WO2017113898A1 - 一种锂离子电池负极材料及其制备方法 - Google Patents

一种锂离子电池负极材料及其制备方法 Download PDF

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WO2017113898A1
WO2017113898A1 PCT/CN2016/099770 CN2016099770W WO2017113898A1 WO 2017113898 A1 WO2017113898 A1 WO 2017113898A1 CN 2016099770 W CN2016099770 W CN 2016099770W WO 2017113898 A1 WO2017113898 A1 WO 2017113898A1
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sio
ion battery
lithium ion
active material
based active
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French (fr)
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屈丽娟
余德馨
任建国
刘俊
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深圳市贝特瑞新能源材料股份有限公司
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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
    • H01M4/38—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
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
    • 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 invention relates to the field of lithium ion batteries, in particular to a lithium ion battery anode material and a preparation method thereof.
  • Lithium-ion batteries are widely used in portable electronic products and electric vehicles because of their high operating voltage, long cycle life, no memory effect, low self-discharge, and environmental friendliness.
  • commercial lithium-ion batteries mainly use graphite-based anode materials. Although its capacity is close to the theoretical specific capacity (372 mAh/g), it still cannot meet the demand for high energy density of lithium-ion batteries in the future.
  • SiO x ( 0 ⁇ x ⁇ 2) materials have attracted much attention due to their higher theoretical specific capacity than graphite, and have become a research hotspot and a future development direction of lithium ion battery anode materials.
  • SiO x ( 0 ⁇ x ⁇ 2) based anode materials mainly focuses on reducing volume change during deintercalation of lithium, improving conductivity, improving circulation, and improving efficiency.
  • the main methods include nanocrystallization of SiO x ( 0 ⁇ x ⁇ 2) particles, compounding with various carbon materials, compounding with metals and metal oxides, and using different binders.
  • these methods have not fundamentally solved the problem of low efficiency and cycle difference of SiO x ( 0 ⁇ x ⁇ 2).
  • the technical problem mainly solved by the present invention is how to solve the technical problem that the material efficiency of SiO x ( 0 ⁇ x ⁇ 2) is low and the cycle is poor.
  • the embodiments of the present invention provide a lithium ion battery anode material and a preparation method thereof, which can effectively prevent mutual peeling and falling off of active materials, reduce volume expansion and contraction, and improve SiO x (0 ⁇ x ⁇ 2).
  • the specific capacity of the base material is effective to improve the cycle stability performance of the SiO x ( 0 ⁇ x ⁇ 2) based material.
  • an aspect of the present invention is that: to provide a negative electrode material for lithium ion battery, the lithium ion battery anode material comprising active material and SiO x group material coated on the surface of the SiO x group activity Highly flexible polymer, said 0 ⁇ x ⁇ 2.
  • the SiO x -based active material is at least one of SiO x , SiO x /C, SiO x /M, wherein the M is an alkali metal, a transition alkali metal, an alkali metal oxide, and a transition alkali metal oxidation
  • the high flexibility polymers 30 ° C ⁇ glass transition temperature ⁇ 300 ° C, 1000 ⁇ number average relative molecular weight ⁇ 800,000, 0 ⁇ cross-linking degree ⁇ 80, 0 ⁇ swelling ratio ⁇ 15 and A single polymer or a combination of polymers having an elongation at break of ⁇ 95% in the electrolyte.
  • the SiO x /C is at least one of SiO x /organic carbon, SiO x /inorganic carbon, SiO x /graphite, SiO x /graphene
  • the M is Li, Li 2 O, B, B 2 at least one of O, Co, CoO, Fe, Fe 2 O 3 , Mg, MgO, Sn, SnO, Ti, TiO 2 , Ag, AgO, and Cr
  • the highly flexible polymer is natural or synthetic Polyacrylates and derivatives thereof, polyimides and derivatives thereof, polyvinylidene fluorides and derivatives thereof, polycyanates and derivatives thereof, polybutylene rubbers and derivatives thereof, poly At least one of vinyl alcohols and derivatives thereof, carboxymethyl celluloses and derivatives thereof, alginic acids and derivatives thereof.
  • the mass ratio of the high flexibility polymer to the SiO x -based active material is greater than 0 and less than 30%.
  • another technical solution adopted by the present invention is to provide a method for preparing the above negative electrode material for a lithium ion battery, the method comprising the steps of: the high flexibility polymer and the SiO x group
  • the active material is uniformly mixed to form a mixture; the mixture is treated such that the highly flexible polymer forms a uniform film on the surface of the SiO x -based active material to obtain the lithium ion battery negative electrode material.
