WO2023213121A1 - 用于锂电池的负极材料及包含其的锂离子二次电池 - Google Patents

用于锂电池的负极材料及包含其的锂离子二次电池 Download PDF

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WO2023213121A1
WO2023213121A1 PCT/CN2023/078540 CN2023078540W WO2023213121A1 WO 2023213121 A1 WO2023213121 A1 WO 2023213121A1 CN 2023078540 W CN2023078540 W CN 2023078540W WO 2023213121 A1 WO2023213121 A1 WO 2023213121A1
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negative electrode
electrode material
silicon oxide
lithium
material according
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PCT/CN2023/078540
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French (fr)
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周燕
王丽
李于利
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株式会社村田制作所
周燕
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Publication of WO2023213121A1 publication Critical patent/WO2023213121A1/zh

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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
    • 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
    • H01M4/04—Processes of manufacture in general
    • 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
    • H01M4/362—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
    • 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
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes

Definitions

  • the present invention relates to the field of lithium ion secondary batteries, and specifically to a negative electrode material for lithium batteries and a lithium ion secondary battery containing the same.
  • silicon oxide materials are currently considered the most suitable anode materials for commercialization.
  • silica itself has problems of low initial efficiency and poor cycle performance.
  • the current mainstream approach is to use silica as a raw material to coat it with carbon.
  • the performance of carbon-coated silica cannot be improved due to inappropriate selection of raw materials. Therefore, there remains a need in the art for silicone oxide materials that exhibit good electrochemical properties and are suitable for carbon coating.
  • the present invention provides a silicon oxide material.
  • This silicon oxide material itself has good capacity and cycle performance, and can be used in conjunction with carbon nanotubes as an electrode active material or as an electrode active material.
  • Raw material for carbon coated silica is a silicon oxide material.
  • the present invention provides a negative electrode material for lithium batteries, including silicon oxide, and the silicon oxide satisfies in terms of chromaticity: 30 ⁇ L ⁇ 50, 3 ⁇ a ⁇ 10, 1.5 ⁇ b ⁇ 10, preferably 35 ⁇ L ⁇ 45, 4 ⁇ a ⁇ 9, 4 ⁇ b ⁇ 10, and the total color difference ⁇ E relative to black is 39 ⁇ E ⁇ 50.
  • the particle size distribution of silicon oxide satisfies 0.5 ⁇ (D90-D10)/D50 ⁇ 2, preferably 0.9 ⁇ (D90-D10)/D50 ⁇ 1.4.
  • the particle size distribution of silicon oxide satisfies the particle size of ⁇ 2 ⁇ m, accounting for 3%-40% of all particles, preferably 10%-30%.
  • silicone oxide is in an amorphous state or a low crystalline state.
  • the size of the crystalline silicon in the silicon oxide is ⁇ 4 nm, preferably ⁇ 1 nm.
  • silicone oxide may or may not contain crystalline silicon dioxide.
  • the XRD spectrum of the silicon oxide has the strongest peak intensity h 1 at 2 ⁇ of 26-27° and 2 ⁇ of 22.5-24°.
  • the ratio of the strongest peak intensity h 2 satisfies h 2 /h 1 ⁇ 1.5, preferably ⁇ 1.3.
  • the capacity-voltage differential curve i.e., dQ/dV curve
  • the first peak appears at 0.25V-0.43V, preferably 0.36V-0.43V.
  • the negative electrode material further includes carbon nanotubes.
  • a negative electrode material for a lithium battery comprising carbon-coated silicon oxide, which is the silicon oxide in the above aspects of the present invention.
  • a lithium ion secondary battery including a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, characterized in that the negative electrode sheet contains the negative electrode material in the above aspects of the present invention.
  • the negative electrode material for lithium batteries of the present invention and the lithium ion secondary battery containing the same, the effect of improving the electrochemical performance of the lithium ion secondary battery is achieved.
  • silicon oxide has been used as anode active material for lithium batteries in the prior art, there are still many questions about how to select a specific silicon dioxide that has good electrochemical properties and is suitable for carbon coating. There are no clear guidelines for silicon.
  • the inventor of the present invention conducted research on improving the performance of silica oxide, and found that the performance of silica oxide is related to the color, particle size distribution, crystal structure and other aspects of the silica oxide material.
  • the present invention proposes for the first time a silicon oxide negative electrode material for lithium batteries.
  • the silicon oxide material itself has good electrochemical properties, so it can be used in conjunction with carbon nanotubes as an electrode active material. It can be used as a raw material for carbon-coated silica.
