Phase transformations and hysteresis in Si-based anode materials

The use of Si-based materials can increase the energy density of lithium ion batteries by at least 20% compared to the conventional graphite-based anodes. However, Si-containing anodes are susceptible to rapid degradation due to severe volume changes on lithiation/delithiation during cycling. This Perspective presents the current understanding of the phase transformations occurring on lithiation/delithiation of Si-based materials and specifically relates these to hysteresis. Challenges and strategies in the pursuit of higher capacity and longer cycle life anodes are discussed. Thermodynamic considerations are shown to represent an important step in the design of electrode materials with improved electrochemical performance.