CN116895760A - Negative electrode active material, negative electrode sheet, lithium ion battery and electronic device - Google Patents

Negative electrode active material, negative electrode sheet, lithium ion battery and electronic device Download PDF

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Publication number
CN116895760A
CN116895760A CN202311018272.XA CN202311018272A CN116895760A CN 116895760 A CN116895760 A CN 116895760A CN 202311018272 A CN202311018272 A CN 202311018272A CN 116895760 A CN116895760 A CN 116895760A
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carbon
silicon
particles
negative electrode
active material
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Inventor
陈聪荣
于立娟
彭果戈
何畅雷
邹喆
陈婷
胡大林
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Guangdong Highpower New Energy Technology Co Ltd
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Guangdong Highpower New Energy Technology Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The application relates to a negative electrode active material, a negative electrode plate, a lithium ion battery and an electronic device. The negative electrode active material includes a silicon-carbon mixture including silicon-carbon particles and graphite particles, the silicon-carbon particles including porous non-graphite particlesA graphitized carbon matrix and nano silicon particles present within the non-graphitized carbon matrix; the silicon carbon mixture satisfies the following relationship: b/(a x v c) 0.7 ∈b<7, preparing a base material; wherein a represents the particle diameter of the silicon carbon particles at Dv50, b represents the particle diameter of the graphite particles at Dv50, c represents the specific surface area of the graphite particles; the particle diameter of the silicon carbon particles at Dv50 and the particle diameter of the graphite particles at Dv50 correspond to a unit of μm, and the specific surface area of the graphite particles corresponds to a unit of m 2 And/g. The scheme provided by the application can improve the cycle performance and the expansion rate of the lithium ion battery.

Description

Negative electrode active material, negative electrode sheet, lithium ion battery and electronic device
Technical Field
The application relates to the technical field of electrochemistry, in particular to a negative electrode active material, a negative electrode plate, a lithium ion battery and an electronic device.
Background
Silicon materials, which are the next generation negative electrode materials for lithium ion batteries, have an ultra-high theoretical specific capacity of 4200mAh/g, are currently considered as the most likely materials to replace the traditional graphite negative electrodes. However, when lithium ions are intercalated into silicon, 300-400% of volume expansion is accompanied, and silicon particles are crushed and the electrochemical performance is lost due to the huge volume expansion; and the formed SEI film is damaged due to the volume effect of silicon, lithium ions are continuously consumed in the process of continuously forming a new SEI film, the capacity is quickly attenuated, the cycle performance of the battery is deteriorated, and the large-scale use of the lithium ion battery is severely limited.
Therefore, how to improve the cycle performance of the lithium ion battery is a technical problem to be solved by those skilled in the art.
Disclosure of Invention
In order to solve or partially solve the problems existing in the related art, the application provides a negative electrode active material, a negative electrode plate, a lithium ion battery and an electronic device, which can inhibit the volume expansion of the battery in the cycle process and improve the cycle performance of the battery.
A first aspect of the present application provides a negative electrode active material comprising a silicon-carbon mixture comprising silicon-carbon particles and graphite particles, the silicon-carbon particles comprising a porous non-graphitized carbon matrix and nano-silicon particles present within the non-graphitized carbon matrix;
the silicon-carbon mixture satisfies the following relationship:
0.7≤b/(a*√c)<7；
wherein a represents the particle diameter of the silicon carbon particles at Dv50, b represents the particle diameter of the graphite particles at Dv50, and c represents the specific surface area of the graphite particles; the particle diameter of the silicon carbon particles at Dv50 and the particle diameter of the graphite particles at Dv50 correspond to a unit of μm, and the specific surface area of the graphite particles corresponds to a unit of m 2 /g。
According to the negative electrode active material, non-graphitized carbon is used as a matrix, silicon carbon particles formed by filling nano silicon particles are used as a silicon-based material in the negative electrode active material, graphite particles are used as a carbon-based material in the negative electrode active material, and the particle size of the silicon carbon particles, the particle size of the graphite particles and the specific surface area of the graphite particles are further limited. On the one hand, the nano silicon particles are small in size, the silicon particles are not pulverized, the electrode active substances are prevented from falling off, meanwhile, the porous non-graphitized carbon matrix provides free space for the expansion of silicon, the volume effect is reduced, the volume expansion of the negative electrode plate in the circulating process is reduced, and the stability of the negative electrode plate is maintained; on the other hand, the nano silicon is filled in the non-graphitized carbon matrix, so that the capacity of the anode material is improved. The particle properties of the silicon carbon particles and the graphite particles are in the range of the application, so that the contact performance between the silicon carbon particles and the graphite particles in the silicon carbon mixture is good, the side reaction of the silicon carbon mixture is reduced, the ion and electron transmission is facilitated, the cycle performance of the lithium ion battery is improved, and the volume expansion of the cathode material in the cycle process is inhibited. Thus, the lithium ion battery has good cycle performance and dynamic performance.
