Garnet-type double-layer solid electrolyte for dendrite-free solid-state Li batteries

Due to its high energy density and better safety performance, all-solid-state lithium batteries are regarded as important energy storage devices to replace the traditional liquid electrolyte Li-ion batteries. However, the problems of poor wettability of Li metal anode | solid-state electrolyte interface and easy growth of lithium dendrite have not been well solved. Here, we have constructed Fe-doped Li7-3xFexLa3Zr2O12 (Fe-LLZO) and Li6.5La3Zr1.5Ta0.5O12 (LLZTO) garnet-type double-layer solid electrolyte. The high density of Li7-3xFexLa3Zr2O12 electrolyte and its interfacial wettability to Li metal not only effectively reduced the interface impedance between Li and solid electrolyte but also could stably cycle for more than 200 h without the growth of lithium dendrites at the rate of 0.1 mA cm−2. In addition, the all-solid-state lithium battery (Li|Fe0.1-LLZO|LLZTO|LFP) with LiFePO4 as a cathode also showed excellent cycle stability and C-rate performance.