In Situ Formed Li₃N Networks by Soft Carbon‐Si₃N₄ for Superior All‐Solid‐State Lithium‐Metal Batteries

Abstract The rapid growth of lithium (Li) dendrites has long hindered the development of all‐solid‐state lithium‐metal batteries (ASSLMB). Here, a composite soft carbon (SC)‐nano Si₃N₄ (SiN) interlayer (SC‐SiN) is designed for in situ formation of Li₃N network (with high ionic conductivity/diffusivity) after lithium embedding in nano‐Si₃N_4, promoting the rapid migration of Li⁺ and guiding the metal Li to be deposited uniformly in a 3D manner within the interlayer. It can solve the problem of rapid consumption of Li⁺ and local charge accumulation at the interface of solid electrolyte and Li metal anode, thus avoiding the growth of Li‐dendrites. The resulting LCO/LPSCl/SC‐SiN‐Li ASSLMB achieves ultra‐high current density (12.5 mA cm⁻²) and ultra‐long cycle life (22 000 cycles with no degradation), as well as ultra‐high area capacity area capacity (15 mAh cm⁻²) and energy density (402.5 Wh kg⁻¹), all of which break existing ASSLMB records. In addition, it is capable of 600 cycles at an areal capacity of 2.7 mAh cm⁻² and 2 C (85.7% capacity retention). A pouch cell is also assembled to delivers high energy density (>320 Wh kg⁻¹). These confirm the application potential of this configuration and are one of the most critical breakthroughs toward the commercialization of the ASSLMB.