In some embodiments of the application, the silicon carbon particles have a Dv50 value a of 4 μm to 15 μm; and/or the Dv50 value b of the graphite is less than 22 μm; and/or the specific surface area c value of the graphite is0.6m 2 /g～5m 2 And/g. In some embodiments of the application, the nano-silicon particles in the silicon-carbon particles have a particle size of 10nm or less. The Dv50 of the silicon carbon particles and the graphite particles and the specific surface area of the graphite particles are in the ranges, so that the particle matching degree of the silicon carbon particles and the graphite particles is good, the side reaction can be reduced, and the volume expansion in the circulation process can be inhibited; meanwhile, the carbon activity in the anode active material is ensured, and the ion and electron transmission performance is improved.
In some embodiments of the present application, the mass fraction of the silicon carbon particles in the anode active material is 1% to 50%. In some embodiments of the application, the mass fraction of oxygen in the silicon carbon particles is less than 10%. In some embodiments of the application, the mass fraction of carbon in the silicon carbon particles is 40% to 80%. The application controls the mass fraction of silicon-carbon particles in the anode active material and the mass fraction of oxygen and carbon in the silicon-carbon particles in a proper range, ensures that the silicon content in the silicon-carbon particles is about 10% -50%, ensures that the silicon-carbon particles have good structural stability while ensuring the carbon content in the silicon-carbon particles, is beneficial to improving the energy density, simultaneously inhibits the expansion of the anode piece, can reduce or avoid the damage of a conductive network in the anode piece caused by the volume expansion of the anode piece, ensures the structural stability of the anode piece, and further reduces the deterioration of the silicon expansion on the battery cycle performance and the battery cycle life.
In some embodiments of the application, the silicon carbon mixture has a protective layer on the surface; preferably, the protective layer has a thickness of 1 μm or less. The protective layer can further restrict the expansion of silicon, so that poor contact of the anode active material caused by the expansion of silicon is reduced or avoided, the damage of the expansion of silicon to the conductive network of the anode piece is reduced, the stability of the anode piece and the lithium ion battery is improved, and the cycle life of the lithium ion battery is prolonged; the thickness of the protective layer is controlled within the range, so that the protective layer can play a role in inhibiting ghost expansion, the negative electrode plate can be ensured to have a stable structure, the collapse of the structure of the negative electrode plate caused by the protective layer in the battery cycle process is avoided, and the battery cycle performance is improved.
In some embodiments of the application, the protective layer comprises at least one of carbon nanotubes, amorphous carbon, or organic polymers. In some embodiments of the application, the carbon nanotubes are selected from at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes, or carbon nanofibers. In some embodiments of the present application, the organic polymer is selected from at least one of lithium carboxymethyl cellulose (CMC-Li), sodium carboxymethyl cellulose (CMC-Na), potassium carboxymethyl cellulose (CMC-K), styrene-butadiene rubber (SBR), styrene-acrylic emulsion, lithium polyacrylate (PAA-Li), sodium polyacrylate (PAA-Na), potassium polyacrylate (PAA-K), lithium alginate (ALG-Li), sodium alginate (ALG-Na), or potassium alginate (ALG-K).
In some embodiments of the application, the non-graphitizing carbon matrix is selected from hard carbon. The hard carbon is a carbon material which is difficult to graphitize by high-temperature treatment fluid at the temperature of more than 2800 ℃, and the disordered structure of the hard carbon is difficult to eliminate at high temperature, so that the action of a framework is born in the negative electrode plate, the stress generated by graphite is uniformly dispersed, the volume expansion of the plate can be better reduced, and the plate has good cycle performance; meanwhile, the reversible specific capacity of the hard carbon can reach 300mAh/g, which is beneficial to improving the voltage and energy density of the lithium ion battery; in addition, the porous hard carbon has a large number of microporous structures, can provide a large number of lithium ion channels and additional lithium storage space, and can absorb the expansion of silicon during charge and discharge to thereby suppress the volume expansion.
In some embodiments of the application, the graphite particles are selected from at least one of natural graphite, artificial graphite, mesophase carbon microsphere graphene, soft carbon, or hard carbon.
In some embodiments of the application, the silicon carbon mixture is free of SiOx; wherein x is more than or equal to 0.5 and less than or equal to 1.6. By selecting a proper silicon-based material, the volume expansion of silicon can be effectively reduced or avoided, and the energy density can be effectively improved.
The second aspect of the application provides a negative electrode plate, which comprises the negative electrode active material of the first aspect of the application.
In some embodiments of the application, the negative electrode sheet has a compacted density PD of 1.50g/cm 3 ～1.75g/cm 3 . When the negative pole piece is pressedThe real density is in the range, so that on one hand, the energy density of the lithium ion battery can be fully ensured, the capacity of the battery is ensured, the manufacturing cost of the battery can be reduced, and the multiplying power performance and the cycle performance of the battery are ensured; on the other hand, the wettability of the pole piece in the preparation process can be ensured, the production efficiency of the pole piece is improved, and the rebound of the negative pole piece can be further reduced, so that the capacity attenuation caused by overlarge expansion force of the battery is further slowed down, the safety risk caused by the rebound of the negative pole piece is further reduced, and the multiplying power performance and the cycle performance of the battery are further improved.
In some embodiments of the application, the negative electrode tab has an OI value that: OI is less than or equal to 7.0. The IO value of the negative pole piece is in the range, so that the expansion of the dispersed pole piece is facilitated, the damage of the expansion to the pole piece structure in the charge and discharge process is reduced, and the cycle performance of the battery is improved.
