WO2019047713A1 - Matériau actif d'électrode négative composite, son procédé de préparation, et batterie au lithium - Google Patents

Matériau actif d'électrode négative composite, son procédé de préparation, et batterie au lithium Download PDF

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WO2019047713A1
WO2019047713A1 PCT/CN2018/101673 CN2018101673W WO2019047713A1 WO 2019047713 A1 WO2019047713 A1 WO 2019047713A1 CN 2018101673 W CN2018101673 W CN 2018101673W WO 2019047713 A1 WO2019047713 A1 WO 2019047713A1
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nano
silicon
active material
anode active
composite anode
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Chinese (zh)
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江正福
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比亚迪股份有限公司
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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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • 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
    • 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
    • H01M4/38—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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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
    • 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 disclosure relates to the field of battery materials, and in particular to a composite anode active material, a preparation method thereof and a lithium battery.
  • Graphite is soft, is a non-metallic mineral, has high temperature resistance, oxidation resistance, corrosion resistance, etc. It also has good thermal conductivity and electrical conductivity, so it has attracted attention in the field of electrochemistry and has been widely used. Graphite has good conductivity, high degree of crystallization and good layered structure, so it is very suitable for repeated insertion-deintercalation of lithium ions. It is the most widely used anode material.
  • the silicon-containing substance is also a negative electrode material, which has a function of increasing the theoretical capacity and is often combined with graphite.
  • CN106532017A discloses a preparation method of SiOx/C surface coated graphite anode material, wherein the specific step is to first prepare SiOx/C material precursor by using SiOx, asphalt and organic acid solution as raw materials. Then, graphite was further added, and samples were prepared by means of spray granulation and high temperature pyrolysis through additives, resins and curing agents.
  • the disclosure can effectively alleviate the volume effect of the silicon material during the charging and discharging process, thereby improving the cycle stability; at the rate of 0.1 C, the first charge and discharge efficiency is 82.42%, the reversible specific capacity is 488.2 mAh/g, and the resin is utilized at the same time.
  • the skeleton formed after solidification can effectively avoid the phenomenon of blocking and agglomeration between the particles during the carbonization process of the additive, so that the prepared material has the characteristics of good dispersibility and uniformity, easy mass production, and low cost.
  • the product prepared by the above method has the following disadvantages: firstly, due to the use of silicon oxide, in the process of lithium intercalation, oxygen must consume a part of the lithium source to form an oxide of lithium which does not have reversible lithium intercalation.
  • the performance in electrochemical performance is the first charge and discharge efficiency.
  • the first charge and discharge efficiency of graphite is between 93% and 95%, and according to the above application, the best first charge and discharge efficiency is about 82%;
  • the material specific capacity of SiOx is too low compared to Si. Therefore, in order to obtain the same specific capacity, more SiOx must be added, which also makes it difficult to further improve the first charge and discharge efficiency, and add more SiOx.
  • the coating difficulty is further improved, and the uniformity of the surface of the graphite coating is not guaranteed, and the electrochemical performance is poor cycle performance.
  • the purpose of the present disclosure is to overcome the problems of low specific capacity, low initial charge and discharge efficiency, and poor cycle performance of carbon and silicon oxide composite anode active materials in the prior art, and a composite anode active material, a preparation method thereof and lithium
  • the composite anode active material has high specific capacity and first charge and discharge efficiency and good cycle performance; in addition, the preparation method of the present disclosure adopts a secondary coating method, which can avoid difficulty in completely coating the primary coating method.
  • the coating method of the present disclosure is more reasonable and advanced, and the side reaction of the material surface and the electrolyte can be further reduced.
  • the present disclosure provides a composite anode active material including a graphite core, a first cladding layer coated on a surface of the graphite core, and a second cladding layer coated on the surface of the first cladding layer, wherein the first cladding layer comprises a mixture of oxides of nano-silicon and nano-silicon and carbon, and the second cladding layer comprises nano-silicon And carbon.
