WO2022178748A1 - 负极活性材料、负极片、电化学装置和电子装置 - Google Patents

负极活性材料、负极片、电化学装置和电子装置 Download PDF

Info

Publication number
WO2022178748A1
WO2022178748A1 PCT/CN2021/077835 CN2021077835W WO2022178748A1 WO 2022178748 A1 WO2022178748 A1 WO 2022178748A1 CN 2021077835 W CN2021077835 W CN 2021077835W WO 2022178748 A1 WO2022178748 A1 WO 2022178748A1
Authority
WO
WIPO (PCT)
Prior art keywords
negative electrode
active material
electrode active
silicon
secondary particles
Prior art date
Application number
PCT/CN2021/077835
Other languages
English (en)
French (fr)
Inventor
苏俊铭
Original Assignee
宁德新能源科技有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 宁德新能源科技有限公司 filed Critical 宁德新能源科技有限公司
Priority to CN202180094556.XA priority Critical patent/CN116941068A/zh
Priority to PCT/CN2021/077835 priority patent/WO2022178748A1/zh
Publication of WO2022178748A1 publication Critical patent/WO2022178748A1/zh

Links

Images

Classifications

    • 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
    • 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
    • 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
    • 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
    • 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

Definitions

  • the present application relates to the technical field of energy storage, and in particular, to a negative electrode active material, a negative electrode sheet, an electrochemical device and an electronic device comprising the negative electrode active material.
  • Electrochemical devices such as Li-ion batteries
  • Li-ion batteries are widely used in smart products due to their high energy density, low maintenance, low self-discharge rate, wide operating temperature range, long cycle life, no memory effect, stable operating voltage, and environmental friendliness ( Including mobile phones, notebooks, cameras and other electronic products), power tools and electric vehicles and other fields.
  • people have put forward higher requirements for the performance of electrochemical devices.
  • the present application provides a negative electrode active material, including a matrix; the matrix includes secondary particles and a carbon layer, the secondary particles include primary particles; the secondary particles have pores inside, and the carbon layer exists on the surface of the pore walls of the pores ; between the negative electrode active material and the secondary particles: 0.5 ⁇ D0/D ⁇ 1; wherein, D is the average particle size of the negative electrode active material; D0 is the average particle size of the secondary particles. In other embodiments, 0.7 ⁇ D0/D ⁇ 1. In other embodiments, 0.9 ⁇ D0/D ⁇ 1.
  • the primary particles comprise a silicon-based material.
  • a carbon layer is present on the surface of the secondary particles.
  • the negative electrode active material further includes a protective layer on the surface of the substrate.
  • the negative active material has a BET specific surface area of 20 m 2 .g -1 to 90 m 2 .g -1 . In other embodiments, the negative active material has a BET specific surface area of 20 m 2 .g -1 to 60 m 2 .g -1 .
  • the mass percentage content of silicon element is 10%-95% based on the mass of the negative electrode active material. In other embodiments, based on the mass of the negative electrode active material, the mass percentage of silicon is 20%-80%. In other embodiments, based on the mass of the negative electrode active material, the mass percentage of silicon is 30%-80%.
  • the secondary particles have an average particle size D0 of 2 ⁇ m to 30 ⁇ m. In some embodiments, the secondary particles have an average particle size D0 of 2 ⁇ m to 20 ⁇ m.
  • the average thickness D1 of the carbon layer is 1 nm to 250 nm. In other embodiments, the average thickness D1 of the carbon layer is 15 nm to 100 nm.
  • the protective layer has an average thickness D2 of 1 nm to 250 nm. In other embodiments, the average thickness D2 of the protective layer is 15 nm to 100 nm.
  • the protective layer includes at least one of a carbon material, a conductive polymer, or an inorganic conductive oxide.
  • the conductive polymer includes at least one of polyacetylene, polythiophene, polypyrrole, polyaniline, polyphenylene vinylene, or polydiacetylene.
  • the inorganic conductive oxide includes at least one of indium tin oxide, tin antimony oxide.
  • the negative active material has a porosity of 15% to 85%. In other embodiments, the negative active material has a porosity of 30% to 60%.
  • the characteristic peak area located in the range of 1300 cm -1 to 1400 cm -1 is ID
  • the characteristic peak area located in the range of 1550 cm -1 to 1650 cm -1 is IG
  • the degree of graphitization ID / IG of the protective layer is 0.5 to 1.9. In some embodiments, the degree of graphitization ID/ IG of the protective layer is 0.7 to 1.5.
  • the present application also provides a negative electrode sheet, comprising a current collector and a negative electrode active material layer, the negative electrode active material layer is located on the surface of the current collector, wherein the negative electrode active material layer comprises the present application The aforementioned negative electrode active material.
  • the present application further provides an electrochemical device, comprising a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte, wherein the negative electrode sheet is the aforementioned negative electrode sheet of the present application.
  • the present application further provides an electronic device including the aforementioned electrochemical device of the present application.
  • the negative electrode active material provided by the present application can provide sufficient buffer space, alleviate the impact of volume expansion on the cycle performance of the electrochemical device, improve the energy density of the battery, and can effectively prevent the internal structure.
  • the impact of damage on the external structure helps to improve the stability of the pole piece and improve the rate performance.
  • Fig. 1 is the three-dimensional cross-sectional structure schematic diagram of negative electrode active material
  • Fig. 2 is the cross-sectional structure schematic diagram of negative electrode active material
  • Fig. 3 is the cross-sectional structure schematic diagram of the matrix in the negative electrode active material
  • Fig. 4 is the transmission electron microscope image of the negative electrode active material surface
  • the reference numerals are: 10-matrix; 11-secondary particles; 12-carbon layer; 13-first pores; 20-protective layer; 21-second pores.
  • the average particle size means that the material powder is photographed and observed by a transmission electron microscope (TEM), and then, using image analysis software, 10 material particles are randomly selected from the TEM photograph, and these materials are determined.
  • primary particles refers to active material particles of a single crystal grain, and two or more primary particles may form secondary particles by agglomeration.
  • the primary particles can have any of a variety of shapes, including rods, spheres, or combinations thereof.
  • secondary particle is formed by the aggregation of two or more primary particles.
  • the negative electrode active material includes a substrate 10 and a protective layer 20 on the surface of the substrate 10 ; the substrate 10 includes secondary particles 11 and a carbon layer 12 , and the secondary particles 11 include primary particles; A pore 13, a carbon layer 12 exists on the surface of the pore wall of the first pore 13; the relationship between the negative electrode active material and the secondary particles 11 satisfies: 0.5 ⁇ D0/D ⁇ 1; wherein, D is the average particle size of the negative electrode active material; D0 is the average particle size of the secondary particles.
  • the primary particles comprise a silicon-based material.
  • Silicon material has a high theoretical gram capacity (up to 4200mAh/g) as the anode active material of electrochemical devices (eg, lithium-ion batteries), so it is used to replace the traditional graphite anode active material, which can improve the energy density of lithium-ion batteries .
  • electrochemical devices eg, lithium-ion batteries
  • the silicon-silicon bonds are broken, and the lithium-silicon bonds are gradually formed, and the silicon particles will undergo a huge volume expansion (300% to 400%) during the lithium intercalation process.
  • the volume expansion of silicon particles is inevitable in the process of lithium intercalation.
  • reducing the particle size of the silicon material can solve the volume expansion problem of the silicon material in the application of lithium ion batteries to a certain extent, because compared with the silicon material with a large particle size, the silicon material with a smaller particle size The material does not experience a large number of particle fragmentation, which can reduce the increase in the exposure of the electrochemical reaction interface in the electrolyte caused by particle fragmentation, thereby reducing the volume expansion caused by side reactions.
  • the large specific surface area will cause a large number of SEI films to grow during the cycle, reducing the first efficiency of lithium-ion batteries;
  • Coating carbon, oxides, conductive polymers and other substances on the surface of silicon materials can solve the problem to a certain extent.
  • the volume expansion problem of silicon materials in lithium-ion battery applications because the coating can avoid the direct contact between the electrolyte and the silicon material, thereby reducing the volume expansion caused by side reactions.
  • carbon, oxides, and conductive polymers are used.
  • the mechanical strength of the coating layer is not enough to resist the huge volume change of the silicon material during the cycle, and it will cause redundant fresh electrochemical reaction interface, consume the electrolyte, and reduce the cycle life of the battery;
  • Composite the silicon material with the graphite particles Granulation can solve the volume expansion problem of silicon materials in the application of lithium-ion batteries to a certain extent, because the composite granulation of silicon materials and graphite particles can relieve the expansion of silicon particles through the graphite gap to a certain extent, and can also pass the secondary generated by the composite granulation.
  • the particles inhibit the expansion of the silicon particles, but the composite granulation of the silicon material and the graphite particles sacrifices the proportion of the silicon component, and only the content of the silicon component in the secondary particles is limited to less than 20%, otherwise it cannot achieve the suppression of the silicon group. Therefore, the energy density of lithium-ion batteries can only be improved in a limited range, and the advantages of high gram capacity of silicon materials cannot be fully utilized.
  • the currently adopted solution of silicon composite graphite particles can only absorb the lithium intercalation expansion of a certain content (about 10%) of the silicon component, but the expansion during the cycle is close to the limit that the full battery can bear, and it is impossible to achieve a further increase in the content of the silicon component.
  • the stability of the electrochemical performance of the material is ensured.
  • Continuing to increase the content of the silicon component according to this scheme will cause irreversible rupture of the silicon composite graphite particles, which will cause the failure of the electrical contact of the negative electrode, which will lead to the accelerated decay of the life of the lithium-ion battery.
  • the secondary particles formed by silicon-containing primary particles are used as the negative electrode active material, which has a high gram capacity and can absorb volume expansion by utilizing the space formed by the internal pores of the secondary particles to achieve the stability of its own structure; on the surface of the secondary particles Covering the carbon layer and the protective layer, wherein the carbon layer covers the pore walls inside the secondary particles, which can form a conductive layer on the inner surface of the secondary particles, increase the electronic conductivity, ensure the electronic contact of the silicon material, and promote the full play of the capacity of the secondary particles
  • the outer protective layer improves the mechanical strength, and can further provide a buffer for the expansion of silicon intercalation, suppress the stress caused by the expansion of internal silicon intercalation, and realize the restraint of the protective layer on the matrix structure, even if the carbon layer on the surface of the secondary particles is In the case of being damaged, the stability of the negative electrode active material structure composed of the secondary particles, the carbon layer and the protective layer can still be ensured, and a certain electrical contact can be maintained.
  • the negative electrode active material of the present application can provide sufficient buffer for the lithium intercalation expansion of silicon, alleviate the influence of volume expansion on the cycle performance of the electrochemical device, improve the energy density of the electrochemical device, and can also effectively prevent the damage of the internal structure to the external structure. It helps to improve the stability of the pole piece and improve the rate performance.
  • the secondary particles have a spherical coral-like structure, and the spherical coral-like structure has more pores inside, which is more conducive to absorbing the volume expansion of silicon.
  • the primary particles are silicon particles, and the secondary particles are formed by aggregating the silicon primary particles.
  • the ratio between the average particle diameter D0 of the secondary particles and the average particle diameter D of the negative electrode active material is set to be greater than or equal to 0.5.
  • carbon layers exist on both the inner surface and the outer surface of the secondary particles.
  • both the inner and outer surfaces of the secondary particles form a conductive layer, which can further Increase the conductivity of the negative electrode active material.
  • the second pores 21 there are second pores 21 between the protective layer 20 and the substrate 10 , and the second pores 21 provide a reserved space for the expansion of silicon intercalation and lithium expansion. If the silicon component in the substrate 10 is removed Lithium is inserted and fragmented, and the second pores 21 provide a residence space for the fragmented silicon components, so that they can still maintain a certain electrical contact and stabilize the performance of the negative electrode active material. The space is closed, and the matrix fragments staying in the second pores 21 will not affect the structure outside the negative electrode active material.
  • the shape of the protective layer may be similar to the shape of the secondary particles, or may not be similar to the shape of the secondary particles; preferably, it is similar to the shape of the secondary particles.
  • the protective layer is configured as a spherical structure.
  • the thickness D1 of the carbon layer is 1 nm to 250 nm. In some embodiments, the thickness D1 of the carbon layer is 15 nm to 100 nm. In some embodiments, the thickness D2 of the protective layer is 1 nm to 250 nm. In some embodiments, the thickness D2 of the protective layer is 15 nm to 100 nm.
  • the thickness of the carbon layer and the protective layer should not be too large, otherwise it will affect the energy density improvement effect of the negative electrode active material to a certain extent; the thickness of the carbon layer and the protective layer should not be too small, if the thickness of the carbon layer is too small, it will affect the carbon layer.
  • the mechanical strength of the layer is not conducive to maintaining the structural stability of the secondary particle silicon intercalation when the volume expands, and it is not conducive to ensuring that the silicon is not in direct contact with the electrolyte during the long-term cycle process, which affects the improvement effect on the cycle performance of the electrochemical device. If the thickness of the protective layer is too small, it is not conducive to suppressing the stress caused by the expansion of internal silicon intercalation, and it is not conducive to maintaining the stability of the structure of the negative electrode active material itself during the preparation process of the electrochemical device, affecting the electrochemical performance of the electrochemical device. performance improvement.
  • the protective layer includes at least one of a carbon material, a conductive polymer, or an inorganic conductive oxide.
  • the conductive polymer includes at least one of polyacetylene, polythiophene, polypyrrole, polyaniline, polyphenylene vinylene, or polydiacetylene.
  • the inorganic conductive oxide includes at least one of indium tin oxide, tin antimony oxide.
  • the protective layer includes a carbon material. Then the graphitization degree of the protective layer affects the performance of the negative electrode active material.
  • the characteristic peak area located in the range of 1300cm- 1 to 1400cm - 1 is ID
  • the characteristic peak area located in the range of 1550cm -1 to 1650cm- 1 is 1 G
