Improvement of stability and solid‐state battery performances of annealed 70Li ₂ S–30P ₂ S ₅ electrolytes by additives

Abstract

Abstract The replacement of liquid electrolyte with solid electrolyte can significantly improve the safety and power/energy density of lithium batteries. 70Li 2 S–30P 2 S 5 is one of the most promising solid electrolytes with high conductivity for solid–state batteries. In this work, the ionic conductivity and stability toward moisture and lithium metal of 70Li 2 S–30P 2 S 5 were enhanced by introducing the different amounts of Li 2 O additives. 65Li 2 S–30P 2 S 5 –1%Li 2 O delivered the highest conductivity, while 65Li 2 S–30P 2 S 5 –5%Li 2 O showed the best moisture stability and improved lithium compatibility. Solid‐state batteries using 65Li 2 S–30P 2 S 5 –5%Li 2 O electrolyte and high‐voltage LiNi 0.6 Mn 0.2 Co 0.2 O 2 cathode exhibited low initial discharge capacity (100 mAh·g −1 ) and Coulombic efficiency (69%). Li 3 InCl 6 electrolytes were introduced both in the cathode mixture to replace sulfide electrolyte and in the interface layer to improve the cathode compatibility for the solid‐state batteries, showing enhanced discharge capacity (175 mAh·g −1 ) and improved initial Coulombic efficiency (86%). Moreover, it also exhibited good performance at − 20 °C.