  • the present disclosure also provides a method of preparing a composite anode active material, the method comprising the steps of:
  • the present disclosure also provides a composite anode active material prepared by the above-described production method.
  • the present disclosure also provides a lithium battery comprising the composite anode active material described above in the present disclosure.
  • the present disclosure mainly has the following beneficial effects:
  • the first layer of coated SiO is subjected to high temperature calcination and then ball milling and recoating, so that the first layer of coated material is a disproportionation product of nano SiO: nano silicon and nano SiO 2
  • the mixture which allows the subsequent coating to completely coat the surface of the graphite core with nano-silicon and nano-SiO 2 using a small amount of carbon precursor, greatly improves the material's first charge and discharge efficiency.
  • the second layer of nano-silicon coating is carried out, the coating effect can be further improved, so that the overall first charge and discharge efficiency of the material is greatly improved compared with the single layer coating alone, and the SiOx is completely packaged. Under the condition of the first charge and discharge efficiency of the graphite surface, the first charge and discharge efficiency of the composite material can reach more than 95%, close to the graphite level.
  • the second layer coating is performed on the basis of the disproportionation product coated with SiO, mainly by coating the nano silicon on the composite material (ie, the surface of the graphite core is coated with the first cladding layer).
  • the surface further enhances the overall specific capacity of the composite; due to the limited specific capacity of SiO, the highest specific capacity is only 1500mAh/g-1700mAh/g, which is much lower than that of nano silicon of 3200mAh/g-3500mAh/g. Specific capacity, so the use of a second layer of cladding to coat the nano-silicon particles on the surface of the composite material can achieve a higher specific capacity than the coating of SiO alone.
  • the disproportionation product of the first layer of SiO coated in the present disclosure is subjected to ball milling nano-treatment, so that the particle size of the nano-silicon particles in the coated disproportionation product is smaller than that of the particle-coated nano-sized SiO alone.
  • the absolute expansion volume of the material is reduced, and the SiO 2 in the disproportionation product after SiO calcination can play a buffering effect on the volume expansion of the nano silicon after lithium insertion, so that the volume expansion of the whole composite material during the lithium insertion process is very Small, this ensures that the composite material of the present disclosure has good cycle performance.
  • Example 1 is an SEM image of a sample S1 prepared in Example 1, the magnification is 3000 times;
  • Figure 5 is an SEM image of the sample DS3 prepared in Comparative Example 3, the magnification is 1000 times;
  • Example 6 is a graph showing the charge and discharge performance of a lithium battery fabricated using the composite negative electrode active material prepared in Example 1;
  • Example 7 is a cycle performance diagram of a lithium battery fabricated using the composite anode active material prepared in Example 1;
  • Fig. 8 is a graph showing the cycle performance of a lithium battery fabricated using the composite negative electrode active material prepared in Comparative Example 1.
  • first and second are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated.
  • features defining “first” and “second” may include at least one of the features, either explicitly or implicitly.
  • the meaning of "a plurality” is at least two, such as two, three, etc., unless specifically defined otherwise.
  • the first feature "on” or “under” the second feature may be a direct contact of the first and second features, or the first and second features may be indirectly through an intermediate medium, unless otherwise explicitly stated and defined. contact.
  • the first feature "above”, “above” and “above” the second feature may be that the first feature is directly above or above the second feature, or merely that the first feature level is higher than the second feature.
  • the first feature “below”, “below” and “below” the second feature may be that the first feature is directly below or obliquely below the second feature, or merely that the first feature level is less than the second feature.
  • a first aspect of the present disclosure provides a composite anode active material comprising a graphite core, a first cladding layer coated on a surface of the graphite core, and a surface coated on the first cladding layer a second cladding layer, wherein the first cladding layer comprises a mixture of oxides of nano-silicon and nano-silicon and carbon, and the second cladding layer comprises nano-silicon and carbon.
