Air-stable Li_(3.12)P_(0.94)Bi_(0.06)S_(3.91)I_(0.18)solid-state electrolyte with high ionic conductivity and lithium anode compatibility toward high-performance all-solid-state lithium metal batteries

Sulfide solid-state electrolytes(SSEs)with superior ionic conductivity and processability are highly promising candidates for constructing all-solid-state lithium metal batteries(ASSLMBs).However,their practical applications are limited by their intrinsic air instability and serious interfacial incompatibility.Herein,a novel glass-ceramic electrolyte Li_(3.12)P_(0.94)Bi_(0.06)S_(3.91)I_(0.18)was synthesized by co-doping Li_(3)PS_(4)with Bi and I for high-performance ASSLMBs.Owing to the strong Bi-S bonds that are thermodynamically stable to water,increased unit cell volume and Li+concentration caused by P5+substitution with Bi3+,and the in situ formed robust solid electrolyte interphase layer LiI at lithium surface,the as-prepared Li_(3.12)P_(0.94)Bi_(0.06)S_(3.91)I_(0.18)SSE achieved excellent air stability with a H2S concentration of only 0.205 cm^(3)g^(-1)(after 300 min of air exposure),outperform-ing Li_(3)PS_(4)(0.632 cm^(3)g^(-1))and the most reported sulfide SSEs,together with high ionic conductivity of 4.05 mS cm^(-1).Furthermore,the Li_(3.12)P_(0.94)Bi_(0.06)S_(3.91)I_(0.18)effectively improved lithium metal stability.With this SSE,an ultralong cyclabil-ity of 700 h at 0.1 mA cm^(-2)was realized in a lithium symmetrical cell.Moreover,the Li_(3.12)P_(0.94)Bi_(0.06)S_(3.91)I_(0.18)-based ASSLMBs with LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)cathode achieved ultrastable capacity retention rate of 95.8%after 300 cycles at 0.1 C.This work provides reliable strategy for designing advanced sulfide SSEs for commercial applications in ASSLMBs.