  • the method further comprises: sieving the treated material to obtain a substance having a particle diameter of less than 50 ⁇ m as the negative electrode material of the lithium ion battery.
  • the highly flexible polymer in a solvent solution of a polymer configured to, the SiO The x -based active material is added to the polymer solution and mixed uniformly to form the mixture.
  • the solvent is at least one of water, benzene, ethanol, polypyrrolidone, isopropanol, acetone, N,N-dimethylformamide, pentane, toluene, and halogenated hydrocarbon.
  • the lithium ion battery anode material of the present invention is coated on the surface of the SiO x -based active material by a highly flexible polymer. Therefore, the surface layer polymer can effectively separate the contact between the electrolyte and the active material to inhibit the formation of the SEI film; the high flexibility of the polymer improves the electrical contact stability between the active particulate materials, and prevents the mutual separation between the active materials and Shedding, reducing volume expansion and contraction, increasing the specific capacity of SiO x ( 0 ⁇ x ⁇ 2) based materials, improving their cycle stability.
  • FIG. 1 is a flow chart of a method for preparing a negative electrode material for a lithium ion battery according to an embodiment of the present invention
  • Example 2 is a schematic diagram showing the first week electrochemical cycle curve of the anode material of the lithium ion battery obtained in Example 1 of the present invention
  • Fig. 3 is a view showing the 50-cycle cycle capacity retention ratio of the lithium ion battery negative electrode material obtained in Example 1 of the present invention.
  • Embodiments of the present invention provide a negative electrode material for a lithium ion battery, the lithium ion negative electrode material comprising a SiO x -based active material and a highly flexible polymer coated on the surface of the SiO x -based active material, wherein 0 ⁇ x ⁇ 2.
  • the SiO x -based active material comprises one or a mixture of two or more of SiO x (0 ⁇ x ⁇ 2), SiO x /C, SiO x /M or a mixture
  • M represents an alkali metal, a transition alkali metal, A combination of one or more of an alkali metal oxide and a transition alkali metal oxide.
  • the above M can be Li, Li 2 O, B, B 2 O, Co, CoO, Fe, Fe 2 O 3, Mg, MgO, Sn, SnO, Ti, TiO 2, Ag, AgO and Cr One or more of the combinations.
  • the above SiO x may be Si, SiO or SiO 2 or a combination of these three substances.
  • SiOx/C may be a combination of one or more of SiO x /organic carbon, SiO x /inorganic carbon, SiO x /graphite, SiO x /graphene.
  • the highly flexible polymer used in the examples of the present invention may be a substance having physical properties satisfying the following conditions: 30 ° C ⁇ glass transition temperature ⁇ 300 ° C, 1000 ⁇ number average relative molecular weight ⁇ 800,000, 0 ⁇ cross-linking degree A single polymer or a combination of polymers of ⁇ 80, 0 ⁇ swelling ratio ⁇ 15 and elongation at break ⁇ 95% in the electrolyte. That is to say, as long as the physical properties satisfy the above conditions, the materials which can satisfy the above conditions can be used singly or in combination with each other as the highly flexible polymer of the embodiment of the present invention.
  • the highly flexible polymer of the examples of the present invention may be natural or synthetic such as polyacrylates and derivatives thereof, polyimides and derivatives thereof, polyvinylidene fluoride and Derivatives, polycyanates and derivatives thereof, polybutylene rubbers and derivatives thereof, polyvinyl alcohols and derivatives thereof, carboxymethyl celluloses and derivatives thereof, alginic acids and derivatives thereof One or more of the combinations.
  • the mass ratio of the high flexibility polymer to the SiO x -based active material in the embodiment of the invention is greater than 0 and less than 30%.
  • a preferred mass ratio is greater than 0.001% and less than 14%, and a more preferred mass ratio is greater than 0.005% and less than 9%.
  • the mass ratio of the highly flexible polymer to the SiO x -based active material is 0.0001, 0.0005, 0.001, 0.005, and the like.
  • the embodiment of the present invention further provides a method for preparing a negative electrode material for a lithium ion battery.
