Vanadium doped ceramic matrix Li6.7La3Zr1.7V0.3O12 enabled PEO-based solid composite electrolyte with high lithium ion transference number and cycling stability

Solid polymer electrolytes (SPEs) have attracted much attention because of their potential in improving energy density and safety. Vanadium doped ceramic matrix Li_6.7La₃Zr_1.7V_0.3O₁₂ (LLZVO) was synthesized by high-temperature annealing, and formed a composite electrolyte with polyethylene oxide (PEO). Compared with pure PEO electrolyte membrane, the composite electrolyte membrane exhibited better ionic conductivity (30 °C: 3.2 × 10^?5 S cm^?1; 80 °C: 3.6 × 10^?3 S cm^?1). The combination of LLZVO was beneficial to improve the lithium ion transference number (t_Li⁺) of SPE, which was as high as 0.81. The Li/SPE/LiFePO₄ battery shows good cycling ability, with a specific capacity of 142 mAh g^?1 after a stable cycle of 150 cycles. Meanwhile, the symmetrical lithium battery with composite electrolyte can work continuously for 1200 h without short circuit at the current density of 0.1 mA cm^?2 at 50 °C, and the capacity is 0.176 mAh. Vanadium doped ceramic matrix LLZVO as an active ionic conductor, improved the overall performance of solid electrolyte.