Mitigating bottleneck effects of LiTa2PO8-based hybrid solid electrolyte through boron doping for enhanced electrochemical performance in all-solid-state lithium batteries

초록

Hybrid solid electrolytes (HSEs) for all-solid-state lithium batteries (ASSLBs) address the limitations of inorganic solid electrolytes and solid polymer electrolytes, providing high electrochemical performance. In this study, we developed a lithium tantalum phosphate (LiTa2PO8, LTPO)-based HSE fabricated as a polymer-in-ceramic (PIC) electrolyte with higher LTPO content compared to poly(vinylidene fluoride-co-hexafluoropropylene) (PVDFHFP). To mitigate the bottleneck effects caused by P5+ in LTPO and high interfacial resistance of the PIC electrolyte, boron was doped at the P sites of LTPO. Consequently, the ionic conductivity of the B 0.100 mol-doped LTPO-based HSE improved to three times (4.0 x 10-4 S cm-1) at 25 degrees C. The Li+ transference number and exchange current density increased to 0.66 and 2.24 mA cm-2, respectively, at 55 degrees C. The ASSLB containing LiFePO4 (LFP) cathode, B0.100-LTPO HSE and Li metal anode demonstrated a high initial specific capacity of 169.7 mAh g-1 at 55 degrees C and 0.2 C. After 100 charge/discharge cycles, the ASSLB exhibited a 96 % capacity retention and a Coulumbic efficiency of over 90 % without short-circuiting due to lithium dendrites.

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