  • the graphitization degree ID / IG of the protective layer is 0.5 to 1.9 .
  • the graphitization degree ID /IG represents the ratio of the peak height of disordered carbon to the peak height of graphitized carbon. If the value of ID /IG is larger, it means that the degree of graphitization of the carbon component is low.
  • the disordered degree of carbon is high, which is conducive to the transport of lithium ions through the carbon component, but at the same time the electronic conductivity decreases; if the value of ID /IG is small, it indicates that the degree of graphitization of the carbon component is high, Carbon is less disordered and has higher electronic conductivity, but has a relatively low ability to transport lithium ions at the same time.
  • ID/ IG value is within the above range, the coverage of carbon components in the protective layer can be ensured, and the ion conduction and electronic conduction capabilities of the protective layer can be balanced, which is helpful to further improve the energy density and energy density of the electrochemical device. rate performance.
  • the graphitization degree ID/ IG of the protective layer is 0.7 to 1.5.
  • protective layers with different degrees of graphitization can be prepared by controlling the sintering temperature and time. Of course, those skilled in the art can also prepare protective layers with the degree of graphitization described in this application by other known methods. .
  • the average particle size of the secondary particles affects the performance of the anode active material.
  • the average particle size D0 of the secondary particles is 2 ⁇ m to 30 ⁇ m.
  • the damage to the structure of the negative electrode sheet caused by the lithium intercalation expansion of the secondary particles is also larger, which will easily lead to loss of electrical contact;
  • the average particle size of the secondary particles If the diameter is larger, it is not conducive to the uniform dispersion of the secondary particles in the negative electrode active material and affects the energy density;
  • the negative electrode active material can also include graphite, and when the aforementioned negative electrode active material and graphite are compounded and granulated, the graphite can be further passed through.
  • the content of silicon element in the negative electrode active material affects the performance of the negative electrode active material.
  • the mass percentage content of silicon element is 10% to 95% based on the mass of the negative electrode active material. The higher the content of silicon element, the higher the gram capacity of the negative electrode active material; at the same time, the higher the content of silicon element, the lower the content of carbon element in the negative electrode active material, and the specific surface area of the negative electrode active material is closer to the specific surface area of the secondary particles , as the Si content increases, the expansion rate of the anode active material in the electrochemical device cycle increases. Therefore, controlling the mass percentage of silicon to meet a certain range can further increase the energy density of the negative electrode active material and improve the cycle performance of the electrochemical device.
  • the mass percentage of silicon element is 20% to 80%. In other embodiments, based on the mass of the negative electrode active material, the mass percentage of silicon is 30%-80%.
  • the measurement of silicon content is not particularly limited. According to an embodiment of the present application, the content of the silicon component in the negative electrode active material can be measured in the following manner:
  • the sample is placed under oxygen-enriched conditions and heated and burned at a high temperature in a high-frequency furnace to oxidize carbon and sulfur into carbon dioxide and sulfur dioxide.
  • the signal is sampled by the computer, converted into a value proportional to the concentration of carbon dioxide and sulfur dioxide after linear correction, and then the value of the whole analysis process is accumulated. After the analysis, the accumulated value is divided by the weight value in the computer, Multiply by the correction factor and deduct the blank to obtain the percentage of carbon and sulfur in the sample.
  • the analysis can be carried out using a high-frequency infrared carbon and sulfur analyzer (Shanghai Dekai HCS-140). After the mass percent content of carbon in the sample is obtained by measurement, the mass percent content of silicon in the negative electrode active material in the present application is obtained by subtracting the mass percent content of carbon from 100%.
  • the negative active material has a BET specific surface area of 20 m 2 .g -1 to 90 m 2 .g -1 .
  • the increase of the specific surface area of the negative active material comes from the abundant pores inside the secondary particles, which can provide buffer space for the volume change caused by the expansion of silicon intercalation and lithium, so that the material itself can absorb the stress caused by the volume change, and will not be affected by it.
  • the structure of the pole piece coating, or even the coating is powdered and peeled off, so that the active material loses electrical contact.
  • the specific surface area of the negative electrode active material satisfies the aforementioned range, the pole piece structure can be further stabilized, and the cycle stability of the cell can be ensured.
  • the negative active material has a BET specific surface area of 20 m 2 .g -1 to 60 m 2 .g -1 .
  • the measurement of the specific surface area is not particularly limited.
  • the specific surface area of the negative electrode active material can be measured in the following manner:
  • the adsorption amount of the sample monolayer was calculated based on Brownnauer-Etter-Taylor adsorption theory (BET) and its formula, so that Calculate the specific surface area of the negative electrode active material particles;
  • BET Brownnauer-Etter-Taylor adsorption theory
  • W is the mass of the gas adsorbed by the negative electrode active material particles under the relative pressure
  • Wm is the gas saturation adsorption amount covering a monolayer
  • the slope is (c-1)/(WmC)
  • the intercept is 1/WmC
  • the total specific surface area is (Wm*N*Acs/M).
  • the negative active material has a porosity of 15% to 85%. In some embodiments, the negative active material has a porosity of 30% to 60%.
  • the anode active material with a certain range of porosity can buffer the expansion of silicon intercalation and lithium, and further improve the performance of the anode active material.
  • porosity refers to the ratio of the volume occupied by pores to the total volume in the structure.
  • the measurement of porosity is not particularly limited. According to one embodiment of the present application, the micropore and mesopore volumes can be measured by, for example, the Brunauer-Emmett-Teller (BET) measurement method or the Hg porosimeter.
  • BET Brunauer-Emmett-Teller
  • the porosity of the negative electrode active material can be adjusted by improving the proportion of silicon content in the negative electrode active material, the average particle size of the secondary particles, etc., and is not particularly limited.
  • the secondary particles are prepared by using silicon-aluminum alloy particles as raw materials, and the porosity of the negative electrode active material can be adjusted by changing the silicon content in the silicon-aluminum alloy particles. The more aluminum components are washed away during preparation, the greater the porosity of the negative active material obtained.
  • a method for preparing a negative electrode active material for preparing the aforementioned negative electrode active material in the present application comprising the following steps:
  • Step S1 the silicon-aluminum alloy particles are dispersed in the liquid phase system, and a surfactant is optionally added;
  • Step S2 adding carbon-containing substances and an optional initiator to the liquid phase system of step S1, stirring and mixing uniformly, to obtain silicon-aluminum alloy particles coated with carbon precursors; wherein, the carbon precursors include pitch, high at least one of molecular polymers;
  • step S3 the carbon-precursor-coated silicon-aluminum alloy particles obtained in step S2 are acid-washed and etched, and filtered to obtain a solid substance;
  • step S4 sintering the solid substance obtained in step S3;
  • step S5 steps S1, S2 and S4 are repeated for the solid substance obtained after the sintering in step S4.
  • step S1 may include the following steps: dispersing the silicon-aluminum alloy particles in a liquid phase system mixed with water and ethanol, then adding a surfactant, and uniformly dispersing the silicon-aluminum alloy particles in the liquid phase under sufficient stirring in the system.
  • the porosity of the finally prepared negative electrode active material can be changed by changing the content ratio of silicon in the silicon-aluminum alloy particles in step S1. The lower the silicon content, the greater the porosity of the negative electrode active material. .
  • step S2 may include the following steps: adding an initiator to the liquid phase system in which the silicon-aluminum alloy particles are uniformly dispersed, keeping stirring for 0.5-12 h to make it evenly mixed, and then adding an appropriate amount of carbon-containing polymerizable After keeping stirring for 2-24 hours, the solid material is filtered out, that is, the silicon-aluminum alloy particles coated with carbon precursor; wherein, the carbon precursor includes phenolic resin, pitch, polyvinylidene fluoride and its derivatives, carboxylate Methyl cellulose and its derivatives, sodium carboxymethyl cellulose and its derivatives, polyvinyl pyrrolidone and its derivatives, polyacrylic acid and its derivatives, styrene-butadiene rubber, polyacrylamide, polyimide, poly At least one of amideimide, polypyrrole, and polyaniline.
  • the carbon precursor includes phenolic resin, pitch, polyvinylidene fluoride and its derivatives, carboxylate Methyl cellulose and its derivative
  • ammonia water can be selected as the initiator in step S2.
  • the polymerizable substance is a substance that can be polymerized to form a high molecular polymer under the action of an initiator.
  • the carbon-containing polymerizable in step S2 may be a combination of resorcinol and formaldehyde.
  • the specific surface area of the finally prepared negative electrode active material can be changed by changing the amount of the carbon-containing polymerizable amount added in step S2, and the content of the carbon component in the negative electrode active material is relatively higher. If the content of silicon in the negative electrode active material is relatively high, the specific surface area of the negative electrode active material is closer to the specific surface area of the silicon secondary particles.
  • the acid in step S3 may include one or a combination of hydrochloric acid, sulfuric acid, nitric acid, oxalic acid, and phosphoric acid.
  • the aluminum in the silicon-aluminum alloy is washed away, and pores are formed at the positions of the washed aluminum, so as to obtain the silicon secondary particles of spherical coral-like structure.
  • the sintering in step S4 is performed in an inert atmosphere, the sintering temperature is 500-1200°C, the heating rate is 0.2-20°C/min, and the holding time is 1-24h.
  • the inert atmosphere may be one or a combination of nitrogen, argon, and helium.
  • step S5 specifically includes: dispersing the sintered solid matter in the liquid phase system, adding optional surfactant, and then adding carbon-containing polymerizable and optional surfactants to the liquid phase system The initiator is stirred and mixed uniformly, so that the surface of the solid substance is coated with a carbon precursor, filtered and sintered to obtain the negative electrode active material.
  • step S5 specifically includes: dispersing the sintered solid matter in the liquid phase system, adding optional surfactant, and then adding conductive polymer monomer and optional initiator to the liquid phase system agent, stirring and mixing uniformly, so that the surface of the solid substance is coated with a conductive polymer to obtain the negative electrode active material.
  • step S5 specifically includes: dispersing the sintered solid substance in the liquid phase system, adding optional surfactant, then adding the inorganic conductive oxide precursor to the liquid phase system, stirring and mixing uniform, and a precipitation reaction is performed to coat the surface of the solid substance with an inorganic conductive oxide to obtain the negative electrode active material.
  • a protective layer is further formed on the surface of the base structure, the protective layer covers the base structure and there are pores between the protective layer and the base structure.
  • the thickness of the carbon layer and protective layer can be varied by varying the amount of carbon-containing polymerizable added.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is disposed on the surface of the negative electrode current collector, and the negative electrode active material layer includes the negative electrode active material described above in this application.
  • the anode active material layer further includes an anode binder.
  • the negative electrode binder is used to improve the bonding properties between the negative electrode active material particles and between the negative electrode active material particles and the negative electrode current collector.
  • the negative electrode binder is known in the art and can be used as a binder for the negative electrode active material layer.
  • the negative electrode binder includes polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyvinyl Ethoxylated polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylic acid (PAA), styrene butadiene rubber, acrylated At least one of styrene-butadiene rubber, epoxy resin and nylon.
  • PAA polyacrylic acid
  • styrene butadiene rubber acrylated At least one of styrene-butadiene rubber, epoxy resin and nylon.
  • the negative electrode active material layer further includes a negative electrode conductive agent.
  • the negative electrode conductive agent is used to improve the conductivity of the negative electrode sheet.
  • the negative electrode conductive agent is a conductive agent known in the art that can be used as the negative electrode active material layer.
  • the negative electrode conductive agent includes at least one of conductive carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotube, graphene, metal powder, metal fiber, and polyphenylene derivatives.
  • the metal in the metal powder and metal fiber includes at least one of copper, nickel, aluminum, and silver.
  • the present application has no particular restrictions on the mixing ratio of the negative electrode active material, the binder, and the conductive agent in the negative electrode active material layer, and the mixing ratio can be controlled according to the desired performance of the electrochemical device.
  • the negative current collector is a metal such as, but not limited to, copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a conductive metal clad polymer substrate, or a combination thereof.
  • the negative electrode sheet has a porosity of 20% to 40%.
  • the above-mentioned porosity of the negative electrode sheet can be obtained by a method known in the art, for example, it can be obtained by adjusting the compaction density, and the porosity decreases as the compaction density increases.
  • the electrochemical device of the present application is, for example, a primary battery or a secondary battery.
  • the secondary battery is, for example, a lithium secondary battery, and the lithium secondary battery includes, but is not limited to, a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.
  • the electrochemical device includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte, and the negative electrode sheet is the aforementioned negative electrode sheet of the present application.
  • the positive electrode sheet is known in the art as a positive electrode sheet that can be used in electrochemical devices.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer.
  • the positive electrode active material layer is provided on the surface of the positive electrode current collector.
  • the positive electrode current collector is a metal, such as, but not limited to, aluminum foil.
  • the positive electrode active material layer includes a positive electrode active material.
  • a positive electrode active material various conventionally known substances that can reversibly intercalate and deintercalate active ions can be used as positive electrode active materials of electrochemical devices known in the art.
  • the positive active material includes a lithium-containing transition metal oxide.
  • the positive active material includes at least one of a composite oxide of lithium and a metal of cobalt, manganese, nickel, or a combination thereof.
  • the positive active material includes LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , LiCo 1-y My O 2 , LiNi 1-y My O 2 , LiMn 2-y My O 4 , LiNi x At least one of Co y Mn z M 1-xyz O 2 , wherein M is selected from Fe, Co, Ni, Mn, Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V, Ti One or more of, and 0 ⁇ y ⁇ 1, 0 ⁇ x ⁇ 1, 0 ⁇ z ⁇ 1, x+y+z ⁇ 1.
