Modulating the Spatio‐Temporal Sequence of Lithium Plating and Stripping via a 3D Host for Solid State Batteries

Solid-state lithium metal batteries (SSLMBs) are now under intensive research for their high energy density and excellent safety. However, the Li transport limitation in Li metal anode (LMA) leads to mass/stress accumulation, dendrite initiation and void formation at the interface, which seriously hinders the development of SSLMBs. Herein, it is demonstrated through in situ electron microscopies that a mixed ionic-electronic conducting (MIEC) 3D host can promote the Li transport in LMA by increasing the diffusion pathways along the carbonaceous framework, carbon/Li interface and Li metal surface, enabling a fast and long-distance (nearly 100 µm) diffusion of Li atoms in LMA. Consequently, the spatio-temporal sequence of Li plating/stripping can be fundamentally changed. Specifically, both deposition and dissolution can occur far away from the interface, thereby mitigating the dendrite and void issues. Impressively, the resulting cells with carbonaceous hosts can achieve excellent cyclability and the highest capacity (28.8 mAh cm^-2) so far. This work provides valuable insight for understanding Li transport and deposition/dissolution mechanisms in MIEC host-based LMAs, and a feasible solution for tackling the interface issues without involving stack pressure in SSLMBs.