A High Air-Stability and Li-Metal-Compatible Li_(3+2x)P_(1?x)Bi_xS_(4?1.5x)O_(1.5x) Sulfide Electrolyte for All-Solid-State Li–Metal Batteries

摘要

All-solid-state batteries are one of the most promising lithium–ion batteriesas they are safe with high energy density and applicable to different occasions.Sulfide solid electrolytes (SSEs) are welcoming due to their good ionicconductivity and processability. However, as the SSE conductor is unstablewhen exposed to air, its development and application are limited. A seriesof new Li_(3+2x)P_(1?x)Bi_xS_(4?1.5x)O_(1.5x) (X = 0.02, 0.04, 0.06, 0.08) solid electrolytesare synthesized by co-doping Li_3PS_4 with Bi and O, and the new electrolyteshave better ionic conductivity and air-stability than Li_3PS_4. The lithiumionic conductivity of Li_(3.12)P_(0.94)Bi_(0.06)S_(3.91)O_(0.09) solid electrolytes reached up to2.8 mS cm~(–1) at room temperature, the highest and 9 times as high as that ofLi_3PS_4. The doped solid electrolytes are compatible with lithium anode, andthe cycling performance is improved. Importantly, the critical current densityof Li_(3.12)P_(0.94)Bi_(0.06)S_(3.91)O_(0.09) electrolytes can reach to 1.2 mA cm~(–2). In particular,the LiLi_(3.12)P_(0.94)Bi_(0.06)S_(3.91)O_(0.09)Li symmetric cells are stable even after 400 hrunning at 1 mA cm~(–2) and 25 ℃. Bi_2O_3 doping SSEs are expected to be thenext generation of all-solid-state lithium batteries due to their good ionicconductivity and air-stability.