  • the nano-silicon coated in the first cladding layer is mainly for improving the overall specific capacity of the material, but in order to reduce the volume expansion effect of the nano-silicon during charging and discharging, on the one hand, the granular particles are selected.
  • Nano-silicon with small diameter which ensures that more nano-silicon particles can be uniformly dispersed on the graphite surface when coated with the same amount of nano-silicon; on the other hand, porous nano-silicon particles with pores are selected, and the existence of their own pores Can further alleviate its volume change.
  • the size of the specific nano-silicon is required to be ⁇ 200 nm, and further, the particle size is 30-100 nm.
  • the nano silicon in the second cladding layer, may be at least one of porous nano silicon and ordinary nano silicon, and further, the nano silicon is porous nano silicon.
  • Porous nano-silicon has the high specific capacity characteristic of ordinary nano-silicon, and its expansion effect after lithium insertion is significantly lower than that of ordinary nano-silicon, so it can meet the requirements of battery cycle performance, and is particularly suitable for use as the second in the present disclosure. Coating composition.
  • the first cladding layer is a SiO disproportionation product, and the SiO disproportionation product has two main functions:
  • the second cladding layer contains nano-silicon, which also has two functions. One is to make it difficult to obtain a smooth surface by one coating (that is, to reduce the specific surface area of the anode active material to some extent), and the other is to solve the problem of separately coating SiO. Increase the problem of limited specific capacity.
  • the amount of each cladding layer is balanced between the most important properties of the two battery materials; as one embodiment of the present disclosure, the graphite core, the first The weight ratio of the content of a coating layer and the second coating layer is (20-25):1:(0.7-0.9).
  • the weight ratio of the content of the graphite core, the first cladding layer and the second cladding layer may be a combination of any one of the range end values in the above ratio, for example, may be (20:1) :0.7), (21:1:0.7), (22:1:0.7), (23:1:0.7), (24:1:0.7), (25:1:0.7), (20:1:0.8) ), (20:1:0.9), (21:1:0.8), (21:1:0.9), (22:1:0.8), (22:1:0.9), (23:1:0.8), (23:1:0.9), (24:1:0.8), (24:1:0.9), (25:1:0.8), and (25:1:0.9).
  • the content of the carbon and the mixture of the oxide of the nano silicon and the nano silicon in the first cladding layer is not particularly limited.
  • the carbon content may be 30 to 70% by weight based on the total amount of the first cladding layer, further 40-60% by weight, still more preferably 45-55% by weight.
  • the content of the mixture of the nano-silicon oxide and the nano-silicon may be from 30 to 70% by weight, further from 40 to 60% by weight, and further from 45 to 55% by weight.
  • the carbon content may be 50 based on the total amount of the second cladding layer. 80% by weight, further 60-70% by weight, further further 62-68% by weight.
  • the content of the nano-silicon may be 20-50% by weight, further 30-40% by weight, and further 32-38% by weight.
  • the percentage of each component is based on the total weight of the composite anode active material: the content of the nano-silicon is 1.5-4.5% by weight; the oxide of the nano-silicon and The content of the mixture of nano-silicon is from 1 to 3% by weight; the content of the carbon is from 3 to 7% by weight; and the content of the graphite is from 88 to 93% by weight.
  • the carbon is amorphous carbon.
  • the nano silicon oxide is required to have a size of ⁇ 200 nm, and further, a particle size of 30 to 100 nm.
  • the nano silicon oxide may be selected from one or more of silicon oxide SiOx in any oxidation state, wherein x ⁇ 2; for example, the silicon oxide SiOx may be SiO, SiO 2 , SiO 0.9 , SiO 1.3 , SiO 1.6 , SiO 0.3, etc., that is, x may be any number less than or equal to 2, including integers and fractions (decimal), that is, x may be 0.1 , 0.2 , 0.3 , 0.4 , 0.5 , 0.6, 0.7 , 0.8, 0.9 Any one of 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2, 0 ⁇ x ⁇ 2.
  • the above-mentioned nano silicon oxide may be a disproportionation product obtained by purchase or a disproportionation reaction of SiO.
