Solid-state lithium-ion battery employing LiBH4–ZrO2 as a solid-state electrolyte

LiBH₄ has been extensively investigated as a solid-state electrolyte for Li-ion battery applications. The crucial point is that the operating temperature for this material needs to be above 120 °C, due to its low ionic conductivity at room temperature. In this study, the Li-ion conductivity of LiBH₄ has been enhanced by mixing it with ZrO₂. The optimal composition of the mixture was found to be 37 v/v% of ZrO₂, exhibiting a Li-ion conductivity of 3.32 × 10^-4 S cm^-1 at 60 °C. The electrochemical stability window of the mixture (2.4 V vs. Li⁺/Li) is slightly higher compared to that of pure LiBH₄. The optimized mixture was used as an electrolyte in TiS₂/Li all-solid-state Li-ion batteries. Two batteries were successfully cycled at 60 °C. The effect of charging profile was investigated to improve the performance of the battery.