锂离子电池是目前比较常见的二次储能器件，具有许多优良的电化学性能，其中

Lithium ion batteries are currently relatively common secondary energy storage devices, which have many excellent electrochemical properties, including high energy density, long service life, fast charging and discharging, and green safety. They are also well received by domestic and foreign experts. Widely concerned, and hope to further improve the electrochemical performance and range of use of lithium-ion batteries. At the same time, with the rapid development of flexible electronic technology, a large number of flexible electronic products such as: scrollable mobile phones, smart bracelets, implantable medical devices, etc. have gradually appeared in the public's field of vision, so how to manufacture flexible electronic devices Matching flexible energy storage elements is very important. As a part of the lithium ion battery, the amount and speed of deintercalation / intercalation of lithium ions will directly affect the electrochemical performance of the entire lithium ion battery. Therefore, the research and commercial production of negative electrode materials have been attracting attention. Among carbon-based materials, graphite is the main negative electrode material for commercial lithium-ion batteries. It has the advantages of large reserves, low price, good conductivity, and stable chemical properties. However, the specific capacity of graphite electrodes is low, only 372mAh / g, magnification Poor performance, can not meet the requirements of high-power, large-capacity lithium-ion batteries. Among tin-based materials, tin dioxide (SnO2) has a high theoretical specific capacity of 782mAh / g, and it has the advantages of low lithium insertion potential, high safety, and environmental friendliness, so it is considered to be very potential A new generation of negative electrode materials for lithium-ion batteries. However, during the intercalation-delithiation reaction, the volume of SnO2 will undergo a huge volume expansion (up to 300%), resulting in the electrode material easily pulverizing and falling off during repeated charge and discharge processes. The cycle performance is poor, which limits its practical application. <br>In view of the above situation, this article focuses on SnO2 and combines it with graphite, graphene, and graphene oxide, respectively, and uses carbon-based materials to slow down the volume expansion of the active material during the charge / discharge cycle, and can also enhance the negative electrode material. Conductivity and vacuum suction filtration method to produce flexible lithium ion battery film, the research content is as follows: <br>(1) Preparation of SnO2 / graphite composite material by hydrothermal method, first of all, the material is pumped by simple vacuum suction filtration method Filtration into a membrane, but found that this method is not feasible, and then the traditional method is first used to make the material into a slurry, and then coated with a doctor blade to make a flexible film and analyze the performance of the material; <br>(2) Vacuum suction filtration Way to prepare pure graphene flexible film and test the electrochemical performance of the material;<br>(3) The SnO2 / graphene composite material is prepared by hydrothermal method, and the composite material is vacuum filtered to form a film to make a flexible electrode, and then the material is characterized and tested to compare the pure graphene flexible electrode and SnO2 / Graphene flexible electrode performance differences, and analyze the reasons; <br>(4) Preparation of SnO2 / graphene oxide composite material by hydrothermal method, vacuum filtration of the composite material into a film, and characterize and test the material , Compare the performance difference between this material and SnO2 / graphene composite material, and explain the reason. <br><br>Keywords: flexibility, lithium ion battery, anode material, graphite, graphene, SnO2, electrochemical performance

