Binary anion and cation co-doping enhance sulfide solid electrolyte performance for all-solid-state lithium batteries

Abstract

Sulfide solid electrolytes are regarded as a pivotal component for all-solid-state lithium batteries (ASSLBs) due to their inherent advantages, such as high ionic conductivity and favorable mechanical properties. However, persistent challenges related to electrochemical stability and interfacial compatibility have remained significant hurdles in their practical application. To address these issues, we propose an anion-cation co-doping strategy for the optimization of Li7P3S11 (LPS) through chemical bonding and structural modifications. The co‐doping effects on the structural and electrochemical properties of SiO2-, GeO2-, and SnO2-doped sulfide electrolytes were systematically investigated. Cations are found to preferentially substitute the P5+ of the P2S74- unit within the LPS matrix, thereby expanding the Li+ diffusion pathways and introducing lithium defects to facilitate ion conduction. Concurrently, oxygen ions partially substitute sulfur ions, leading to improved electrochemical stability and enhanced interfacial performance of the sulfide electrolyte. The synergistic effects resulting from the incorporation of oxides yield several advantages, including superior ionic conductivity, enhanced interfacial stability, and effective suppression of lithium dendrite formation. Consequently, the application of oxide-doped sulfide solid electrolytes in ASSLBs yields promising electrochemical performances. The cells with doped-electrolytes exhibit higher initial coulombic efficiency, superior rate capability, and cycling stability when compared to the pristine LPS. Overall, this research highlights the potential of oxide-doped sulfide solid electrolytes in the development of advanced ASSLBs.