The mechanics of large-volume-change transformations in high-capacity battery materials

High-capacity next-generation materials for Li-ion and Na-ion batteries often undergo significant volume changes (up to similar to 300%) during reaction with Li or Na. These largevolume- change transformations cause mechanical fracture and pulverization of active battery materials, which can have detrimental effects on battery cycle life. Recent years have seen significant efforts dedicated to understanding the mechanics of such largevolume- change transformations in alloying anode materials. This review paper introduces recent work focused on various aspects of the mechanics of alloying anode materials, including in situ characterization of real-time reaction mechanisms and mechanical degradation processes, measurements of mechanical properties, measurements and simulations of spatiotemporal stress generation and evolution in active battery materials and structures, and studies on the interplay between chemistry and mechanics during reaction. In addition, mechanical effects across length scales within battery electrode structures are discussed. As demonstrated herein, the improved understanding of the mechanics of large-volume-change transformations has been essential for the rational design of durable high-capacity electrodes for Li-ion and Na-ion batteries. (C) 2016 Elsevier Ltd. All rights reserved.