  • a negative electrode material for lithium batteries including silicon oxide, and the silicon oxide satisfies in terms of chromaticity: 30 ⁇ L ⁇ 50, 3 ⁇ a ⁇ 10, 1.5 ⁇ b ⁇ 10, preferably 35 ⁇ L ⁇ 45, 4 ⁇ a ⁇ 9, 4 ⁇ b ⁇ 10, and the total color difference ⁇ E relative to black is 39 ⁇ E ⁇ 50.
  • silicone oxide with a specific chromaticity a silicone oxide negative electrode material for lithium batteries with good electrochemical properties can be obtained.
  • silicone oxide materials with colorimetric values within the range defined by the invention have good capacity, efficiency and cycle performance, and that these properties increase with increasing colorimetric within the range of the invention.
  • the chromaticity value is too low or too high, the first capacity, efficiency, and cycle performance of the silicon oxide material deteriorate.
  • the color of silica material is determined by factors such as the quality of the raw materials of silica (such as the purity of silicon and silica, the raw materials for preparing silica), particle size and purity (such as the content of impurities such as Fe and Cu).
  • the quality of the raw materials of silica such as the purity of silicon and silica, the raw materials for preparing silica
  • particle size and purity such as the content of impurities such as Fe and Cu.
  • the chromaticity of silica oxide materials and the material structure is still under study, it has been determined that when there are more fine particles in silica oxide materials, the chromaticity of the material is greater.
  • the existence form and content of metals in silica raw materials and finished powders will also affect the properties of the materials. Chroma. For example, when Fe in the silicon oxide material exists in the form of iron oxide and the amount is large, the chromaticity of the material will be smaller. Therefore, the chromaticity of silicon oxide materials reflects the structural and compositional characteristics
  • the inventor also found that the chromaticity value of the silicon oxide material is also related to the peak position in the dQ/dV curve during the electrochemical reaction.
  • the peak position of the material with a larger chromaticity value is usually larger, and the peak position of the material is usually larger. Batteries with large peak positions have relatively better electrochemical performance.
  • the particle size distribution of silicon oxide satisfies 0.5 ⁇ (D90-D10)/D50 ⁇ 2, preferably 0.9 ⁇ (D90-D10)/D50 ⁇ 1.4.
  • the particle size distribution of silica satisfies the number of particles with a particle size ⁇ 2 ⁇ m accounting for 3%-40% of all particles, preferably 10%-30%.
  • silicone oxide is in an amorphous or low crystalline state.
  • the size of the crystalline silicon in the silicone oxide is ⁇ 4 nm, preferably ⁇ 1 nm.
  • the silica contains or does not contain silica.
  • the silica contains crystalline silica
  • the ratio of the strongest peak intensity h 1 at 2 ⁇ of 26-27° in the XRD spectrum of silica to the strongest peak intensity h 2 at 22.5-24° Satisfies h 2 /h 1 ⁇ 1.5, preferably ⁇ 1.3.
  • the particle size distribution and crystal structure of the silicon oxide material are also related to the performance of the material.
  • the particle size distribution parameter (D90-D10)/D50 of a material reflects the width of the particle size distribution. The larger the value, the wider the particle size distribution.
  • the proportion of particles with a particle size ⁇ 2 ⁇ m reflects the number of fine particles in the material.
  • the fine particles in the material can be filled between the large particles, improving the compaction density and rate performance of the electrode sheet.
  • the volume expansion effect of small particles is smaller, which helps to improve the cycle performance of the battery.
  • the inventor found that if the (D90-D10)/D50 value is too large and the number of particles ⁇ 2 ⁇ m is too small, the cycle performance of the battery may deteriorate. If the (D90-D10)/D50 value is too small and the number of ⁇ 2 ⁇ m particles is too large, the battery capacity may be reduced.
  • the ratio of the strongest peak intensity h 1 at 2 ⁇ 26-27° in the XRD spectrum of silicon oxide to the strongest peak intensity h 2 at 22.5-24° 2 ⁇ reflects the crystalline dioxide in the silicon oxide material. Silicon content. The higher the value, the higher the content of crystalline silica.
  • the presence of a small amount of crystalline silica in the silica material can improve cycle performance, but too much crystalline silica will cause battery capacity and efficiency to deteriorate.
  • the first occurrence of The peak is located at 0.25V-0.43V, preferably 0.36V-0.43V.
  • the chromaticity value of the silicon oxide material is also related to the position of the peak in the dQ/dV curve during the electrochemical reaction.
  • the electrochemical properties of materials with peak positions within the scope of the present invention are also related. Performance is relatively good.
