zone formation, while only reducing energy density < 2%, compatible with existing production lines, increasing manufacturing cost < 5%.

[0083] The present application solves the problem of uneven electrolyte infiltration of super-long pole pieces in large cylindrical batteries, while considering energy density and process compatibility.

[0084] The features of this technical solution are:

[0085] Radial gradient microchannel structure: Laser micro-machining to manufacture tapered microchannels with a diameter of 5-30 μm and a depth of 10-50 μm. From the outside to the center of the pole piece, the channel diameter gradually increases, and the density decreases from 15% to 5%.

[0086] Gradient lyophilic surface modification: Plasma treatment introduces hydroxyl and carboxyl groups on the inner wall of the microchannel, and the lyophilicity increases from the outside to the center, with a contact angle decreasing from 65° to 25°.

[0087] Multi-level capillary transport network: A 1-3 μm secondary capillary network is provided between the primary microchannels, forming an interconnected three-dimensional liquid transport structure.

[0088] Technical effects:

[0089] 1. Infiltration efficiency: Under the action of capillary force, radial infiltration is completed within 10 seconds.

[0090] 2. Infiltration uniformity: > 98%, eliminating dry zones.

[0091] 3. Performance and cost: Energy density is reduced by < 2%, manufacturing cost is increased by < 5%, and it is compatible with existing production lines.

[0092] Example 4

[0093] The secondary capillary network material of the present application can be selected from a lyophilic composite system resistant to electrolyte: "PVA - nanocellulose (CNF) composite system", or a lyophilic polymer resistant to lithium salt (such as polyethylene oxide (PEO) / polyvinylidene fluoride - hexafluoropropylene (PVDF-HFP) blend).

[0094] Formulation: PVA (80%) + CNF (20%, diameter 50-100 nm, length 1-5 μm), concentration 0.5-1.0 wt%; or PVDF-HFP (90%) + PEO (10%), concentration 0.8 wt%.

[0095] The nanofiber structure of CNF can enhance the mechanical strength of the secondary network and resist electrolyte swelling; PVDF-HFP / PEO has excellent compatibility with electrolyte (LiPF6 system). The PVA swelling problem is solved, the long-term stability of the secondary network is improved, and the battery cycle life (capacity retention rate 80%) is improved.

[0096] PVA-nanocellulose composite provides excellent mechanical support and ion conduction performance, with a Young's modulus of 3.5-4.2 GPa while maintaining >85% ion conductivity.

[0097] Optimal ratio: PVA: nanocellulose = 7:3 (weight ratio)

[0098] Tensile strength: 120 MPa (pure PVA only 75 MPa)

[0099] Electrolyte absorption rate: 285% (pure PVA only 180%)

[0100] Stability in electrolyte: weight loss <2% after 30 days of immersion

[0101] Crosslinking degree: 15% (glutaraldehyde crosslinking)

[0102] Less than 10%: excessive swelling in electrolyte

[0103] More than 20%: significant decrease in ion conductivity

[0104] The inner wall of the microchannel can be provided with a support layer, using a flexible nanocoating;

[0105] After plasma modification, add the "atomic layer deposition (ALD) Al2O3 nanocoating" step (thickness 5-20 nm), and then construct the secondary network.

[0106] Operation steps: ALD equipment uses pulse type (Al source: trimethylaluminum, oxygen source: water), deposition temperature 120°C, deposition cycle 10-20 times (control thickness).

[0107] The Al2O3 nanolayer has flexibility and corrosion resistance, and can support the microchannel structure when the electrode is cycled and swells (especially for silicon-based negative electrodes, with an expansion rate >20%), preventing the collapse of the channel; at the same time, it does not affect the hydrophilicity of the hydroxyl / carboxyl group (contact angle fluctuation ≤3°).

[0108] With the support layer, it can simultaneously adapt to graphite negative electrodes and high-expansion silicon-based negative electrodes.

[0109] The ALD-deposited Al2O3 nanocoating (thickness 5-20 nm) forms a protective layer at the electrode / electrolyte interface, inhibits side reactions, and reduces SEI film thickening. According to the Butler-Volmer equation, the interface impedance can be reduced by about 40%.

[0110] The optimal thickness of the Al2O3 nanocoating is 10 nm.

