Mechanical influence mechanisms of silicon anodes in solid-state batteries under low stack pressure
Fei Yang, Qian Xu, Xin Qin, Lu Zhao, Lu Guo, Yongheng Zhang, Debin Kong, Junwei Han, Linjie Zhi
Abstract
Microparticulate silicon (Si) has been successfully used in solid lithium-ion battery anodes due to its strength in high gravimetric/volumetric capacity and low risk of dendrite growth. Nevertheless, the operation condition of low stack pressure challenges the cycle life of the assembled microparticulate Si-based solid-state batteries. In this work, we unveiled that solely low volume expansion of the Si anode is insufficient to achieve good cyclic stability for solid-state batteries under low stack pressure, and the intimate Si anode-solid electrolyte interfacial contact must be considered, which is found to be influenced by the mechanical deformation of Si. As a result, for the batteries with organic/inorganic composite solid-state electrolytes, the low-expansion microparticulate silicon oxide (SiO x ) anode is employed and achieves stable cycling performance and high areal capacity (23 mAh cm −2 ) with good interfacial compatibility under 0 MPa stack pressure. For all-solid-state batteries using sulfide solid-state electrolyte, the hybrid of microparticulate SiO x and Si combined with the low expansion of SiO x and good plastic deformation ability of Si is applied and affords superior cyclic stability under decreased stack pressure. This work refreshes the understanding of the anode design principle for low-stack-pressure solid-state batteries using organic/inorganic composite solid-state electrolytes or sulfide solid-state electrolytes.