Enabling superior electrochemical performances of Li10SnP2S12-based all-solid-state batteries using lithium halide electrolytes

Li 10 GeP 2 S 12 shows great potential as solid electrolytes for solid-state batteries due to its ultrahigh Li-ion conductivity. However, the high cost of Ge and the poor stability limit its applications. Replacing Ge with Sn can significantly lower the cost and maintains the high conductivity, while the corresponding Li 10 SnP 2 S 12 still suffers the low interfacial stability with the bare high voltage layered oxide cathodes. Herein, Li 10 SnP 2 S 12 with high Li-ion conductivity up to 4.79 mS cm −1  has been synthesized. All-solid-state battery using the cathode consisting of bare LiNi 0.6 Co 0.2 Mn 0.2 O 2 and Li 10 SnP 2 S 12 shows low capacities and poor cyclability due to side reactions between those two particles. To improve the interfacial stability, a highly conductive Li 3 InCl 6 electrolyte is introduced both in the cathode mixture and between the cathode layer and Li 10 SnP 2 S 12 solid electrolyte layer. This new configuration delivers superior electrochemical performances at different operating temperatures. It delivers high initial discharge capacities of 176.1 mAh g −1 , 186.9 mAh g −1 , and 73.7 mAh g −1 at 0.1C when operated at room temperature, 60 o C, and −20 o C, respectively. The superior battery performances are attributed to the excellent electrochemical stability of Li 3 InCl 6 electrolyte towards bare LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode. This work provides a guideline to design Li 10 SnP 2 S 12 -based all-solid-state lithium batteries with high energy density and long span life.