Negative electrode plates, batteries, and electrical devices

Abstract

A negative electrode plate, a battery, and an electrical device. The negative electrode plate comprises a current collector and a negative electrode active material layer covering at least one surface of the current collector, the negative electrode active material layer comprising a negative electrode active material, silicon dioxide aerogel, and a binder. The negative electrode active material is filled with silicon dioxide aerogel, which accounts for 0.1% to 5% of the total mass of the negative electrode active material layer.

Description

[Technical Field]

[0001] (Priority Information) This disclosure claims priority to China Patent Application No. 202310338143.2, filed on 31 March 2023, which is incorporated herein by reference in its entirety.

[0002] This disclosure relates to the field of battery technology, and more particularly to negative electrodes, batteries, and electrical devices. [Background technology]

[0003] Secondary batteries (e.g., lithium-ion batteries) are widely used in new energy vehicles, portable electronic products, and large-scale energy storage devices due to their advantages such as high operating voltage, high energy density, long cycle life, and low self-discharge. Along with the relentless pursuit of higher energy density and rapid charging technologies for secondary batteries in downstream applications, the compressed density and thickness of battery electrode sheets are increasing, which leads to serious problems for the negative electrode plate, such as low porosity and poor wettability of the electrolyte. In conventional technology, the conductivity of the negative electrode plate is improved by increasing the conductive agent content in the negative electrode plate, thereby enhancing the conductive ability of carriers (e.g., lithium ions) on the negative electrode plate. However, excessive conductive agent increases the electrical contact interface between the negative electrode plate and the electrolyte, resulting in increased side reactions of the negative electrode plate and a reduced cycle life of the secondary battery.

[0004] Therefore, it is necessary to provide a novel negative electrode plate to meet the application requirements for rapid charging performance and long cycle life of secondary batteries (e.g., lithium-ion batteries). [Overview of the Initiative]

[0005] With this in mind, this disclosure provides a negative electrode plate. The negative electrode plate can effectively increase the battery's cycle performance and rapid charging performance by improving its liquid retention capacity and carrier ion permeability.

[0006] A first aspect of the present disclosure provides a negative electrode plate comprising a current collector and a negative electrode active material layer coated on at least one surface of the current collector, wherein the negative electrode active material layer comprises a negative electrode active material, silica aerogel, and a binder, the silica aerogel filling the negative electrode active material, and the silica aerogel accounting for 0.1% to 5% of the total mass of the negative electrode active material layer.

[0007] In this disclosure, the negative electrode active material layer of the negative electrode plate contains 0.1% to 5% silica aerogel, which is advantageous for improving the rate performance and cycle life of the negative electrode plate and the battery. Firstly, the porous structure of silica aerogel is beneficial for enhancing the electrolyte absorption effect of the negative electrode plate, as the electrolyte penetrates from the pores of the silica aerogel into the negative electrode active material, shortening the carrier ion (lithium ion) conduction pathway and improving the electrochemical kinetics performance of the negative electrode plate and the battery. Secondly, the 0.1% to 5% silica aerogel filling the negative electrode active material is beneficial for improving the pore structure of the negative electrode plate, mitigating uneven pores in the electrode sheet caused by disorderly expansion and contraction of the negative electrode active material during the charging and discharging processes of the battery, and further improving the polarization phenomenon and rate performance of the battery. Thirdly, silica aerogel has a low dielectric constant, which reduces side reactions between the conductive interface exposed by the negative electrode plate and the electrolyte, thereby increasing the battery's cycle life.

[0008] The second aspect of the present disclosure provides a battery including a positive electrode sheet, an electrolyte, a separator, and a negative electrode sheet provided in the first aspect of the present disclosure.

[0009] Since the battery includes the negative electrode sheet provided in the first aspect of the present disclosure, it has high rate performance and cycle life and can meet more application requirements.

[0010] The third aspect of the present disclosure provides an electrical device including the battery provided in the second aspect of the present disclosure.

