Soft Carbon‐Thiourea with Fast Bulk Diffusion Kinetics for Solid‐State Lithium Metal Batteries

The development of all-solid-state lithium-metal batteries (ASSLMBs) is impeded by low coulomb efficiency, short lifetime, poor rate performance, and other problems caused by the rapid growth of lithium (Li) dendrites. Herein, a multiple-diffusion-channel N,S-doped soft carbon with expanded layer spacing is designed/developed by thiourea calcination for dendrite-free anodes. Since the enlarged layer spacing can improve Li⁺ transportation rate within the layers and N,S-doping can facilitate Li⁺ transport between the layers, the bulk phase diffusion (not just surface diffusion) kinetics can be improved, which in turn reduces the local current density, inhibits the growth of Li dendrites, and improves the rate performance. The resulting ASSLMB achieves record-high current density (15 mA cm^-2 ), areal capacity (20 mAh cm^-2 ), energy density (403 Wh kg^-1 ), and ultra-long cycle life (13 000 cycles). >305 Wh kg^-1 pouch cells are realized, representing one of the most critical breakthroughs for real-world application of ASSLMBs.