  • a method of preparing a composite anode active material comprising the steps of:
  • the mixture of the oxide of the nano silicon and the nano silicon may be obtained by purchase or may be prepared.
  • the preparation method of the mixture of the nano silicon oxide and the nano silicon may be As follows: a high-temperature calcination under an inert atmosphere using SiO2 as a raw material, and a disproportionation reaction occurs to obtain a mixture of nano-silicon oxide and nano-silicon.
  • Nano-silicon and nano-SiO 2 are disproportionation products obtained by disproportionation of SiO.
  • Nano-SiO 2 and nano-silicon are uniformly dispersed.
  • the nano-SiO 2 and nano-silicon are uniformly coated on the graphite surface by kneading. On the one hand, it is beneficial to the negative active material. Uniform expansion during use improves cycle performance; on the other hand, the uniform dispersion of nano-silicon in the coating can effectively increase the specific capacity of the material.
  • the grinding is not particularly limited, and may be, for example, ball milling, flat grinding or round grinding; the grinding is ball milling according to an embodiment of the present disclosure.
  • the graphite core is coated by the method of secondary coating, and on the one hand, the prepared product has the advantages of the combination of the nano silicon oxide and the nano silicon particle, and the other is superior.
  • secondary coating can avoid this situation. This will further reduce the side reaction of the material surface and the electrolyte.
  • the mixture of the nano-silicon oxide and the nano-silicon in the present disclosure may be a mixture of oxide SiOx and nano-scale silicon of various oxidation states of nano-scale silicon in an arbitrary ratio.
  • the size of the nano silicon is required to be ⁇ 200 nm, and further, the particle size is 30-100 nm.
  • the size of the nano-silicon oxide is required to be ⁇ 200 nm, and further, the particle size is 30-100 nm, and the nano-silicon oxide may be selected from one or more of silicon oxide SiOx in any oxidation state.
  • x ⁇ 2 for example, in an embodiment of the present disclosure, the silicon oxide SiOx may be SiO, SiO 2 , SiO 0.9 , SiO 1.3 , SiO 1.6 , SiO 0.3 , or the like, that is, wherein x may be less than Any number equal to 2, including integers and fractions (decimal), ie, x can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6 Any one of 1.7, 1.8, 1.9, and 2, further, 0 ⁇ x ⁇ 2; further, may include at least at least a common nano silicon oxide such as SiO and SiO 2
  • the mixture of the nano-silicon oxide and the nano-silicon can be obtained by ball milling the silicon source to a nano-sized size and then performing calcination.
  • the nanometer size is not particularly limited and may be, for example, 1-100 nm.
  • the silicon source may be a large particle silicon source conventional in the art, for example, in the present disclosure, the silicon source is SiO.
  • the calcination conditions may include a temperature of 600 to 1200 ° C and a time of 1 to 10 hours.
  • the calcination process is carried out under an inert atmosphere, for example, under an argon or nitrogen atmosphere.
  • the process of mixing and grinding the mixture of the nano-silicon oxide and the nano-silicon and the first carbon source may be carried out by a ball milling method conventional in the art.
  • the ball milling time can be from 1 to 20 hours, further from 5 to 15 hours.
  • the first carbon source may be a conventional selection in the art.
  • the first carbon source may be selected from one or more of the group consisting of glucose, sucrose, phenolic resin, asphalt, and citric acid.
  • the weight ratio of the mixture of the nano-silicon oxide and the nano-silicon and the first carbon source may be (0.5-1.5): 1, Further (0.8-1.2): 1, more preferably 1:1;
  • the weight ratio of the first coating material to the amount of graphite may be 1: (20-25), further 1: (22-24).
  • the kneading process in the step (2), can be carried out in a kneader conventional in the art.
  • the kneading operating conditions may include a temperature of 50 to 300 ° C and a time of 1 to 10 hours.
  • the conditions of the primary calcination may include a temperature of 600 to 1200 ° C and a time of 1 to 10 h.