Brief Description of the Drawings

[0011] [Figure 1] FIG. 1 is a SEM image of a cross-section of a vertical current collector of a negative electrode sheet provided in Example 1 of the present disclosure. [Figure 2] FIG. 2 is an EDS elemental distribution image of C, O, Si, and Cu in the SEM image provided in FIG. 1 of the present disclosure.

Embodiments for Carrying Out the Invention

[0012] The present disclosure is further described by using embodiments and comparative examples that are merely used for explaining the present disclosure, and the present disclosure is not limited to the following embodiments. Any modification or equivalent substitution of the technical solution of the present disclosure that does not deviate from the scope of the technical solution of the present disclosure shall fall within the protection scope of the present disclosure.

[0013] One embodiment of the present disclosure provides a negative electrode sheet, which includes a current collector and a negative electrode active material layer coated on at least one surface of the current collector. The negative electrode active material layer includes a negative electrode active material, silica aerogel, and a binder, and the silica aerogel accounts for 0.1% to 5% of the total mass of the negative electrode active material layer.

[0014] In the present disclosure, the negative electrode active material layer of the negative electrode plate contains 0.1% to 5% of silica aerogel, which is advantageous for improving the rate performance and cycle life of the negative electrode plate and the battery. First, the porous structure of the silica aerogel allows the electrolyte to penetrate from the pores of the silica aerogel into the negative electrode active material, shortening the carrier ion (lithium ion) path and enhancing the electrochemical kinetics performance of the negative electrode plate and the battery by strengthening the electrolyte absorption effect of the negative electrode plate. Second, 0.1% to 5% of silica aerogel is filled in the negative electrode active material, which is beneficial for improving the pore structure of the negative electrode plate, reducing the uneven pores of the electrode sheet caused by the disordered expansion and contraction of the negative electrode active material during the charging and discharging processes of the battery, and further improving the polarization phenomenon and rate performance of the battery. Third, the silica aerogel has a low dielectric constant, which can reduce the side reaction between the conductive interface exposed by the negative electrode plate and the electrolyte and increase the cycle life of the battery.

[0015] In addition, the silica aerogel has stable chemical properties, does not破坏 the electrochemical reaction system inside the battery, has good heat insulation, can improve the safety performance of the battery, and has a low price according to the application requirements of the industrial grade.

[0016] For example, the silica aerogel may account for 0.1%, 0.5%, 1%, 2%, 3%, 5%, etc. of the total mass of the negative electrode active material layer.

[0017] In the present disclosure, the negative electrode active material layer may be coated on one surface of the current collector. Alternatively, the negative electrode active material layer may be coated on both surfaces of the current collector. When the negative electrode active material layer is coated on both surfaces of the current collector, the thickness, surface density, component content, etc. of the negative electrode active material layers disposed on both surfaces of the current collector may be independently designed according to the application requirements, and may be the same or different.

[0018] In the present disclosure, the negative electrode active material may be a carbon-based material.

[0019] In the present disclosure, the negative electrode active material may alternatively be a combination of a carbon-based material and one or more of a silicon-based material, a tin-based material, or a lithium titanate material. In this case, the carbon-based material accounts for 80% to 97% of the total mass of the negative electrode active material.

[0020] The carbon-based material may be one or a combination of artificial graphite, natural graphite, soft carbon, hard carbon, mesophase carbon microbeads, and carbon fiber.

[0021] The silicon-based material may be one or a combination of elemental silicon, silicon oxide (SiO x , where 0 < x < 2), and a silicon alloy. The tin-based material may be one or a combination of elemental tin, tin oxide (SnO x , where 0 < x ≤ 2), and a tin alloy.

[0022] In the present disclosure, the current collector may be any one of a copper foil, a carbon-coated copper foil, a polymer-coated copper foil, a carbon cloth, a carbon nanotube film, or a carbon paper.

[0023] In the present disclosure, the current collector may alternatively be any one of an aluminum foil, a carbon-coated aluminum foil, and a polymer-coated aluminum foil (e.g., used as a negative electrode current collector for a sodium-ion battery).

