Computational study on the effects of mechanical constraint on the performance of silicon nanosheets as anode materials for lithium-ion batteries

Silicon (Si), with the highest theoretical capacity (~ 4200 mA h g^{- 1}) and abundant reserves in the Earth’s crust, stands out as one of the most promising candidate anode materials for Lithium-ion batteries (LIBs). However, Si anode exhibits significant volume expansion during lithiation, resulting in serious problems, such as rapid degradation and low cycling life of LIBs. To alleviate these problems, considerable efforts have been undertaken to study the lithiation process of Si. However, most of the previous works modeled Si anodes as free-standing objects and neglected the mechanical constraint on Si by the accessory materials in the anode. This chapter is devoted to the investigation of the effects of the mechanical constraint on the performances of Si nanosheets as the active material for LIBs using customized techniques for simulating lithiation and delithiation with molecular dynamics. Our results show that strong mechanical constraint would largely affect the capacity and lithiation rate of the Si nanosheets. Strategies for improving the capacity and lithiation rate of the constrained Si nanosheets are proposed, giving rise to guidelines for the design of Si-based composite anodes for high-performance lithium-ion batteries.