  • the positive electrode active material layer further includes a positive electrode binder and a positive electrode conductive material.
  • the positive electrode binder is known in the art and can be used as a binder for the positive electrode active material layer. Binders such as, but not limited to, polyvinylidene fluoride. The positive electrode binder is used to improve the binding properties of the positive electrode active material particles to each other and between the positive electrode active material particles and the current collector.
  • the conductive material is a conductive material known in the art that can be used as the positive electrode active material layer. Positive electrode conductive materials such as but not limited to conductive carbon black, conductive paste. The positive conductive material is used to provide electrical conductivity to the electrode.
  • the preparation method of the positive electrode sheet is known in the art and can be used for the preparation of the positive electrode sheet of the electrochemical device.
  • a solvent is usually added, the positive electrode active material is added with a binder, and a conductive material and a thickener are added as required, and then dissolved or dispersed in the solvent to prepare the positive electrode slurry.
  • the solvent is evaporated and removed during the drying process.
  • the solvent is known in the art and can be used as the positive electrode active material layer, such as but not limited to N-methylpyrrolidone (NMP).
  • NMP N-methylpyrrolidone
  • the present application has no particular restrictions on the mixing ratio of the positive electrode active material, the positive electrode binder, and the positive electrode conductive material in the positive electrode active material layer, and the mixing ratio can be controlled according to the desired performance of the electrochemical device.
  • Electrolytes are electrolytes known to those skilled in the art that can be used in electrochemical devices.
  • the electrolyte includes an organic solvent and an electrolyte salt.
  • the organic solvent may be an organic solvent known in the art that can be used for the electrolyte.
  • the organic solvent includes at least one of propylene carbonate (PC), ethylene carbonate (EC), and diethyl carbonate (DEC).
  • PC propylene carbonate
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • the mixing ratio of each component in the organic solvent is not particularly limited.
  • the electrolyte salt may be an electrolyte salt known to those skilled in the art that may be used in the electrolyte.
  • the electrolyte salt is a lithium salt, such as LiPF6 .
  • the electrolyte may further include additives, which may be additives known to those skilled in the art that may be used in the electrolyte.
  • Separation membranes are those known to those skilled in the art that can be used in electrochemical devices.
  • the separator is arranged between the positive electrode sheet and the negative electrode sheet to prevent short circuit.
  • the separator includes a polymer or inorganic formed from a material that is stable to the electrolyte of the present application.
  • the release film includes a substrate layer and a surface treatment layer disposed on at least one surface of the substrate layer.
  • the substrate layer is a non-woven fabric, membrane or composite membrane with a porous structure.
  • the material of the substrate layer is selected from at least one of polyethylene (PE), polypropylene, polyethylene terephthalate, and polyimide.
  • the substrate layer is selected from any one of polypropylene porous membrane, polyethylene porous membrane, polypropylene non-woven fabric, polyethylene non-woven fabric or polypropylene-polyethylene-polypropylene porous composite membrane.
  • the surface treatment layer is a polymer layer or an inorganic layer, or a layer formed by mixing polymers and inorganic substances.
  • the inorganic layer includes inorganic particles and a binder, the inorganic particles are selected from the group consisting of aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, ceria, nickel oxide, zinc oxide, One or a combination of calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and barium sulfate, and the binder is selected from polyvinylidene fluoride, Vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene One or
  • the polymer layer comprises a polymer selected from the group consisting of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinyl At least one of vinylidene fluoride or poly(vinylidene fluoride-hexafluoropropylene).
  • the electrochemical device further includes an overpack housing.
  • the overwrap case is an overwrap case known in the art that can be used in an electrochemical device and is stable to the electrolyte used, such as, but not limited to, a metal-type overwrap case.
  • the electronic device of the present application is any electronic device, such as but not limited to notebook computers, pen-type computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, headsets, video recorders , LCD TV, Portable Cleaner, Portable CD Player, Mini Disc, Transceiver, Electronic Notepad, Calculator, Memory Card, Portable Recorder, Radio, Backup Power, Motor, Automobile, Motorcycle, Power-assisted Bicycle, Bicycle, Lighting Appliances, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, lithium-ion capacitors.
  • the electrochemical device of the present application is not only applicable to the electronic devices exemplified above, but also applicable to energy storage power stations, marine vehicles, and air vehicles.
  • Airborne vehicles include airborne vehicles within the atmosphere and airborne vehicles outside the atmosphere.
  • the electronic device comprises an electrochemical device as previously described herein.
  • the graphite, the prepared negative electrode active material, the conductive agent (conductive carbon black, Super P) and the binder PAA are mixed according to the weight ratio of about 70%: 15%: 5%: 10%, and an appropriate amount of water is added. It is kneaded at a content of about 55 wt % to 70 wt %. An appropriate amount of water is added to adjust the viscosity of the slurry to about 4000-6000 Pa ⁇ s to prepare a negative electrode slurry.
  • the prepared negative electrode slurry is coated on the negative electrode current collector copper foil, dried and cold pressed to obtain a negative electrode sheet.
  • the LiCoO 2 , conductive carbon black and polyvinylidene fluoride (PVDF) are fully stirred and mixed in N-methylpyrrolidone solvent according to the weight ratio of about 95:2.5:2.5 to obtain a uniform positive electrode slurry;
  • the positive electrode slurry is coated on the positive electrode current collector aluminum foil, dried, and cold pressed to obtain a positive electrode sheet.
  • the PE porous polymer film is used as the separator.
  • the organic solvents propylene carbonate (PC), ethylene carbonate (EC), and diethyl carbonate (DEC) were mixed uniformly in a weight ratio of 1:1:1, and fully dried lithium salt LiPF was added. 6 Mix evenly to obtain an electrolyte with a LiPF 6 concentration of 1.15 mol/L.
  • the prepared positive electrode sheet, separator film and negative electrode sheet are stacked in sequence, so that the separator film is placed between the positive electrode sheet and the negative electrode sheet for isolation, and then rolled to obtain a bare cell; the bare cell is placed in an outer package In the casing, a liquid injection port is left, and the electrolyte prepared above is poured from the liquid injection port, and then packaged; and then a lithium ion battery is obtained through technological processes such as formation, degassing, and trimming.
  • Example 1 The difference from Example 1 is that the mass proportion of silicon in the silicon-aluminum alloy powder is 50%.
  • Example 1 The difference from Example 1 is that the mass proportion of silicon in the silicon-aluminum alloy powder is 70%.
  • the average particle size of the silicon-aluminum alloy powder was 8.1 ⁇ m.
  • the average particle size of the silicon-aluminum alloy powder was 15.6 ⁇ m.
  • Example 3 The difference from Example 3 is that 10g of resorcinol and 25g of formaldehyde are added in step 2.
  • Example 3 The difference from Example 3 is that 1 g of resorcinol and 2.5 g of formaldehyde are added in step 2.
  • Example 3 The difference from Example 3 is that 20g of resorcinol and 50g of formaldehyde are added in step 6.
  • step 4 the temperature is raised to 700°C at a rate of 5°C/min.
  • step 4 the temperature is raised to 900°C at a rate of 5°C/min.
  • step 4 the temperature is raised to 1100°C at a rate of 5°C/min.
  • Example 3 The difference from Example 3 is that the mass proportion of silicon in the silicon-aluminum alloy powder is 20%.
  • the temperature was raised to 1300°C at a rate of 5°C/min in step 4.
  • step 4 the temperature is raised to 500°C at a rate of 5°C/min.
  • Comparative Example 1 directly used silicon secondary particles as the negative electrode active material.
  • Comparative Example 2 did not carry out carbon coating treatment on the secondary particles.
  • Comparative Example 3 did not carry out protective layer coating treatment on the secondary particles.
  • the material powder was photographed and observed by a high-resolution transmission electron microscope (HR-TEM), and then, 10 active material particles were randomly selected from the TEM photograph using image analysis software, and the area of each active material particle was obtained.
  • HR-TEM high-resolution transmission electron microscope
  • the process of obtaining the particle diameter R of the active material particles described above is performed, and the particle diameters of the obtained 100 (10 ⁇ 10) active material particles are arithmetically averaged to obtain the average particle diameter D of the negative electrode active material.
  • the thicknesses of the carbon layer and the protective layer of each of the 100 (10 ⁇ 10) active material particles are measured, and the average thickness of the carbon layer D1 and the average thickness of the protective layer D2 can be obtained by arithmetic averaging.
  • the aforesaid negative electrode sheet was cut into circular sheets with a diameter of 1 cm with a punching machine in a dry environment, a metal lithium sheet was used as a counter electrode in a glove box, a celgard composite membrane was selected as the separator, and an electrolyte solution was added to assemble a button cell.
  • the battery is charged and discharged using the LAND series battery test test to test its charge and discharge performance. After the coin cell was cycled for 5 cycles, the gram capacity with a discharge cut-off voltage of 2.0 V was recorded as the gram capacity of the negative electrode active material.
  • the test temperature is 25°C and 45°C, charge to 4.4V at 0.7C constant current, charge to 0.025C at constant voltage, and discharge to 3.0V at 0.5C after standing for 5 minutes.
  • the capacity obtained in this step was taken as the initial capacity, and 0.7C charge/0.5C discharge was carried out for cycle test, and the capacity decay curve was obtained by taking the ratio of the capacity in each step to the initial capacity.
  • the number of cycles at 25°C up to the capacity retention rate of 90% is recorded as the cycle performance at room temperature of the battery, and the number of cycles at 45°C until the capacity retention rate is 80% is recorded as the high temperature cycle performance of the battery.
  • the test temperature is 25°C and 45°C, and the thickness of the lithium-ion battery at half charge (50% state of charge (SOC)) is measured with a screw micrometer. 0.5C discharge to 3.0V, repeat the above charging and discharging process, when the cycle reaches 500 cycles, the lithium-ion battery is in a fully charged (100% SOC) state, and then use a screw micrometer to test the thickness of the lithium-ion battery at this time, which is the same as the initial half-charge. By comparing the thickness of the lithium ion battery at (50% SOC), the expansion rate of the fully charged (100% SOC) lithium ion battery at this time can be obtained.
  • SOC state of charge
  • Comparative example 2 did not carry out the carbon layer covering treatment, and comparative example 3 did not carry out the protective layer restraint treatment, and the cycle performance and rate performance of the lithium ion battery were affected.
  • the electronic conductivity of the material without the carbon layer coating is poor, and the rate performance of the material is obviously lower, and the silicon material without the protection of the protective layer also loses a large number of electronic conductive sites. It is more likely to lose electrical contact later, resulting in a decrease in discharge rate, and the silicon material bound by the protective layer can still be restrained by the protective layer even after the silicon is fragmented and pulverized, maintaining a certain electronic conductivity.
  • the average particle size of the secondary particles is affected by the particle size of the silicon-aluminum alloy balls used, it can be seen from Examples 3-5 that the performance of the silicon-carbon material prepared from the secondary particles with a smaller D0 value is better.
  • the reasons are as follows A few points: (1) The larger the D0, the greater the effect of the lithium intercalation and expansion of the silicon carbon material on the structure of the negative pole piece, and the easier it is to lose electrical contact; (2) The larger the D0, the more difficult the uniform dispersion of the silicon carbon material.
  • the average particle size of graphite particles is generally greater than 15 ⁇ m, and the larger the average particle size of the silicon-carbon material, the more difficult it is to match graphite in particle size distribution, and it is easier to affect the structural stability of the negative pole piece; (4) The smaller the D0, the more the prepared silicon carbon material can withstand higher compaction density, maintain its own structure during the preparation process of the battery, and absorb the volume expansion of silicon intercalation.
  • Examples 1-3 illustrates the influence of the silicon content in the silicon carbon material on the material properties: the higher the silicon content, the higher the gram capacity of the material; at the same time, because the silicon content increases, the expansion rate of the battery also increases.
  • the comparison between Examples 6-7 and Comparative Example 2 illustrates the effect of carbon layer coating on the properties of silicon carbon materials: the carbon layer coating is conducive to improving the electronic conductivity of silicon carbon materials, thereby improving the rate performance of the battery, and It can prevent the formation of excessive SEI and reduce its adverse effect on the expansion rate of the battery; and it is difficult for the thinner carbon layer to maintain the structure when the silicon intercalates and expands, and it is not enough to ensure that the silicon does not interact with the electrolyte during long-term cycling.
  • Direct contact; Comparative Example 2 directly shows that without the carbon layer coating treatment, the cycle performance of the battery is significantly reduced, and the expansion rate is significantly improved.
  • Examples 8-9 and Comparative Example 3 illustrates the effect of the restraint of the protective layer on the performance of the silicon carbon anode material: as mentioned above, without restraint of the protective layer, the silicon spheres will lose electricity after fragmentation during cycling. contact, deteriorating the cycle performance of the battery, and with the restraint of the protective layer, even if the silicon ball is broken, it is still in the inner cavity of the protective layer, and a certain electrical contact can still be maintained to stabilize the performance of the material; but also, the thinner protective layer On the one hand, it is difficult to suppress the stress caused by the expansion of internal silicon intercalation, and on the other hand, it is difficult to maintain its own structure during the battery preparation process, so it shows reduced electrochemical performance and cell expansion rate performance.
  • Example 3 and 10-12 and 14-15 illustrates the influence of the degree of graphitization ID/ IG of the protective layer on the properties of the silicon-carbon material: when the ID/ IG value is large, it indicates that the carbon group The lower degree of graphitization is conducive to the transport of lithium ions through the carbon component, and the carbon component with a lower degree of graphitization has lower electronic conductivity; and when the ID/ IG value is small, the graphitization of the carbon component The degree is higher, the electronic conductivity is high, and the ability to transport lithium ions is relatively poor.
  • the performance of Example 3 is the best. With the increase of the heat treatment temperature in step (4), the value of ID/ IG decreases .
  • Example 14 The too low ID/ IG in Example 14 is unfavorable for the ionic conductivity, while the treatment temperature in Example 15 is as high as 1300°C. At this temperature, silicon and carbon easily form an inert SiC component, which is not conducive to electron and ion conduction, and has no lithium intercalation activity, so the discharge rate is reduced.