[0024] In this disclosure, the binder includes one or a combination thereof from among styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), polyacrylic ethylene acrylic acid (PEAA), sodium alginate, carboxymethyl chitosan, polyacrylonitrile (PAN), and polyvinyl alcohol (PVA).

[0025] In some embodiments of this disclosure, the porosity of the negative electrode plate is 20% to 80%.

[0026] In this disclosure, the negative electrode plate comprises silica aerogel. It can be understood that the pores of the negative electrode plate include pores of the silica aerogel, gaps formed by the disorderly deposition of the silica aerogel and the negative electrode active material, and gaps formed after the disorderly deposition of the negative electrode active material. The porosity of the negative electrode plate is in the range of 20% to 80%, the shuttle efficiency of carriers (lithium ions) in the negative electrode plate is good, and the negative electrode plate and battery have high rate performance. In addition, the negative electrode plate has a high liquid storage capacity, which can provide more sufficient electrolyte in the battery cycle process and increase the battery cycle life. For example, the porosity of the negative electrode plate may be 20%, 30%, 50%, 60%, 80%, etc.

[0027] In this disclosure, the porosity of the negative electrode plate is more preferably 30% to 60%. When the porosity of the negative electrode plate is within this range, higher mechanical performance of the negative electrode plate can be ensured, and the cycle stability of the battery can be further improved.

[0028] The method for determining the porosity of the negative electrode plate is to cut the negative electrode plate into a film piece with a specific area, dry the film piece in a vacuum drying oven at 120 °C for 12 hours, take out the film piece and put it into a dryer for cooling, and then examine the porosity. First, the thickness of the sample is measured by using a ten-thousandth gauge (the thickness of the current collector foil is estimated), the apparent volume (V1) of the sample is calculated in light of the surface area and thickness of the sample, and the true volume (V2) of the sample is measured by using a true density analyzer (the volume of the current collector foil is estimated). The porosity of the negative electrode plate = (true volume (V2) / apparent volume (V1)) * It can be obtained as 100%.

[0029] In some embodiments of the present disclosure, the dielectric constant of the silica aerogel is ε, where 0 < ε ≤ 10. That is, the silica aerogel is non-conductive under the action of an external electric field so that the contact interface between the negative electrode plate and the electrolyte can be stabilized, the side reaction between the negative electrode plate and the electrolyte can be alleviated, and the Coulomb efficiency of the battery can be improved. In addition, excessive consumption of the electrolyte can be suppressed, and the cycle life of the battery can be increased

[0030] In some embodiments of the present disclosure, the bulk density of the silica aerogel is 0.003 - 0.500 g / cm 3 For example, the bulk density of the silica aerogel can be 0.003 g / cm 3 , 0.010 g / cm 3 , 0.050 g / cm 3 , 0.100 g / cm 3 , 0.300 g / cm 3 , 0.500 g / cm 3 and so on.

[0031] During the charging and discharging processes of the negative electrode plate, the pore structure of the negative electrode plate changes irregularly with the expansion and contraction of the negative electrode active material. As a result, the pore distribution on the negative electrode plate becomes uneven, which can lead to a clear difference in electrolyte diffusion and carrier ion transfer flux. The battery rate cannot be fully utilized. Thus, the bulk density of the silica aerogel is 0.003~0.500 g / cm³. 3 Within this range, the electrolyte ions on the negative electrode plate have appropriate storage capacity and diffusion pathways, thereby further improving the battery's rate performance. The bulk density of the silica aerogel is excessively low (0.003 g / cm³). 3 If the bulk density of the silica aerogel on the negative electrode plate is excessively high (less than 0.5 g / cm³), the dispersibility of the silica aerogel will be affected. 3 When the value exceeds a certain limit, the buffering effect on the expansion and contraction of the negative electrode active material is not clear.