The third aspect of the application provides a lithium ion battery, comprising the negative electrode plate of the second aspect of the application.
A fourth aspect of the application provides an electronic device comprising a lithium ion battery according to the third aspect of the application.
The technical scheme provided by the application can comprise the following beneficial effects: through the matching of particle diameters between the silicon carbon particles and the graphite particles, the relation between the specific surface area of the graphite particles and the silicon carbon particles is optimized, so that side reactions of the silicon carbon particles and the graphite particles are reduced, ion and electron transmission in the silicon carbon particles and the graphite particles is improved, volume expansion in the charge and discharge processes of the battery is further inhibited, and the cycle performance of the lithium ion battery is improved.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and other embodiments may be obtained according to these drawings to those skilled in the art.
FIG. 1 is an electron microscopic view of the silicon carbon particles of example 3 of the present application;
FIG. 2 is a graph showing the electrical properties of example 5 and comparative example 4 of the present application.
Detailed Description
In order that the application may be readily understood, the application will be described in detail. Before the present application is described in detail, it is to be understood that this application is not limited to particular embodiments described. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.
Where a range of values is provided, it is understood that each intervening value, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the application. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges, and are also encompassed within the application, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the application.
Unless defined otherwise, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. Although any methods and materials equivalent to those described herein can also be used in the practice or testing of the present application, the preferred methods and materials are now described.
At present, in order to solve the problem of expansion of silicon in the circulation process, various means such as carbon coating, metal mixing, polymer coating and the like are adopted by technicians, and certain defects are still caused although the method has certain effects. For example, the carbon coating is a core-shell structure formed by taking silicon particles as a core and coating conductive carbon materials at the periphery, and the carbon layer can provide buffering and protecting effects, but the expansion of silicon is not restrained at the later period of circulation, so that the coating layer is broken, the side reaction at the later period is further increased, the lithium ion consumption is increased, and the capacity reduction of the battery is accelerated. In addition, silicon particles are made into extremely fine crystallites by using the emerging silane deposition technique, but when used as a negative electrode material, the expansion ratio is still higher than that of conventional graphite.
According to the application, by controlling the relation between the particle size of the silicon carbon particles and the graphite particles in the anode active material and the specific surface area of the graphite particles in a proper range, the side reaction in circulation can be reduced, so that the lithium ion battery containing the anode active material has good circulation performance.
A first embodiment of the present application provides a negative electrode active material including a silicon-carbon mixture including silicon-carbon particles and graphite particles, the silicon-carbon particles including a porous non-graphitized carbon matrix and nano-silicon particles present in the non-graphitized carbon matrix; the silicon-carbon mixture satisfies the following relationship: b/(a x v c) 0.7 ∈b<7, preparing a base material; wherein a represents the particle diameter of the silicon carbon particles at Dv50, b represents the particle diameter of the graphite particles at Dv50, c represents the specific surface area of the graphite particles; the Dv50 of the silicon carbon particles and the Dv50 of the graphite particles correspond to a unit of μm, and the specific surface area of the graphite particles corresponds to a unit of m 2 And/g. For example, the value of b/(a) c) may be 0.7, 0.8, 0.9, 1.0, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.5, 3.0, 3.5, 4.0, 5.0, 6.0, or 7.0, etc., and may be other values within the above range.
In the application, the following components are added: when the silicon carbon particles and the graphite particles meet the condition that b/(a×v c) <7, the cycle performance of the lithium ion battery is improved; when b/(a×v c) of the silicon carbon particles and the graphite particles is too low, the cycle performance is deteriorated and the expansion ratio is increased; with the continuous increase of b/(a x v c), the volume expansion rate in the circulation process is continuously reduced, and the circulation performance is continuously improved; when b/(a x c) increases to a certain extent, the dynamics is insufficient, the number of circulation turns is not increased or even reduced, but the expansion rate is not greatly different.
In some embodiments, the silicon carbon particles have a Dv50 value a of 4 μm to 15 μm, for example, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, or 15 μm, etc., and other values within the above range.
In some embodiments, the graphite has a Dv50 value b of less than 22 μm, which may be, for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, etc., as well as other values within the above ranges.
In some embodiments, the graphite has a specific surface area c value of 0.6m 2 /g～5m 2 /g, for example, may be 0.6m 2 /g、0.7m 2 /g、0.8m 2 /g、0.9m 2 /g、1.0m 2 /g、1.1m 2 /g、1.2m 2 /g、1.3m 2 /g、1.4m 2 /g、1.5m 2 /g、1.6m 2 /g、1.7m 2 /g、1.8m 2 /g、2.0m 2 /g、3.0m 2 /g、4.0m 2 /g or 5.0m 2 For example,/g, other values within the above range may be used.
The particle size of the silicon carbon particles, the particle size of the graphite particles and the specific surface area of the graphite particles are in the ranges, so that the cycle performance improvement effect of the lithium ion battery is good; when the Dv50 of the silicon carbon particles is less than 4 μm or more than 15 μm, or the Dv50 of the graphite particles is more than 22 μm, the expansion ratio is increased and the cycle performance is greatly deteriorated.