[0111] 5nm: Insufficient protection; capacity retention is only 82% after 200 cycles.

[0112] 10nm: Optimal balance point, capacity retention >92% after 500 cycles.

[0113] 20nm: Excessive impedance leads to a 15% decrease in rate performance.

[0114] Deposition temperature: 120°C (optimal)

[0115] Below 100°C: Insufficient film density, low Li+ diffusion coefficient

[0116] 120°C: Dense and homogeneous, with a Li+ diffusion coefficient of 1.2 × 10⁻⁶. -10 cm² / s

[0117] Precursor selection: TMA + H2O (optimal)

[0118] Growth rate: 1.1 Å / cycle

[0119] Impurity content: 98%

[0120] The laser processing of this invention can employ partitioned synchronous scanning + multi-beam parallel processing, specifically as follows:

[0121] The femtosecond laser system has been upgraded to "3-way synchronous beam output", corresponding to the outer / middle / center regions of the electrode respectively;

[0122] The scanning path is a "radial radial scan" to reduce beam backlash.

[0123] Pre-positioning vision system: AI algorithms identify the edge / center position of the electrode in advance, eliminating the need for beam calibration on a per-electrode basis.

[0124] In this way, the processing time of monopolar laser is shortened, the production capacity is increased, and the cycle time requirements of mass production lines are met.

[0125] like Figure 3 As shown, the microchannel structure of this invention adopts a "conical-inverted trapezoidal" composite cross-section:

[0126] The "pure conical microchannel" (thin on the outside, thick on the inside) was changed to a composite cross-section of "conical on the outside + inverted trapezoidal on the inside":

[0127] Outer region 41 (0-1 / 3 of the active material layer thickness): Maintain a cone shape (5-10 μm in diameter, 10-20 μm in depth) to ensure rapid electrolyte introduction;

[0128] Inner region 42 (1 / 3 -1 active material layer thickness): Inverted trapezoidal cross-section (upper base 20-30 μm, lower base 15-25 μm, depth 35-50 μm), less active material removal than pure conical.

[0129] Processing method: achieved by femtosecond laser "double pulse scanning" (first pulse coning, second pulse trimming inverted trapezoidal).

[0130] Through the above improvement, the active material retention rate of the pole piece is improved, the energy density loss is reduced, and the infiltration speed is not affected.

[0131] Example 5

[0132] As shown in Figure 4 The microchannel structure of the present application adopts a "conical-inverted trapezoidal" composite cross-section:

[0133] Microchannel structure parameters

[0134] Conical section:

[0135] Inlet diameter: 25 μm

[0136] Depth: 40 μm

[0137] Conical angle: 12°

[0138] Inverted trapezoidal section:

[0139] Upper width: 15 μm

[0140] Lower width: 20 μm

[0141] Depth: 30 μm

[0142] Channel density: 400 / cm²

[0143] Channel arrangement: hexagonal array, center distance 500 μm

[0144] The conical-inverted trapezoidal composite cross-section microchannel can realize rapid transmission and uniform distribution of lithium ions, reduce polarization effect, and improve charge and discharge efficiency. According to Fick's diffusion law, this structure can increase ion diffusion flux by about 35%.

[0145] The rest of the technical solutions are the same as in Example 4.

[0146] Example 6

[0147] In combination with the above innovative solutions, the inventors further propose a continuously improved solution, namely adopting an electrode sheet electrolyte infiltration optimization comprehensive technical solution: through a multi-layer coating process on the surface of the electrode sheet, a uniform "U"-shaped groove is formed. This structure not only increases the acceptance area of the electrolyte, but also gradually increases the porosity from the current collector side to the far side (20%→42%), with an adjacent layer porosity increase rate of 2%. At the same time, it ensures that the electrolyte can effectively and quickly penetrate into the main body of the electrode sheet, achieving an electrolyte distribution uniformity of >95%. After coating the cellulose ether polymer, the electrolyte infiltration rate is increased to 0.5-1.5 mm / s^-0.5, which can significantly improve the porosity and electrolyte infiltration without changing the structure of the electrode sheet and avoiding mechanical damage, and improve the capacity utilization and cycle life of the battery to meet the use requirements under large current and low temperature conditions. This technical solution can simplify the preparation steps and reduce the preparation cost through a reasonable process flow, ensuring the stable performance of the battery under various harsh conditions.

