All-solid-state lithium-sulfur batteries with three-dimensional mesoporous electrode structures

Although the characteristics of lithium-sulfur batteries are advantageous for various applications, batteries with liquid electrolytes show capacity fading due to the dissolution of polysulfides. All-solid-state lithium-sulfur batteries with highly reversible characteristics are developed using a three-dimensional carbon matrix framework structure for the sulfur cathode. Sulfur is introduced into a carbon replica framework with a pore size of 8-100 nm. The composite electrode structure provides high electronic conduction and allows high cathode utilization during the battery reaction. The capacity of cells using a LiAl alloy as the negative electrode and the thio-LISICON (lithium superionic conductor) electrolyte increases when the pore size of the carbon replica is decreased from 100 nm to less than 15 nm. The highest capacity is obtained for the carbon replica with a pore size of 8.6 nm and a wall thickness of 4.7 nm. An examination of the relationship between the charge-discharge capacity and the structure of carbon replicas with different pore sizes and wall thicknesses indicates that three-dimensional highly ordered mesoporous carbon with a small pore size is a promising electrode structure for lithium-sulfur all-solid-state batteries.