[0032] In addition, 0.003~0.500 g / cm³ 3 Silica aerogels with a bulk density in the range of 0.1% to 5% can also be used as an effective buffering medium to prevent irreversible damage to the negative electrode plate caused by excessive pressure when the negative electrode plate is rolled up, otherwise preventing the electrolyte from penetrating the negative electrode plate.

[0033] In some embodiments of this disclosure, the specific surface area of ​​the silica aerogel is 100 to 1500 m². 2 The value is / g. For example, the specific surface area of ​​silica aerogel is 100m². 2 / g, 300m 2 / g, 500m 2 / g, 800m 2 / g, 1000m 2 / g, 1200m 2 / g, or 1500m 2 / g can also be used.

[0034] It can be understood that silica aerogel has a relatively large specific surface area, can absorb more electrolytes, and thus improves the liquid storage capacity of the negative electrode plate. In this way, the specific surface area of ​​silica aerogel is 100-1500 m². 2 If the values ​​are within the range of / g, the battery cycle life can be further increased.

[0035] In some embodiments of this disclosure, the silica aerogel comprises mesopores and macropores, and the sum of the volumes of the mesopores and macropores accounts for 60% to 99.99% of the total pore volume of the silica aerogel. For example, the sum of the volumes of the mesopores and macropores may account for 60%, 70%, 80%, 85%, 90%, 95%, or 99.99% of the total pore volume of the silica aerogel.

[0036] Internationally, pores are generally classified into three categories according to their size: micropores, mesopores (i.e., intermediate pores), and macropores. Micropores are those with a diameter of less than 2 nm, mesopores are those with a diameter in the range of 2 to 50 nm, and macropores are those with a diameter greater than 50 nm. Silica aerogels contain mesopores beneficial for electrolyte storage, providing a buffer pool for electrolytes to be released when needed, which is beneficial for improving storage capacity on the negative electrode plate and enhancing the circulating stability and rate performance of the negative electrode plate. Silica aerogels also contain macropores that provide channels for electrolyte transport. Electrolyte ions stored in mesopores diffuse through macropores to the surface of the negative electrode active material, thereby reducing the electrolyte diffusion pathway on the negative electrode plate and improving the rate performance of the battery. Thus, when the sum of the volumes of mesopores and macropores in the silica aerogel accounts for 60% to 99.99% of the total pore volume of the silica aerogel, the battery has better cycle performance and rate performance.

[0037] The sum of the mesopore and macropore volumes in silica aerogel is obtained based on the ratio of the sum of the mesopore and macropore volumes to the total cumulative pore volume in the BET test results of silica aerogel.

[0038] In some embodiments of this disclosure, the silica aerogel has an average particle size of 0.05 to 100 μm.

[0039] The average particle size of the silica aerogel disclosed in this invention is in the range of 0.05 to 100 μm, which allows for better packing effect and further promotion of electrolyte absorption and diffusion depending on the requirements for use of the negative electrode active material in various particle size ranges. For example, the particle size of the silica aerogel may be 0.05 μm, 0.1 μm, 0.5 μm, 1.0 μm, 2.0 μm, 3.0 μm, 10 μm, 20 μm, 50 μm, or 100 μm, etc.

[0040] In this disclosure, the average particle size of the silica aerogel is more preferably 0.5 to 50 μm. If the average particle size of the silica aerogel is excessively small and the surface energy is excessively large, this will affect the dispersibility of the silica aerogel on the negative electrode plate. If the average particle size of the silica aerogel is excessively large, this will affect the contact effect of the silica aerogel with the negative electrode active material.

[0041] The method for measuring the average particle size of silica aerogel is as follows: Silica aerogel was dispersed in anhydrous ethanol by ultrasound for 5 minutes and tested using a laser particle size analyzer. D50 represents the particle size of the silica aerogel, i.e., the particle size corresponding to less than 50% of the total volume on the particle size distribution curve.

[0042] In some embodiments of this disclosure, the negative electrode active material layer further comprises a conductive agent.

[0043] In this disclosure, the negative electrode plate comprises both silica aerogel and a conductive agent, and the electrochemical performance of the battery can be further improved through the synergistic effect of the silica aerogel and the conductive agent.