[0148] Features of this technical solution:

[0149] Gradient porosity structure: through a multi-layer coating process on the surface of the electrode sheet, a uniform "U"-shaped groove structure is formed, which gradually increases the porosity from the current collector side to the far side (20%→42%), with an adjacent layer porosity increase rate of 2%, increasing the electrolyte acceptance area.

[0150] Cellulose ether polymer: coating a specific cellulose ether polymer on the surface of the electrode sheet to improve the electrolyte infiltration rate to 0.5-1.5 mm / s^-0.5, promoting the rapid penetration of the electrolyte.

[0151] The gradient porosity structure can improve the electrolyte distribution, and the cellulose ether polymer has good liquid affinity, which has been scientifically verified.

[0152] By optimizing the microstructure of the electrode sheet and designing specific flow channel holes, it is ensured that the electrolyte can effectively and quickly penetrate into the main body of the electrode sheet, achieving an electrolyte distribution uniformity of >95%.

[0153] The electrode sheet electrolyte infiltration optimization solution significantly improves the electrolyte infiltration efficiency, distribution uniformity, and electrode sheet porosity, improves the battery capacity utilization and cycle life without damaging the electrode sheet, and adapts to harsh use scenarios.

[0154] Example 7:

[0155] As shown in Figure 5 , this embodiment creates a radial-axial double-gradient micro-pore network on the surface of the electrode sheet through laser precision micro-machining technology:

[0156] 1) Radial gradient design: From the inner layer to the outer layer of the pole piece, the pore diameter gradually increases from 5 μm to 30 μm, and the porosity increases from 15% to 35%, forming a gradient of electrolyte infiltration driving force;

[0157] 2) Axial gradient design: Along the length direction of the pole piece, a group of "trunk-branch" structure microchannels are set every 50 mm, the trunk channel 7 has a width of 40-60 μm, the branch channel 8 has a width of 8-15 μm, and the depth is controlled to be 60-80% of the thickness of the active material layer 2;

[0158] 3) Surface modification treatment: Hydroxyl and carboxyl functional groups are introduced on the inner wall of the micro-pore through plasma treatment, the contact angle is reduced to below 15°, and the wettability is improved.

[0159] The structure utilizes the capillary force driving principle and surface tension gradient effect to realize the improvement of the electrolyte infiltration rate by 300%, the infiltration uniformity is greater than 95%, the mechanical strength of the pole piece is reduced by not more than 5%, and the energy density loss is less than 2%. The process adopts picosecond laser processing (power 0.5-2 W, pulse width 10-30 ps, scanning speed 200-500 mm / s), is compatible with the existing production line, and the cost increase is less than 3%.

[0160] The present application forms a radial-axial double gradient micro-pore network through laser micro-processing technology, the picosecond laser power is 0.5-2 W, the pulse width is 10-30 ps, and the scanning speed is 200-500 mm / s, which can be flexibly adjusted according to the type of pole piece.

[0161] The embodiment creates a radial-axial double gradient micro-pore network on the surface of the pole piece, utilizes the capillary force driving principle and surface tension gradient effect to promote the rapid and uniform infiltration of the electrolyte. The radial gradient design increases the micro-pore diameter from 5 μm to 30 μm from the inner layer to the outer layer, and the porosity increases from 15% to 35%, forming a gradient of electrolyte infiltration driving force.

[0162] Axial gradient "trunk-branch" structure: A group of "trunk-branch" structure microchannels are set every 50 mm along the length direction of the pole piece, the trunk channel has a width of 40-60 μm, the branch channel has a width of 8-15 μm, and the depth is 60-80% of the thickness of the active material layer, forming a liquid transmission network similar to a tree structure.

[0163] Further, a 15° inclination angle is arranged at the branch channel inlet of the axial microchannel, that is, the included angle between the branch channel 8 and the trunk channel 7 is 75°, which guides the electrolyte to flush the channel and reduces the risk of blockage.

