All-solid-state lithium-ion batteries (ASSLIBs) without organic liquid electrolytes have attracted considerable attention as a solution to existing safety issues. Si is the most promising anode active material for increasing the energy density of such batteries owing to its high theoretical capacity. However, the stress relaxation of Si with large structural fluctuations is a major challenge to its practical use. In the present study, nanoporous Si particles and a sulfide-based solid electrolyte are composited to accommodate the volumetric expansion. To the best of our knowledge, this is a novel approach in the case of ASSLIBs. We find that the capacity retention of highly dispersed Si composite anodes is 80% up to 150 cycles. Such excellent cyclability is explained by our results, which suggest the following microstructural behavior. The pores in the Si particles act as buffer regions for large volume changes. In addition, the strains arising from the slightly expanded Si particles are relieved by the elasticity of the surrounding sulfide-based solid electrolyte. In summary, this study is a significant step toward the development of high-performance ASSLIBs for various applications.
Stress relaxation of Si with large structural fluctuations is a critical challenge for its practical application in lithium-ion batteries (LIBs). In this study, nanoporous Si particles, which are prepared by Mg2Si reduction of mesoporous SiO2 spheres, are applied as an anode active material for all-solid-state LIBs (ASSLIBs) with a Li3PS4 solid electrolyte. Nanoporous Si half-cells exhibit an excellent cyclability with a high-capacity retention of about 90% at 50 cycles compared to non-porous Si half-cells below 20%. The cross-sectional characteristics of nanoporous and non-porous Si composite anodes are compared using electrochemical impedance spectroscopy and field emission scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy. Based on these results, we conclude that the expansion/contraction of nanosized Si pores and the elastic deformation of Li3PS4 effectively relieve the structural stress derived from the volume change of Si particles/aggregates during lithiation and delithiation, resulting in high cycle stability. These findings provide valuable information for the rational design of Si-based anodes for high-performance ASSLIBs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.