  • a method for preparing a negative electrode material for a lithium ion battery according to an embodiment of the present invention includes the following steps:
  • the SiO x -based active material comprises one or a mixture of two or more of SiO x (0 ⁇ x ⁇ 2), SiO x /C, SiO x /M or a mixture
  • M represents an alkali metal, a transition alkali metal, A combination of one or more of an alkali metal oxide and a transition alkali metal oxide.
  • the above M may be Li, Li 2 O, B, B 2 O, Co, CoO, Fe, Fe 2 O 3 , Mg, MgO, Sn, SnO, Ti, TiO 2 , Ag, AgO, and Cr.
  • the above SiO x may be Si, SiO or SiO 2 or a combination of these three substances.
  • SiOx/C may be a combination of one or more of SiO x /organic carbon, SiO x /inorganic carbon, SiO x /graphite, SiO x /graphene.
  • the highly flexible polymer used in the examples of the present invention may be a substance having physical properties satisfying the following conditions: 30 ° C ⁇ glass transition temperature ⁇ 300 ° C, 1000 ⁇ number average relative molecular weight ⁇ 800,000, 0 ⁇ cross-linking degree A single polymer or a combination of polymers of ⁇ 80, 0 ⁇ swelling ratio ⁇ 15 and elongation at break ⁇ 95% in the electrolyte. That is to say, as long as the physical properties satisfy the above conditions, the materials which can satisfy the above conditions can be used singly or in combination with each other as the highly flexible polymer of the embodiment of the present invention.
  • the highly flexible polymer of the examples of the present invention may be natural or synthetic such as polyacrylates and derivatives thereof, polyimides and derivatives thereof, polyvinylidene fluoride and Derivatives, polycyanates and derivatives thereof, polybutylene rubbers and derivatives thereof, polyvinyl alcohols and derivatives thereof, carboxymethyl celluloses and derivatives thereof, alginic acids and derivatives thereof One or more of the combinations.
  • the mass ratio of the high flexibility polymer to the SiO x -based active material in the embodiment of the invention is greater than 0 and less than 30%.
  • a preferred mass ratio is greater than 0.001% and less than 14%, and a more preferred mass ratio is greater than 0.005% and less than 9%.
  • the mass ratio of the highly flexible polymer to the SiO x -based active material is 0.0001, 0.0005, 0.001, 0.005, and the like.
  • the highly flexible polymer and the SiOx-based active material may be mixed by any one of solid phase mixing or solid-liquid phase mixing.
  • two mixed, the composition further uniformly mixed with a highly flexible polymer-based active material SiO x by centrifugation, and a way of ball milling or mechanical agitation in a variety of ways, such that a highly flexible polymer uniformly Dispersed on the surface of the SiO x -based active material.
  • the high flexibility is dissolved in the solvent and the polymer solution is prepared, and SiO is x group added to the polymer solution the active substance mixed to form a mixture.
  • the solvent as the highly flexible polymer may be one of water, benzene, ethanol, polypyrrolidone, isopropanol, acetone, N,N-dimethylformamide, pentane, toluene and halogenated hydrocarbon. Or a combination of multiple.
  • the two materials are directly weighed according to the mass ratio, and then mixed together, which can further assist the ball mill and stir well to uniformly mix the two.
  • the highly flexible polymer is uniformly dispersed on the surface of the SiO x -based active material.
  • the mixture is subjected to a composite modification treatment so that the highly flexible polymer forms a uniform film on the surface of the SiO x -based active material.
  • the composite modification treatment of the mixture can be specifically achieved by placing the mixture in a vacuum or a gas-proof drying oven at a temperature of 80-500 ° C for 0.5-5 hours. Then cooled to room temperature.
  • the above temperature conditions may be 100 ° C, 120 ° C, 150 ° C, 200 ° C, 250 ° C, 350 ° C, 400 ° C, etc.
  • the above holding time may be 1 hour, 1.5 hours, 2 hours, 3 hours 4 hours and so on.
  • the protective gas may be an inert gas.
  • the protective gas may be a combination of one or more of nitrogen, helium, neon, argon, helium, and neon.
  • the sieving treatment can be carried out by a corresponding molecular sieve.
  • a lithium ion battery anode material and a preparation method thereof according to an embodiment of the present invention, it is understood that the present invention forms a uniform protective layer film on the surface of SiO x by a highly flexible polymer, and on the other hand, a highly flexible polymer is used to isolate the active material. Contact with the electrolyte inhibits the formation of the SEI film, thereby reducing the generation of irreversible capacity of the material during charge and discharge.
