Rapid preparation and performances of garnet electrolyte with sintering aids for solid-state Li–S battery

Lithium-sulfur (Li–S) batteries are attractive due to their high theoretical energy density . However, conventional Li–S batteries with liquid electrolytes undergo polysulfide shuttle-effect and lithium dendrite formation during charge/discharge process, leading to poor electrochemical performance and safety issues. Garnet type Li 7 La 3 Zr 2 O 12 (LLZO) solid-state electrolyte (SSE) restricts the penetration of polysulfides and exhibits high ionic conductivity at room temperature (RT). Herein, Li 6.5 La 3 Zr 1.5 Nb 0.5 O 12 (LLZNO) ceramic electrolyte using Li 3 PO 4 (LPO) as sintering aids (LLZNO-LPO) is prepared by the rapid sintering method and is applied to construct a shuttle-effect free solid-state Li–S battery . The SSE displays high conductive pure cubic-LLZO phase; during the rapid sintering, LPO melts and junctions the voids between the grains, thus improves Li + conductivity. As a result, the LLZNO-LPO ceramic electrolyte with Li + conductivity of 4.3 × 10 −4  S cm −1 and high critical current density (CCD) of 1.2 mA cm −2 is obtained at RT. The Li–S solid-state battery which utilizes LLZNO-LPO ceramic electrolyte can deliver an initial discharge capacity of 943 mA h·g −1 and 602 mA h·g −1 retention after 60 cycles. In the same time, the initial coulombic efficiency is as high as 99.5%, indicating that the SSE can effectively block the polysulfide shuttle towards the Li anode and fulfill a shuttle-free Li–S battery.