  • the process of the primary calcination is carried out under an inert atmosphere.
  • the inert atmosphere may be provided by nitrogen, helium, argon or the like.
  • the introduction of the nano-silicon particles can reduce the decrease in the first charge and discharge efficiency due to the single cladding of the silicon oxide, and since the nano-silicon particles have an oxidation relative to the silicon The better specific capacity, the introduction of nano-silicon particles can also increase the specific capacity of the product.
  • the nano-silicon may be porous nano-silicon particles. Compared with ordinary nano-silicon particles, porous nano-silicon has less volume expansion when intercalating lithium, so the porous nano-silicon particles are introduced for secondary coating, so that the composite negative active material prepared by the present disclosure can not only obtain a higher first charge. Discharge efficiency and specific capacity, but also significantly improved cycle performance.
  • the porous nano-silicon particles may have a particle size of 30 to 100 nm.
  • the porous nano-silicon particles refer to nanoparticles having a porosity of 5% to 30%.
  • the weight ratio of the amount of the nano silicon to the second carbon source may be 1: (1.5 - 2.5), preferably 1: (1.8 - 2.2), more preferably It is 1:2.
  • the second carbon source may be a conventional selection in the art.
  • the second carbon source is one or more of asphalt, glucose, and sucrose.
  • the first carbon source is different from the second carbon source, mainly because in the present disclosure, the first carbon source mainly functions as conductivity, and the second carbon source mainly functions as The castability is relatively good, and the surface of the formed product is smooth, and the specific surface area is small, specifically less than 3 m 2 /g.
  • the first carbon source and the second carbon source are selected from the components specifically defined above, a better effect can be obtained.
  • the ball milling process in the step (3), can be carried out by a ball milling method conventional in the art.
  • the ball milling time can be from 10 to 40 hours, further from 15 to 30 hours.
  • the weight ratio of the second cladding material to the primary particles may be 1: (25-35), further 1: (28- 32).
  • the kneading process in the step (4), can be carried out in a kneading machine conventional in the art.
  • the kneading time may be from 12 to 36 hours.
  • the conditions of the secondary calcination may include a temperature of 600 to 1200 ° C and a time of 1 to 10 h.
  • the secondary calcination process is performed under an inert atmosphere.
  • the inert atmosphere may be provided by nitrogen, helium, argon or the like.
  • the first cladding material, the second cladding material, and the graphite are used in an amount such that the graphite core in the prepared composite anode active material is coated on the surface of the graphite core.
  • the weight ratio of a cladding layer and a second cladding layer coated on the surface of the first cladding layer is (20-25):1:(0.7-0.9).
  • the weight ratio of the graphite core, the first cladding layer and the second cladding layer may be a combination of any one of the range end values in the above ratios, for example, may be (20:1:0.7), (21:1:0.7), (22:1:0.7), (23:1:0.7), (24:1:0.7), (25:1:0.7), (20:1:0.8), (20 :1:0.9), (21:1:0.8), (21:1:0.9), (22:1:0.8), (22:1:0.9), (23:1:0.8), (23:1) : 0.9), (24:1:0.8), (24:1:0.9), (25:1:0.8), and (25:1:0.9).
  • the weight ratio of the cladding layer to the graphite core can be adjusted according to actual needs. By this adjustment, the amount of the nano silicon particles and the nano silicon oxide can be adjusted to achieve the balance of the first effect, the cycle performance and the capacity, and the other. It is also possible to adjust the ratio of the amount of amorphous carbon to nano-silicon and silicon oxide to achieve uniform coating.
  • the present disclosure also provides a composite anode active material prepared by the above-described production method.
  • the composite anode active material has two coating layers, so that the composite anode active material has high first charge and discharge efficiency and specific capacity, and has good cycle performance.
  • the present disclosure also provides a lithium battery containing the composite anode active material of the present disclosure.