The Dv50 of the present application refers to the particle size corresponding to the cumulative volume distribution percentage of the material reaching 50%. The Dv50 values of both the silicon carbon particles and the graphite particles described herein can be determined using instruments and methods well known in the art. For example, the following means may be used: 0.02g of powder sample is added into a 50ml clean beaker, 20ml of deionized water is added, 3 to 5 drops of surfactant with mass concentration of 1% are added dropwise, the powder sample is completely dispersed in water, then ultrasonic vibration is carried out for 5 minutes in a power 120W ultrasonic cleaner, and the particle size distribution is tested by using a laser particle size analyzer (model MasterSizer 2000).
The specific surface area of the graphite according to the present application can be obtained according to a method well known in the art, and is not limited herein. For example, the method can be calculated as follows:
1. and (3) testing: weighing 1.5g to 3.5g of powder sample, placing the powder sample into a test sample tube of a specific surface area and porosity analyzer (model TriStar II 3020), and degassing at 200 ℃ for 120min for testing;
2. and (3) calculating: after the adsorption amount of the gas on the solid surface at different relative pressures is measured at a constant temperature and a low temperature, the adsorption amount of the sample monolayer is obtained based on the Brownol Ettylor adsorption theory and a formula (BET formula) thereof, so that the specific surface area of the anode material is calculated.
The BET formula is:
wherein W represents the mass of gas adsorbed by the solid sample under relative pressure; wm represents the gas saturation adsorption amount of a monolayer; (c 1)/(WmC) represents a slope; 1/WmC represents the intercept. The total surface area St is: st= (wm×n×acs/M), and the specific surface area S is: s=st/m, where m represents the sample mass and Acs represents each N 2 The average area occupied by the molecules is
In some embodiments, the nano-silicon particles in the silicon-carbon particles have a particle size of 10nm or less. The nano silicon particles in the silicon-carbon particles are in the range, the size is small, the silicon particles are not pulverized, the electrode active substances can be prevented from falling off, meanwhile, the porous non-graphitized carbon matrix provides free space for the expansion of silicon, the volume effect is reduced, the volume expansion of the negative electrode plate in the circulation process is reduced, and the stability of the negative electrode plate is maintained.
In some embodiments, the mass fraction of the silicon-carbon particles in the negative electrode active material is 1% to 50%, for example, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 40%, 50%, etc., and may be other values within the above range.
In some embodiments, the mass fraction of oxygen in the silicon carbon particles is less than 10%, for example, may be greater than 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, etc., and may be other values within the above ranges.
In some embodiments, the mass fraction of carbon in the silicon-carbon particles may be 40% to 80%, for example, 40%, 45%, 50%, 60%, 65%, 75% or 80%, etc., and may be other values within the above range.
In the application, the mass fraction of carbon in the silicon-carbon particles, the mass fraction of silicon in the silicon-carbon particles and the mass fraction of oxygen in the silicon-carbon particles can be tested by an inductively coupled plasma (inductively coupled plasma, ICP) method, if not otherwise described.
In some embodiments, the silicon carbon mixture surface has a protective layer; the thickness of the protective layer may be, for example, 1 μm or less. In some embodiments, the protective layer comprises at least one of carbon nanotubes, amorphous carbon, or an organic polymer. Optionally, the carbon nanotubes are selected from at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes or carbon nanofibers. Optionally, the organic polymer is selected from at least one of lithium carboxymethyl cellulose (CMC-Li), sodium carboxymethyl cellulose (CMC-Na), potassium carboxymethyl cellulose (CMC-K), styrene-butadiene rubber (SBR), styrene-acrylic emulsion, lithium polyacrylate (PAA-Li), sodium polyacrylate (PAA-Na), potassium polyacrylate (PAA-K), lithium alginate (ALG-Li), sodium alginate (ALG-Na), or potassium alginate (ALG-K).
In some embodiments, the silicon-carbon particles include a porous non-graphitized carbon matrix and nano-silicon particles present within the non-graphitized carbon matrix. Optionally, the non-graphitizing carbon matrix is selected from hard carbon.
In some embodiments, the graphite particles are selected from at least one of natural graphite, synthetic graphite, mesophase carbon microsphere graphene, soft carbon, or hard carbon.
In some embodiments, the silicon carbon mixture is free of SiOx; wherein x is more than or equal to 0.5 and less than or equal to 1.6.
In some embodiments, the negative active material further includes a conductive agent and a binder. Wherein, the conductive agent can be selected from one or more of conductive carbon black, acetylene black, ketjen black, carbon dots, carbon nanotubes, graphene, carbon nanofibers and superconductive carbon, and the application is not limited thereto. The binder may be at least one selected from polyacrylic acid (PAA), sodium Polyacrylate (PAAs), polyacrylamide (PAM), polyvinyl alcohol (PVA), styrene-butadiene rubber (SBR), sodium Alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).
The second embodiment of the application provides a negative electrode plate, which comprises a negative electrode current collector and a negative electrode film layer formed by coating the negative electrode active material on the surface of the negative electrode current collector. The negative electrode current collector may be selected from a metal foil or a composite current collector, for example, the metal foil may be selected from copper foil; the composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
In some embodiments, the negative electrode sheet has a compacted density PD of 1.50g/cm 3 ～1.75g/cm 3 For example, it may be 1.50g/cm 3 、1.55g/cm 3 、1.60g/cm 3 、1.65g/cm 3 、1.70g/cm 3 Or 1.75g/cm 3 And the like, and may be other values within the above-described range. Calculating the compaction density of the negative electrode plate: compacted density = mass per unit area of negative electrode active material layer (g/cm 2 ) Negative electrode active material layer thickness (cm).
