Lithium–sulfur (Li–S) batteries are one of the most promising next-generation energy storage technologies due to their high theoretical energy and low cost.^[1-2] However, Li–S cells with practically high energy still suffer from a very limited cycle life with reasons which remain unclear.^[3] Here, through cell study under practical conditions, we prove that an internal short circuit is a root cause of early cell failure and was ascribed to the crosstalk between the S cathode and Li anode. The cathode topography dictates S reactions through influencing the local resistance and electrolyte distribution, particularly under lean electrolyte conditions. The inhomogeneous reactions of S cathodes are easily mirrored by the Li anodes, resulting in exaggerated localized Li plating/stripping, Li filament formation and eventually cell internal short circuit. Manipulating cathode topography was proven effective to extend the cell cycle life under practical conditions. The findings of this work shed new light on the electrode design for extending cycle life of high-energy Li–S cells, which are also applicable for other rechargeable Li or metal batteries. Details of the progress will be discussed at the conference.

References

[1] X. L. Ji, K. T. Lee, L. F. Nazar, Nature Materials 2009, 8, 500-506.

[2] J. Xiao, Advanced Energy Materials 2015, 5.

[3] Y. L. Cao, M. Li, J. Lu, J. Liu, K. Amine, Nature Nanotechnology 2019, 14, 200-207.