  • the composite anode active material of the present disclosure has a coating layer added to the core-shell material of the prior art, and the nano-silicon is coated on the composite material by secondary coating (ie, the graphite core surface package)
  • the surface of the first cladding composite Therefore, by adjusting the ratio of the oxide of the nano-silicon and the nano-silicon, on the one hand, the adverse effect on the first charge and discharge efficiency due to the SiOx coating alone can be reduced; on the other hand, due to the use of the two-layered structure, the material The surface and electrolyte side reactions are reduced, so the first charge and discharge efficiency can be close to the level of graphite.
  • ordinary nano-silicon oxides have a specific capacity of about 1600 mAh/g at the current level, and nano-silicon particles generally have a specific capacity of about 2700-3200 mAh/g, which is nearly double that of silicon oxide.
  • the disclosed negative electrode material has a large specific capacity compared with the prior art due to the introduction of nano-silicon on the second cladding layer.
  • the nano-silicon is required to have a large expansion space after lithium intercalation, the silicon oxide is intercalated with lithium. After the required expansion space is small, the use of the two solves the problem of material cracking caused by excessive volume expansion after lithium intercalation by the nano-silicon, so that better cycle performance can be obtained during the cycle of the battery.
  • SiO, SiO 0.3 , SiO 0.9 , SiO 1.3 , SiO 1.6 , porous nano-silicon and nano-silicon were all purchased from TBEA.
  • Sucrose was purchased from Guangdong Guanghua Chemical Factory Co., Ltd.
  • Citric acid was purchased from Guangdong Guanghua Chemical Factory Co., Ltd.
  • This embodiment is intended to illustrate a composite negative electrode active material prepared by the production method of the present disclosure.
  • This embodiment is intended to illustrate a composite negative electrode active material prepared by the production method of the present disclosure.
  • This embodiment is intended to illustrate a composite negative electrode active material prepared by the production method of the present disclosure.
  • This embodiment is intended to illustrate a composite negative electrode active material prepared by the production method of the present disclosure.
  • the composite anode active material was prepared according to the preparation method in Example 1, except that the weight ratio of the calcined product to the sucrose was 2:1 in the preparation of the first coating material.
  • a composite negative electrode active material S4 was obtained.
  • This embodiment is intended to illustrate a composite negative electrode active material prepared by the production method of the present disclosure.
  • the composite anode active material was prepared in accordance with the production method of Example 1, except that the weight ratio of the primary particles to the second coating material was 35:1, and the composite anode active material S5 was obtained.
  • This embodiment is intended to illustrate a composite negative electrode active material prepared by the production method of the present disclosure.
  • the composite anode active material was prepared according to the preparation method in Example 1, except that in the step (1), a mixture of nano-silicon oxide SiO and nano-silicon was used to obtain a composite anode active material S6.
  • This embodiment is intended to illustrate a composite negative electrode active material prepared by the production method of the present disclosure.
  • a composite anode active material was prepared according to the preparation method in Example 1, except that in the step (1), a mixture of nano-silicon oxide SiO 0.9 and nano-silicon was used to obtain a composite anode active material S7.
  • This embodiment is intended to illustrate a composite negative electrode active material prepared by the production method of the present disclosure.
  • a composite anode active material was prepared according to the preparation method in Example 1, except that in the step (1), a mixture of nano-silicon oxide SiO 1.3 and nano-silicon was used to obtain a composite anode active material S8.
  • This embodiment is intended to illustrate a composite negative electrode active material prepared by the production method of the present disclosure.
  • a composite anode active material was prepared according to the preparation method in Example 1, except that in the step (1), a mixture of nano-silicon oxide SiO 1.6 and nano-silicon was used to obtain a composite anode active material S9.
  • the composite anode active material was prepared in accordance with the preparation method in Example 1, except that the second anode coating was not carried out to obtain a composite anode active material DS1.
  • the composite anode active material was prepared according to the preparation method in Example 1, except that the graphite was coated directly with the second cladding material to obtain a composite anode active material DS2.
