The Superior Electrochemical Property of LiTFSI@(Ba+Nb)-co-doped Li 7 La 2.75 Ba 0.25 Zr 1.75 Nb 0.25 O 12 @PEO Composite Membrane in All-Solid-State Lithium Battery

It is popular to choose the cubic phase Li 7 La 3 Zr 2 O 12 (c-LLZO) to synthesize the PEO-based complex membrane in all-solid-state battery. In this work, Ba/Nb elements were selected to achieve Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 (LLZNO) and Li 7 La 2.75 Ba 0.25 Zr 1.75 Nb 0.25 O 12 (LLBZNO) with high ion conductivity, which effectively enhance the electrochemical properties of the complex solid membrane and the all-solid-state battery. The higher ion mobility of LLBZNO compared to that of LLZNO and LLZO is calculated by ab-initio molecular dynamics (AIMD) simulation and further confirmed by experiments. Results show that the cubic phase of LLBZNO is more stable than that of LLZNO. The complex membrane of LLBZNO@ polyethylene oxide (PEO) (CPE-2-x wt%) exhibits the better electrochemical properties than LLZNO@PEO (CPE-1-x wt%) complex membrane. In detail, the CPE-2–10 wt% has the outstanding lithium transfer number ( t Li + ) of 0.63, as well as the excellent compatibility with lithium metal anode. In addition, at 0.1 mA∙cm −2 , the lithium/CPE-2–10 wt%/lithium symmetric cell remains stable after 1000 h. It is LLBZNO that makes LLBZNO@PEO composite polymer electrolyte(CPE) the potential for the application in all-solid-state lithium battery. The AIMD simulation is adopted to investigate the essence of Li + mobility. The AIMD simulation results and the experimental conclusions complement each other. The higher Li + mobility of LLBZNO makes the comprehensive property of LiTFSI@ LLBZNO @PEO membrane better. LiTFSI@ LLBZNO @PEO membrane exhibits superior interface stability of 1200 h without short circuit in symmetric cell.