Abstract

本申请提供一种负极活性材料、负极片、电化学装置和电子装置。该负极活性材料包括基体; 基体包括二次颗粒以及碳层，二次颗粒包含一次颗粒; 二次颗粒内部具有孔隙，孔隙的孔壁表面存在碳层; 负极活性材料与二次颗粒之间满足: 0.5≤D0/D<1; D为负极活性材料的平均粒径; D0为二次颗粒的平均粒径。本申请提供的负极活性材料能够提供充分的缓冲空间，缓解体积膨胀对电化学装置循环性能的影响，提升电池的能量密度，还能够有效防止内部结构破坏对外部结构的影响，有助于提高极片稳定性和改善倍率性能。

Description

负极活性材料、负极片、电化学装置和电子装置 技术领域
本申请涉及储能技术领域，具体涉及一种负极活性材料及包含该负极活性材料的负极片、电化学装置和电子装置。
背景技术
电化学装置，例如锂离子电池，具有高能量密度、低维护、自放电率低、工作温度范围宽、长循环寿命、无记忆效应、工作电压稳定和环境友好等特性被广泛用于智能产品(包括手机、笔记本、相机等电子产品)、电动工具和电动汽车等领域。随着技术的快速发展以及市场需求的多样性，人们对电化学装置的性能提出了更高的要求。
发明内容
在一些实施例中，本申请提供了一种负极活性材料，包括基体；基体包括二次颗粒以及碳层，二次颗粒包含一次颗粒；二次颗粒内部具有孔隙，孔隙的孔壁表面存在碳层；负极活性材料与二次颗粒之间满足：0.5≤D0/D<1；其中，D为负极活性材料的平均粒径；D0为二次颗粒的平均粒径。在另一些实施例中，0.7≤D0/D<1。在另一些实施例中，0.9≤D0/D<1。
在一些实施例中，一次颗粒包含硅基材料。
在一些实施例中，二次颗粒的表面存在碳层。
在一些实施例中，负极活性材料还包括位于基体表面的保护层。
在一些实施例中，保护层和基体之间具有孔隙。
在一些实施例中，负极活性材料的BET比表面积为20m 2.g -1至90m 2.g -1。在另一些实施例中，负极活性材料的BET比表面积为20m 2.g -1至60m 2.g -1。
在一些实施例中，基于负极活性材料的质量，硅元素的质量百分含量为10％-95％。在另一些实施例中，基于负极活性材料的质量，硅元素的质量百分含量为20％-80％。在另一些实施例中，基于负极活性材料的质量，硅元素的质量百分含量为30％-80％。
在一些实施例中，二次颗粒的平均粒径D0为2μm至30μm。在一些实施例中，二次颗粒的平均粒径D0为2μm至20μm。
在一些实施例中，碳层的平均厚度D1为1nm至250nm。在另一些实施例中，碳层的平均厚度D1为15nm至100nm。
在一些实施例中，保护层的平均厚度D2为1nm至250nm。在另一些实施例中，保护层的平均厚度D2为15nm至100nm。
在一些实施例中，保护层包括碳材料、导电聚合物或无机导电氧化物中的至少一种。
在一些实施例中，导电聚合物包括聚乙炔、聚噻吩、聚吡咯、聚苯胺、聚苯撑乙烯或聚双炔中的至少一种。
在一些实施例中，无机导电氧化物包括氧化铟锡、氧化锡锑中的至少一种。
在一些实施例中，负极活性材料具有15％至85％的孔隙率。在另一些实施例中，负极活性材料具有30％至60％的孔隙率。
在一些实施例中，保护层的拉曼光谱中，位于1300cm -1至1400cm -1范围内的特征峰面积为I D，位于1550cm -1至1650cm -1范围内的特征峰面积为I G，保护层的石墨化度I D/I G为0.5至1.9。在一些实施例中，保护层的石墨化度I D/I G为0.7至1.5。
在一些实施例中，本申请还提供了一种负极片，包括集流体和负极活性物质层，所述负极活性物质层位于所述集流体的表面，其中，所述负极活性物质层包括本申请的前述负极活性材料。
在一些实施例中，本申请再提供了一种电化学装置，包括正极片、负极片、隔离膜以及电解液，其中，所述负极片为本申请的前述负极片。
在一些实施例中，本申请又提供了一种电子装置，包括本申请的前述电化学装置。
本申请的技术方案至少具有以下有益的效果：本申请提供的负极活性材料能够提供充分的缓冲空间，缓解体积膨胀对电化学装置循环性能的影响，提升电池的能量密度，还能够有效防止内部结构破坏对外部结构的影响，有助于提高极片稳定性、并改善倍率性能。
附图说明
图1为负极活性材料的立体剖视结构示意图；
图2为负极活性材料的剖视结构示意图；
图3为负极活性材料中基体的剖视结构示意图；
图4为负极活性材料表面的透射电镜图；
其中，附图标记为：10-基体；11-二次颗粒；12-碳层；13第一孔隙；20-保护层；21-第二孔隙。
具体实施方式
将理解的是，所公开的实施例仅是本申请的示例，本申请可以以各种形式实施，因此，本文公开的具体细节不应被解释为限制，而是仅作为权利要求的基础且作为表示性的基础用于教导本领域普通技术人员以各种方式实施本申请。
在本申请中，平均粒径指的是通过透射电子显微镜(TEM)对材料粉体进行拍摄观察，然后，使用图像解析软件，从TEM照片中随机地选出10个材料颗粒，求出这些材料颗粒各自的面积，接着，假设材料颗粒是球形，通过以下公式求出各自的粒径R(直径)：R＝2×(S/π) 1/2；其中，S为材料颗粒的面积；将所得10个材料颗粒的粒径进行算数平均，从而求得所述材料颗粒的平均粒径。
在本申请中，术语“一次颗粒”为单一晶粒的活性材料颗粒，两个及以上的一次颗粒可通过聚集形成二次颗粒。在一些实施例中，所述一次颗粒可具有多种形状的任一种，包括棒状、球状或其组合。术语“二次颗粒”为由两个及以上的一次颗粒聚集而形成。
负极活性材料
参见图1至图3，负极活性材料包括基体10以及位于基体10表面的保护层20；基体10包括二次颗粒11以及碳层12，二次颗粒11包括一次颗粒；二次颗粒11内部具有第一孔隙13，第一孔隙13的孔壁表面存在碳层12；负极活性材料与二次颗粒11之间满足：0.5≤D0/D<1；其中，D为负极活性材料的平均粒径；D0为二次颗粒的平均粒径。
在一些实施例中，一次颗粒包含硅基材料。硅材料作为电化学装置(例如，锂离子电池)的负极活性材料具有较高的理论克容量(高达4200mAh/g)，因此被用于替代传统石墨负极活性材料，能够提升锂离子电池的能量密度。但是，随着锂离子嵌入硅的晶格中，硅-硅键断裂，锂-硅键逐渐生成，硅颗粒在嵌锂过程中会发生巨大的体积膨胀(300％至400％)，这种巨大的体积膨胀是硅颗粒嵌锂过程中不可避免的，在循环过程中体积的变化将会引起硅颗粒的碎裂，且将直接增加锂离子电池整体的膨胀和变形的风险，进而限制硅材料在锂离子电池中的大规模应用以及锂离子电池能量密度的进一步提升。
发明人发现：(1)减小硅材料的粒径能够一定程度上解决硅材料在锂离子电池应用中的体积膨胀问题，因为相较于大粒径的硅材料，具有较小粒径的硅材料不会发生大量的颗粒碎裂现象，能够减少因颗粒碎裂导致在电解液中电化学反应界面的暴露增加，进而减少副反应造成的体积膨胀，但是，较小粒径的硅材料具有较大的比表面积，将会在循环过 程中引起大量SEI膜的生长，降低锂离子电池的首效；(2)在硅材料表面包覆碳、氧化物、导电聚合物等物质能够一定程度上解决硅材料在锂离子电池应用中的体积膨胀问题，因为包覆能够避免电解液与硅材料的直接接触，进而减少副反应造成的体积膨胀，但是，目前采用碳、氧化物、导电聚合物制备的包覆层的机械强度不足以抵抗硅材料循环过程中巨大的体积变化，且会造成多余的新鲜电化学反应界面，消耗电解液，降低电池的循环寿命；(3)将硅材料与石墨颗粒复合造粒能够一定程度上解决硅材料在锂离子电池应用中的体积膨胀问题，因为硅材料与石墨颗粒复合造粒能够一定程度上通过石墨间隙缓解硅颗粒的膨胀，还能够通过复合生成的二次颗粒抑制硅颗粒的膨胀，但是硅材料与石墨颗粒复合造粒牺牲了硅组分的比例，并且只有将硅组分在二次颗粒中的含量限制在20％以下，否则其不能达到抑制硅组分膨胀的作用，因此只能在有限范围内提升锂离子电池的能量密度，不能充分发挥硅材料的高克容量的优势。目前采用的硅复合石墨颗粒的方案只能吸收一定含量(约10％)硅组分的嵌锂膨胀，但其循环过程中的膨胀已经接近全电池可承受的极限，无法实现硅组分含量进一步提升的同时，保证材料电化学性能的稳定性，按照此方案继续提升硅组分含量会使硅复合石墨颗粒发生不可逆的破裂，使负极电接触失效，进而导致锂离子电池寿命的衰减加速。
本申请以含硅一次颗粒形成的二次颗粒作为负极活性材料，其具有较高的克容量并能够利用二次颗粒内部孔隙形成的空间吸收体积膨胀，实现自身结构的稳定；在二次颗粒表面覆盖碳层和保护层，其中，碳层覆盖二次颗粒内部的孔壁，能够在二次颗粒内表面形成导电层，增加电子电导，保证硅材料的电子接触，促进二次颗粒容量的充分发挥，同时，外部覆盖保护层提升机械强度，并且能够进一步为硅嵌锂膨胀提供缓冲，抑制内部硅嵌锂膨胀带来的应力，实现对基体结构的保护层拘束，即使在二次颗粒表面碳层被破坏的情况下，仍能够保证由二次颗粒、碳层和保护层组成的负极活性材料结构的稳定性、并保持一定的电接触。因此，本申请的负极活性材料能够为硅嵌锂膨胀提供充分的缓冲，缓解体积膨胀对电化学装置循环性能的影响，提升电化学装置的能量密度，还能够有效防止内部结构破坏对外部结构的影响，有助于提高极片稳定性和改善倍率性能。在一些实施例中，所述二次颗粒具有球形珊瑚状结构，球形珊瑚状结构内部具有较多的孔隙，更利于吸收硅体积膨胀。在一些实施例中，一次颗粒为硅颗粒，二次颗粒由硅一次颗粒聚集而形成。
本申请的负极活性材料设置二次颗粒的平均粒径D0与负极活性材料的平均粒径D之间的比值大于等于0.5，通过保证含硅二次颗粒在负极活性材料中的占比，能够避免因碳层和保护层占比较大而造成电化学装置能量密度的降低。
在一些实施例中，如图2和图3所示，二次颗粒内部的孔壁表面和外表面均存在碳层，此时，二次颗粒的内表面和外表面均形成导电层，能够进一步增加负极活性材料的导电性。