  • Test instrument (JSM-5610LV model, JEOL manufacturer, etc.) scanning electron microscope;
  • Test method The microstructure of the sample was observed by a scanning electron microscope.
  • Example 1 is an SEM image of the sample S1 prepared in Example 1, the magnification is 3000 times, and it can be seen from the figure that the surface of the sample is smooth and uniform, indicating that the secondary coating effect in the present disclosure is remarkable;
  • 3 is an SEM image of the sample DS1 prepared in Comparative Example 1, the magnification is 1000 times, as can be seen from the figure, the surface of the sample is rough and the coating is incomplete;
  • Figure 5 is an SEM image of the sample DS3 prepared in Comparative Example 3, with a magnification of 1000 times. As can be seen from the figure, the sample surface is rough, has a lot of debris, and the coating is incomplete.
  • the composite anode active material prepared by the method of the present disclosure has a good coating effect and a uniform surface, and the coating effect is poor and the surface is rough by other prior art methods.
  • the composite anode active material prepared in each of the examples and the comparative examples was made into a button lithium battery;
  • the counter electrode is lithium sheet (Shanghai Senyu Fine Chemical Co., Ltd.;
  • the first charge and discharge efficiency and specific capacity of the test materials were tested using the BK-6016 battery detection system of Guangzhou Lanqi Electronic Industry Co., Ltd.;
  • the specific charge and discharge system is: three-stage lithium intercalation for a period of lithium de-lithium, with lithium constant current of 0.2C to 5mV, then lithium with a constant current of 0.1C to 5mV, and then with lithium constant current of 0.05C to 5mV, put on for 5min, 0.2C constant current delithiation to 1.5V, the first charge and discharge efficiency is the ratio of delithiation specific capacity and lithium intercalation specific capacity;
  • the specific capacity is the delithiation specific capacity (mAh/g);
  • the capacity retention of the battery after 100 cycles was the ratio of the 100th delithiation capacity of the battery to the first delithiation ratio.
  • Example 6 is a graph showing the charge and discharge performance of the button battery made of the sample S1 in Example 1;
  • Example 1 The composite anode active materials prepared in Example 1 and Comparative Example 1 were made into a button lithium battery;
  • the counter electrode is lithium sheet (Shanghai Senyu Fine Chemical Co., Ltd.);
  • test results are shown in Figure 7, Figure 8, respectively, for Figure 7 need to be explained, due to the cycle Good performance leads to overlap of re-discharge data, which is normal.

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Abstract

L'invention concerne un matériau actif d'électrode négative composite, son procédé de préparation et une batterie au lithium. Le matériau actif d'électrode négative composite comprend un noyau de graphite, une première couche de revêtement appliquée sur la surface du noyau de graphite et une deuxième couche de revêtement appliquée sur la première couche de revêtement, la première couche de revêtement comprenant du carbone et un mélange de nano-oxyde de silicium et de nanosilicium, et la deuxième couche de revêtement comprenant du nanosilicium et du carbone.
PCT/CN2018/101673 2017-09-05 2018-08-22 Matériau actif d'électrode négative composite, son procédé de préparation, et batterie au lithium WO2019047713A1 (fr)

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KR20210050348A (ko) * 2019-10-28 2021-05-07 주식회사 엘지화학 음극 활물질의 제조 방법, 음극 활물질, 이를 포함하는 음극, 및 상기 음극을 포함하는 이차 전지
CN111640919B (zh) * 2020-05-14 2021-10-22 浙江金鹰新能源技术开发有限公司 一种高首效硅碳负极材料及其制备方法、锂离子电池
CN112133896B (zh) * 2020-09-15 2022-04-19 捷威动力工业嘉兴有限公司 一种高容量石墨-硅-氧化亚硅复合材料及其制备方法、应用
CN112713274B (zh) * 2020-12-29 2022-10-21 宁波杉杉新材料科技有限公司 纳米硅碳复合材料、制备方法、应用和锂离子电池

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