  • the different positions of the lithium insertion peaks are mainly due to the differences in the internal phase and structure of the material caused by the preparation process of the silicon oxide material. It should be understood that since most silicon oxide materials have an amorphous structure, existing technology has not been able to explain the direct relationship between the position of the lithium insertion peak and the material structure, but the relationship between it and battery performance can be characterized experimentally.
  • the silicon oxide of the present invention can be used in combination with carbon nanotubes as an electrode active material for lithium batteries, or can also be used to prepare carbon-coated silicon oxide as an electrode for lithium batteries. Active substances.
  • the silica material of the present invention can improve the initial capacity and cycle performance of carbon-coated silica.
  • a lithium ion secondary battery including a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, characterized in that the negative electrode sheet includes the above-mentioned components of the above aspects of the present invention. Silicone oxide material.
  • the lithium ion battery used in the examples was prepared by the following steps.
  • the negative electrode sheet can be made according to conventional methods in this field. Silicone oxide material or carbon-coated silicone material, conductive agent (such as conductive carbon black, conductive graphite, vapor-grown carbon fiber, carbon nanotubes or any combination thereof), binder (such as styrene-butadiene rubber (SBR) ), polyacrylic acid (PAA), polyimide (PI) binder, preferably PAA binder) are dispersed in the solvent water to form a uniform negative electrode slurry, and the negative electrode slurry is coated On the negative electrode current collector, after drying, the negative electrode piece is obtained.
  • conductive agent such as conductive carbon black, conductive graphite, vapor-grown carbon fiber, carbon nanotubes or any combination thereof
  • binder such as styrene-butadiene rubber (SBR)
  • PAA polyacrylic acid
  • PI polyimide
  • the mass of silicone oxide, conductive agent Super-P, carbon nanotubes, and PAA binder prepared in Examples 3 and 9 was 80:9.9:0.1:10.
  • the silicon oxide prepared in Examples 3 and 9 was carbon-coated, respectively, and the carbon-coated silicon oxide, conductive agent Super-P, carbon nanotubes, and PAA were bonded
  • the agent is mixed and stirred according to the mass ratio of 80:9.9:0.1:10, and an appropriate amount of deionized water is added to adjust the solid content to form a uniform negative electrode slurry, and then the negative electrode slurry is coated on the surface of the negative electrode current collector copper foil. After drying, the negative electrode sheet is obtained.
  • the battery After the capacity test, the battery is charged at a current of 0.1C, and then a charge and discharge cycle test is performed using a current of 1C to test the capacity retention rate of the battery after 100 cycles.
  • the charge and discharge cut-off voltage is 0V-1.5V.
  • Silicon oxide negative electrode materials and negative electrode half cells were prepared by the methods and parameters described in the examples.
  • the material parameters of the prepared silicon oxide material were measured according to the test method described above, and the capacity and cycle test of the prepared half-cell were performed according to the test method described above. The test results are shown in Tables 2 and 3 below.
  • the chromaticity value of the silicon oxide material shows better electrochemistry performance.
  • the electrochemical performance is better than when the proportion is 0 (Example 5), but lower than when the proportion is 10%-30% (Example 1-3); when the ratio is 33% (Example 6), the electrochemistry is also better than when the ratio is 0 but lower than when the ratio is 10%-30%.
  • Example 4 Regarding the impact of the size of crystalline silicon in silicon oxide materials on performance, it can be seen from the comparison between Example 4 and other examples, especially Examples 1-3, that the size of crystalline silicon is less than 4 nm, preferably less than 1 nm. Silicon materials exhibit better electrochemical properties.
  • Example 6 Regarding the influence of the crystalline silica content in the silicon oxide material on the performance, it can be seen from the comparison between Example 6 and other Examples, especially Examples 1-3, that the XRD spectrum is at 2 ⁇ of 26-27°.
  • the ratio of the strongest peak intensity h 1 to the strongest peak intensity h 2 at 2 ⁇ 22.5-24° satisfies h 2 /h 1 ⁇ 1.5, especially silicon oxide materials ⁇ 1.3 show better electrochemical performance .
  • silicone oxide material of the present invention can be used in conjunction with carbon nanotubes, and can also be used to form carbon-coated silicone oxide, and has a more excellent initial capacity. and capacity retention.
  • silicone oxide materials Examples 12 and 14 that do not meet the conditions defined in the present invention still have poor initial capacity and capacity retention even after adding carbon nanotubes or being coated with carbon.

