Integrated cathode-electrolyte (Li6.55La3Zr1.55Ta0.45O12/PEO-LiTFSI) architecture driven excellent performance of solid-state lithium metal batteries

The solid electrolytes in solid-state lithium batteries suffer due to low room temperature conductivity (< 10(-4) S cm(-1)) and sluggish lithium-ion transport at the electrode-electrolyte interface. To fabricate solid-state lithium metal batteries employing composite solid electrolyte, Ta-doped Li7La3Zr2O12 (LLZTO) with room temperature conductivity similar to 6.1 x 10(-4) S cm(-1) was synthesized and dispersed in polyethylene oxide-lithium bis(trifluoromethanesulfonyl)imide (PEO-LiTFSI) polymer-salt matrix in different proportions. The sample SCE20 (20 wt% LLZTO & 80 wt% PEO-LITFSI), showing the best effective lithium-ion conductivity amongst all compositions (similar to 1.44 x 10(-4) S cm(-1)), was used to fabricate lithium symmetric cells and all-solid-state cells with LiFePO4 cathode in conjunction with lithium metal as the anode. The fabricated lithium symmetric cells showed high cyclability (>1100 h) with a low overpotential of similar to 180 mV at a current density of similar to 0.4 mA cm(-2). The LiFePO4 cells with monolithic cathode-SCE20 electrolyte architecture in conjunction with lithium metal as the anode exhibited similar to 50 % lower interfacial resistance and delivered similar to 84.2 % capacity retention after 1000 cycles at 1C with an initial discharge capacity of similar to 133 mAh g(-1). This facile, cost-efficient design of integrated cathode-electrolyte architecture by a doctor blade coating method can drive the application of solid-state lithium metal batteries on a commercial scale.