Unraveling the Mechanisms of Lithium-Alloy Plating in Ag-C Anode: In situ SEM Study

The Ag-C composite anodes facilitate stable Li_xAg deposition in solid-state batteries. However, the role of carbon and the kinetics of lithium migration and deposition in the composite structure remain unclear. Few studies have focused on this critical research area owing to a shortage of effective, non-destructive characterization methods that can directly observe the Li alloy deposition process in solid-state batteries in real time. In this study, Li alloy formation on the Ag-C anode is investigated through operando X-ray diffraction (XRD) analysis and scanning electron microscopy combined with in situ probing. This enables the observation of the composition and morphology of the Li_xAg alloy as it evolves within the Ag-C composite anode during discharge. Further insights from scanning transmission electron microscopy-electron energy loss spectroscopy and first-principles simulations on lithiophilicity and the energy barrier for lithium migration reveal a complex lithium migration and deposition mechanism within the Ag-C anode.