Advances in Silicon Anodes for Solid-State Batteries: From the Particle 'Size Effect' Perspective
Silicon-based (Si-based) anodes are core candidates for next-generation high-energy solid-state batteries (SSBs) due to their high theoretical capacity (~4200 mAh g−1). However, their practical application is constrained by the 'size effect', which influences mechanical integrity and electrochemical performance. This review systematically examines the failure mechanisms of nano-silicon (nSi) and micro-silicon (mSi) anodes when paired with sulfide and organic-inorganic composite solid-state electrolytes (SSEs). Key functional parameters of these SSEs are discussed, along with strategies to mitigate interfacial impedance and accommodate volume changes. Recent progress in structural and interface modifications is highlighted, including the use of hard-carbon-stabilized Li–Si anodes (achieving stable cycling) and pressure-free operation. The review identifies core challenges, such as achieving intimate solid–solid contact and managing mechanical stress, and outlines future directions for 'size effect' regulation to accelerate commercialization of high-energy Si-based SSBs.