In some embodiments, the negative electrode tab has an OI value that satisfies: OI is less than or equal to 7.0. Alternatively, the OI value of the negative electrode sheet may be 7.0, 6.0, 5.0, 4.5, 4.0, 3.5, 3.0, 2.8, 2.5, 2.0, 1.8, 1.5, or 1.0, etc., but may be other values within the above range. In the present application, the OI value refers to a ratio of a diffraction peak-to-peak area of the 004 crystal face to a diffraction peak-to-peak area of the 110 crystal face of the anode active particle, which can be characterized by using an X-ray diffractometer.
In some embodiments, the negative electrode sheet may be prepared by: dispersing graphite particles, silicon carbon particles, a conductive agent and a binder in a solvent (such as deionized water) to form a negative electrode slurry; and (3) coating the negative electrode slurry on the surface of a negative electrode current collector, and obtaining a negative electrode plate after the procedures of drying, cold pressing and the like.
In other embodiments of the present application, the negative electrode sheet may be prepared by: and dispersing the silicon carbon particles and the graphite particles in a solvent to obtain a first mixture, adding materials (such as carbon nano tubes) used for the protective layer to obtain a second mixture, and drying, sintering and other working procedures to obtain the negative electrode active material. Dispersing the prepared negative electrode active material, a conductive agent and a binder in a solvent to form negative electrode slurry, coating the negative electrode slurry on the surface of a negative electrode current collector, and obtaining a negative electrode plate after the procedures of drying, cold pressing and the like.
The third embodiment of the application provides a lithium ion battery, which comprises a positive electrode plate, a separation film, electrolyte and the negative electrode plate. In the charging and discharging process of the lithium ion battery, lithium ions are inserted and separated back and forth between the positive pole piece and the negative pole piece; the electrolyte plays a role in conducting lithium ions between the positive pole piece and the negative pole piece; the isolating film is arranged between the positive pole piece and the negative pole piece, and mainly plays a role in preventing the positive pole piece and the negative pole piece from being short-circuited, and meanwhile ions can pass through the isolating film.
In the present application, the positive electrode of the lithium ion battery may be any positive electrode known in the art, and is not particularly limited.
In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, and the positive electrode current collector may be a metal foil or a composite current collector, for example, aluminum may be used as the metal foil. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
The positive electrode film layer is formed by coating a positive electrode active material on the surface of a positive electrode current collector. The positive electrode active material may includeAt least one of the following materials: olivine structured lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. Among them, olivine structured lithium-containing phosphates include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also abbreviated as LFP)), composite material of lithium iron phosphate and carbon, and manganese lithium phosphate (such as LiMnPO) 4 ) At least one of a composite material of lithium manganese phosphate and carbon, and a composite material of lithium manganese phosphate and carbon. Lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (e.g., liCoO) 2 ) Lithium nickel oxide (e.g. LiNiO) 2 ) Lithium manganese oxide (e.g. LiMnO 2 、LiMn 2 O 4 ) Lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., liNi) 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM) 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O 2 (also referred to as NCM) 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O 2 (also referred to as NCM) 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O 2 (also referred to as NCM) 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM) 811 ) Lithium nickel cobalt aluminum oxide (e.g. LiNi 0.85 Co 0.15 Al 0.05 O 2 ) And at least one of its modified compounds and the like.
In some embodiments, the positive electrode active material may further include a conductive agent. The conductive agent includes, but is not limited to, at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
In some embodiments, the positive electrode active material may further include a binder. The binder includes, but is not limited to, at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymers, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymers, tetrafluoroethylene-hexafluoropropylene copolymers, and fluoroacrylate resins.
In some embodiments, the positive electrode sheet may be prepared by: dispersing a positive electrode active material, a conductive agent and a binder in a solvent (such as N-methyl pyrrolidone) to form a positive electrode paste; and (3) coating the positive electrode slurry on a positive electrode current collector, and obtaining a positive electrode plate after the procedures of drying, cold pressing and the like.
In some embodiments, the separator of the present application may be arbitrarily selected from known porous structure separators having good chemical and mechanical stability. The material of the isolating film may be at least one selected from glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of the respective layers may be the same or different, and are not particularly limited.
In some embodiments, the positive electrode tab, the negative electrode tab, and the separator may be manufactured into an electrode assembly through a winding process or a lamination process.
The electrolyte according to the present application may be any electrolyte known in the art, and is not particularly limited. In some embodiments, the electrolyte includes an electrolyte salt and a solvent. Wherein the electrolyte salt may be at least one selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium difluorosulfonimide, lithium bistrifluoromethanesulfonimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalato borate, lithium dioxaoxalato borate, lithium difluorodioxaato phosphate and lithium tetrafluorooxalato phosphate. The solvent may be at least one selected from methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethylene propyl carbonate, butylene carbonate, fluoroethylene carbonate, propylene carbonate, ethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1, 4-butyrolactone, sulfolane, dimethyl sulfone, methyl sulfone and diethyl sulfone.