[0164] Surface modification enhances wettability: Hydroxyl and carboxyl functional groups are introduced on the inner wall of the micro-pore through plasma treatment, the contact angle is reduced to below 15°, and the surface wettability is significantly improved. The surface modification treatment and the variable porosity structure synergistically optimize the ion transmission path.

[0165] Further, after the radial gradient micro-hole processing, a low-temperature plasma treatment process (power 50-80W, treatment time 10-20s) is performed to construct an electrophilic coating (hydroxyl modification) on the inner wall of the micro-hole. Through the dual driving of "capillary force gradient and surface hydrophilicity", the contact angle of the electrolyte with the inner wall of the micro-hole is reduced, and the infiltration time is shortened.

[0166] The embodiment realizes the rapid and uniform infiltration of electrolyte and the optimization of ion transmission through the synergistic effect of the double-gradient micro-hole network, the tree-shaped micro-channel and the surface modification.

[0167] The present application realizes the leap-forward improvement of electrolyte infiltration efficiency and uniformity under the premise of almost no influence on the performance of the pole piece and the production cost, and is fully compatible with the existing production line.

[0168] The technical solution of the embodiment has the following characteristics:

[0169] Synergistic effect of double-gradient structure: the radial gradient builds the driving force of electrolyte infiltration, and the axial "trunk-branch" channel optimizes the transmission path, so that the infiltration rate is increased by 300% and the uniformity is more than 95%.

[0170] Surface modification strengthens the wettability: the plasma treatment introduces hydroxyl and carboxyl groups, and the contact angle is reduced to below 15°, which further accelerates the electrolyte spreading from the interface characteristics.

[0171] Dual balance of performance and cost: the mechanical strength is reduced by ≤5%, the energy density loss is <2%, the cost increase of picosecond laser process is <3%, and the existing production line can be directly used.

[0172] Controllable processing precision: the radial micro-hole diameter is 5-30μm, the porosity is 15%-35%, the axial channel size and depth are adapted to the material performance of the active material layer, and the processing precision is guaranteed.

[0173] Flexible process adjustment: picosecond laser power 0.5-2W, pulse width 10-30ps, scanning speed 200-500mm / s, which can be adjusted according to the type of pole piece.

[0174] Further, the present application provides the following improved technical solutions: a multi-layer pole piece structure combined with a cellulose ether polymer to improve the electrolyte infiltration.

[0175] By combining the multi-layer coating process and the use of cellulose ether polymers, the electrolyte wettability is improved. In the multi-layer structure of the electrode sheet, the micropores formed in each layer are precisely controlled by 3D printing technology, ensuring uniform pore distribution and good structural integrity; at the same time, the cellulose ether polymer is used to form in-situ gel pores in each layer, improving the porosity and wettability. This not only improves the rapid penetration and distribution performance of the electrolyte, but also ensures the structural stability of the electrode sheet and the long-term stability of the electrochemical performance. The production process can use the existing production line and is suitable for large-scale application.

[0176] Further, by providing tab areas and tab-free areas on the cylindrical battery electrode sheet, as well as slotting grooves, circular arc transition connections and other structures, the electrolyte wettability is improved.

[0177] The cellulose ether polymer can form pores in-situ in the active material layer of the electrode sheet, improving the porosity and electrolyte wettability without changing the structure of the electrode sheet or causing mechanical damage to the electrode sheet.

[0178] The multi-layer coating process of the present application is combined with 3D printing technology, and the electrode sheet structure is constructed by the multi-layer coating process. The micropore structure of each layer is precisely controlled by 3D printing technology, ensuring uniform pore distribution and good structural integrity, solving the problem that the porosity and mechanical strength of traditional single-layer electrode sheets are difficult to balance.

[0179] The variable porosity electrode sheet structure and the micropore design can improve the electrolyte wettability and ion migration rate. The present application further optimizes this technology through the radial-axial double gradient structure, which can achieve a 300% improvement in electrolyte wettability rate and a uniformity of >95%.

[0180] The present application adds cellulose ether polymers to the active material layer. The polymer can form pores in-situ in the active material layer and convert to a gel state after being soaked in electrolyte, realizing in-situ gelation of cellulose ether polymers, significantly improving electrolyte wettability and electrode sheet liquid retention rate, while not changing the structure of the electrode sheet or causing mechanical damage.

