【作者】 李伟；

【导师】 雷勇；

【作者基本信息】 上海大学 ， 环境工程， 2019， 硕士

【摘要】 由于便携式电子设备的快速发展,锂离子电池行业对电力存储的需求持续增长。然而,全球锂资源的持续不足和分布不均限制了锂离子电池在未来的应用。因此,钾离子电池作为资源分布广泛、成本低廉、能量密度高的二次电池引起了极大的关注。与锂离子电池相比,钾离子电池的负极材料体系还不是很完善,需要不断创新;同时,对于材料体系的结构、形貌等的优化,也是必要的。本文旨在通过简单的水热法制备合成纳米片自组装成的花型氯化氧铋(BiOCl),首次作为钾离子电池的负极材料,在有机相电解液中研究其电化学性能,并探究其储能机理。同时,利用水热和退火法制备硫化锡包覆氧化石墨烯(SnS@GO),首次作为钾离子电池的负极材料,揭示GO包覆与电极的电导率对负极材料的电化学性能的影响。这对未来研究钾离子电池电极材料的研究提供参考与新思路。本论文的内容包括以下几个方面:1.本文利用水热法合成的BiOCl,对其作为钾离子电池负极材料在有机电解液中的电化学性能进行了测试,通过改变电解液、碳包覆,实现了对BiOCl产物自身物相、形貌和电化学性能的优化。最终确定纯BiOCl(未包覆碳)在KFSI电解液的情况下,当50 mA/g电流密度时,提供了366.6 mAh/g的高容量,并在50圈循环后保持了58%的比容量;而且在1 A/g电流密度下,比容量达到175.6 mAh/g,表现出很高的倍率性能。还通过非原位XRD、XPS、SEM测试,对电极材料物相、结构、形貌进行了深入分析,并分析其储能机理。2.本文利用水热法和退火法合成的SnS@GO材料,对其作为钾离子电池负极材料在有机电解液中的电化学性能进行了测试,通过改变温度和时间、GO包覆量、电解液,实现了对锡硫化物物相、组分、晶型、结构、形貌尺寸和电化学性能的优化。最终确定SnS@GO-30mg、40mg、50mg在电解液KFSI的条件下,性能最优,当50 mA/g电流密度时,分别提供了476 mAh/g、507.8 mAh/g、514.2 mAh/g的高比容量,并在第50圈循环后,放电比容量仍然较高,分别为304.6 mAh/g、65.2 mAh/g、116.3 mAh/g。并通过长循环、大电流密度和阶梯倍率来分析SnS@GO-30mg、40mg、50mg性能差异的机理。更多还原

【Abstract】 Due to the rapid development of portable electronic devices,the demand for power storage in the lithium-ion battery(LIB)industry continues to grow.However,the continued shortage and uneven distribution of global lithium resources have limited the future application of LIBs.Therefore,potassium-ion batteries(PIBs)have attracted great attention as the secondary batteries with widely distributed resources,low cost,and high energy density.Compared with LIBs,the anode material system of PIBs is under developed and needs constant innovations.At the same time,it is necessary to optimize the structure and morphology of the material system.This thesis aims to prepare the nano-sheet self-assembled flower-type oxychloride bismuth(BiOCl)by a simple hydrothermal method.It is the first time as the anode material of potassium ion battery for studying its electrochemical performance in organic selectrolyte and exploring its energy storage mechanism.At the same time,tin sulfide coated graphene oxide(SnS@GO)was prepared by hydrothermal and annealing.It is the first time as the anode material of potassium ion battery for revealing the effect of GO coating and the electrical conductivity on the electrochemical performance of the anode material.The thesis provides insights into the future research of PIB electrode materials.The thesis includes the following aspects:1.BiOCl synthesized by a hydrothermal method was used to test the electrochemical performance as an anode material of PIBs in organic electrolytes.The choice of the electrolytes and carbon coating optimized the phase,morphology and electrochemical performance of the BiOCl product.It was finally determined that uncoated BiOCl provided a high capacity of 366.6 mAh/g at a current density of50 mA/g in the electrolyte containing KFSI and maintained a specific capacity of58% after 50 cycles.At a current density of 1 A/g,the specific capacity reached175.6 mAh/g,showing high rate performance.The phase,structure and morphologyof the electrode material were analyzed by ex-situ XRD,XPS and SEM tests to study the energy storage mechanism.2.SnS@GO composite synthesized by a hydrothermal method and a subsequent annealing process was used to test the electrochemical performance as an anode material of PIBs in organic electrolytes.By changing the temperature and time,GO coating amount,and electrolytes,the phase,composition,structure,morphology and electrochemical properties of the anode were optimized.It was finally determined that SnS@GO-30 mg,40mg,and 50 mg had the best performance under the condition of the electrolyte containing KFSI.When the current density was 50mA/g,the high capacities of 476,507.8 and 514.2 mAh/g were obtained for different amount of GO,respectively.After the 50 th cycle,the discharge specific capacity was still high,i.e.,304.6,65.2,and 116.3 mAh/g,respectively.The difference of the performance of SnS@GO-30 mg,40mg and 50 mg was demonstrated by long-term cycle and rate capability at different current densities.更多还原