  • the high flexibility of the polymer is used to stabilize the surface structure of the active material, and the electrical contact stability between the active material particles during charging and discharging is increased, thereby fundamentally improving the active substance of SiO x ( 0 ⁇ x ⁇ 2). Structure to achieve the effect of improving cycle performance.
  • the above process of the invention has the advantages of green environmental protection, no toxic and harmful intermediate product formation, easy availability of raw materials, simple and clear process, low requirements on equipment, low cost and easy commercial use on a large scale.
  • the lithium ion battery prepared by using the material has a mass specific capacity of 1500mAh/g or more, and the capacity retention rate after 92 weeks is more than 92%. As low as 50% or less.
  • the heat treatment was carried out at 500 ° C for 4 h, and cooled to room temperature to obtain a hydroxymethylcellulose-coated SiO x negative electrode material.
  • the ratio of the material is 1.3m 2 /g
  • the lithium ion battery prepared by using the material the mass specific capacity of the material reaches 1500mAh / g or more
  • the capacity retention rate after the 50-week cycle is 92% or more
  • the pole piece expansion ratio As low as 50% or less.

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Abstract

一种锂离子电池负极材料及其制备方法，其中，锂离子电池负极材料的制备方法包括：将高柔韧性聚合物与SiO x基活性物质混合均匀形成混合物，对混合物进行处理使得高柔韧性聚合物在SiO x基活性物质表面形成均一薄膜，得到锂离子电池负极材料。通过上述方式，能够有效阻止活性物质之间的相互剥离和脱落，减小体积膨胀收缩，提高SiO x(0≤x≤2)基材料的比容量，从而有效改善SiO x(0≤x≤2)基材料的循环稳定性能。

Description

一种锂离子电池负极材料及其制备方法 技术领域
本发明涉及锂离子电池领域，具体涉及一种锂离子电池负极材料及其制备方法。
背景技术
锂离子电池因具有工作电压高、循环使用寿命长、无记忆效应、自放电小、环境友好等优点，在便携式电子产品和电动汽车领域中广泛应用。目前，商业化的锂离子电池主要采用石墨类负极材料，虽然它的容量已接近理论比容量(372mAh/g)，但仍无法满足未来锂离子电池对高能量密度的需求。SiOx(0≤x≤2)材料以比石墨高的理论比容量而备受关注，成为研究热点和未来锂离子电池负极材料的发展方向。