[0181] The present application precisely controls the size, distribution and connectivity of micropores in each layer, forming a rapid electrolyte transmission channel from the outside to the inside. The multi-layer micropore cooperative transmission mechanism solves the problem of dry area inside large cylindrical batteries, optimizes the ion migration path, and reduces the internal resistance.

[0182] The multi-layer coating process of the present application is combined with 3D printing technology and uses cellulose ether polymers, which can achieve the cooperative optimization of electrolyte wettability, electrode sheet porosity and mechanical strength. The process is compatible with existing production lines and has controllable cost, suitable for large-scale application of large cylindrical batteries.

[0183] The application constructs the pole piece structure through multi-layer coating, and 3D printing precisely controls the size, distribution and connectivity of each layer of micropores, so that the pores are uniform and the structure is complete.

[0184] The application takes into account the rapid penetration of electrolyte, the stability of pole piece structure and the long-term stability of electrochemical performance, and solves the contradiction between the porosity and strength of the traditional single-layer pole piece.

[0185] Example 8

[0186] A large cylindrical battery pole piece and a preparation method thereof, comprising the following steps:

[0187] (1) The active material LiCoO2, the conductive agent carbon black, the binder carboxymethyl cellulose sodium and the dispersant polyvinylpyrrolidone are mixed according to the mass ratio of 90:5:12:1, and an appropriate amount of N-methylpyrrolidone (NMP) is added as a solvent, the solid content of the slurry is controlled to be 45%, and the slurry is stirred for 8 hours to form a uniform slurry;

[0188] (2) The above slurry is coated on the surface of the aluminum foil current collector, the pole piece surface density is adjusted by controlling the scraper height, and the pole piece single surface density reaches 40 mg / cm 2 . The coated pole piece is dried at 100 DEG C for 12 hours;

[0189] (3) Laser micro-machining technology is used to form first micropores with a diameter of 60 μm on the surface of the pole piece, the pore depth is 20 μm, and the pore spacing is 180 μm. Then, the second micropores with a diameter of 80 μm are formed on the surface of the first micropores by 3D printing technology, and the height difference between the second micropores and the first micropores is 15 μm;

[0190] The laser micro-machining technology and the 3D printing technology are used to form micropores respectively;

[0191] (4) A third coating layer with a thickness of 15 μm is formed on the surface of the second micropores. The third micropores with a diameter of 100 μm are formed on the basis of the third micropores by 3D printing technology, and the height difference between the second micropores and the third micropores is 10 μm;

[0192] (5) A fourth coating layer with a thickness of 18 μm is formed on the surface of the fourth micropores. The fourth micropores with a diameter of 110 μm are formed on the basis of the fourth micropores by 3D printing technology, and the height difference between the third micropores and the fourth micropores is 12 μm;

[0193] (6) A fifth coating layer with a thickness of 12 μm is formed on the surface of the fifth micropores. The fifth micropores with a diameter of 80 μm are formed on the basis of the fourth micropores by 3D printing technology, and the height difference between the fourth micropores and the fifth micropores is 10 μm. The porosity of the last coating layer is 38%;

[0194] (7) Laser micro-machining technology is used to form micro-holes with a diameter of 70 μm on the surface of the pole piece, and the hole depth is 25 μm, which is used to form a rapid diffusion channel for the electrolyte;

[0195] (8) The cellulose ether polymer polyvinyl alcohol (solid content 20%) is uniformly dispersed in the active material layer to form an in-situ porosity of 8%;

[0196] (9) The prepared pole piece is rolled to control the rolling pressure, so that the single-sided thickness of the pole piece reaches 105 μm, and the compaction density is 3.92 g / cm 3 ;

[0197] (10) Ion beam etching technology is used to form a hole array on the surface of the rolled pole piece, the hole center distance is 200 μm, the upper hole diameter is 20 μm, the lower hole diameter is 20 μm, the hole depth is 50 μm, and the distance between the bottom of the half-hole and the current collector is 55 μm.