In some embodiments, the electrolyte further optionally includes an additive. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives capable of improving certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high or low temperature performance of the battery, and the like.
A fourth embodiment of the present application provides an electronic device including the above lithium ion battery. The lithium ion battery is used as a power source of the electronic device and can also be used as an energy storage unit of the electronic device. The electronic device may include mobile equipment (e.g., cell phones, notebook computers, etc.), electric vehicles (e.g., electric only vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto.
In order that the application may be more readily understood, the application will be further described in detail with reference to the following examples, which are given by way of illustration only and are not limiting in scope of application. The starting materials or components used in the present application may be prepared by commercial or conventional methods unless specifically indicated.
Example 1:
(1) Preparation of negative pole piece (direct pulping method)
Step 1, mixing graphite particles, silicon carbon particles (the carbon content is 52 percent, the oxygen content is less than 1 percent), a conductive agent and a binder according to the mass ratio of 70:15:5:10, adding deionized water as a solvent to prepare slurry with the solid content of 60 percent, adding a proper amount of deionized water, and adjusting the viscosity of the slurry to 5000 Pa.s to prepare the cathode slurry.
Step 2, coating the prepared negative electrode slurry on one surface of a copper foil with the thickness of 8 mu m, and drying at 110 ℃ to obtain a negative electrode plate with the compacted density of 1.70g/cm 3 Cold-pressing the pole piece to a negative pole piece with the coating thickness of 100 mu m. And repeating the coating steps on the other surface of the negative electrode plate to obtain the negative electrode plate with the negative electrode active material layer coated on both sides, wherein the OI value of the negative electrode plate is 3.64. Cutting the negative electrode plate into specifications of 74mm multiplied by 867mm, and welding the electrode lugs for later use.
(2) Preparation of positive electrode plate
Mixing positive active material lithium cobaltate, conductive carbon black and polyvinylidene fluoride (PVDF) according to the mass ratio of 95:2.5:2.5, then adding N-methyl pyrrolidone (NMP) as a solvent, preparing slurry with the solid content of 75%, and uniformly stirring. Uniformly coating the slurry on one surface of an aluminum foil with the thickness of 12 mu m, drying at 90 ℃ and compacting the positive electrode plate with the density of 4.15g/cm 3 And cold-pressing the pole piece to the positive pole piece with the thickness of the positive active material layer of 110 mu m, and repeating the steps on the other surface of the positive pole piece to obtain the positive pole piece with the positive active material layer coated on both sides. And cutting the positive electrode plate into a specification of 76mm multiplied by 851mm, and welding the tab for later use.
(3) Preparation of a separator film
A Polyethylene (PE) porous polymeric film having a thickness of 15 μm was used as a separator.
(4) Preparation of electrolyte
Mixing a nonaqueous organic solvent Propylene Carbonate (PC), ethylene Carbonate (EC) and diethyl carbonate (DEC) according to a mass ratio of 1:1:1 in an environment with a water content of less than 10ppm, adding lithium hexafluorophosphate (LiPF 6) into the nonaqueous organic solvent, dissolving and uniformly mixing, and adding fluoroethylene carbonate (FEC) to obtain the electrolyte. Wherein, the molar concentration of LiPF6 in the electrolyte is 1.15mol/L, and the mass concentration of FEC in the electrolyte is 12.5%.
(5) Preparation of lithium ion batteries
And sequentially stacking the prepared positive pole piece, the isolating film and the negative pole piece, so that the isolating film is positioned between the positive pole piece and the negative pole piece to play a role of isolation, and winding to obtain the electrode assembly. And (3) filling the electrode assembly into an aluminum plastic film packaging bag, dehydrating at 80 ℃, injecting the prepared electrolyte, and carrying out the procedures of vacuum packaging, standing, formation, shaping and the like to obtain the lithium ion battery.
Examples 2-6 can be carried out in the same manner as in example 1, examples 2-6 differing from example 1 in that the individual parameters take different values, the specific differences being seen in Table 1.
Example 7
Example 7 is different from example 1 in the preparation method of the negative electrode sheet only, and the preparation of other materials can be referred to in example 1.
(1) Preparation of negative electrode sheet (Mixed granulation method)
Step A, silicon carbon particles (the carbon content is 52 percent, and the oxygen content is less than 1 percent) and graphite particles are mixed in a solvent according to the mass ratio of 15:70 to form a first mixture;
step B, calculating the addition amount of the carbon nano tube (the material used for the protective layer) according to 1% of the total mass of the silicon carbon particles and the graphite particles, and mixing the carbon nano tube with the first mixture to form a second mixture;
step C, spray drying the second mixture to form granules;
step D, sintering the pelleting product obtained in the step C under inert atmosphere (such as helium) to obtain anode active material particles, wherein the thickness of a protective layer in the anode active material particles is 1 mu m;
and E, mixing the anode active material particles prepared in the step D, a conductive agent (conductive carbon black) and a binder (PAA) according to the mass ratio of 85:5:10, adding deionized water as a solvent to prepare slurry with the solid content of 60%, and adding a proper amount of deionized water to adjust the viscosity of the slurry to 5000 Pa.s to prepare the anode slurry.