目前，对SiOx(0≤x≤2)基负极材料的研究主要集中在减小脱嵌锂过程中的体积变化、提高导电性能、改善循环、提高效率方面。主要的方法有将SiOx(0≤x≤2)颗粒纳米化、与各种碳材料复合、与金属及金属氧化物复合，以及采用不同的粘结剂等。但这些方法都没有从根本上解决SiOx(0≤x≤2)材料效率低，循环差的不足。
发明内容
本发明主要解决的技术问题是如何解决SiOx(0≤x≤2)材料效率低，循环差的技术问题。
有鉴于此，本发明实施例提供一种锂离子电池负极材料及其制备方法，能够有效阻止活性物质之间的相互剥离和脱落，减小体积膨胀收缩，提高SiOx(0≤x≤2)基材料的比容量，从而有效改善SiOx(0≤x≤2)基材料的循环稳定性能。
为解决上述技术问题，本发明采用的一个技术方案是：提供一种锂 离子电池负极材料，所述锂离子电池负极材料包括SiOx基活性物质以及包覆在所述SiOx基活性物质表面的高柔韧性聚合物，所述0≤x≤2。
其中，所述SiOx基活性物质为SiOx、SiOx/C、SiOx/M中的至少一种，其中，所述M为碱金属、过渡碱金属、碱金属氧化物以及过渡碱金属氧化物中的至少一种；所述高柔韧性聚合物为30℃≤玻璃化温度≤300℃、1000≤数均相对分子量≤80万、0≤交联度≤80、0≤溶胀比≤15且电解液中断裂伸长率＜95％的单一聚合物或多种聚合物的组合。
其中，所述SiOx/C为SiOx/有机碳、SiOx/无机碳、SiOx/石墨、SiOx/石墨烯中的至少一种，所述M为Li、Li2O、B、B2O、Co、CoO、Fe、Fe2O3、Mg、MgO、Sn、SnO、Ti、TiO2、Ag、AgO以及Cr中的至少一种；所述高柔韧性聚合物为天然或合成的聚丙烯酸酯类及其衍生物、聚酰亚胺类及其衍生物、聚偏氟乙烯类及其衍生物、聚氰酸酯类及其衍生物、聚丁苯橡胶类及其衍生物、聚乙烯醇类及其衍生物、羧甲基纤维素类及其衍生物、海藻酸类及其衍生物中的至少一种。
其中，所述高柔韧性聚合物与所述SiOx基活性物质的质量比大于0小于30％。
为解决上述技术问题，本发明采用的另一个技术方案是：提供一种上述锂离子电池负极材料的制备方法，所述方法包括以下步骤：将所述高柔韧性聚合物与所述SiOx基活性物质混合均匀形成混合物；对所述混合物进行处理使得所述高柔韧性聚合物在所述SiOx基活性物质表面形成均一薄膜，得到所述锂离子电池负极材料。
其中，所述对所述混合物进行处理使得所述高柔韧性聚合物在所述SiOx基活性物质表面形成均一薄膜，得到所述锂离子电池负极材料包括：将所述混合物置于真空或通保护气体的80-500℃的干燥箱中，保温0.5-5小时后冷却至室温，以得到所述锂离子电池负极材料，所述保护气体为氮气、氦气、氖气、氩气、氪气以及氙气中的至少一种。
其中，所述方法还包括：对经所述处理后的物质进行筛分处理，以得到粒径小于50微米的物质作为所述锂离子电池负极材料。
其中，所述高柔韧性聚合物与所述SiOx基活性物质通过固相混合或 固液相混合的任何一种方式混合，通过离心、球磨以及机械搅拌中的至少一种方式混合均匀形成所述混合物。
其中，当所述高柔韧性聚合物与所述SiOx基活性物质通过固液相混合的方式进行混合时，将所述高柔韧性聚合物溶于溶剂配置成聚合物溶液，将所述SiOx基活性物质加入所述聚合物溶液中混合均匀形成所述混合物。
其中，所述溶剂为水、苯、乙醇、聚吡咯烷酮、异丙醇、丙酮、N，N-二甲基甲酰胺、戊烷、甲苯以及卤代烃中的至少一种。
本发明的有益效果是：区别于现有技术的情况，本发明的锂离子电池负极材料，通过高柔韧性聚合物包覆在SiOx基活性物质表面。从而可以利用表层聚合物有效隔离电解液与活性物质间的接触，抑制SEI膜的形成；利用聚合物的高柔韧性提高活性颗粒物质间的电接触稳定性，阻止活性物质之间的相互剥离和脱落，减小体积膨胀收缩，提高SiOx(0≤x≤2)基材料的比容量，改善其循环稳定性能。
附图说明
图1是本发明实施例提供的一种锂离子电池负极材料的制备方法的流程图；
图2是本发明实施例1所得锂离子电池负极材料首周电化学循环曲线示意图；
图3是本发明实施例1所得锂离子电池负极材料50周循环容量保持率示意图。
具体实施方式