[0198] Example 9

[0199] A large cylindrical battery pole piece and a preparation method thereof, comprising the following steps:

[0200] (1) The active material LiMn2O4, the conductive agent carbon nanotube, the binder polyvinylpyrrolidone and the dispersant polyethylene glycol are mixed according to the mass ratio of 92:3:10:1, and a proper amount of diethyl ether ketone (DEC) is added as a solvent, the solid content of the slurry is controlled to be 48%, and the slurry is stirred for 7 hours to form a uniform slurry;

[0201] (2) The above slurry is coated on the surface of the aluminum alloy foil current collector, the pole piece surface density is adjusted by controlling the doctor blade height, and the pole piece single-sided surface density reaches 42 mg / cm 2 . The coated pole piece is dried at 120°C for 10 hours;

[0202] (3) Laser micro-machining technology is used to form first micro-holes with a diameter of 50 μm on the surface of the pole piece, the hole depth is 30 μm, and the hole distance is 220 μm. Then, the second micro-holes with a diameter of 70 μm are formed on the surface of the first micro-holes by 3D printing technology, and the height difference between the second micro-holes and the first micro-holes is 18 μm;

[0203] (4) A second coating layer is formed on the surface of the second micro-holes with a thickness of 12 μm. Third micro-holes with a diameter of 90 μm are formed on the basis of the second micro-holes by 3D printing technology, and the height difference between the second micro-holes and the third micro-holes is 12 μm;

[0204] (5) A third coating layer is formed on the surface of the third micro-holes with a thickness of 20 μm. Fourth micro-holes with a diameter of 100 μm are formed on the basis of the third micro-holes by 3D printing technology, and the height difference between the third micro-holes and the fourth micro-holes is 14 μm;

[0205] (6) A fourth coating layer with a thickness of 15 μm is formed on the fourth microporous surface. A fifth micropore with a diameter of 80 μm is formed on the fourth micropore by 3D printing technology, and the height difference between the fourth micropore and the fifth micropore is 12 μm. The porosity of the last coating layer is 40%;

[0206] (7) A micropore with a diameter of 60 μm and a depth of 20 μm is formed on the surface of the pole piece by laser micromachining technology, which is used to form a rapid diffusion channel for electrolyte;

[0207] (8) A cellulose ether polymer polyacrylic acid (solid content 18%) is uniformly dispersed in the active material layer to form an in-situ porosity of 7%;

[0208] (9) The prepared pole piece is rolled to control the rolling pressure, so that the thickness of the pole piece is 103 μm and the compaction density is 3.95 g / cm 3 ;

[0209] (10) Ion beam etching technology is used to form a pore array on the surface of the rolled pole piece, with a pore center distance of 190 μm, an upper pore diameter of 18 μm, a lower pore diameter of 18 μm, a pore depth of 45 μm, and a distance between the bottom of the half-hole and the current collector of 52 μm.

[0210] The terms "one embodiment", "certain embodiments", "specific examples" or "several examples" as used in the specification are intended to represent that a particular feature, structure, material or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. It is specifically noted that the terms "one embodiment", "certain embodiments", "specific examples" or "several examples" as used in the specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0211] The above embodiments are only exemplary descriptions of the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements or improvements made by those skilled in the art within the technical scope disclosed in the present application, as long as they are within the spirit and principles of the present application, should be covered within the protection scope of the present application.

Claims

1. A battery electrode suitable for large cylindrical batteries, comprising a current collector (1) and an active material layer (2) on the surface of the current collector (1), characterized in that: The battery electrode has a gradient porosity structure, and the gradient porosity gradually increases from the side closer to the current collector (1) to the side farther away from the current collector (1); the active material layer is provided with an electrolyte transport channel.

2. The battery electrode sheet suitable for large cylindrical batteries according to claim 1, characterized in that, The gradient porosity gradually increases from 15-20% on the side closer to the current collector (1) to 35-42% on the side farther from the current collector (1); the active material layer (2) is formed into 5-10 sub-coating layers through a multi-layer coating process, each sub-coating layer having a thickness of 10μm-20μm, and the porosity of adjacent layers increasing at a rate of 1%-3%.

3. A battery electrode suitable for large cylindrical batteries according to claim 2, characterized in that, The electrolyte transport channel includes multiple through holes formed on both sides of the base layer by 3D printing technology, and two sizes of micropores set on the surface of the electrode; the micropores include a first micropore with a diameter of 50-80μm and a second micropore with a diameter of 60-110μm, and the arrangement interval of the micropores is 170-240μm.