参见图2和图3，在一些实施例中，保护层20和基体10之间具有第二孔隙21，第二孔隙21为硅嵌锂膨胀提供预留空间，如果基体10中的硅组分脱嵌锂碎裂，第二孔隙21为碎裂的硅组分提供停留空间，使其仍能够保持一定的电接触，稳定负极活性材料性能的发挥，同时，由于基体10被保护层20形成的结构空间封闭，停留在第二孔隙21中基体碎片不会影响负极活性材料外部的结构。本申请对保护层的形状没有特殊的限定，保护层的形状可以是与二次颗粒的形状相近，也可以是与二次颗粒的形状不相近的；优选为与二次颗粒的形状相近，在一些实施例中，保护层设置为球形结构。
在一些实施例中，所述碳层的厚度D1为1nm至250nm。在一些实施例中，所述碳层的厚度D1为15nm至100nm。在一些实施例中，所述保护层的厚度D2为1nm至250nm。在一些实施例中，所述保护层的厚度D2为15nm至100nm。碳层和保护层的厚度不能过大，否则会在一定程度上影响负极活性材料对能量密度的改善效果；碳层和保护层的厚度不能过小，如果碳层的厚度过小，则影响碳层的机械强度，不利于维持二次颗粒硅嵌锂体积膨胀时的结构稳定性，不利于在长期循环过程中保证硅不与电解液直接接触，影响对电化学装置的循环性能的改善效果，如果保护层的厚度过小，不利于抑制内部硅嵌锂膨胀带来的应力，不利于在在电化学装置的制备过程中维持负极活性材料自身结构的稳定性，影响对电化学装置的电化学性能的改善效果。
在一些实施例中，所述保护层包括碳材料、导电聚合物或无机导电氧化物中的至少一种。在一些实施例中，导电聚合物包括聚乙炔、聚噻吩、聚吡咯、聚苯胺、聚苯撑乙烯或聚双炔中的至少一种。在一些实施例中，无机导电氧化物包括氧化铟锡、氧化锡锑中的至少一种。
在一些实施例中，所述保护层包括碳材料。则保护层的石墨化度影响负极活性材料的性能。在一些实施例中，所述保护层的拉曼光谱中，位于1300cm -1至1400cm -1范围内的特征峰面积为I D，位于1550cm -1至1650cm -1范围内的特征峰面积为I G，所述保护层的石墨化度I D/I G为0.5至1.9。在本申请中，石墨化度I D/I G表示无序碳峰高与石墨化碳峰高的比值，如果I D/I G的值较大，则说明碳组分的石墨化程度较低，碳的无序化程度较高，利于锂离子通过碳组分进行传输，但同时电子导电率下降；如果I D/I G的值较小，则说明碳组分的石墨化程度较高，碳的无序化程度较低，电子导电率较高，但同时传输锂离子的能力相对较低。当I D/I G值位于上述范围内时，能够保证保护层中碳组分的覆盖范围，保护层的离 子传导和电子传导的能力达到平衡，有助于进一步改善电化学装置的能量密度和倍率性能。在一些实施例中，所述保护层的石墨化度I D/I G为0.7至1.5。在本申请中，可以通过控制烧结温度和时间来制备具有不同石墨化度的保护层，当然，本领域技术人员也可以通过其他公知的方法制备具有本申请所述的石墨化度范围的保护层。
二次颗粒的平均粒径影响负极活性材料的性能。在一些实施例中，所述二次颗粒的平均粒径D0为2μm至30μm。第一，如果二次颗粒的平均粒径较大，则二次颗粒因硅嵌锂膨胀对负极片结构造成的破坏也较大，容易导致失去电接触；第二，如果二次颗粒的平均粒径较大，则不利于二次颗粒在负极活性材料中的均匀分散，影响能量密度；第三，负极活性材料还可以包括石墨，当将前述负极活性材料与石墨复合造粒时能够进一步通过石墨间隙缓解硅颗粒的膨胀，而石墨颗粒的平均粒径普遍大于15μm，如果二次颗粒的平均粒径较大，则不利于在粒径分布上与石墨颗粒进行匹配，影响负极片的结构稳定性；第四，具有相对较小平均粒径的二次颗粒制备得到的负极活性材料能够承受相对较高的压实密度，在电化学装置的制备过程中能够较好地保持自身结构的稳定性，吸收硅嵌锂的体积膨胀。在一些实施例中，所述二次颗粒的平均粒径D0为2μm至20μm。
负极活性材料中硅元素的含量影响负极活性材料的性能。在一些实施例中，基于所述负极活性材料的质量，硅元素的质量百分含量为10％至95％。硅元素的含量越高，负极活性材料的克容量越高；同时，硅元素含量越高，负极活性材料中碳元素的含量则越低，负极活性材料的比表面积越接近二次颗粒的比表面积，随着硅含量的增加，负极活性材料的电化学装置循环中膨胀率增加。因此，控制硅元素的质量百分含量满足一定的范围能够进一步提高负极活性材料的能量密度，改善电化学装置的循环性能。在一些实施例中，基于所述负极活性材料的质量，硅元素的质量百分含量为20％至80％。另一些实施例中，基于负极活性材料的质量，硅元素的质量百分含量为30％-80％。在本申请中，硅含量的测量不受特别限制。根据本申请的一个实施方式，可以通过以下方式测量负极活性材料中的硅组分的含量：
将样品置于富氧条件下由高频炉高温加热燃烧使碳、硫氧化成二氧化碳、二氧化硫，该气体经处理后进入相应的吸收池，对相应的红外辐射进行吸收再由探测器转化成对应的信号；此信号由计算机采样，经线性校正后转换成与二氧化碳、二氧化硫浓度成正比的数值，然后把整个分析过程的取值累加，分析结束后，此累加值在计算机中除以重量值，再乘以校正系数，扣除空白，即可获得样品中碳、硫百分含量。其中，分析可利用高频红外碳硫分析仪(上海徳凯HCS-140)进行。测量得到样品中碳的质量百分含量之后，以100％ 减去碳的质量百分含量即为本申请中负极活性材料中硅的质量百分含量。
在一些实施例中，所述负极活性材料的BET比表面积为20m 2.g -1至90m 2.g -1。负极活性材料比表面积的增加来自于二次颗粒内部丰富的孔隙，其可以为硅嵌锂膨胀带来的体积变化提供缓冲空间，使材料自身能够吸收体积变化带来的应力，不至于因此而影响极片涂层的结构，甚至涂层粉化、剥落，以致活性物质失去电接触。当负极活性材料的比表面积满足前述范围时，能够进一步稳定极片结构，保障电芯循环稳定性。在一些实施例中，所述负极活性材料的BET比表面积为20m 2.g -1至60m 2.g -1。在本申请中，比表面积的测量不受特别限制。根据本申请的一个实施方式，可以通过以下方式测量负极活性材料的比表面积：
称取1.5-3.5g负极活性材料颗粒样品装入TriStar II 3020的测试测试样品管中，200℃脱气120min后进行测试。比表面积的测试原理如下：
在恒温低温下，测定不同相对压力时的气体在负极活性材料颗粒表面的吸附量后，基于布朗诺尔-埃特-泰勒吸附理论(BET)及其公式求得试样单分子层吸附量，从而计算出负极活性材料颗粒的比表面积；
BET比表面积公式：
Figure PCTCN2021077835-appb-000001
其中：W为相对压力下负极活性材料颗粒所吸附的气体的质量，Wm为铺满一单分子层的气体饱和吸附量，斜率为(c-1)/(WmC)，截距为1/WmC，总比表面积为(Wm*N*Acs/M)。
比表面积：S＝St/m，其中m为负极活性材料颗粒样品的质量，Acs表示每个N 2分子的所占据的平均面积：
Figure PCTCN2021077835-appb-000002
在一些实施例中，所述负极活性材料具有15％至85％的孔隙率。在一些实施例中，所述负极活性材料具有30％至60％的孔隙率。具有一定范围的孔隙率的负极活性材料能够缓冲硅嵌锂膨胀，进一步改善负极活性材料的性能。在本申请中，术语“孔隙率”是指由孔隙所占的体积对结构中的总体积的比率。在本申请中，孔隙率的测量不受特别限制。根据本申请的一个实施方式，可以通过例如布鲁诺尔-埃米特-特勒(Brunauer-Emmett-Teller，BET)测量方法或Hg孔隙率计来测量微孔和中孔体积。可以通过改善负极活性材料中硅含量占比、二次颗粒平均粒径等方法调整负极活性材料的孔隙率，不受特别的限制。根据本申请的一个实施方式，以硅铝合金颗粒为原料制备二次颗粒，可以通过改变硅铝合金颗粒中硅含量来调整负极活性材料的孔隙率，硅铝合金颗粒中硅含量越少，在制备时被洗去的铝组分越多，得到的负极活性材料的孔隙率越大。
负极活性材料的制备方法
一种负极活性材料的制备方法，用于制备本申请前述的负极活性材料，包括以下步骤：
步骤S1，将硅铝合金颗粒分散在液相体系中，可选地加入表面活性剂；
步骤S2，向步骤S1的液相体系中加入含碳物质和可选的引发剂，搅拌并混合均匀，得到包覆碳前驱物的硅铝合金颗粒；其中，所述碳前驱物包括沥青、高分子聚合物中的至少一种；
步骤S3，对步骤S2得到的包覆碳前驱物的硅铝合金颗粒进行酸洗刻蚀，过滤，得到固体物质；
步骤S4，将步骤S3中得到的固体物质进行烧结；
步骤S5，将步骤S4烧结后得到的固体物质重复步骤S1、S2和S4。
在一些实施例中，步骤S1可以包括以下步骤：将硅铝合金颗粒分散在水和乙醇混合的液相体系中，再加入表面活性剂，在充分搅拌下将硅铝合金颗粒均匀分散在液相体系中。在本申请的实施方式中，可以通过改变步骤S1中硅铝合金颗粒中硅的含量占比来改变最终制备得到的负极活性材料的孔隙率，硅含量越少，负极活性材料的孔隙率越大。
在一些实施例中，步骤S2可以包括以下步骤：向均匀分散有硅铝合金颗粒的液相体系中加入引发剂，保持搅拌0.5-12h以使其混合均匀，再加入适量的含碳的可聚合物，保持搅拌2-24h后，过滤出固体物质，即为包覆碳前驱物的硅铝合金颗粒；其中，所述碳前驱物包括酚醛树脂、沥青、聚偏氟乙烯及其衍生物、羧甲基纤维素及其衍生物、羧甲基纤维素钠及其衍生物、聚乙烯基吡咯烷酮及其衍生物、聚丙烯酸及其衍生物、丁苯橡胶、聚丙烯酰胺、聚酰亚胺、聚酰胺酰亚胺、聚吡咯，聚苯胺中的至少一种。在一些实施例中，步骤S2中的引发剂可以选用氨水。在步骤S2中，所述可聚合物为能够在引发剂的作用下聚合形成高分子聚合物的物质。在一些实施例中，步骤S2中的含碳的可聚合物可以选用间苯二酚和甲醛的组合。在本申请的实施方式中，可以通过改变步骤S2中加入的含碳的可聚合物的量的量来改变最终制备得到的负极活性材料的比表面积，负极活性材料中碳组分的含量相对越少，负极活性材料中硅的含量相对越多，负极活性材料的比表面积越接近硅二次颗粒的比表面积。
