Enhancement of lithium-ion conductivity for Li_2.2C_0.8B_0.2O₃ by spark plasma sintering

Abstract

Lithium-ion conductivity of Li_2.2C_0.8B_0.2O₃ pellet is 2.1 × 10⁻⁶ S cm⁻¹ at 30°C after sintering at 450°C by spark-plasma sintering (SPS) process, which is about three times higher than the conductivity of the pellet sintered at 660°C in conventional furnace. The ionic resistance at grain boundary was especially minimalized by SPS process, which would be related to the grain-growth suppression under densification as confirmed by surficial SEM image. Improvement of charge–discharge capacity could be measured at all-solid-state lithium battery assembled by the SPS process (LiCoO₂–Li_2.2C_0.8B_0.2O₃ composite electrolyte/Li_2.2C_0.8B_0.2O₃/dry polymer/Li foil) compared with the same compositions of the battery assembled by conventional furnace sintering, which would be due to the enhancement of the ionic transfer at LiCoO₂/Li_2.2C_0.8B_0.2O₃ hetero interface as well as Li_2.2C_0.8B_0.2O₃/Li_2.2C_0.8B_0.2O₃ grain-boundary resistance.