Free-Standing Architecture of Spatially Branched Nanowire Electrodes for Boosting Interfacial Stability in Solid-State Lithium-Ion Batteries

Solid-state batteries show substantial promise for reducing the inherent safety risks associated with the flammability of liquid organic electrolytes. Nevertheless, their performance is often constrained by unstable solid-solid interfaces between the electrolyte and the electrodes. Herein, branch-structured SnO₂ nanowire electrodes were developed, with the ultimate goal to improve electrode/electrolyte interfacial contact in solid-state lithium-ion batteries. The nanowire electrodes were fabricated directly on the current collector without electrochemically inactive additives. Notably, the branch length was precisely tunable by adjusting the growth duration, enabling the spontaneous formation of hierarchical pore structures by a physical "pushing effect" between adjacent branches. These interconnected microscale pore networks enhanced the infiltration capacity of the poly(ethylene oxide)/Li₇La₃Zr₂O₁₂ composite electrolyte, facilitating lithium-ion dynamics both in-plane and across electrode thickness. Moreover, the branch architectures promoted stable solid-solid contact areas with the electrolyte, leading to marked improvements in fast-charging performance and deliverable energy density over repeated charge/discharge cycles.