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Abstract

本发明提供了一种用于锂电池的负极材料及包含其的锂离子二次电池。所述用于锂电池的负极材料包含氧化亚硅，所述氧化亚硅在色度方面满足：30≤L≤50，3≤a≤10，1.5≤b≤10，优选35≤L≤45，4≤a≤9，4≤b≤10，并且相对于黑色的总色差ΔE为39≤ΔE≤50。通过本发明的用于锂电池的负极材料及包含其的锂离子二次电池，实现了改善锂离子二次电池的电化学性能的效果。

Description

用于锂电池的负极材料及包含其的锂离子二次电池 技术领域
本发明涉及锂离子二次电池领域，具体而言，涉及一种用于锂电池的负极材料及包含其的锂离子二次电池。
背景技术
近年来，随着电子技术的不断更新，人们对用于支持电子设备的能源供应的电池装置的需求也在不断增加。现如今，需要能够存储更多电量且能够输出高功率的电池。传统铅酸电池以及镍氢电池等已经不能满足新型电子制品的需求。因此，锂电池引起了人们的广泛关注。在对锂电池的开发过程中，已经较为有效地提高了其容量和性能。
为了提高电池的能量密度，氧化亚硅材料被认为是目前最适合商业化的负极材料。但氧化亚硅本身存在首次效率低及循环性能差的问题，为了解决这些问题，目前的主流做法是将氧化亚硅作为原材料对其进行碳包覆。但很多情况下，由于原材料的选取不合适导致碳包覆的氧化亚硅的性能无法得到改善。因此，本领域中仍然存在对于表现出良好的电化学性能，并且适于进行碳包覆的氧化亚硅材料的需要。
发明内容
针对现有技术中的上述问题，本发明提供了一种氧化亚硅材料，此类氧化亚硅材料本身具有良好的容量及循环性能，可以与碳纳米管配合使用作为电极活性物质，也可以作为碳包覆氧化亚硅的原材料。
为了实现上述目的，根据本发明的一个方面，本发明提供了一种用于锂电池的负极材料，包含氧化亚硅，该氧化亚硅在色度方面满足：30≤L≤50， 3≤a≤10，1.5≤b≤10，优选35≤L≤45，4≤a≤9，4≤b≤10，并且相对于黑色的总色差ΔE为39≤ΔE≤50。
进一步地，在上述负极材料中，氧化亚硅的粒径分布满足0.5≤(D90-D10)/D50≤2，优选0.9≤(D90-D10)/D50≤1.4。
进一步地，在上述负极材料中，氧化亚硅的粒径分布满足粒径<2μm的颗粒数量占所有颗粒数量的3％-40％，优选10％-30％。
进一步地，在上述负极材料中，氧化亚硅处于非晶态或低结晶态。
进一步地，在上述负极材料中，当氧化亚硅处于低结晶态时，氧化亚硅中的晶体硅的尺寸＜4nm，优选＜1nm。
进一步地，在上述负极材料中，氧化亚硅包含或不含晶体二氧化硅。
进一步地，在上述负极材料中，当氧化亚硅包含晶体二氧化硅时，氧化亚硅的XRD谱图在2θ为26-27°处的最强峰强度h1与2θ为22.5-24°处的最强峰强度h2的比值满足h2/h1＜1.5，优选≤1.3。
进一步地，在上述负极材料中，在由负极材料制成的半电池根据首次嵌锂曲线以0.05C的电流测得的容量-电压微分曲线(即dQ/dV曲线)中，在0-0.5V电压范围内，首次出现的峰位于0.25V-0.43V，优选0.36V-0.43V。
进一步地，在上述负极材料中，负极材料还包含碳纳米管。
根据本发明的另一个方面，提供了一种用于锂电池的负极材料，包含碳包覆的氧化亚硅，该氧化亚硅是本发明的上述各个方面中的氧化亚硅。
根据本发明的又一个方面，提供了一种锂离子二次电池，包括正极片、负极片、隔膜以及电解液，其特征在于，所述负极片包含本发明的上述各个方面中的负极材料。
通过本发明的用于锂电池的负极材料及包含其的锂离子二次电池，实现了改善锂离子二次电池的电化学性能的效果。
具体实施方式
需要说明的是，在不冲突的情况下，本申请中的实施例及实施例中的特征可以相互组合。下面将结合实施例来详细说明本发明。