以下，结合具体实施例以及附图对本发明进行详细说明，需要说明的是，以下本发明实施例中所提到的具体物质，只是作为一种举例进行说明，并不以此为限，即相同条件下，还可以用本发明实施例中所列举具体物质相似的其他物质来替代实现本发明的技术方案，本发明不进行一一举例说明。本领域技术人员在不需要付出创造性劳动的情况下，采用本发明实施例所列物质相似或者结构类似的其他物质来实现本发明， 也属于本发明保护的范围。
本发明实施例提供一种锂离子电池负极材料，该锂离子负极材料包括SiOx基活性物质以及包覆在SiOx基活性物质表面的高柔韧性聚合物，其中，0≤x≤2。
其中，SiOx基活性物质包括SiOx(0≤x≤2)、SiOx/C、SiOx/M中的一种或两种及以上混合物或复合物，M代表碱金属、过渡碱金属、碱金属氧化物以及过渡碱金属氧化物中的一种或者多种的组合。举例来说，上述的M可以是Li、Li2O、B、B2O、Co、CoO、Fe、Fe2O3、Mg、MgO、Sn、SnO、Ti、TiO2、Ag、AgO以及Cr中的其中一种或者多种的组合。上述SiOx可以是Si、SiO或SiO2，也可以是这三种物质的组合。SiOx/C可以是SiOx/有机碳、SiOx/无机碳、SiOx/石墨、SiOx/石墨烯中的其中一种或者多种的组合。
其中，本发明实施例中所用到的高柔韧性聚合物可以是物理特性满足以下条件的物质：30℃≤玻璃化温度≤300℃、1000≤数均相对分子量≤80万、0≤交联度≤80、0≤溶胀比≤15且电解液中断裂伸长率＜95％的单一聚合物或多种聚合物的组合。也就是说，只要物理特性同时满足以上条件的物质都可以单一的或者相互组合的作为本发明实施例的高柔韧性聚合物。举例来说，本发明实施例的高柔韧性聚合物可以是天然的或合成的以下物质：比如聚丙烯酸酯类及其衍生物、聚酰亚胺类及其衍生物、聚偏氟乙烯类及其衍生物、聚氰酸酯类及其衍生物、聚丁苯橡胶类及其衍生物、聚乙烯醇类及其衍生物、羧甲基纤维素类及其衍生物、海藻酸类及其衍生物中的其中一种或者多种的组合。
其中，作为一种优选的实现方案，本发明实施例中高柔韧性聚合物与SiOx基活性物质的质量比大于0小于30％。优选的质量比大于0.001％小于14％，更优选的质量比为大于0.005％小于9％。比如高柔韧性聚合物与SiOx基活性物质的质量比0.0001、0.0005、0.001、0.005等等。
本发明实施例还提供一种锂离子电池负极材料的制备方法，如图1所示，本发明实施例的锂离子电池负极材料的制备方法包括以下步骤：
S11：将高柔韧性聚合物与SiOx基活性物质混合均匀形成混合物。
其中，SiOx基活性物质包括SiOx(0≤x≤2)、SiOx/C、SiOx/M中的一种或两种及以上混合物或复合物，M代表碱金属、过渡碱金属、碱金属氧化物以及过渡碱金属氧化物中的一种或者多种的组合。举例来说，上述的M可以是Li、Li2O、B、B2O、Co、CoO、Fe、Fe2O3、Mg、MgO、Sn、SnO、Ti、TiO2、Ag、AgO以及Cr中的其中一种或者多种的组合。上述SiOx可以是Si、SiO或SiO2，也可以是这三种物质的组合。SiOx/C可以是SiOx/有机碳、SiOx/无机碳、SiOx/石墨、SiOx/石墨烯中的其中一种或者多种的组合。
其中，本发明实施例中所用到的高柔韧性聚合物可以是物理特性满足以下条件的物质：30℃≤玻璃化温度≤300℃、1000≤数均相对分子量≤80万、0≤交联度≤80、0≤溶胀比≤15且电解液中断裂伸长率＜95％的单一聚合物或多种聚合物的组合。也就是说，只要物理特性同时满足以上条件的物质都可以单一的或者相互组合的作为本发明实施例的高柔韧性聚合物。举例来说，本发明实施例的高柔韧性聚合物可以是天然的或合成的以下物质：比如聚丙烯酸酯类及其衍生物、聚酰亚胺类及其衍生物、聚偏氟乙烯类及其衍生物、聚氰酸酯类及其衍生物、聚丁苯橡胶类及其衍生物、聚乙烯醇类及其衍生物、羧甲基纤维素类及其衍生物、海藻酸类及其衍生物中的其中一种或者多种的组合。
其中，作为一种优选的实现方案，本发明实施例中高柔韧性聚合物与SiOx基活性物质的质量比大于0小于30％。优选的质量比大于0.001％小于14％，更优选的质量比为大于0.005％小于9％。比如高柔韧性聚合物与SiOx基活性物质的质量比0.0001、0.0005、0.001、0.005等等。
