Enhancement of ionic conductivity and air stability by co-doping Li10SnP2S12 with Nb and O

Li 10 SnP 2 S 12 represents a quintessential sulfide solid-state electrolyte that has garnered considerable interest within the domain of solid-state batteries. However, it still has much room for enhancing its ionic conductivity and air stability. In this paper, Li 10 SnP 2 S 12 was modified by solid-phase sintering method using different doping amounts of Nb 2 O 5 . XRD refinement confirmed that Nb and O elements were successfully doped into the P and S sites, in which the ionic conductivity of Li 10 SnP 1.96 Nb 0.04 S 11.9 O 0.1 was up to 2.93 mS cm −1 at room temperature. After Nb 2 O 5 doping, the lattice volume expands due to the larger ionic radius of Nb 5+ compared to P 5+ . This expansion broadens the channels through which lithium ions travel, thereby enhancing Li + conductivity. O doping improves the stability of the sulfide against moisture and forms a strong P O bond with P, which resists further oxidation . The air stability test demonstrated enhanced air stability of the doped electrolyte. The AC impedance test conducted at various temperatures confirmed that the doped electrolyte exhibits lower activation energy , which facilitates an enhancement in Li + conductivity. Finally, the assembled Li-In/Li 10 SnP 1.96 Nb 0.04 S 11.9 O 0.1 /LNO@LCO battery exhibits higher first turn discharge specific capacity and good cycle stability. • Various ratio of Nb 2 O 5 is doped into Li 10 SnP 2 S 12 sulfide solid electrolyte. • High ionic conductivity can be obtained by appropriate Nb 2 O 5 doping. • O doping improves the stability of the sulfide against moisture and forms a strong P O bond with P. • The all-solid-state battery with Li 10 SnP 1.96 Nb 0.04 S 11.9 O 0.1 as the electrolyte has good electrochemical performance.