Architectural Strategies for High-Energy Silicon-Rich Anodes: Managing Expansion and Degradation

Silicon has long been recognized as a promising anode material for next-generation lithium-ion batteries owing to its higher capacity compared to conventional graphite. [1] However, silicon adoption is practically limited by its large lithiation-induced volume change, restricting its content to below ~10 wt% in commercial graphite-silicon composite anodes. As a result, Si-majority anodes impose a requirement for additional free volume within the cell-level architecture, which reduces practical energy density. [2] In this study, we developed a silicon anode based on a three-dimensionally structured porous current collector that suppresses electrode-level expansion while converting conventionally dense current-collector volume into electrochemically active space, thereby maximizing electrode energy density. The three-dimensional architecture reveals failure mechanisms that differ fundamentally from those observed in conventional planar silicon anodes, particularly under high silicon mass loading. Rather than being dominated by bulk electrode fracture or delamination driven by macroscopic expansion, degradation in the three-dimensionally structured electrodes is governed by processes localized at the silicon surface and interfaces. Coupling the three-dimensional architecture with controlled silicon surface modification mitigates interfacial degradation and extends electrochemical durability. A chemo-mechanical understanding of these failure pathways in porous electrode architectures, combined with surface management, provides critical insights into the practical implementation of Si-majority anodes with high volumetric and gravimetric energy density. [1] J. W. Choi, D. Aurbach, Nature Reviews Materials, 2016, 1, 16013 [2] N. Kim, Y. Kim, J. Sung, J. Cho, Nature Energy, 2023, 8, 921