Effect of Li 3 BO 3 addition to NASICON-type single-phase all-solid-state lithium battery based on Li 1.5 Cr 0.5 Ti 1.5 (PO 4 ) 3

Abstract

All-solid-state Li-ion battery is expected as the post Li-ion battery because of its high reliability and safety. However, the biggest issue for the all-solid-state Li-ion battery is the interfacial resistance between electrode and electrolyte rather than the bulk ionic conductivity of the solid electrolyte. In order to reduce the interfacial resistance, we recently adopted a new concept, “single-phase all-solid-state battery”, which is made of a single material. In principle, single-phase all-solid-state battery has low interfacial resistance between the solid electrolyte and electrodes, because the solid electrolyte and electrodes are same material. Here, the electrochemical properties of single-phase all-solid-state battery based on Li 1.5 Cr 0.5 Ti 1.5 (PO 4 ) 3 and the effect of Li 3 BO 3 additive as flux to Li 1.5 Cr 0.5 Ti 1.5 (PO 4 ) 3 are shown. The pellet of Li 1.5 Cr 0.5 Ti 1.5 (PO 4 ) 3 with Li 3 BO 3 additive showed higher density by filling the voids of Li 1.5 Cr 0.5 Ti 1.5 (PO 4 ) 3 . As the result of the low electronic conductivity of Li 3 BO 3 , the overpotential was increased. However, the electron leakage was suppressed. On the other hand, the operation voltage and the reversible capacity were improved due to the high lithium-ionic conductivity of Li 3 BO 3 . It was found that Li 3 BO 3 additive is useful for the improvement of the single-phase battery.