[0044] In some embodiments of this disclosure, the conductive agent accounts for 0.1% to 5% of the total volume of the active material layer.

[0045] The conductive agent in the negative electrode plate is filled into the negative electrode active material, stores liquid, and can conduct electricity to some extent. However, it can be understood that its exposed conductive interface increases side reactions of the electrolyte. Therefore, the content of the conductive agent within the above range can ensure the conductivity and liquid storage capacity of the negative electrode plate, suppress side reactions of the electrode sheet, and guarantee the battery's rate performance and cycle life.

[0046] In some embodiments of this disclosure, the mass ratio of silica aerogel to the conductive agent is (0.2 to 10):1. When the mass ratio of silica aerogel to the conductive agent is within the range of (0.2 to 10):1, the synergistic effect between the silica aerogel and the conductive agent is stronger, and the overall performance of the battery is better.

[0047] In this disclosure, the conductive agent may be one of conductive carbon black, carbon nanotubes, graphene, and carbon fibers, or a combination thereof. The conductive carbon black material may be one of acetylene black, furnace black, channel black, thermal black, lamp black, and Ketjen black, or a combination thereof. The carbon nanotubes may be one of carbon nanotubes having various diameters (1 to 100 nm) and various lengths (0.05 to 100 μm), or a combination thereof. The graphene may be one of graphene having various numbers of layers (1 to 1000 layers), or a combination thereof.

[0048] Accordingly, one embodiment of the present disclosure further provides a battery comprising a positive electrode plate, an electrolyte, a separator, and a negative electrode plate provided in the first embodiment. Since the battery comprises a negative electrode plate provided in the first embodiment of the present disclosure, the battery has high rate performance and cycle life and meets a wider range of application requirements.

[0049] In this disclosure, the battery may be either a lithium-ion battery or a sodium-ion battery.

[0050] In this disclosure, the positive electrode plate includes a current collector and a positive electrode active material layer coated on at least one surface of the current collector. The active material layer includes a positive electrode active material, a conductive agent, and a binder.

[0051] In this disclosure, the positive electrode active material layer may be coated on one surface of the current collector, or on both surfaces of the current collector. When the positive electrode active material layer is coated on both surfaces of the current collector, the thickness, surface density, component content, etc., of the positive electrode active material layer disposed on each surface of the current collector may be designed independently, the same, or different, depending on the application requirements.

[0052] In this disclosure, the positive electrode current collector may be any one of the following: aluminum foil, carbon-coated aluminum foil, polymer-coated aluminum foil, carbon cloth, carbon nanotube film, or carbon paper.

[0053] In this disclosure, the separator may be one of polyethylene, polypropylene, and polyvinylidene fluoride, or a composite separator.

[0054] In this disclosure, the positive electrode active material may be one or a combination thereof of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and olivine-type lithium-containing phosphate. The positive electrode active material is suitable for lithium-ion batteries.

[0055] In this disclosure, the positive electrode active material may be one or a combination thereof of a transition metal oxide, a polyanionic compound, an organic polymer, and a Prussian blue / white analog material. The positive electrode active material is suitable for sodium-ion batteries.

[0056] In this disclosure, the electrolyte is an organic solvent in which carrier ions are dissolved. This disclosure does not limit the electrolyte, and the electrolyte may be procured in-house depending on the actual circumstances.

[0057] One embodiment of the present disclosure further provides an electrical device. By using a battery provided in an embodiment of the present disclosure, the electrical device can have a higher market competitiveness.

[0058] In some embodiments of this disclosure, the electrical device includes, but is not limited to, a mobile phone, a notebook computer, a tablet computer, or a wearable electronic device such as a smartwatch, an e-cigarette, a new energy vehicle, an electric moped, an energy storage base station, and the like. [Examples]

[0059] The technical solutions of this disclosure will be further described in several embodiments below.

