Improvement of Rate Performance for All-Solid-State Na 15 Sn 4 /Amorphous TiS 3 Cells Using 94Na 3 PS 4 ·6Na 4 SiS 4 Glass-Ceramic Electrolytes

Rate performance of all-solid-state sodium cells (Na 15 Sn 4 /Na 3 PS 4 glass-ceramic/ a -TiS 3 ) was investigated. The resistance attributable to Na 15 Sn 4 negative electrode was increased with the discharge-charge cycles. The addition of acetylene-black (AB) to the Na 15 Sn 4 electrode suppressed the resistance increase and improved the rate performance; eg. the capacity at the current density of 0.13 mA cm −2 increased from ca. 65 mAh g −1 to ca. 175 mAh g −1 . In addition, the replacement of Na 3 PS 4 glass-ceramic by 94Na 3 PS 4 ·6Na 4 SiS 4 (mol%) glass-ceramic with a higher sodium ion conductivity decreased the cell resistance related to solid electrolyte (separator and positive electrode) and thus increased the cell capacity from ca. 36 mAh g −1 to ca. 185 mAh g −1 at the current density of 0.25 mA cm −2 .