Mechanically heterogeneous alloy enables low-pressure silicon anodes for all-solid-state batteries

Abstract

Silicon promises an ideal anode material for all-solid-state lithium-ion battery (ASSLIB) owing to its high capacity, dendrite-free behavior, and low cost. However, the high stack pressures (≥ 50 MPa) typically required to prevent contact deactivation of silicon anode are impractical for large-scale commercialization. Here, we reveal the mechanical design requirements for low-stack-pressure Si-based solid-state anodes and demonstrate low-pressure operation (2 MPa) by introducing mechanically heterogeneous Li1.3Ga, which integrates mixed ionic-electronic conductivity with soft amorphous LixGa for local compliance and rigid crystalline Li1Ga for framework anchoring. This hierarchical soft/hard architecture maintains stable ionic-electronic conducting percolations, suppresses interfacial contact loss and preserves anode integrity. Consequently, the home-made NCM83||Si full cells exhibit a jellyroll specific energy of 337 Wh kg−1 at 2.06 mA cm−2 and sustain stable long-term cycling for over 1200 cycles at 5 MPa, while the pouch cell operates stably at 2 MPa. This work provides a promising pathway toward commercially viable low-stack-pressure silicon anodes for ASSLIBs.