在一些实施例中，步骤S3中的酸可以包括盐酸、硫酸、硝酸、草酸、磷酸中的一种或者组合。在经过步骤S3的酸洗刻蚀后，硅铝合金中的铝被洗去，洗去的铝的位置形成孔隙，得到球形珊瑚状结构的硅二次颗粒。
在一些实施例中，步骤S4中烧结在惰性气氛中进行，烧结温度为500-1200℃，升温 速率为0.2-20℃/min，保温时间为1-24h。在一些实施例中，惰性气氛可以是氮气、氩气、氦气中的一种或者组合。在经过步骤S4的烧结后，球形珊瑚状结构的硅二次颗粒内部的孔壁上覆盖一层碳层，形成负极活性材料的基体结构。
在一些实施例中，步骤S5具体地包括：将烧结后的固体物质分散在液相体系中，加入可选的表面活性剂，再向液相体系中加入含碳的可聚合物和可选的引发剂，搅拌并混合均匀，使固体物质表面包覆碳前驱物，过滤后烧结，得到所述负极活性材料。在一些实施例中，步骤S5具体地包括：将烧结后的固体物质分散在液相体系中，加入可选的表面活性剂，再向液相体系中加入导电聚合物单体和可选的引发剂，搅拌并混合均匀，使固体物质表面包覆导电聚合物，得到所述负极活性材料。在一些实施例中，步骤S5具体地包括：将烧结后的固体物质分散在液相体系中，加入可选的表面活性剂，再向液相体系中加入无机导电氧化物前驱体，搅拌并混合均匀，进行沉淀反应使固体物质表面包覆无机导电氧化物，得到所述负极活性材料。在经过步骤S5处理之后，基体结构的表面进一步形成一层保护层，保护层包覆该基体结构并且保护层和该基体结构之间具有孔隙。在本申请的一些实施方式中，可以通过改变加入的含碳的可聚合物的量改变碳层和保护层的厚度。
负极片
在一些实施例中，负极片包含负极集流体和负极活性物质层，所述负极活性物质层设置于所述负极集流体的表面，所述负极活性物质层包含本申请前述的负极活性材料。
在一些实施例中，负极活性物质层还包含负极粘结剂。负极粘结剂用于改善负极活性材料颗粒之间以及负极活性材料颗粒与负极集流体之间的粘结性能。负极粘结剂是本领域公知的可被用作负极活性物质层的粘结剂。在一些实施例中，负极粘结剂包括聚乙烯醇、羧甲基纤维素、羟丙基纤维素、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚偏1,1-二氟乙烯、聚乙烯、聚丙烯、聚丙烯酸(PAA)、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂、尼龙中的至少一种。
在一些实施例中，负极活性物质层还包含负极导电剂。负极导电剂用于改善负极片的导电率。负极导电剂是本领域公知的可被用作负极活性物质层的导电剂。在一些实施例中，负极导电剂包括导电碳黑、乙炔黑、科琴黑、碳纤维、碳纳米管、石墨烯、金属粉、金属纤维和聚亚苯基衍生物中的至少一种。在一些实施例中，金属粉、金属纤维中的金属包括铜、镍、铝、银中的至少一种。
本申请对于负极活性物质层中负极活性材料、粘结剂、导电剂的混合比例没有特别的限制，可以根据期望的电化学装置性能控制其混合比例。
在一些实施例中，负极集流体为金属，例如但不限于铜箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜、包覆有导电金属的聚合物基板或它们的组合。
在一些实施例中，所述负极片具有20％至40％的孔隙率。在本申请的实施例中，负极片的上述孔隙率可以本领域公知的方法获得，例如可以通过调整压实密度获得，孔隙率随着压实密度的增加而减小。
[电化学装置]
本申请的电化学装置例如为一次电池、二次电池。二次电池例如为锂二次电池，锂二次电池包含但不限于锂金属二次电池、锂离子二次电池、锂聚合物二次电池或锂离子聚合物二次电池。在一些实施例中，电化学装置包含正极片、负极片、隔离膜以及电解液，所述负极片为本申请前述的负极片。
正极片
正极片是本领域技术公知的可被用于电化学装置的正极片。在一些实施例中，正极片包含正极集流体以及正极活性物质层。正极活性物质层设置于正极集流体的表面上。
在一些实施例中，正极集流体为金属，金属例如但不限于铝箔。
在一些实施例中，正极活性物质层包括正极活性材料。正极活性材料可选用本领域技术公知的各种可被用作电化学装置的正极活性材料的能够可逆地嵌入、脱嵌活性离子的传统公知的物质。在一些实施例中，正极活性材料包含含锂过渡金属氧化物。在一些实施例中，正极活性材料包含锂与钴、锰、镍的金属或其组合的复合氧化物中的至少一种。在一些实施例中，正极活性材料包含LiCoO 2、LiNiO 2、LiMn 2O 4、LiCo 1-yM yO 2、LiNi 1-yM yO 2、LiMn 2-yM yO 4、LiNi xCo yMn zM 1-x-y-zO 2中的至少一种，其中，M选自Fe、Co、Ni、Mn、Mg、Cu、Zn、Al、Sn、B、Ga、Cr、Sr、V、Ti中的一种或多种，且0≤y≤1,0≤x≤1,0≤z≤1,x+y+z≤1。
在一些实施例中，正极活性物质层还包含正极粘结剂和正极导电材料。正极粘结剂是本领域公知的可被用作正极活性物质层的粘结剂。粘结剂例如但不限于聚偏二氟乙烯。正极粘结剂用于改善正极活性材料颗粒彼此间以及正极活性材料颗粒与集流体之间的粘结性能。导电材料是本领域公知的可被用作正极活性物质层的导电材料。正极导电材料例如 但不限于导电碳黑、导电浆料。正极导电材料用于为电极提供导电性。
在一些实施例中，正极片的制备方法是本领域技术公知的可被用于电化学装置的正极片的制备方法。在一些实施例中，在正极浆料的制备中，通常加入溶剂，正极活性材料加入粘结剂并根据需要加入导电材料和增稠剂后溶解或分散于溶剂中制成正极浆料。溶剂在干燥过程中挥发去除。溶剂是本领域公知的可被用作正极活性物质层的溶剂，溶剂例如但不限于N-甲基吡咯烷酮(NMP)。
本申请对于正极活性物质层中的正极活性材料、正极粘结剂、正极导电材料的混合比例没有特别的限制，可以根据期望的电化学装置性能控制其混合比例。
电解液
电解液是本领域技术公知的可被用于电化学装置的电解液。在一些实施例中，电解液包括有机溶剂和电解质盐。
有机溶剂可以是本领域技术公知的可被用于电解液的有机溶剂。在一些实施例中，有机溶剂包括碳酸丙烯酯(PC)、碳酸乙烯酯(EC)、碳酸二乙酯(DEC)中的至少一种。有机溶剂中各组分的混合比例没有特别的限制。
电解质盐可以是本领域技术公知的可被用于电解液的电解质盐。在一些实施例中，电解质盐为锂盐，例如LiPF 6。
在一些实施例中，电解液还可以包括添加剂，添加剂可以是本领域技术公知的可被用于电解液的添加剂。
隔离膜
隔离膜是本领域技术公知的可被用于电化学装置的隔离膜。隔离膜设置在正极片和负极片之间，用于防止短路。
本申请对隔离膜的材料和形状没有特别限制。在一些实施例中，隔离膜包括由对本申请的电解液稳定的材料形成的聚合物或无机物。
在一些实施例中，隔离膜包括基材层和表面处理层，表面处理层设置在基材层的至少一个表面上。
在一些实施例中，基材层为具有多孔结构的无纺布、膜或复合膜。在一些实施例中，基材层的材料选自聚乙烯(PE)、聚丙烯、聚对苯二甲酸乙二醇酯和聚酰亚胺中的至少一种。在一些实施例中，基材层选自聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯 无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜中的任意一种。
在一些实施例中，表面处理层是聚合物层或无机物层，或者是混合聚合物与无机物所形成的层。在一些实施例中，无机物层包括无机颗粒和粘结剂，无机颗粒选自氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙和硫酸钡中的一种或几种的组合，粘结剂选自聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯和聚六氟丙烯中的一种或几种的组合。在一些实施例中，聚合物层包括聚合物，聚合物的材料选自聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚偏氟乙烯或聚(偏氟乙烯-六氟丙烯)中的至少一种。
外包装壳体
在一些实施例中，电化学装置还包含外包装壳体。外包装壳体是本领域技术公知的可被用于电化学装置并且对于所使用的电解液稳定的外包装壳体，例如但不限于金属类外包装壳体。
[电子装置]
本申请的电子装置是任何电子装置，例如但不限于笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池、锂离子电容器。注意的是，本申请的电化学装置除了适用于上述例举的电子装置外，还适用于储能电站、海运运载工具、空运运载工具。空运运载装置包含在大气层内的空运运载装置和大气层外的空运运载装置。
在一些实施例中，电子装置包含本申请前述的电化学装置。
下面结合实施例，进一步阐述本申请。应理解，这些实施例仅用于说明本申请而不用于限制本申请的范围。
在下述实施例、对比例中，所使用到的试剂、材料以及仪器如没有特殊的说明，均可 商购获得或合成获得。
实施例1
(1)负极活性材料的制备
①取100g硅铝合金粉末(平均粒径为2.7μm、硅质量占比为30％)加入6000ml水和乙醇混合液(水和乙醇的体积比为2：1)中，加入十六烷基三甲基溴化铵表面活性剂，充分搅拌1h使硅铝合金粉末均匀分散；②然后向其中加入氨水，搅拌1h后再加入8g间苯二酚和20g甲醛，充分搅拌10h，过滤；③将过滤得到的固体物质加入盐酸溶液中，保持搅拌12h，过滤；④将过滤得到的固体物质置于氩气气氛中，以5℃/min的速度升温至850℃，烧结5h；⑤将烧结后的固体物质置于加入3000ml水和乙醇混合液(水和乙醇的体积比为2：1)中，加入十六烷基三甲基溴化铵表面活性剂，充分搅拌1h使其均匀分散；⑥然后向其中加入氨水，搅拌1h后再加入4g间苯二酚和10g甲醛，充分搅拌10h，过滤；⑦将过滤得到的固体物质置于氩气气氛中，以5℃/min的速度升温至850℃，烧结5h，制得负极活性材料。