4. A battery electrode suitable for large cylindrical batteries according to claim 1, characterized in that, A radial gradient distribution of microchannel network is provided on the surface of the electrode. The microchannel network is a conical microchannel (4) with a diameter of 5-30 μm and a depth of 10-50 μm formed on the surface of the electrode using laser micromachining technology. From the outer side of the electrode to the central region, the channel diameter gradually increases and the density decreases from 15% to 5%.

5. A battery electrode suitable for large cylindrical batteries according to claim 4, characterized in that, The inner wall of the microchannel is plasma-treated to form a gradient of hydrophilicity, and has hydroxyl and carboxyl functional groups, so that the hydrophilicity of the inner wall of the channel gradually increases from the outside to the center region, and the contact angle decreases from 65° to 25°.

6. A battery electrode suitable for large cylindrical batteries according to claim 4 or 5, characterized in that, A secondary capillary network (5) with a diameter of 1-3 μm is provided between the main microchannels to form an interconnected three-dimensional liquid transport network.

7. A battery electrode suitable for large cylindrical batteries according to claim 1, characterized in that, A radial-axial dual-gradient micropore network is provided on the surface of the electrode: 1) Radial gradient: from the inner layer to the outer layer of the electrode, the micropore diameter gradually increases from 5μm to 30μm, and the porosity increases from 15% to 35%, forming an electrolyte wetting driving force gradient; 2) Axial gradient: a set of "trunk-branch" structure microchannels is set every 50mm along the length of the electrode. The width of the trunk channel (7) is 40-60μm, the width of the branch channel (8) is 8-15μm, and the channel depth is 60-80% of the thickness of the active material layer (2); The dual-gradient microporous network is fabricated using picosecond laser processing with the following parameters: power 0.5-2W, pulse width 10-30ps, and scanning speed 200-500mm / s.

8. A battery electrode suitable for large cylindrical batteries according to claim 1, characterized in that, The electrode includes a U-shaped groove structure formed by multi-layer coating, which causes the porosity of the electrode to be distributed in a gradient; the surface of the electrode is coated with a cellulose ether polymer, which forms pores in situ in the active material layer and transforms into a gel state.

9. A battery electrode suitable for large cylindrical batteries according to claim 1, characterized in that, The electrode further includes a coating layer, which is a cellulose ether polymer; wherein: The current collector (1) is made of aluminum foil or aluminum alloy foil with a thickness of 4-12 μm; The active material layer (2) is prepared using a multilayer coating process, including the following steps: 1) Mix the active material with the solvent and coat it on the surface of the current collector (1) with a thickness of 10-20 μm to form the first coating layer; 2) The first coating layer is formed on the surface using 3D printing technology to create multiple first micropores with a diameter of 50-80μm, arranged at intervals of 170-240μm; 3) A second coating layer with a thickness of 10-20 μm is formed on the surface of the first micropore; 4) A second micropore with a diameter of 60-110μm is formed on the surface of the second coating layer based on the first micropore using 3D printing technology, and the height difference between the first micropore and the second micropore is 10-20μm; 5) Repeat steps 3) and 4) until the desired number of layers is reached; The porosity of the coating layers varies in a gradient, with the porosity increase rate between adjacent coating layers controlled at 1-3%; the porosity of the last coating layer is 35-42%. A third micropore with a diameter of 50-80 μm is also provided on the surface of the electrode. It is prepared by laser micromachining technology and has a depth of 10-30 μm to form a fast diffusion channel for electrolyte. The cellulose ether polymer is selected from one or more of polyvinyl alcohol, polyacrylic acid, and polyvinylpyrrolidone, with a solid content of 15-25%, and forms an in-situ porosity of 5-10% in the active material layer (2); During the electrolyte wetting process, the micropores between the coating layers and the surface micropores form a rapid electrolyte penetration network, with the wetting rate controlled at 0.5-1.5 mm / s. After wetting, the electrode sheet achieves an electrolyte distribution uniformity of over 95%, eliminating dry areas.

10. A large cylindrical battery, characterized in that, Includes the battery electrode sheet suitable for large cylindrical batteries as described in any one of claims 1-9.

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