High critical current density in Li6.4La3Zr1.4Ta0.6O12 electrolyte via interfacial engineering with complex hydride

Garnet-type solid-state batteries (SSBs) are considered to be one of the most promising candidates to realize next-generation lithium metal batteries with high energy density and safety. However, the dendrite-induced short-circuit and the poor interfacial contact impeded the practical application. Herein, interface engineering to achieve low interfacial resistance without high temperature calcination was developed, which Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (LLZTO) was simply coated with complex hydride (Li 4 (BH 4 ) 3 I (3L1L)) in various mass ratios n (Li 4 (BH 4 ) 3 I)-(100− n )LLZTO (10 ≤  n  ≤ 40). The interfacial conductivity increases by more than three orders of magnitude from 8.29 × 10 −6 S·cm −1 to 1.10 × 10 −2 S·cm −1 . Symmetric Li cells exhibit a high critical current density (CCD) of 4.0 mA·cm −2 and an excellent cycling stability for 200 h at 4.0 mA·cm −2 . SSBs with polymeric sulfur-polyacrylonitrile (SPAN) cathode achieve a high discharge capacity of 1149 mAh·g −1 with a capacity retention of 91% after 100 cycles (0.2 C). This attempt guides a simple yet efficient strategy for obtaining a stable Li/LLZTO interface, which would promote the development of solid-state batteries. Graphical abstract