(2)负极片的制备
将石墨、制得的负极活性材料、导电剂(导电碳黑，Super P)和粘结剂PAA按照约70％：15％：5％：10％的重量比混合，加入适量的水，在固体含量为约55wt％-70wt％下捏合。加入适量的水，调节浆料的粘度为约4000-6000Pa·s，制成负极浆料。将制得的负极浆料涂布在负极集流体铜箔上，烘干，冷压，得到负极片。
(3)正极片的制备
将LiCoO 2、导电炭黑和聚偏二氟乙烯(PVDF)按照约95:2.5:2.5的重量比在N-甲基吡咯烷酮溶剂中充分搅拌混合均匀，制得均匀的正极浆料；将制得的正极浆料涂布在正极集流体铝箔上，烘干，冷压，得到正极片。
(4)隔离膜的制备
以PE多孔聚合薄膜作为隔离膜。
(5)电解液的制备
在干燥氩气环境下，将有机溶剂碳酸丙烯酯(PC)、碳酸乙烯酯(EC)、碳酸二乙酯(DEC)按照1：1：1的重量比混合均匀，加入充分干燥的锂盐LiPF 6混合均匀，得到LiPF 6浓度为1.15mol/L的电解液。
(6)锂离子电池的制备
将制得的正极片、隔离膜、负极片按顺序叠好，使隔离膜处于正极片和负极片中间以 起到隔离的作用，然后卷绕得到裸电芯；将裸电芯置于外包装壳体中，留下注液口，从注液口灌注上述制备的电解液，封装；然后经过化成、脱气、切边等工艺流程得到锂离子电池。
实施例2
与实施例1不同的是，硅铝合金粉末中硅质量占比为50％。
实施例3
与实施例1不同的是，硅铝合金粉末中硅质量占比为70％。
实施例4
与实施例3不同的是，硅铝合金粉末的平均粒径为8.1μm。
实施例5
与实施例3不同的是，硅铝合金粉末的平均粒径为15.6μm。
实施例6
与实施例3不同的是，步骤②中加入10g间苯二酚和25g甲醛。
实施例7
与实施例3不同的是，步骤②中加入1g间苯二酚和2.5g甲醛。
实施例8
与实施例3不同的是，步骤⑥中加入20g间苯二酚和50g甲醛。
实施例9
与实施例3不同的是，步骤⑥
中加入2g间苯二酚和5g甲醛。
实施例10
与实施例3不同的是，步骤④中以5℃/min的速度升温至700℃。
实施例11
与实施例3不同的是，步骤④中以5℃/min的速度升温至900℃。
实施例12
与实施例3不同的是，步骤④中以5℃/min的速度升温至1100℃。
实施例13
与实施例3不同的是，硅铝合金粉末中硅质量占比为20％。
实施例14
与实施例3不同的是，步骤④中以5℃/min的速度升温至1300℃。
实施例15
与实施例3不同的是，步骤④中以5℃/min的速度升温至500℃。
对比例1
与实施例1不同的是，对比例1直接将硅二次颗粒作为负极活性材料。
对比例2
与实施例1不同的是，对比例2没有对二次颗粒进行碳层覆盖处理。
对比例3
与实施例1不同的是，对比例3没有对二次颗粒进行保护层包覆处理。
实施例1-15以及对比例1-3中的具体参数值请见表1。
测试方法
负极活性材料/二次颗粒的平均粒径、碳层/保护层厚度的测量：
通过高分辨透射电子显微镜(HR-TEM)对材料粉体进行拍摄观察，然后，使用图像解析软件，从TEM照片中随机地选出10个活性材料颗粒，求出活性材料颗粒各自的面积，接着，假设活性材料颗粒是球形，通过以下公式求出各自的粒径R(直径)：R＝2×(S/π) 1/2；其中，S为活性材料颗粒的面积；对10张TEM图像进行求出上述活性材料颗粒粒径R的处理，并将所得100(10×10)个活性材料颗粒的粒径进行算数平均，从而求得所述负极活性材料的平均粒径D。同时，测量上述100(10×10)个活性材料颗粒各自的碳层和保护层的厚度，并分别进行算数平均，即可求得碳层的平均厚度D1以及保护层的平均厚度D2。
二次颗粒的平均粒径D0通过下式计算获得：D0＝D-D1-D2。
石墨化度I D/I G的测试：使用仪器ER Evolution进行拉曼分析，测量对比D峰和G峰的面积比值得到保护层的石墨化度。
负极活性材料的克容量测试：
将前述负极片在干燥环境中用冲压机切成直径为1cm的圆片，在手套箱中以金属锂片作为对电极，隔离膜选择celgard复合膜，加入电解液组装成扣式电池。运用蓝电(LAND)系列电池测试测试对电池进行充放电测试，测试其充放电性能。扣式电池循环5圈之后，放电截至电压为2.0V的克容量记为负极活性材料的克容量。
放电倍率测试：
在25℃下，将锂离子电池以0.2C放电到3.0V，静置5min，以0.5C充电到4.45V，恒压充电到0.05C后静置5min，调整放电倍率，分别以0.2C、2.0C进行放电测试，分别得到放电容量，将2C与0.2C下的比值记为放电倍率。
常温/高温循环性能测试：
测试温度为25℃和45℃，以0.7C恒流充电到4.4V，恒压充电到0.025C，静置5分钟后以0.5C放电到3.0V。以此步骤得到的容量为初始容量，进行0.7C充电/0.5C放电进行循环测试，以每一步的容量与初始容量做比值，得到容量衰减曲线。
以25℃循环截至到容量保持率为90％的圈数记为电池的常温循环性能，以45℃循环 截至到容量保持率为80％的圈数记为电池的高温循环性能。
常温/高温满充膨胀率测试：
测试温度为25℃和45℃，用螺旋千分尺测试半充(50％充电状态(SOC))时锂离子电池的厚度，以0.7C恒流充电到4.4V，恒压充电到0.025C，再以0.5C放电到3.0V，重复上述充放电流程，循环至500圈时，锂离子电池处于满充(100％SOC)状态下，再用螺旋千分尺测试此时锂离子电池的厚度，与初始半充(50％SOC)时锂离子电池的厚度对比，即可得此时满充(100％SOC)锂离子电池的膨胀率。
表1 实施例1-15以及对比例1-3的参数
Figure PCTCN2021077835-appb-000003
表2 实施例1-15以及对比例1-3的性能测试结果
Figure PCTCN2021077835-appb-000004
由表1和表2的数据分析可以得到，当负极活性材料的二次颗粒内部具有孔隙，并进行碳层覆盖、保护层拘束处理后，兼具较好的循环性能和倍率性能。对比例1的硅二次颗粒表面不存在碳层和保护层，硅颗粒暴露在电解液中，由于没有碳层保护以防止过量SEI的生成，以及没有保护层维持二次颗粒的结构，导致颗粒碎裂和SEI的不断沉积，锂离子电池的循环性能和倍率性能均较差。对比例2未进行碳层覆盖处理，对比例3未进行保护层拘束处理，锂离子电池的循环性能和倍率性能均受到影响。没有碳层包覆的材料电子电导率较差，材料的倍率性能明显较低，而没有保护层保护的硅材料也失去了大量电子导电位点，同时因为没有保护层拘束，硅嵌锂粉化后更易失去电接触，造成放电倍率的下降，而具有保护层拘束的硅材料，即便在硅碎裂粉化后仍能被保护层拘束其中，维持一定的电子电导。
因为二次颗粒的平均粒径受所使用的硅铝合金球的粒径影响，对比实施例3-5可知D0值更小的二次颗粒制备的硅碳材料的性能更佳，其原因有以下几点：(1)D0越大，硅碳材料的嵌锂膨胀对负极极片的结构破环作用越大，越容易失去电接触；(2)D0越大，硅碳材料的均匀分散越困难；(3)石墨颗粒的平均粒径普遍大于15μm，硅碳材料的平均粒 径越大，越难以在粒径分布上与石墨进行匹配，更容易影响负极极片的结构稳定性；(4)D0越小，制备得到的硅碳材料越能够承受更高的压实密度，在电池的制备过程中保持自身结构，吸收硅嵌锂的体积膨胀。
实施例1-3之间的对比说明了硅碳材料中硅的含量对材料性能的影响：硅含量越高，材料的克容量也高；同时因为硅含量增加，也引起电池的膨胀率增加。
实施例6-7和对比例2之间的对比说明了碳层包覆对硅碳材料性能的影响：碳层的包覆有利于提高硅碳材料的电子电导，进而提电池的倍率性能，且能防止过量SEI的生成，降低其带来的对电池膨胀率的不利影响；且较薄的碳层难以在硅嵌锂膨胀时维持结构，亦不足以在长期循环过程中保证硅不与电解液直接接触；对比例2则直接说明了没有碳层包覆处理，电池的循环性能明显下降、且膨胀率显著提高。
实施例8-9和对比例3之间的对比说明了保护层拘束对硅碳负极材料性能的影响：如前所述，没有保护层的拘束，硅球在循环过程中碎裂之后会失去电接触，劣化电池循环性能，而具有保护层拘束的情况下，即便硅球碎裂，仍在保护层内腔中，仍可保持一定电接触，稳定材料性能发挥；但同样，较薄的保护层一方面难以抑制内部硅嵌锂膨胀带来的应力，另一方面也难以在电池制备过程中维持自身结构，所以表现出降低的电化学性能和电芯膨胀率表现。
实施例3和10-12、14-15之间的对比说明了保护层的石墨化度I D/I G对硅碳材料性能的影响：当I D/I G值较大时，说明碳组分石墨化程度较低，有利于锂离子通过碳组分进行传输，同时石墨化程度较低的碳组分电子电导率较低；而I D/I G值较小时，碳组分的石墨化程度较高，电子电导率高，传输锂离子的能力相对较差。在实施例对比中即表现为实施例3的性能最佳。随着步骤④中的热处理温度提升，I D/I G的值降低，实施例14中过低的I D/I G不利于离子电导，而实施例15中的处理温度高至1300℃，在这个温度下，硅和碳容易形成惰性的SiC组分，即不利于电子和离子传导，也没有嵌锂活性，所以导致其放电倍率降低。
以上描述仅为本申请的较佳实施例以及对所运用技术原理的说明。本领域技术人员应当理解，本申请中所涉及的公开范围，并不限于上述技术特征的特定组合而成的技术方案，同时也应涵盖在不脱离上述公开构思的情况下，由上述技术特征或其等同特征进行任意组合而形成的其它技术方案。例如上述特征与本申请中公开的具有类似功能的技术特征进行互相替换而形成的技术方案。