锂离子电池是目前比较常见的二次储能器件，具有许多优良的电化学性能，其中包括能量密度高、使用寿命长、可以快速充放电以及绿色安全等突出优点，因此也受到国内内外专家的广泛关注，并且希望能够进一步提高锂离子电池的电化学性能和使用范围。同时，伴随着柔性电子工艺的迅猛发展，一大批柔性电子产品如：可卷屏手机、智能手环、植入式医疗器械等逐渐出现在大众的视野之中，那么如何制造出与柔性电子器件相匹配的柔性储能元件就显得十分重要。负极材料作为锂离子电池的一部分，其脱/嵌锂离子的多少、快慢，会直接对整个锂离子电池的电化学性能产生大的影响，因此负极材料的研究和商业化生产一直受人瞩目。目前在碳基材料中，石墨是商业化锂离子电池主要的负极材料，其具有储量大、价格低、导电性好、化学性质稳定的优点，然而石墨电极比容量低，只有372mAh/g，倍率性能差，不能满足高功率、大容量的锂离子电池的要求。在锡基材料当中，二氧化锡（SnO2）具有较高的理论比容量，为782mAh/g,而且其具有嵌锂电势低、安全性高、环境友好等优点，因此被认为是非常具有潜力的新一代锂离子电池负极材料，然而在嵌-脱锂的反应过程中， SnO2体积会发生巨大的体积膨胀(高达300%)，导致电极材料在反复充放电过程中容易粉化和脱落，充放电循环性能差，从而限制了其实际应用。<br>针对以上情况，本文以SnO2为中心，分别将其与石墨、石墨烯、氧化石墨烯相结合，用碳基材料来减缓活性物质在充/放电循环过程中的体积膨胀，同时也可以增强负极材料的导电性，并采用真空抽滤的方法，制作出柔性的锂离子电池薄膜，研究内容如下：<br>（1）采用水热法制备SnO2/石墨复合材料，首先用简单真空抽滤的方式将材料抽滤成膜，但发现此方法不可行，随后便采用传统方式，先将材料制成浆料，然后用刮刀涂布的方法，制作柔性薄膜，并分析材料的性能；<br>（2）采用真空抽滤的方式制备纯石墨烯柔性薄膜，并测试材料的电化学性能；<br>（3）采用水热法制备SnO2/石墨烯复合材料，并用真空抽滤的方法将复合材料抽滤成膜，制作成柔性电极，然后对材料进行表征和测试，比较纯石墨烯柔性电极和SnO2/石墨烯柔性电极存在的性能差异，并分析原因；<br>（4）采用水热法制备SnO2/氧化石墨烯复合材料，用真空抽滤装置将复合材料抽滤成膜，并对材料进行表征和测试，比较该材料与SnO2/石墨烯复合材料的性能差异，并解释原因。<br><br>关键词：柔性，锂离子电池，负极材料，石墨，石墨烯，SnO2，电化学性能

Lithium ion battery is a common secondary energy storage device at present, which has many excellent electrochemical properties, including high energy density, long service life, rapid charge and discharge and green safety. Therefore, it is also widely concerned by experts at home and abroad, and hopes to further improve the electrochemical performance and use range of lithium ion battery. At the same time, with the rapid development of flexible electronic technology, a large number of flexible electronic products, such as: rolling screen mobile phones, smart bracelets, implantable medical devices and so on, have gradually appeared in the public's vision, so how to make flexible energy storage components matching with flexible electronic devices is very important. As a part of lithium-ion battery, the amount and speed of lithium-ion removal / insertion of anode materials will directly affect the electrochemical performance of the whole lithium-ion battery, so the research and commercial production of anode materials have been attracting people's attention. At present, graphite is the main anode material of commercial lithium-ion battery, which has the advantages of large reserves, low price, good conductivity and stable chemical properties. However, the specific capacity of graphite electrode is low, only 372mah / g, with poor rate performance, which can not meet the requirements of high-power and large capacity lithium-ion battery. Among tin based materials, SnO2 has a high theoretical specific capacity of 782mah / g, Moreover, it has the advantages of low potential, high safety and environmental friendliness. Therefore, it is considered to be a new generation of cathode materials for lithium-ion batteries with great potential. However, in the process of intercalation and delilication reaction, SnO2 has a huge volume expansion (up to 300%), which leads to the electrode materials easy to pulverize and fall off in the process of repeated charge and discharge, and poor cycle performance of charge and discharge, thus limiting its practical application.<br>In view of the above situation, this paper takes SnO2 as the center, combines it with graphite, graphene and graphene oxide respectively, uses carbon based materials to slow down the volume expansion of active substances in the process of charge / discharge cycle, at the same time, it can also enhance the conductivity of negative materials, and uses the method of vacuum suction filtration to make flexible lithium-ion battery films. The research contents are as follows:<br>(1) SnO2 / graphite composite material was prepared by hydrothermal method. Firstly, the material was filtered into membrane by simple vacuum filtration method, but it was found that this method was not feasible. Then, the traditional method was adopted. Firstly, the material was made into slurry, then the flexible membrane was made by scraper coating method, and the properties of the material were analyzed;<br>(2) The graphene flexible film was prepared by vacuum filtration and its electrochemical properties were tested;<br>(3) SnO2 / graphene composite was prepared by hydrothermal method, and the composite was filtered into membrane by vacuum filtration method to make flexible electrode. Then the material was characterized and tested. The performance differences between pure graphene flexible electrode and SnO2 / graphene flexible electrode were compared, and the reasons were analyzed;<br>(4) SnO2 / graphene oxide composite was prepared by hydrothermal method. The composite was filtered into membrane by vacuum filtration device. The properties of the composite were compared with that of SnO2 / graphene composite and the reasons were explained.<br>Key words: flexibility, lithium-ion battery, anode material, graphite, graphene, SnO2, electrochemical performance