A review of the multiscale mechanics of silicon electrodes in high-capacity lithium-ion batteries

Abstract

Over the past decade, there has been a significant advancement in understanding the mechanics of silicon (Si) electrodes in lithium (Li)-ion batteries. Much of this interest in Si electrodes as ideal anode materials for high-capacity Li-ion batteries stems from its theoretical specific capacity of 4200 mAh g−1, which is an order-of-magnitude higher than that of conventional graphite electrodes (372 mAh g−1). However, the high capacity of Li ions is also accompanied by a ∼300% volume expansion of the Si electrode during Li intercalation, which results in massive cracking of the electrode and capacity fade. In this review article, we summarize recent progress in elucidating the underlying fracture and failure mechanics of Si electrodes using multiscale computations and experiments, spanning the quantum, atomistic, microscopic, and macroscopic length scales. We focus on four fundamental mechanics issues: (i) the mechanical properties and fracture behavior of lithiated Si electrodes; (ii) the interfacial mechanics between Si thin-film electrodes and current collectors; (iii) the deformation and failure mechanics of the solid electrolyte interphase; and (iv) the design of Si electrodes for improved mechanical performance. Current challenges and possible future directions for the field of mechanics of materials in pursuit of high-capacity rechargeable batteries are also discussed.