其中，高柔韧性聚合物与SiOx基活性物质可以通过固相混合或者固液相混合的任何一种方式混合。在具体实现时，将两者混合后，进一步通过离心、球磨以及机械搅拌的一种方式或多种方式组合将高柔韧性聚合物与SiOx基活性物质混合均匀，使得高柔韧性聚合物均匀分散在SiOx基活性物质的表面。
其中，当高柔韧性聚合物与SiOx基活性物质通过固液相混合的方式进行混合时，可以通过以下具体实现方式实现：将高柔韧性均为溶于溶 剂配置成聚合物溶液，将SiOx基活性物质加入聚合物溶液混合均匀形成混合物。其中，作为高柔韧性聚合物的溶剂可以是水、苯、乙醇、聚吡咯烷酮、异丙醇、丙酮、N，N-二甲基甲酰胺、戊烷、甲苯以及卤代烃中的其中一种或者多种的组合。
而当高柔韧性聚合物与SiOx基活性物质以固相混合时，直接按照质量配比称取两种物质，然后混合在一起，可以进一步辅助采用球磨，搅拌的方式使两者充分混合均匀，使得高柔韧性聚合物均匀分散在SiOx基活性物质的表面。
S12：对混合物进行处理使得高柔韧性聚合物在SiOx基活性物质表面形成均一薄膜，得到锂离子电池负极材料。
对混合物进行复合改性处理，从而使得高柔韧性聚合物在SiOx基活性物质表面形成均一薄膜。
其中作为一种优选的实现方案，对混合物进行复合改性处理可以通过以下方式具体实现：将混合物置于真空或通保护气体的干燥箱中，于80-500℃温度条件下保温0.5-5小时，然后冷却至室温。举例来说，上述的温度条件可以是100℃、120℃、150℃、200℃、250℃、350℃、400℃等等，上述的保温时间可以是1小时、1.5小时、2小时、3小时、4小时等等。其中，保护气体可以是惰性气体，举例而言，保护气体可以是氮气、氦气、氖气、氩气、氪气以及氙气中的其中一种或者多种的组合。
其中，作为一种优选，在经过上述处理后，进一步通过筛分处理，除去处理后的产物中粒径中大于50微米的产物或杂质，以得到粒径小于50微米的聚合物包覆SiOx基活性物质的负极材料，以作为锂离子电池负极材料。具体可以通过对应的分子筛来进行筛分处理。
本发明实施例的锂离子电池负极材料及其制备方法的详细说明，可以理解，本发明通过高柔韧性聚合物在SiOx表面形成均一保护层薄膜，一方面利用高柔韧性聚合物隔离活性物质与电解液之间的接触，抑制SEI膜的形成，从而降低材料在充放电过程中不可逆容量的产生。另一方面利用聚合物的高柔韧性，稳定活性物质的表面结构，增加活性物质颗粒间在充放电过程中的电接触稳定性，从根本上改善SiOx(0≤x≤2) 活性物质的结构，从而达到提高循环性能的效果。
此外，本发明上述方法处理过程绿色环保，无有毒有害中间产物生成，且原料易得，工艺简单明了，对设备要求不高，成本低廉，易于大规模商业使用。
为了进一步说明本发明的技术方案，以下通过具体实施例进行举例说明，以下所述实施例只是本发明所列举的具有代表性的有限个实施例，所提到的具体物质、配方比例以及反应条件只不过是本发明上述所提到的物质、配方比例以及反应条件的具体体现，并不用以限制本发明的保护范围。
实施例1
将SiOx(x＝1.8)与聚乙烯醇烯类聚合物按质量比92∶8称取，通过固相混合将聚合物均匀分散于SiOx材料中，然后置于气氛炉中500℃热处理4h，冷却至室温取出得聚乙烯醇包覆SiOx负极材料。经测试，该材料的比表1.6m2/g，使用该材料制备的锂离子电池，该材料的质量比容量达到1500mAh/g以上(请参阅图2)，50周循环后容量保持率92％以上(请参阅图3)，极片膨胀率低至50％以下。
实施例2
取8g海藻酸丙二醇酯，均匀分散在2000g醇水混合液中，搅拌半小时后加入92g的SiOx(x＝0.6)粉末，然后500℃干燥4h后取出得海藻酸丙二醇酯包覆SiOx负极材料。经测试，该材料的比表1.5m2/g，使用该材料制备的锂离子电池，该材料的质量比容量达到1500mAh/g以上，50周循环后容量保持率92％以上，极片膨胀率低至50％以下。
实施例3
将SiOx(x＝1.5)/有机碳与羟甲基纤维素类聚合物按质量比90∶10，通过固相混合将聚合物均匀分散于SiOx/有机碳材料中，然后置于气氛炉中500℃热处理4h，冷却至室温取出得羟甲基纤维素包覆SiOx负极材料。经测试，该材料的比表1.3m2/g，使用该材料制备的锂离子电池，该材料的质量比容量达到1500mAh/g以上，50周循环后容量保持率92％以上，极片膨胀率低至50％以下。