Claims (10)

  1. 一种负极活性材料，包括基体；
    所述基体包括二次颗粒以及碳层，所述二次颗粒包含一次颗粒；
    所述二次颗粒内部具有孔隙，所述孔隙的孔壁表面存在所述碳层；
    所述负极活性材料与所述二次颗粒之间满足：0.5≤D0/D<1；
    其中，D为所述负极活性材料的平均粒径；D0为所述二次颗粒的平均粒径。
  2. 根据权利要求1所述的负极活性材料，其满足以下条件的至少一者：
    i)0.7≤D0/D<1；
    ii)所述一次颗粒包含硅基材料；
    iii)所述二次颗粒的表面存在所述碳层；
    iv)所述负极活性材料还包括位于所述基体表面的保护层。
  3. 根据权利要求2所述的负极活性材料，其满足以下条件的至少一者：
    a)所述保护层和所述基体之间具有孔隙；
    b)所述负极活性材料的BET比表面积为20m 2.g -1至90m 2.g -1；
    c)基于所述负极活性材料的质量，所述负极活性材料中硅元素的质量百分含量为10％至95％；
    d)所述负极活性材料具有15％至85％的孔隙率。
  4. 根据权利要求2所述的负极活性材料，其满足以下条件的至少一者：
    e)所述二次颗粒的平均粒径D0为2μm至30μm；
    f)所述碳层的平均厚度D1为1nm至250nm；
    g)所述保护层的平均厚度D2为1nm至250nm；
    h)所述保护层包括碳材料、导电聚合物或无机导电氧化物中的至少一种。
  5. 根据权利要求2所述的负极活性材料，其中，所述保护层的拉曼光谱中，位于1300cm -1至1400cm -1范围内的特征峰面积为I D，位于1550cm -1至1650cm -1范围内的特征 峰面积为I G，所述保护层的石墨化度I D/I G为0.5至1.9。
  6. 根据权利要求5所述的负极活性材料，其中，所述保护层的石墨化度I D/I G为0.7至1.5。
  7. 根据权利要求2所述的负极活性材料，其满足以下条件的至少一者：
    i)所述负极活性材料的BET比表面积为20m 2.g -1至60m 2.g -1；
    j)基于所述负极活性材料的质量，所述负极活性材料中硅元素的质量百分含量为30％至80％；
    k)所述负极活性材料具有30％至60％的孔隙率；
    l)所述二次颗粒的平均粒径D0为2μm至20μm；
    m)所述碳层的平均厚度D1为15nm至100nm；
    n)所述保护层的平均厚度D2为15nm至100nm。
  8. 一种负极片，包括集流体和负极活性物质层，所述负极活性物质层位于所述集流体的表面，其中，所述负极活性物质层包括根据权利要求1-7中任一项所述的负极活性材料。
  9. 一种电化学装置，包括根据权利要求8中所述的负极片。
  10. 一种电子装置，包括根据权利要求9所述的电化学装置。
PCT/CN2021/077835 2021-02-25 2021-02-25 负极活性材料、负极片、电化学装置和电子装置 WO2022178748A1 (zh)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CN202180094556.XA CN116941068A (zh) 2021-02-25 2021-02-25 负极活性材料、负极片、电化学装置和电子装置
PCT/CN2021/077835 WO2022178748A1 (zh) 2021-02-25 2021-02-25 负极活性材料、负极片、电化学装置和电子装置

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2021/077835 WO2022178748A1 (zh) 2021-02-25 2021-02-25 负极活性材料、负极片、电化学装置和电子装置

Publications (1)

Publication Number Publication Date
WO2022178748A1 true WO2022178748A1 (zh) 2022-09-01

Family

ID=83048653

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2021/077835 WO2022178748A1 (zh) 2021-02-25 2021-02-25 负极活性材料、负极片、电化学装置和电子装置

Country Status (2)

Country Link
CN (1) CN116941068A (zh)
WO (1) WO2022178748A1 (zh)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024087817A1 (zh) * 2022-10-24 2024-05-02 珠海冠宇电池股份有限公司 一种负极片及锂离子电池

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105406046A (zh) * 2015-12-21 2016-03-16 深圳市金润能源材料有限公司 钛酸锂负极材料及其制备方法
CN105895892A (zh) * 2015-02-16 2016-08-24 信越化学工业株式会社 非水电解质二次电池及其负极活性物质、以及非水电解质二次电池用负极材料的制造方法
CN108292745A (zh) * 2016-06-02 2018-07-17 株式会社Lg化学 负极活性材料、包含它的负极和包含该负极的锂二次电池
CN108352519A (zh) * 2016-06-02 2018-07-31 株式会社Lg化学 负极活性材料、其制备方法、包含其的负极和包含该负极的锂二次电池
CN109728257A (zh) * 2017-10-27 2019-05-07 超能高新材料股份有限公司 锂离子电池负极材料
US20200161635A1 (en) * 2018-11-19 2020-05-21 Apple Inc. Interconnected Silicon Porous Structure For Anode Active Material
CN111670511A (zh) * 2018-01-31 2020-09-15 株式会社Lg化学 负极活性材料、包含所述负极活性材料的负极和包含所述负极的锂二次电池

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105895892A (zh) * 2015-02-16 2016-08-24 信越化学工业株式会社 非水电解质二次电池及其负极活性物质、以及非水电解质二次电池用负极材料的制造方法
CN105406046A (zh) * 2015-12-21 2016-03-16 深圳市金润能源材料有限公司 钛酸锂负极材料及其制备方法
CN108292745A (zh) * 2016-06-02 2018-07-17 株式会社Lg化学 负极活性材料、包含它的负极和包含该负极的锂二次电池
CN108352519A (zh) * 2016-06-02 2018-07-31 株式会社Lg化学 负极活性材料、其制备方法、包含其的负极和包含该负极的锂二次电池
CN109728257A (zh) * 2017-10-27 2019-05-07 超能高新材料股份有限公司 锂离子电池负极材料
CN111670511A (zh) * 2018-01-31 2020-09-15 株式会社Lg化学 负极活性材料、包含所述负极活性材料的负极和包含所述负极的锂二次电池
US20200161635A1 (en) * 2018-11-19 2020-05-21 Apple Inc. Interconnected Silicon Porous Structure For Anode Active Material

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024087817A1 (zh) * 2022-10-24 2024-05-02 珠海冠宇电池股份有限公司 一种负极片及锂离子电池

Also Published As

Publication number Publication date
CN116941068A (zh) 2023-10-24

Similar Documents

Publication Publication Date Title
US10581072B2 (en) Anode active material and a lithium secondary battery including the same
CN111029543B (zh) 负极材料及包含其的电化学装置和电子装置
CN114975980A (zh) 负极材料及使用其的电化学装置和电子装置
WO2021108983A1 (zh) 二次电池、装置、人造石墨及制备方法
CN111370695B (zh) 负极活性材料及使用其的电化学装置和电子装置
JP7480284B2 (ja) 球状化カーボン系負極活物質、その製造方法、それを含む負極、及びリチウム二次電池
JP7367201B2 (ja) 二次電池、装置、人造黒鉛及び製造方法
CN112820869B (zh) 负极活性材料、电化学装置和电子装置
EP3678229A1 (en) Anode active material and anode using same, electrochemical device and electronic device
WO2022205152A1 (zh) 一种负极极片、包含该负极极片的电化学装置和电子装置
WO2022140982A1 (zh) 一种负极极片、包含该负极极片的电化学装置及电子装置
US20230261180A1 (en) Negative electrode plate and electrochemical apparatus and electronic apparatus including the negative electrode plate
CN111146433B (zh) 负极及包含其的电化学装置和电子装置
US20220223850A1 (en) Negative electrode, electrochemical device containing same, and electronic device
JP2023538082A (ja) 負極およびこれを含む二次電池
WO2022178748A1 (zh) 负极活性材料、负极片、电化学装置和电子装置
WO2021088167A1 (zh) 正极及包含其的电化学装置和电子装置
WO2023015561A1 (zh) 电化学装置及电子装置
EP4184616A1 (en) Silicon-carbon negative electrode material, negative electrode plate, secondary battery, battery module, battery pack, and electrical apparatus
WO2022140978A1 (zh) 一种负极极片、包含该负极极片的电化学装置及电子装置
WO2022140952A1 (zh) 硅碳复合颗粒、负极活性材料及包含它的负极、电化学装置和电子装置
CN115836408A (zh) 负极活性材料、电化学装置和电子装置
CN114094188B (zh) 一种电化学装置及包含该电化学装置的电子装置
WO2022205143A1 (zh) 一种负极极片、包含该负极极片的电化学装置和电子装置
WO2022099561A1 (zh) 硅基材料、其制备方法及其相关的二次电池、电池模块、电池包和装置

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 21927189

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 202180094556.X

Country of ref document: CN

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 21927189

Country of ref document: EP

Kind code of ref document: A1