Step F, coating the prepared negative electrode slurry on one surface of a copper foil with the thickness of 8 mu m, and drying at 110 ℃ to obtain a negative electrode plate with the compacted density of 1.70g/cm 3 Cold-pressing the pole piece to a negative pole piece with the coating thickness of 100 mu m. And repeating the coating steps on the other surface of the negative electrode plate to obtain the negative electrode plate with the negative electrode active material layer coated on both sides, wherein the OI value of the negative electrode plate is 3.64. Cutting the negative electrode plate into specifications of 74mm multiplied by 867mm, and welding the electrode lugs for later use.
Example 8 and comparative example 1 can be carried out in the same manner as in example 7, and example 8 and comparative example 1 differ from example 7 in that the individual parameters have different values, and the specific differences are shown in Table 1.
Comparative examples 2 to 6 can be prepared by the same method as in example 1, and comparative examples 2 to 6 are different from example 1 in that the individual parameters are different values, and the specific differences can be seen in table 1.
TABLE 1
Testing and analysis:
(1) And (3) testing the cycle performance:
the test temperature was 25℃or 45℃and was charged to 4.4V at a constant current of 0.7℃and 0.025℃at a constant voltage, and after standing for 5 minutes, was discharged to 3.0V at 0.5 ℃. And taking the capacity obtained in the step as initial capacity, performing a cyclic test by adopting 0.7C charge/0.5C discharge, and obtaining a capacity attenuation curve by taking the ratio of the capacity of each step to the initial capacity. The number of turns with 25 ℃ cycle cut-off capacity retention rate of 90% is recorded as the room temperature cycle performance of the battery, and the number of turns with 45 ℃ cycle cut-off capacity retention rate of 80% is recorded as the high temperature cycle performance of the battery; the more turns, the better the cycling performance of the battery. The cycle performance of the material was compared by comparing the number of cycles in the two cases described above. The relevant test results are shown in table 2.
(2) And (3) testing the full charge expansion rate of the lithium ion battery:
and testing the thickness of the lithium ion battery in a half-charge State (SOC) by using a spiral micrometer, namely, the thickness of the lithium ion battery in a 50% state of charge (SOC) state, and testing the thickness of the lithium ion battery at the moment by using the spiral micrometer when the lithium ion battery is fully charged in 400 circles, namely, in a 100% SOC state. And dividing the thickness of the same lithium ion battery after full charge by the thickness of the same lithium ion battery during half charge to obtain the expansion rate of the full charge lithium ion battery at the moment. The relevant test results are shown in table 2.
TABLE 2
As is clear from examples 1 to 8 in table 2, when the particle diameters of the silicon carbon particles and the graphite particles and the specific surface areas of the graphite particles satisfy 0.7.ltoreq.b/(a.v.c) <7, the number of turns at the room temperature cycle cut-off 90% is substantially 300 or more, and the number of turns at the high temperature cycle cut-off 80% is substantially 200 or more, the lithium ion battery has good cycle performance; the expansion rate is lower than 8.5% in the room temperature circulation process, lower than 8.4% in the high temperature circulation process, and lower in the circulation process.
As is clear from the comparison of examples 1 to 5 in Table 2, when the particle diameters of the silicon carbon particles and the graphite particles and the specific surface area of the graphite particles satisfy 0.7.ltoreq.b/(a.v.c) <7, the number of cycles increases as the particle diameter of the silicon carbon particles increases, the side reaction decreases during the cycle, and the cycle performance improves.
As is clear from the comparison of examples 5 and 6 in table 2, when the particle diameters of the silicon carbon particles and the graphite particles and the specific surface area of the graphite particles satisfy 0.7.ltoreq.b/(a.v.c) <7, the increase in the silicon carbon particle diameter to a certain extent causes deterioration of the cycle performance due to insufficient dynamics, but the expansion ratio is not greatly different. Therefore, it is necessary to control the particle diameters of the silicon carbon particles and the graphite particles and the specific surface areas of the graphite particles within a proper range.
As can be seen from the comparison of examples 4, 5, 7, 8 and comparative examples 1 and 2 in table 2, in the process of preparing the negative electrode sheet, graphite particles and silicon-carbon particles are mixed and granulated, and then the granulated product is prepared into the negative electrode sheet, so that the cycle performance can be further improved and the volume expansion in the cycle process can be reduced. On the one hand, the matching effect between graphite particles and silicon carbon particles in the mixing granulation process is better, and the expansion of the negative electrode plate in the circulation process can be further limited, so that the side reaction in the circulation process is reduced; on the other hand, the carbon nano tube is introduced in the mixing granulation process to serve as a protective layer, so that the expansion of silicon can be further restrained, and the cycle performance of the lithium ion battery is further improved.
As is clear from the comparison between example 1 and comparative example 2 in Table 2, when the Dv50 of the silicon carbon particles is less than 4. Mu.m, the cycle performance is seriously deteriorated and the expansion ratio is increased; as is evident from the comparison between example 6 and comparative example 3, when the Dv50 of silicon carbon is more than 15. Mu.m, the cycle performance is seriously deteriorated; as is evident from the comparison between example 3 and comparative example 5, when the Dv50 of the graphite particles is more than 22. Mu.m, the cycle performance is seriously deteriorated. Therefore, in order to solve the problem of battery cycle performance, it is necessary to control the particle diameters of the silicon carbon particles and the graphite particles within a proper range.
