Polymer-Stabilized Li–Si Alloy Anode with Enhanced Structural Integrity for All-Solid-State Batteries

Lithium metal and silicon have emerged as promising anodes for all-solid-state lithium batteries with elevated energy densities. However, the growth of lithium dendrites in lithium anodes raises short-circuiting risk, while silicon suffers from inherently low ionic/electronic conductivity and huge volume expansion. As a compromise alternative, we synthesized a dendrite-free and high-capacity lithium–silicon (abbreviated as LS) alloy anode and further innovatively integrated it with the polymer polyamide (PA). The resulting continuous and ordered ion–electron-conducting percolation network of LS@PA effectively improves ionic/electronic conductivity and addresses solid–solid interfacial incompatibility. In addition, the flexibility of the polymer cladding layer inhibits volume expansion and ensures structural integrity during lithium plating and stripping. A low overpotential of 40 mV for the LS@PA symmetrical cell after 1,000 h at 0.4 mA cm⁻² and an ultrahigh critical current density of 19.6 mA cm⁻² are exhibited. When all-solid-state batteries with a LiNi_0.8Co_0.1Mn_0.1O₂ cathode and a Li_5.6PS_4.6Cl_1.4 sulfide-based solid electrolyte are assembled, superior long-term cycling with a high capacity retention of 82.5% for 300 cycles is delivered, as well as low expansion after cycling as visualized by scanning electron microscopy–energy-dispersive spectroscopy and cross-sectional polishing–scanning electron microscopy. This work provides a feasible approach to developing high-performance LS alloy anodes for practical applications of all-solid-state batteries.