Suppressing lithium dendrite growth enabled by high-performance garnet LLZO for graphite-based full cell solid-state lithium batteries

Cycling performance and Coulombic efficiency of full cell solid-state lithium batteries (SSLBs) are far from satisfactory since low-performance garnet Li7La3Zr2O12 causes uneven plating/stripping process and severe Li deposition. Herein, Ta-doped garnet Li6.5La3Zr1.5Ta0.5O12 (LLZTO) with high Li-ion conductivity and high density is employed to promote the electrochemical performances of full cell SSLBs. The Li-ion conductivity reaches 6.65 x 10-4 S cm-1 with a density of 96.2%. High-performance LLZTO facilitates the Li-ion transport and reduces the Li deposition along grain boundaries. Full cell LiFePO4/LLZTO/Graphite SSLBs display an excellent cycling stability, where the capacity retention remains 85.7% with a Coulombic efficiency over 99% after 40 cycles at 0.1C. The smooth charge-discharge voltage platforms indicate stable REDOX reactions with uniform Li plating/stripping process. This work combines the advantages of graphite electrode and SSLBs with environmental benignity and economic viability, accelerating future SSLBs large-scale industrial application.