实施例4
取2g聚偏氟乙烯类聚合物，均匀分散在500g聚吡咯烷酮水混合液中，搅拌半小时后加入98g的SiOx/石墨烯(x＝0.8)粉末，然后500℃干燥4h后取出得聚偏氟乙烯类聚合物包覆SiOx负极材料。经测试，该材料的比表1.7m2/g，使用该材料制备的锂离子电池，该材料的质量比容量达到1500mAh/g以上，50周循环后容量保持率92％以上，极片膨胀率低至50％以下。
以上所述仅为本发明的实施例，并非因此限制本发明的专利范围，凡是利用本发明说明书及附图内容所作的等效结构或等效流程变换，或直接或间接运用在其他相关的技术领域，均同理包括在本发明的专利保护范围内。

Claims (11)

  1. 一种锂离子电池负极材料，其特征在于，所述锂离子电池负极材料包括SiOx基活性物质以及包覆在所述SiOx基活性物质表面的高柔韧性聚合物，所述0≤x≤2。
  2. 根据权利要求1所述的锂离子电池负极材料，其特征在于，所述SiOx基活性物质为SiOx、SiOx/C、SiOx/M中的至少一种，其中，所述M为碱金属、过渡碱金属、碱金属氧化物以及过渡碱金属氧化物中的至少一种。
  3. 根据权利要求1或2所述的锂离子电池负极材料，其特征在于，所述高柔韧性聚合物为30℃≤玻璃化温度≤300℃、1000≤数均相对分子量≤80万、0≤交联度≤80、0≤溶胀比≤15且电解液中断裂伸长率＜95％的单一聚合物或多种聚合物的组合。
  4. 根据权利要求2或3所述的锂离子电池负极材料，其特征在于，所述SiOx/C为SiOx/有机碳、SiOx/无机碳、SiOx/石墨、SiOx/石墨烯中的至少一种，所述M为Li、Li2O、B、B2O、Co、CoO、Fe、Fe2O3、Mg、MgO、Sn、SnO、Ti、TiO2、Ag、AgO以及Cr中的至少一种；所述高柔韧性聚合物为天然或合成的聚丙烯酸酯类及其衍生物、聚酰亚胺类及其衍生物、聚偏氟乙烯类及其衍生物、聚氰酸酯类及其衍生物、聚丁苯橡胶类及其衍生物、聚乙烯醇类及其衍生物、羧甲基纤维素类及其衍生物、海藻酸类及其衍生物中的至少一种。
  5. 根据权利要求1所述的锂离子电池负极材料，其特征在于，所述高柔韧性聚合物与所述SiOx基活性物质的质量比大于0小于30％。
  6. 一种权利要求1-5任一项所述的锂离子电池负极材料的制备方法，其特征在于，所述方法包括以下步骤：
    将所述高柔韧性聚合物与所述SiOx基活性物质混合均匀形成混合物；
    对所述混合物进行处理使得所述高柔韧性聚合物在所述SiOx基活性物质表面形成均一薄膜，得到所述锂离子电池负极材料。
  7. 根据权利要求6所述的制备方法，其特征在于，所述对所述混合物进行处理使得所述高柔韧性聚合物在所述SiOx基活性物质表面形成均一薄膜，得到所述锂离子电池负极材料包括：
    将所述混合物置于真空或通保护气体的80-500℃的干燥箱中，保温0.5-5小时后冷却至室温，以得到所述锂离子电池负极材料，所述保护气体为氮气、氦气、氖气、氩气、氪气以及氙气中的至少一种。
  8. 根据权利要求6或7所述的制备方法，其特征在于，所述方法还包括：
    对经所述处理后的物质进行筛分处理，以得到粒径小于50微米的物质作为所述锂离子电池负极材料。
  9. 根据权利要求6所述的制备方法，其特征在于，所述高柔韧性聚合物与所述SiOx基活性物质通过固相混合或固液相混合的任何一种方式混合，通过离心、球磨以及机械搅拌中的至少一种方式混合均匀形成所述混合物。
  10. 根据权利要求9所述的制备方法，其特征在于，当所述高柔韧性聚合物与所述SiOx基活性物质通过固液相混合的方式进行混合时，将所述高柔韧性聚合物溶于溶剂配置成聚合物溶液，将所述SiOx基活性物质加入所述聚合物溶液中混合均匀形成所述混合物。
  11. 根据权利要求10所述的制备方法，其特征在于，所述溶剂为水、苯、乙醇、聚吡咯烷酮、异丙醇、丙酮、N，N-二甲基甲酰胺、戊烷、甲苯以及卤代烃中的至少一种。
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