如在背景技术部分中所说明的，现有技术中虽然已经将氧化亚硅用于锂电池的负极活性材料，但是对于如何选择具有良好的电化学性能并且适于进行碳包覆的特定氧化亚硅没有明确的指导。本发明人针对改进氧化亚硅的性能问题进行研究，并发现氧化亚硅的性能与氧化亚硅材料的色度、粒度分布、晶体结构等方面存在关联。作为研究的结果，本发明首次提出了一种用于锂电池的氧化亚硅负极材料，该氧化亚硅材料本身具有良好的电化学性能，因此可以与碳纳米管配合使用作为电极活性物质，也可以作为碳包覆氧化亚硅的原材料。
根据本申请的一个典型的实施方式，提供了一种用于锂电池的负极材料，包含氧化亚硅，该氧化亚硅在色度方面满足：30≤L≤50，3≤a≤10，1.5≤b≤10，优选35≤L≤45，4≤a≤9，4≤b≤10，并且相对于黑色的总色差ΔE为39≤ΔE≤50。
本发明人出乎意料地发现，通过选择具有特定的色度的氧化亚硅，可以获得具有良好的电化学性能的用于锂电池的氧化亚硅负极材料。例如，发明人发现具有本发明限定的范围内色度值的氧化亚硅材料具有良好的容量、效率和循环性能，并且这些性能在本发明的范围内随色度的增加而提高。另一方面，当色度值过低或过高时，氧化亚硅材料的首次容量、效率和循环性能劣化。
氧化亚硅材料的色度由氧化亚硅的原材料品质(例如制备氧化亚硅的原材料硅及二氧化硅的纯度)、粒径及纯度(例如Fe，Cu等杂质的含量)等因素决定。尽管氧化亚硅材料的色度与材料结构之间的关系还在研究中，但目前已经确定当氧化亚硅材料中细颗粒较多时，材料的色度较大。另外，氧化亚硅原材料及成品粉体中金属的存在形式及其含量也会影响材料的 色度。例如，当氧化亚硅材料中的Fe以氧化铁形式存在时及其量较多时，会导致材料的色度偏小。因此，氧化亚硅材料的色度反映了该材料在结构及组成上的特征，从而可以推断氧化亚硅材料的色度与材料的电化学性能之间存在一定的关联性。
另外，发明人还发现，氧化亚硅材料的色度值与其在电化学反应过程中的dQ/dV曲线中峰的位置也有关系，色度值较大的材料的峰位通常较大，而该峰位大的电池电化学性能相对较好。
在本申请的一些实施方式中，氧化亚硅的粒径分布满足0.5≤(D90-D10)/D50≤2，优选0.9≤(D90-D10)/D50≤1.4。
在本申请的一些实施方式中，氧化亚硅的粒径分布满足粒径<2μm的颗粒数量占所有颗粒数量的3％-40％，优选10％-30％。
在本申请的一些实施方式中，氧化亚硅处于非晶态或低结晶态。当氧化亚硅处于低结晶态时，氧化亚硅中的晶体硅的尺寸＜4nm，优选＜1nm。
在本申请的一些实施方式中，氧化亚硅包含或不含二氧化硅。当氧化亚硅包含晶体二氧化硅时，氧化亚硅的XRD谱图在2θ为26-27°处的最强峰强度h1与2θ为22.5-24°处的最强峰强度h2的比值满足h2/h1＜1.5，优选≤1.3。
发明人发现，氧化亚硅材料的粒径分布以及晶体结构也与材料的性能存在关联。例如，材料的粒径分布参数(D90-D10)/D50反映了粒径分布的宽窄。该值越大代表粒径分布越宽。而粒径<2μm的颗粒数量占比则反映了材料中细颗粒的数量。发明人发现，在本发明的范围内，当粒径分布较宽时，有利于提高电极材料浆料的加工性能。而材料中的细颗粒可以填充在大颗粒之间，提高电极片的压实密度及倍率性能等。并且，在电化学反应过程中，小颗粒的体积膨胀效应较小，有助于提高电池的循环性能。
另一方面，发明人发现，如果(D90-D10)/D50值过大，同时<2μm的颗粒数过小，可能会导致电池的循环性能变差。如果(D90-D10)/D50值过小，同时<2μm颗粒数过大，可能会导致电池容量降低。
此外，发明人发现，氧化亚硅材料中晶体硅和二氧化硅晶体的存在也会影响材料的性能。例如，类似以上阐述的，当材料中晶体硅的尺寸过大时，对电池的体积膨胀、循环性能等存在不利影响。氧化亚硅的XRD谱图在2θ为26-27°处的最强峰强度h1与2θ为22.5-24°处的最强峰强度h2的比值反映了氧化亚硅材料中的晶体二氧化硅含量。该值越高代表晶体二氧化硅的含量越高。氧化亚硅材料中少量晶体二氧化硅的存在可以提高循环性能，但晶体二氧化硅过多会导致电池容量及效率劣化。
在本申请的一些实施方式中，在由负极材料制成的半电池根据首次嵌锂曲线以0.05C的电流测得的容量-电压微分曲线中，在0-0.5V电压范围内，首次出现的峰位于0.25V-0.43V，优选0.36V-0.43V。
