SUMMARY

Lithium-ion batteries are the current dominant energy storage solution for portable electronics and electric vehicles. The growing demand in these applications, however, requires next-generation lithium-ion batteries with an unprecedented combination of low cost, high capacity, and high reliability. Silicon and germanium are two promising candidate anode materials for advanced lithium-ion batteries because of their high theoretical capacity. Nevertheless, major drawbacks of these high-performance materials are the huge volume changes and the associated stress buildup and failures during electrochemical cycling. To obtain a thorough understanding of the fracture characteristics of lithiated electrode materials, an integrated experimental and computational investigation is proposed in this study. An in-house designed experimental setup has been successfully employed to measure the fracture toughness of lithiated silicon and germanium as a function of the lithium concentration. Informed by the experimentally measured fracture characteristics, we will develop a computational cohesive zone model and integrate it with a chemo-mechanical two-way coupling continuum model to study the fracture behaviors of lithiated electrodes under combined electrochemical and mechanical loading. This highly integrative experimental and computational work has profound implications for the design and development of next-generation, high-performance lithium-ion batteries.