[0060] (Example 1) A negative electrode active material (artificial graphite), a conductive agent (conductive carbon black), sodium carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), and silica aerogel were mixed in a ratio (mass ratio) of 96:0.5:1:2:0.5. The powder materials and the pure mixture were stirred using a homogenizer to form a negative electrode slurry, which was then uniformly coated onto a copper foil. For the silica aerogel, the dielectric constant was 2.1, the average particle size (D50) was 3 μm, the sum of the volumes of mesopores and macropores was 65%, and the bulk density was 0.4 g / cm³. 3 Its specific surface area is 500 m². 2 It was / g.

[0061] Lithium iron phosphate (LiFePO4), a positive electrode active material, a conductive agent (CNT), and a binder (PVDF) were mixed in a ratio (mass ratio) of 97:1:2. The powder materials and NMP were stirred using a homogenizer to form a positive electrode slurry, which was then uniformly coated onto aluminum foil.

[0062] Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a 1:1:1 volume ratio to prepare an electrolyte containing 1 M LiPF6.

[0063] A 1.5Ah stacked battery was prepared using a polypropylene separator.

[0064] (Example 2) The only difference from Example 1 was that the mass ratio of the negative electrode active material (artificial graphite), conductive agent (conductive carbon black), carboxymethylcellulose sodium (CMC), styrene-butadiene rubber (SBR), and silica aerogel was 96:0.9:1:2:0.1.

[0065] (Example 3) The only difference from Example 1 was that the mass ratio of the negative electrode active material (artificial graphite), conductive agent (conductive carbon black), carboxymethylcellulose sodium (CMC), styrene-butadiene rubber (SBR), and silica aerogel was 96:0.1:1:2:0.9.

[0066] (Example 4) The only difference from Example 1 was that the mass ratio of the negative electrode active material (artificial graphite), conductive agent (conductive carbon black SP), concentrate (CMC), binder (SBR), and silica aerogel was 94.55:2.0:1:2:0.45.

[0067] (Example 5) The only difference from Example 1 was that the mixing ratio of the negative electrode active material (artificial graphite), conductive agent (conductive carbon black SP), concentrate (CMC), binder (SBR), and silica aerogel was 94.8:0.2:1:2:2.0.

[0068] (Example 6) The only difference from Example 1 was that the mass ratio of the negative electrode active material (artificial graphite), conductive agent (conductive carbon black SP), concentrate (CMC), binder (SBR), and silica aerogel was 96:0:1:2:1.

[0069] (Example 7) The only difference from Example 1 was that the mass ratio of the negative electrode active material (artificial graphite), conductive agent (conductive carbon black SP), concentrate (CMC), binder (SBR), and silica aerogel was 95:0:1:2:2.

[0070] (Example 8) The only difference from Example 1 was that the mass ratio of the negative electrode active material (artificial graphite), conductive agent (conductive carbon black SP), concentrate (CMC), binder (SBR), and silica aerogel was 94:0:1:2:3.

[0071] (Example 9) The only difference from Example 1 was that the mass ratio of the negative electrode active material (artificial graphite), conductive agent (conductive carbon black SP), concentrate (CMC), binder (SBR), and silica aerogel was 93:0:1:2:4.

[0072] (Example 10) The only difference from Example 1 was that the mass ratio of the negative electrode active material (artificial graphite), conductive agent (conductive carbon black SP), concentrate (CMC), binder (SBR), and silica aerogel was 92:0:1:2:5.

[0073] (Example 11) The only difference from Example 10 was that the sum of the mesopore and macropore volumes of the silica aerogel was 42%.

[0074] (Example 12) The only difference from Example 10 was that the sum of the volumes of mesopores and macropores in the silica aerogel was 99%.

[0075] (Example 13) The difference from Example 10 is that the bulk density of the silica aerogel is 0.8 g / cm³. 3 That was all.

[0076] (Example 14) The difference from Example 10 is that the bulk density of the silica aerogel is 0.02 g / cm³. 3 That was all.

