Hard-carbon-stabilized Li–Si anodes for high-performance all-solid-state Li-ion batteries

All-solid-state batteries (ASSBs) with Li metal anodes or Si anodes are promising candidates to achieve high energy density and improved safety, but they suffer from undesirable lithium dendrite growth or huge volume expansion, respectively. Here we synthesize a hard-carbon-stabilized Li–Si alloy anode in which sintering of Si leads to the transformation of micro-metre particles into dense continuum. A 3D ionic-electronic-conductive network composed of plastically deformable Li-rich phases (Li 15 Si 4 and LiC 6 ) that enlarges active area and relieves stress concentration is created in the anode, leading to improved electrode kinetics and mechanical stability. With the hard-carbon-stabilized Li-Si anode, full cells using LiCoO 2 or LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathodes and Li 6 PS 5 Cl electrolyte achieve favourable rate capability and cycle stability. In particular, the ASSB with LiNi 0.8 Co 0.1 Mn 0.1 O 2 at high loading of 5.86 mAh cm −2 delivers 5,000 cycles at 1 C (5.86 mA cm −2 ), demonstrating the potential of using hard-carbon-stabilized Li–Si alloy anodes for practical applications of ASSBs.