Dual CuCl doped argyrodite superconductor to boost the interfacial compatibility and air stability for all solid-state lithium metal batteries

The decent ductileness, high ionic conductivity, low cost, and versatility over synthesis methods make Li-argyrodite a promising for all-solid-state lithium batteries. However, its serious interfacial incompatibility with Li anode, dendrite growth, and intrinsic air instability impedes its practicability. Herein, we report a CuCl dual doped Li-argyrodite sulfide superb-conductor (Li6+3xP1−xCuxS5−xCl1+x) prepared to overcome these issues via ball-mill free synthesis approach. The maximum Li+ conductivity of 4.34 mS cm−1 at room temperature with ultrawide voltage stability up to 8 V vs. Li/Li+ was achieved in Li6.3P0.9Cu0.1S4.9Cl1.1 (LPSC-1) via a both composite and planar electrode system and can suppress dendrite formation at a current density of 3 mA cm−2 at 50 оC. The symmetrical cell cycled at 0.1 and 1 mA cm−2 also demonstrates remarkable reversibility with negligible overpotential alteration for more than 2400 h and 400 h. An ex-situ XPS and AC impedance analysis proved enhanced interfacial compatibility at Li | SE and achieved a critical current density of 3 mA cm−2. More interestingly, incorporating soft acid Cu in LPSC-1 boosts the air stability and suppresses H2S generation by two-folds. The XRD for the LPSC-1 before and after air exposure proves the decrease in the oxophilicity of the sulfide solid electrolyte.