如本文以上所述的，发明人发现氧化亚硅材料的色度值与其在电化学反应过程中的dQ/dV曲线中峰的位置也有关系，具有在本发明范围内的峰位的材料电化学性能相对较好。嵌锂峰位置不同主要是由于氧化亚硅材料的制备工艺造成的材料内部物相及结构的不同。应理解，由于氧化亚硅材料大部分为非晶结构，现有技术尚未能够解释嵌锂峰位置与材料结构的直接关系，但其与电池性能之间的关系可以通过实验表征。
根据本发明的另一个典型的实施方式，本发明的氧化亚硅可以与碳纳米管配合使用作为锂电池的电极活性物质，也可以用于制备碳包覆的氧化亚硅，作为锂电池的电极活性物质。
发明人发现，本发明的氧化亚硅材料与适量的碳纳米管搭配使用作为活性物质时可以降低与电解质的副反应，降低电池析锂概率、极片膨胀率，提高锂电池的放电容量、倍率性能及循环性能，降低电池成本。在作为碳包覆的氧化亚硅的原材料时，本发明的氧化亚硅材料能够改善碳包覆氧化亚硅的首次容量及循环性能。
根据本发明的另一个典型的实施方式，提供了一种锂离子二次电池，包括正极片、负极片、隔膜以及电解液，其特征在于，所述负极片包含本发明的上述各个方面中的氧化亚硅材料。
以下结合具体实施例对本发明作进一步详细描述，这些实施例不应理解为用来限制本发明所要求保护的范围。
实施例
通过以下步骤制备实施例中使用的锂离子电池。
氧化亚硅材料的制备：
将一定粒径的硅粉及二氧化硅按一定摩尔比进行混合，置于震动器上振动12h至混合均匀，取1kg左右混合均匀的粉体压成块体，然后放于真空升华炉上加热至所需温度，通过调整真空度，加热时间，收集端温度等制备所需的块状氧化亚硅前驱体。将收集的块状氧化亚硅前驱体置于破碎机破碎至毫米级，然后将毫米级的粉体置于气流粉碎机中粉碎，通过气流分级器分出不同粒径的粉体，最后将不同粒径的粉体进行混掺，获得特定粒径的粉体。
其中，在本发明以下实施例中使用的氧化亚硅材料的制备过程及参数详见表1。
表1.实施例中使用的氧化亚硅材料的制备过程及参数

负极片的制备：
负极片可以按照本领域的常规方法制作。将氧化亚硅材料或碳包覆的氧化亚硅材料、导电剂(例如导电炭黑、导电石墨、气相生长碳纤维、碳纳米管或它们的任意组合)、粘结剂(例如丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚酰亚胺(PI)粘结剂中的一种或多种，优选PAA粘结剂)分散于溶剂水中，形成均匀的负极浆料，将负极浆料涂覆在负极集流体上，经烘干后，得到负极片。
对于下文中的实施例1-10中使用的具体负极片，将氧化亚硅材料、导电剂Super-P(导电炭黑)、PAA粘结剂按82:8:10的质量比在适量的去离子水中充分搅拌混合，通过调节固含量使其形成均匀的负极浆料，然后将负极浆料涂覆于负极集流体铜箔的表面上，经干燥得到负极片。
另外，对于下文中的实施例11和12，分别将实施例3和9中制备的氧化亚硅、导电剂Super-P、碳纳米管、PAA粘结剂按80:9.9:0.1:10的质量比混合搅拌，加入适量的去离子水调节固含量使其形成均匀的负极浆料，然后将负极浆料涂覆于负极集流体铜箔的表面上，经干燥得到负极片。对于下文中的实施例13和14，分别将实施例3和9中制备的氧化亚硅进行碳包覆，将碳包覆的氧化亚硅、导电剂Super-P、碳纳米管、PAA粘结剂按80:9.9:0.1:10的质量比混合搅拌，加入适量的去离子水调节固含量使其形成均匀的负极浆料，然后将负极浆料涂覆于负极集流体铜箔的表面上，经干燥得到负极片。
电池组装：
将制备的负极片、隔膜、锂片、垫片、电池壳依次叠放并注入100ml电解液，用封口机进行封口组装成负极半电池。
测试方法
通过以下方法测试氧化亚硅材料的各种参数以及制成的电池的电化学性能。
(1)色度值的测量：
取适量氧化亚硅样品置于样品杯中，使用分光测色仪(杭州彩谱科技有限公司，型号CS800)进行色度测试，获得色度值L、a和b，其中L表示黑白、a表示红绿、b表示黄蓝。以黑色为基准，通过以下公式计算色差ΔE：
ΔE＝(L2+a2+b2)1/2
(2)晶体硅尺寸的测量：