[0077] (Example 15) The difference from Example 10 is that the specific surface area of ​​the silica aerogel is 1450 m². 2 The only thing that was the value was / g.

[0078] (Example 16) The difference from Example 10 is that the silica aerogel has a particle size of 20 μm and a specific surface area of ​​250 m². 2 The only thing that was the value was / g.

[0079] (Example 17) The difference from Example 10 is that the silica aerogel has a particle size of 20 μm and a specific surface area of ​​1000 m². 2 The only thing that was the value was / g.

[0080] To highlight the beneficial effects of the embodiments of this disclosure, the following comparative examples are provided.

[0081] (Comparative Example 1) The only difference from Example 1 was that the mass ratio of the negative electrode active material (artificial graphite), conductive agent (conductive carbon black), carboxymethylcellulose sodium (CMC), styrene-butadiene rubber (SBR), and silica aerogel was 91.99:5:1:2:0.01.

[0082] (Comparative Example 2) The only difference from Example 5 was that the mass ratio of the negative electrode active material (artificial graphite), conductive agent (conductive carbon black), carboxymethylcellulose sodium (CMC), styrene-butadiene rubber (SBR), and silica aerogel was 90:0:1:2:7.

[0083] The silica aerogel content, the conductive agent content, and the porosity parameters in the negative electrode plate of this disclosure are shown in Table 1. The performance test results of the battery are shown in Table 2.

[0084] [Table 1]

[0085] (Electrochemical performance test) The batteries prepared above (including the batteries used in the comparative example) were subjected to room-temperature tests using the Land Electronics CT3002A battery test system, and the test results are summarized in Table 2.

[0086] Battery discharge capability test. At 25°C, a 0.1C / 0.1C cycle test was performed on the battery within the voltage range of 2.0V to 3.8V (charging was performed at 0.1C to a voltage of 3.8V, followed by a 30-minute rest period, and then discharging was performed at 0.1C to a voltage of 2.0V - this sequence constituted one cycle). After three cycles, the discharge capability of the battery in the third cycle was recorded and used as the battery's discharge capability.

[0087] (First cycle charge / discharge test) At 25°C, a 0.1C / 0.1C cycle test was performed on the battery within the voltage range of 2.0V to 3.8V (charging was performed at 0.1C to a voltage of 3.8Vm, followed by a 10-minute rest period, and then discharging was performed at 0.1C to a voltage of 2.0V - this sequence constituted one cycle). The battery's first-cycle charge ratio capacity and discharge ratio capacity were recorded, and the first-cycle charge / discharge efficiency was calculated from these, where the battery's first-cycle discharge efficiency (%) is (first-cycle charge ratio capacity / first-cycle discharge ratio capacity). * It was calculated as 100%.

[0088] (Discharge rate test) At 25°C, the battery was charged to a voltage of 3.8V at a rate of 0.1C, followed by a 30-minute rest period, and then discharged to a voltage of 2.0V at a rate of 3C. This cycle was repeated three times consecutively. The charge / discharge data from the third cycle onward was used to calculate the battery's discharge efficiency for rate performance evaluation. Discharge rate (%) is calculated as (3rd cycle discharge ratio capacity (3C) / 3rd cycle charge ratio capacity (0.1C)). * It was calculated as 100%.

[0089] (Charge level test) At 25°C, the battery was charged to 3.8V at 3C, followed by a 30-minute rest period, and then discharged to 2.0V at 0.1C. This cycle was repeated three times consecutively. The charge / discharge data from the third cycle onwards was used to calculate the battery's charging efficiency. The charge rate (%) is calculated as (3rd cycle discharge ratio capacity (0.1C) / 3rd cycle charge ratio capacity (3C)). * It was calculated as 100%.

[0090] Cycle life test. At 25°C, the battery was charged to 3.8V at 1C, followed by a 10-minute rest period, and then discharged to 2.0V at 1C. This cycle was repeated 1000 times consecutively. The capacity retention rate was recorded, where the capacity retention rate (%) after 1000 cycles is (discharge ratio capacity after 1000 cycles / discharge ratio capacity after the third cycle). * It was calculated as 100%.

