Building better solid-state batteries with silicon-based anodes

Silicon (Si)-based solid-state batteries (Si-SSBs) are attracting tremendous attention because of their high energy density and unprecedented safety, making them become promising candidates for next-generation energy storage systems. Nevertheless, the commercialization of Si-SSBs is significantly impeded by enormous challenges including large volume variation, severe interfacial problems, elusive fundamental mechanisms, and unsatisfied electrochemical performance. Besides, some unknown electrochemical processes in Si-based anode, solid-state electrolytes (SSEs), and Si-based anode/SSE interfaces are still needed to be explored, while an in-depth understanding of solid-solid interfacial chemistry is insufficient in Si-SSBs. This review aims to summarize the current scientific and technological advances and insights into tackling challenges to promote the deployment of Si-SSBs. First, the differences between various conventional liquid electrolyte-dominated Si-based lithium-ion batteries (LIBs) with Si-SSBs are discussed. Subsequently, the interfacial mechanical contact model, chemical reaction properties, and charge transfer kinetics (mechanical-chemical kinetics) between Si-based anode and three different SSEs (inorganic (oxides) SSEs, organic-inorganic composite SSEs, and inorganic (sulfides) SSEs) are systemically reviewed, respectively. Moreover, the progress for promising inorganic (sulfides) SSE-based Si-SSBs on the aspects of electrode constitution, three-dimensional structured electrodes, and external stack pressure is highlighted, respectively. Finally, future research directions and prospects in the development of Si-SSBs are proposed.