材料学院系列学术讲座

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2017-05-18 来源:科学研究部

报告承办单位:材料科学与工程学院

报告内容: 1.通过调控枝晶生长方向制备可循环充放电的Li-金属电极

2. 高电化学性能石墨烯修饰纳米杂化金属氧化物用于锂离子电池中的研究

报告人姓名: 谢剑

报告人所在单位: 普渡大学印第安纳波利斯分校

报告人职称/职务及学术头衔:教授

报告时间:2017年5月20日上午9:00

报告地点:新能源大楼1号楼302多功能会议室

报告人简介: 谢剑,博士后,普渡大学印第安纳波利斯分校的机械工程教授。已发表55篇期刊论文,拥有11项专利,近8年获得研究经费超过468万美元。主要研究方向为聚合物燃料电池,锂金属电池研究,纳米及复合材料。他是包括Nature在内12家杂志期刊的审稿人,同时也是美国国家科学基金委(NSF), 能源高级研究计划署(ARPA-E),美国能源部燃料电池技术处(DOE),加拿大国家科学基金委的基金评审人。曾在洛斯阿拉莫斯国家实验室工作4年,连续5年在电化学协会会议被任命为聚合物电解质燃料电池研讨会的分会主席。

报告摘要:

Meeting the increasing demand on high specific energy Li ion batteries (LIBs) ultimately lies on the breakthrough of novel anode and cathode materials.  Multi-valence metal oxides are ideal candidates as cathode materials for LIBs due to their capacity of holding more Li+ ions per molecule. However, most metal oxides have issues on (1) low intrinsic electric conductivity, (2) slow lithium-ion diffusion, and (3) irreversible phase transitions upon deep discharge which prevent them from practical application. We have developed a novel method of incorporating graphene sheets into the nano-structure of metal oxide which solved these long stranding issues. The example is a V2O5 system synthesized via sole-gel process. The resulting graphene-modified nanostructured vanadium pentoxide hybrids contain only 2 wt. % graphene, yet exhibits extraordinary electrochemical performance: a specific capacity of 438 mAh/g, approaching the theoretical value (443 mAh/g), a long cyclability, and significantly enhanced rate capability. Such performance is the result of the combined effects of the graphene on structural stability, electronic conduction, vanadium redox reaction, and Li+ diffusion supported by AC impedance, cryo-TEM, in operando synchrotron HEXRD, and XANES studies. This novel method provides a new avenue to create nanostructured metal oxide/graphene materials for advanced battery applications.