As is clear from the comparison between examples 5 and 6 and comparative examples 4 and 6 in table 2, the Dv50 of the silicon carbon particles, the Dv50 of the graphite and the specific surface area of the graphite should satisfy the relationship of 0.7.ltoreq.b/(a×v c) <7, so that the side reaction during the circulation of the negative electrode active material can be suppressed, the ionic electron transport path can be improved, and the circulation performance can be improved and the volume expansion during the circulation can be reduced.
FIG. 1 is an electron micrograph of silicon carbon particles of example 3 of the present application. As can be seen from the figure, the morphology of the silicon carbon particles is irregular, most of the particles are in the range of 4-15 μm in size, and the small particles are fewer.
FIG. 2 is a graph showing the electrical properties of example 5 and comparative example 4 of the present application. As can be seen from the graph, the battery capacity retention rates of the example 5 are obviously better than those of the comparative example 4 under the discharge rates of 0.5C, 1C, 1.5C and 2C of the battery, and the battery discharge rate performance of the example 5 is obviously better than that of the comparative example 4, which indicates that the cycle performance of the lithium ion battery can be greatly improved and the cycle life of the battery can be prolonged when the negative electrode active material is applied to the lithium ion battery.
It should be noted that the above-described embodiments are only for explaining the present application and do not constitute any limitation of the present application. The application has been described with reference to exemplary embodiments, but it is understood that the words which have been used are words of description and illustration, rather than words of limitation. Modifications may be made to the application as defined in the appended claims, and the application may be modified without departing from the scope and spirit of the application. Although the application is described herein with reference to particular means, materials and embodiments, the application is not intended to be limited to the particulars disclosed herein, as the application extends to all other means and applications having the same function.

Claims (10)

1. A negative electrode active material characterized by: comprising a silicon-carbon mixture comprising silicon-carbon particles and graphite particles, the silicon-carbon particles comprising a porous non-graphitized carbon matrix and nano-silicon particles present within the non-graphitized carbon matrix;
the silicon-carbon mixture satisfies the following relationship:
0.7≤b/(a*√c)<7；
wherein a represents the particle diameter of the silicon carbon particles at Dv50, b represents the particle diameter of the graphite particles at Dv50, and c represents the specific surface area of the graphite particles; the particle diameter of the silicon carbon particles at Dv50 and the particle diameter of the graphite particles at Dv50 correspond to a unit of μm, and the specific surface area of the graphite particles corresponds to a unit of m 2 /g。
2. The anode active material according to claim 1, wherein:
the Dv50 value a of the silicon carbon particles is 4-15 mu m;
and/or the Dv50 value b of the graphite particles is less than 22 μm;
and/or the specific surface area c value of the graphite particles is 0.6m 2 /g～5m 2 /g；
And/or, the particle size of nano silicon particles in the silicon-carbon particles is less than or equal to 10nm.
3. The anode active material according to claim 1, wherein:
the mass fraction of silicon carbon particles in the anode active material is 1% -50%;
and/or the mass fraction of oxygen in the silicon carbon particles is less than 10%;
and/or the mass fraction of carbon in the silicon-carbon particles is 40% -80%.
4. The anode active material according to any one of claims 1 to 3, wherein: the surface of the silicon-carbon mixture is provided with a protective layer; preferably, the protective layer has a thickness of 1 μm or less.
5. The anode active material according to claim 4, wherein: the protective layer comprises at least one of carbon nanotubes, amorphous carbon, or organic polymers; preferably, the carbon nanotubes are selected from at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes or carbon nanofibers; the organic polymer is at least one selected from carboxymethylcellulose lithium (CMC-Li), carboxymethylcellulose sodium (CMC-Na), carboxymethylcellulose potassium (CMC-K), styrene-butadiene rubber (SBR), styrene-acrylic emulsion, lithium polyacrylate (PAA-Li), sodium polyacrylate (PAA-Na), potassium polyacrylate (PAA-K), lithium alginate (ALG-Li), sodium alginate (ALG-Na) or potassium alginate (ALG-K).
6. The anode active material according to any one of claims 1 to 5, characterized in that: the non-graphitizing carbon matrix is selected from hard carbon; and/or the graphite particles are selected from at least one of natural graphite, artificial graphite, mesophase carbon microsphere graphene, soft carbon or hard carbon.
7. The anode active material according to any one of claims 1 to 6, characterized in that: the silicon carbon mixture is free of SiOx; wherein x is more than or equal to 0.5 and less than or equal to 1.6.
8. A negative electrode sheet comprising the negative electrode active material according to any one of claims 1 to 7; preferably, the compacted density PD of the negative electrode plate is 1.50g/cm 3 ～1.75g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the Preferably, the OI value of the negative electrode sheet satisfies: OI is less than or equal to 7.0.
9. A lithium ion battery comprising the negative electrode tab of claim 8.
10. An electronic device comprising the lithium-ion battery of claim 9.
CN202311018272.XA 2023-08-11 2023-08-11 Negative electrode active material, negative electrode sheet, lithium ion battery and electronic device Pending CN116895760A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117334916A (en) * 2023-12-01 2024-01-02 宁德时代新能源科技股份有限公司 Negative electrode plate, preparation method thereof, battery and electric equipment

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