The lithium/sulfur (Li/S) battery has been attracting increasing attention due to their higher theoretical specific energy density (2,600 Wh kg⁻¹). However, the practical energy density of the Li/S battery (soft package) is still low, accompanied other unsolved problems as poor cycle life, low safety as well as worse rate capability. In order to solve these problems, much research effort has been engaged in developing better cathode materials (carbon/sulfur), cathode structure, electrolyte and separators.

By improving the performance of key materials and structure (including the C/S composite, separators and electrolyte), the energy density of the Li/S battery has been improved to over 900 Wh/kg and 1000 Wh/L. For another thing, the Li/S cathode could reach over 100 cycles with capacity retention of 70% (still over 800 mAh/g (S)) with energy density of 300 Wh/kg. In this presentation, the design and preparation of key materials (especially cathode and electrolyte) for soft package batteries will be presented. The key issues and solutions that affect the cycle life and energy density of Li/S batteries would be discussed in detail.