取适量氧化亚硅样品使用树脂进行包埋，然后采用超薄切片机进行切片，将切下的薄片采用TEM(赛默飞，TALOS F200X)进行多个硅晶粒尺寸测量，并对测得的值求平均。应注意，对于硅晶粒<1μm的样品，由于样品内部只有极少量晶体存在，无法确定具体的尺寸数值，因此使用<1μm表示
(3)峰强度比值h2/h1的测定：
将适量氧化亚硅粉末样品装入样品台中，用载玻片将粉末样品表面压平、压紧，将多余的粉体刮走。然后将制好的样品放置于XRD设备(Bruker，型号D8)中进行测试。测试条件：测试范围10°-80°，步进0.02°/min,扫描速度：1°/min。在获得的XRD谱图中读取26°-27°的最强峰强度h1与22.5°-24°的最强峰强度h2，并计算h2/h1。
(4)dQ/dV曲线嵌锂峰的测定：
以0.05C的电流对负极半电池进行充放电，记录容量及电压数据，然后对容量及电压进行微分处理，得到dQ/dV曲线。在dQ/dV曲线上读取0-0.5V嵌锂阶段出现的第一个峰位置。
(5)粒径<2μm的颗粒数的测量：
取适量氧化亚硅粉末样品置于含有分散剂的水中，搅拌至分散，然后采用激光粒度仪进行测试，以数量分布为基准统计粒径<2μm的颗粒数量。
(6)电池容量的测量：
在25℃环境下，使用0.1C的充放电倍率、0V-1.5V的充放电电压范围，对负极半电池循环2次获取首次容量及首次效率和第2圈的容量及效率。
(7)电池循环性能的测量：
将容量测试结束后的电池在0.1C电流下充电，然后使用1C电流进行充放电循环测试，测试100次循环后电池的容量保持率。充放电截止电压为0V-1.5V。
测试结果
通过实施例中描述的方法和参数制备氧化亚硅负极材料和负极半电池。对制备的氧化亚硅材料根据以上描述的测试方法测量材料参数，对制备的半电池根据以上描述的测试方法进行容量及循环测试。测试结果如下表2和3所示。
表2.实施例1-10中的氧化亚硅材料参数及电池性能
表3.实施例11-14中的氧化亚硅材料参数及电池性能
由表2的结果可以看出，本发明的氧化亚硅材料(实施例1-3)在初始容量和循环性能方面表现出最优的性能。该结果证明了本发明提供的氧化亚硅材料具有良好的容量及循环性能。
关于氧化亚硅材料的色度值对性能的影响，通过实施例1-3与实施例8-10的比较可以看出，具有色度值30≤L≤50，3≤a≤10，1.5≤b≤10，尤其是35≤L≤45，4≤a≤9，4≤b≤10，并且相对于黑色的总色差ΔE为39≤ΔE≤50的氧化亚硅材料表现出更好的电化学性能。
关于氧化亚硅材料的粒径分布对性能的影响，通过实施例1-3与实施例5、6、10的比较可以看出，粒径分布满足0.5≤(D90-D10)/D50≤2，特别是0.9≤(D90-D10)/D50≤1.4的氧化亚硅材料表现出更好的电化学性能。另外，通过实施例1-3与实施例5-7的比较可以看出，粒径分布满足粒径<2μm的颗粒数量占所有颗粒数量的3％-40％，特别是10％-30％的氧化亚 硅材料表现出更好的电化学性能。例如，当粒径<2μm的颗粒比例为5％时(实施例7)，电化学性能优于该比例为0的情况(实施例5)，但低于该比例为10％-30％的情况(实施例1-3)；当该比例为33％时(实施例6)，电化学同样优于该比例为0的情况但低于该比例为10％-30％的情况。
关于氧化亚硅材料中的晶体硅的尺寸对性能的影响，通过实施例4与其他实施例，特别是实施例1-3的比较可以看出，晶体硅尺寸＜4nm，优选＜1nm的氧化亚硅材料表现出更好的电化学性能。
关于氧化亚硅材料中的晶体二氧化硅含量对性能的影响，通过实施例6与其他实施例，特别是实施例1-3的比较可以看出，XRD谱图在2θ为26-27°处的最强峰强度h1与2θ为22.5-24°处的最强峰强度h2的比值满足h2/h1＜1.5，特别是≤1.3的氧化亚硅材料表现出更好的电化学性能。
关于氧化亚硅材料中的容量-电压微分曲线与性能的关系，通过实施例1-3与实施例9和实施例5、6、10的比较可以看出，由其制成的半电池根据首次嵌锂曲线以0.05C的电流测得的容量-电压微分曲线中，在0-0.5V电压范围内，首次出现的峰位于0.25V-0.43V，特别是0.36V-0.43V的氧化亚硅材料表现出更好的电化学性能。