[0091] [Table 2]

[0092] As can be seen from the data in Tables 1 and 2, compared to Comparative Examples 1 and 2, the negative electrode plate provided in the embodiments of this disclosure contains silica aerogel in an appropriate mass percentage, and the silica aerogel partially or entirely replaces the conductive agent to be filled in the negative electrode active material to adjust the porosity of the negative electrode plate, which can significantly improve the battery's rate performance (discharge rate and charge rate) and cycle performance. Figures 1 and 2 are SEM images of the vertical current collector cross-section of the negative electrode plate in Example 1 of this disclosure, and its corresponding EDS images. It can be seen from the figures that the silicon element (silica aerogel) is evenly dispersed in the negative electrode material. In Comparative Example 1, a small amount of silica aerogel is added to the negative electrode plate, resulting in low porosity of the electrode sheet, meandering diffusion pathways for the electrolyte, and therefore high lithium-ion transfer impedance, which in turn results in poor rate performance of the battery. By adding silica aerogel to the negative electrode plate to optimize the pore structure within the negative electrode plate and to increase the porosity and liquid absorption rate of the negative electrode plate, it is found to be significantly beneficial in promoting the adsorption and transfer of electrolytes.

[0093] In addition, data from Examples 1-6 show that adding both an appropriate conductive agent and silica aerogel to the negative electrode plate creates a synergistic effect between the two, which can further enhance the electronic and ionic conductivity of the negative electrode plate, thereby improving the battery's rate performance and cycle performance.

[0094] The data from Examples 10-12 show that changing the volume of mesopores and macropores in the silica aerogel on the negative electrode plate affects the porosity and cycle performance of the electrode sheet.

[0095] The data from Examples 10 and 13 and 14 show that the density of the silica aerogel affects the rate performance of the battery.

[0096] The data from Examples 10 and 15-17 show that the specific surface area of ​​silica aerogel affects the battery cycle.

[0097] The above description is an exemplary embodiment of the present disclosure. It should be noted that those skilled in the art may make several further improvements and modifications to this application without departing from the principles of the present disclosure. Such improvements and modifications also fall within the scope of the present disclosure.

Claims

1. A negative electrode plate comprising a current collector and a negative electrode active material layer coated on at least one surface of the current collector, wherein the negative electrode active material layer comprises a negative electrode active material, silica aerogel, and a binder, the silica aerogel is filled into the negative electrode active material, and the silica aerogel accounts for 0.1% to 5% of the total mass of the negative electrode active material layer.

2. The negative electrode plate according to claim 1, wherein the porosity of the negative electrode plate is 20% to 80%.

3. The bulk density of the silica aerogel is 0.003 to 0.500 g / cm³. ３ The negative electrode plate according to claim 1 or 2.

4. The specific surface area of ​​the silica aerogel is 100 to 1500 m². ２ A negative electrode plate according to any one of claims 1 to 3, wherein the value is / g.

5. The negative electrode plate according to any one of claims 1 to 4, wherein the silica aerogel comprises mesopores and macropores, and the sum of the volumes of the mesopores and macropores accounts for 60% to 99.99% of the total pore volume of the silica aerogel.

6. The negative electrode plate according to any one of claims 1 to 5, wherein the average particle size of the silica aerogel is 0.05 to 100 μm.

7. The negative electrode plate according to any one of claims 1 to 6, wherein the negative electrode active material layer further comprises a conductive agent.

8. The negative electrode plate according to claim 7, wherein the conductive agent accounts for 0.1% to 5% of the total mass of the negative electrode active material layer.

9. The negative electrode plate according to claim 7 or 8, wherein the mass ratio of the silica aerogel to the conductive agent is (0.2 to 10):

1.

10. A battery comprising a positive electrode plate, an electrolyte, a separator, and a negative electrode plate according to any one of claims 1 to 9.

11. An electrical device comprising the battery described in claim 10.

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