Solid polymer electrolyte soft interface layer with 3D lithium anode for all-solid-state lithium batteries

Garnet electrolyte-based lithium (Li) metal batteries, which employ garnet-type Li7La3Zr2O12 (LLZO) as electrolyte and Li metal as anode, are regarded as a promising candidate for high-energy batteries. However, Li dendrites formation as well as poor solid-solid contact between the electrolyte and electrodes result in high interfacial resistance, large polarizations, and low Coulombic efficiency. Herein, we demonstrated that solid polymer electrolyte (SPE) soft interface layer deposited on garnet electrolyte (Ta-doped LLZO (LLZTO)) surface along with 3D Li metal anode can address these obstacles. In this architecture, SPE layer was deposited on garnet electrolyte surface to endow connected interface between the electrolyte and electrodes and thus settled the interface contact issue. 3D Li metal anode can accomplish dendrite-suppression by increasing Li ions deposition sites to lower the effective current density and render a uniform Li nucleation with 3D frameworks. With this ingenious arrangement, the solid-state 3D Li︱SPE-LLZTO-SPE︱3D Li symmetrical cell exhibits a stable voltage profile over 700 h and solid-state LiFePO4︱SPE-LLZTO-SPE︱3D Li full cell also shows an extremely superior cyclability and high Coulombic efficiency even at 90 °C. This work provides an alternative option for manufacturing safe and stable solid-state Li metal batteries.