另外，从表3的实施例11和13可以看出，本发明的氧化亚硅材料可以与碳纳米管配合使用，也可以用于形成碳包覆的氧化亚硅，并具有更加优异的初始容量和容量保持率。而不符合本发明限定的条件的氧化亚硅材料(实施例12和14)即使在添加碳纳米管或被碳包覆后仍然具有不良的初始容量和容量保持率。
总之，通过使用根据本发明选择具有特定参数的氧化亚硅材料作为锂离子电池的负极材料，与根据现有技术的氧化亚硅材料相比，获得了电池的电化学性能的改善。
以上所描述的仅为本发明的优选实施例，并不用于限制本发明，对于本领域的技术人员来说，本发明可以有各种更改和变化。凡在本发明的精 神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (11)

  1. 一种用于锂电池的负极材料，包含氧化亚硅，其特征在于，所述氧化亚硅在色度方面满足：30≤L≤50，3≤a≤10，1.5≤b≤10，优选35≤L≤45，4≤a≤9，4≤b≤10，并且相对于黑色的总色差ΔE为39≤ΔE≤50。
  2. 根据权利要求1所述的负极材料，其特征在于，所述氧化亚硅的粒径分布满足0.5≤(D90-D10)/D50≤2，优选0.9≤(D90-D10)/D50≤1.4。
  3. 根据权利要求1或2所述的负极材料，其特征在于，所述氧化亚硅的粒径分布满足粒径<2μm的颗粒数量占所有颗粒数量的3％-40％，优选10％-30％。
  4. 根据权利要求1或2所述的负极材料，其特征在于，所述氧化亚硅处于非晶态或低结晶态。
  5. 根据权利要求4所述的负极材料，其特征在于，当所述氧化亚硅处于低结晶态时，所述氧化亚硅中的晶体硅的尺寸＜4nm，优选＜1nm。
  6. 根据权利要求4所述的负极材料，其特征在于，所述氧化亚硅包含或不含晶体二氧化硅。
  7. 根据权利要求6所述的负极材料，其特征在于，当所述氧化亚硅包含晶体二氧化硅时，所述氧化亚硅的XRD谱图在2θ为26-27°处的最强峰强度h1与2θ为22.5-24°处的最强峰强度h2的比值满足h2/h1＜1.5，优选≤1.3。
  8. 根据权利要求1或2所述的负极材料，其特征在于，在由所述负极材料制成的半电池根据首次嵌锂曲线以0.05C的电流测得的容量-电 压微分曲线中，在0-0.5V电压范围内，首次出现的峰位于0.25V-0.43V，优选0.36V-0.43V。
  9. 根据权利要求1或2所述的负极材料，其特征在于，所述负极材料还包含碳纳米管。
  10. 一种用于锂电池的负极材料，包含碳包覆的氧化亚硅，其特征在于，所述氧化亚硅是权利要求1-8任一项中限定的氧化亚硅。
  11. 一种锂离子二次电池，包括正极片、负极片、隔膜以及电解液，其特征在于，所述负极片包含权利要求1-10中任一项所述的负极材料。
PCT/CN2023/078540 2022-05-06 2023-02-27 用于锂电池的负极材料及包含其的锂离子二次电池 WO2023213121A1 (zh)

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CN101106196A (zh) * 2006-06-29 2008-01-16 索尼株式会社 电极集流体及其检查方法、电池电极及其制备方法以及二次电池及其制备方法
WO2019150725A1 (ja) * 2018-02-05 2019-08-08 株式会社豊田自動織機 炭素被覆シリコン材料
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CN1781202A (zh) * 2003-03-31 2006-05-31 日本电气株式会社 二次电池用正极活性材料、二次电池、及二次电池用正极活性材料的制造方法
CN101106196A (zh) * 2006-06-29 2008-01-16 索尼株式会社 电极集流体及其检查方法、电池电极及其制备方法以及二次电池及其制备方法
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