Operando pair distribution function measurements of silicon anodes

Silicon has approximately 10 times the capacity of the state-of-the-art anode material for lithium ion batteries (LIBs). To fully utilise the charge capacity of Si, it is crucial to understand why it loses capacity so quickly when the battery is put through cycles of charge and discharge, and why nanosizing of the Si is effective in extending its cycle life. The best way to gain information about the structural changes during cycling which cause deactivation is by an operando study in a working battery. We aim use total X-ray scattering to obtain the pair distribution functions (PDFs) of working nano-Si anodes. Previous studies of crystalline Si have given some insight in the structural mechanics of cycling, but do not give clean enough data. To mitigate this, we have developed a new operando battery cell. This will then give information about the structural changes of Si combined with electrochemical data.

硅的容量约为当前最先进锂离子电池（LIBs）负极材料的10倍。为充分挖掘硅的充电容量潜力，阐明其在充放电循环中容量快速衰减的核心机制，以及硅纳米化何以有效延长其循环寿命，是至关重要的研究课题。要获取循环过程中导致硅失活的结构变化相关信息，最优途径是在工作电池中开展原位（operando）研究。本研究拟采用全X射线散射技术，获取工作状态下纳米硅负极的对分布函数（PDFs）。过往针对晶体硅的相关研究虽为循环过程中的结构力学行为提供了一定见解，但所获数据的清晰度尚未达到理想要求。为解决这一问题，我们研发了一款新型原位（operando）电池单体。该装置将结合电化学测试数据，为解析硅的结构变化提供详实可靠的信息。