Lithium-Mediated Reconstruction Activates Carbon Additives into Ion-Electron Percolative Media for All-Solid-State Batteries

All-solid-state batteries (ASSBs) promise high safety and energy density but suffer from poor rate capability due to ineffcient ion/electron transport in composite electrodes. Conventional carbon conductive additives (CCAs) provide electronic conduction but lack ionic transport and interfacial compatibility. Herein, a lithium-mediated reconstruction strategy converts CCAs into ion–electron percolative media, with enhanced interfacial compatibility, addressing charge-transport limitations in ASSBs. Using vapor-grown carbon fibers (VGCF) as a model, reconstructed VGCF (LRVGCF) features expanded interlayer spacing, high electronic conductivity (164.01 S·cm^–1), and enhanced ionic conductivity (1.67 mS·cm^–1), ∼16× higher than pristine VGCF. Simultaneously, lithium-induced surface chemical homogenization suppresses electrolyte reduction and mitigates crack formation, stabilizing transport pathways. With 2 wt % LRVGCF, silicon anodes deliver 2188.8 mAh·g^–1 at 3C, 3.7× higher than bare silicon, while full cells with LiNi_0.88Co_0.06Mn_0.06O₂ achieve a 4× capacity increase at 2C. This strategy is broadly applicable to various anodes and CCAs, establishing a general approach for high-rate ASSBs.