Lithium-sulfur (Li-S) batteries are promising candidates for next generation electrical energy storage devices due to their high specific energy. Despite intense research, there are still a number of technical challenges in developing a high performance Li-S battery. To elucidate the issues, an all solid-state Li-S battery was fabricated using Li₃PS₄ solid electrolyte. Most of the theoretical capacity of sulfur, 1600 mAhg⁻¹ was attained in the initial discharge-charge cycles with a high coulombic efficiency approaching 99%. To verify the benefit of the solid state electrolyte, galvanostatic stripping-deposition tests were also carried out on a symmetrical Li/Li cell and compared with those of a liquid electrolyte (1 M- lithium bis(trifluoromethane sulfonyl) imide (LiTFSI) in a mixture of 1,3-dioxolane (DOL)-diethoxyethane (DEE)). The kinetics and thermodynamics of the solid-state cell are discussed from the viewpoint of the charge transfer processes. This study demonstrates both the merits and drawbacks of using the solid sulfide electrolyte in a Li-S battery and facilitates the further improvement of this important high energy storage device.

A lithium‐ion battery is reported using a sulfur–carbon composite cathode, a graphite anode, and a dimethoxyethane‐dioxolane‐lithium bis‐(trifluoromethanesulfonyl)imide (DOL‐DME‐LiTFSI) electrolyte advantageously added by lithium nitrate (LiNO₃) and a selected polysulfide (Li₂S₈). The suppressed sulfur dissolution, due to the Li₂S₈ buffer action, as well as reduced shuttle reactions by the film‐forming properties of the LiNO₃ positively affect the lithium‐ion cell behavior in terms of delivered capacity, coulombic efficiency, and cycle life. The lithium–sulfur cell shows a stable capacity of 750 mAh g⁻¹ for over 200 cycles with an enhanced cycling efficiency. Furthermore, the full lithium‐ion sulfur battery using a graphite‐based anode shows a working voltage of about 2 V and delivers a stable capacity of 500 mAh g⁻¹. The full cell has enhanced safety content, due to the replacement of the lithium metal anode by suitable intercalation electrode, and shows a theoretical energy density as high as 1000 Wh kg⁻¹ at high current rate of 1 C. The remarkable safety level, low materials cost, and high practical energy density, expected to exceed 300 Wh kg⁻¹, suggest the battery reported is a suitable energy storage system for future applications.