Mechanical properties of silicon-based electrodes

Silicon has been widely studied as a next-generation anode material for Li-ion batteries (LIB), as it has a high gravimetric capacity of up to 3570 mAh g^-1 and a low average discharge voltage of about 0.4 V vs. Li/Li⁺. One of the most significant challenges is to maintain reversibility of the electrode despite the large volume expansion of more than 280% from the Li-Si alloy reaction. In this chapter, we will focus on the mechanical issues that a Si anode undergoes during charge and discharge and discuss some of the recent developments to alleviate the problem. The chapter will begin with an introduction to the lithiation process and volume expansion of Si. Characterization(s), in particular on single particles and nanowires, gave us visual observations of how the expansion and contraction occur. In the final analysis, materials must be processed into electrodes for practical applications, thus the amount of thickness change and its reversibility become important factors that govern battery stability. Other developments to sustain the cycle performance of Si electrodes will be addressed.