High-energy Li-S batteries hold the promise of prolonging the electric vehicles’ mileage, but have been largely impeded by the polysulfide shuttle effect. It is recently reported that the uniform Li₂S passivation layer deposited on the Li anode formed by side reactions (Li+(S_x)^2-→Li₂S) can perform a role in inhibiting polysulfide corrosion, however the Li dendrite growth usually leads to the collapse of the passivation layer and aggravates the side reactions [1, 2].

In this work, we propose to separate the Li₂S passivation layer from the Li dendrites, which is realized by fabricating a SiO₂ nanosphere layer impregnated with Li₂S. With such a pre-passivation strategy, the Li-S batteries exhibit a substantial prolonged cycle life (4 mg cm^-2 sulfur loading, > 3.6 mAh cm^-2, 84% capacity retention) for the reasons: (i) the impregnated Li₂S within the SiO₂ spheres chemically anchor the polysulfides and thus largely suppress the polysulfide crossover; (ii) the mechanically strong SiO₂ layer is capable of effectively mitigating the Li dendrite growth. The achieved results suggest that our strategies of building up a passivation layer separated from the Li anode is facile and effective, and can be readily for use in battery production.

Key words: Li-S battery; passivation layer; shuttle effect; Li dendrite.

References
[1] W. Li, H. Yao, K. Yan, G. Zheng, Z. Liang, Y.-M. Chiang, Y. Cui, Nature communications, 6 (2015).
[2] C. Yan, X.-B. Cheng, C.-Z. Zhao, J.-Q. Huang, S.-T. Yang, Q. Zhang, Journal of Power Sources, 327 (2016) 212-220.