Effects of intermediate layer on interfacial resistance for all-solid-state lithium batteries using lithium borohydride

All-solid-state lithium batteries using LiBH4 electrolyte and LiCoO2 cathode were prepared, and the effect of the intermediate layers between LiBH4 and LiCoO2 was demonstrated by electrochemical measurement. Li3PO4, LiNbO3 and Al2O3 thin films with smooth surfaces deposited by PLD were utilized for the intermediate layer. With the intermediate layer, the interfacial resistance between LiBH4 and LiCoO2 decreased by as much as 3 orders of magnitude by suppressing the interfacial reaction between LiBH4 and LiCoO2. A 10–25nm-thick Li3PO4 intermediate layer was found to be the most effective to suppress the interfacial resistance. •All-solid-state batteries using LiBH4 as a solid electrolyte were prepared.•Large interfacial resistance between LiBH4 and LiCoO2 is the main issue.•Li3PO4, LiNbO3 and Al2O3 were adopted as the intermediate layers.•The 10–25nm-thick Li3PO4 layer presents the best characteristics.