Formulating energy density for designing practical lithium-sulfur batteries

Li-S batteries are a promising next-generation storage technology and the assessment of their performance is critical for their development. Here the authors analyse key Li-S cell parameters, formulate the energy density calculation and discuss design targets for practical applications. The lithium-sulfur (Li-S) battery is one of the most promising battery systems due to its high theoretical energy density and low cost. Despite impressive progress in its development, there has been a lack of comprehensive analyses of key performance parameters affecting the energy density of Li-S batteries. Here, we analyse the potential causes of energy loss during battery operations. We identify two key descriptors (R-weight and R-energy) that represent the mass- and energy-level compromise of the full-cell energy density, respectively. A formulation for energy density calculations is proposed based on critical parameters, including sulfur mass loading, sulfur mass ratio, electrolyte/sulfur ratio and negative-to-positive electrode material ratio. The current progress of Ah-level Li-S batteries is also summarized and analysed. Finally, future research directions, targets and prospects for designing practical high-performance Li-S batteries are proposed.

Automated summary

The authors analyze key Li-S cell parameters, propose an energy density calculation, and discuss the design targets for practical high-performance Li-S batteries.