Li-S Batteries: Challenges, Achievements and Opportunities

To realize a low-carbon economy and sustainable energy supply, the development of energy storage devices has aroused intensive attention. Lithium-sulfur (Li-S) batteries are regarded as one of the most promising next-generation battery devices because of their remarkable theoretical energy density, cost-effectiveness, and environmental benignity. However, the practical application of Li-S batteries is hindered by such challenges as low sulfur utilization (< 80%), fast capacity fade, short service life (< 200 redox cycles), and severe self-discharge. The reasons behind the challenges are: (1) low conductivity of the active materials, (2) large volume changes during redox cycling, (3) serious polysulfide shuttling and, (4) lithium-metal anode contamination/corrosion and dendrite formation. Significant achievements have been made to address these problems in the past decade. In this review, the recent advances in material synthesis and technology development are analysed in terms of the electrochemical performance of different Li-S battery components. The critical analysis was conducted based on the merits and shortcomings of the reported work on the issues facing the individual component. A versatile 3D-printing technique is also examined on its practicability for Li-S battery production. The insights on the rational structural design and reasonable parameters for Li-S batteries are highlighted along with the “five 5s” concept from a practical point of view. The remaining challenges are outlined for researchers to devote more efforts on the understanding and commercialization of the devices in terms of the material preparation, cell manufacturing, and characterization. Graphical Abstract: [Figure not available: see fulltext.]