Mitigation of shuttle effect in Li-S battery using a self-assembled ultrathin molybdenum disulfide interlayer.

Lithium-sulfur batteries are promising for low-cost and high energy storage, but their applications are still limited by poor cycling stability owing to soluble lithium polysulfide shuttling during battery operation. Avoiding shuttle effect is challenging but essential to avoid active material loss and prevent performance decay. Here we use an ultrathin layer of MoS2 with thickness of 10-40 nm, which is 1-2 orders of magnitude thinner than conventional interlayers, for Li-S batteries to mitigate polysulfide shuttling. The MoS2 layer formed by exfoliated nanoflakes is deposited by a scalable liquid-based self-assembly method. With less than 1% of additional weight in the cathode, the MoS2 interlayer with complete coverage inhibits polysulfide diffusion across the separator, and therefore remarkably improves the battery performances. Reversible specific capacity reaches 1010 mA h g-1 and 600 mAh g-1 at 0.5 C and 2 C rate, respectively, which decay slowly over 400 cycles (0.11% per cycle). Moreover, the MoS2 film with high density of catalytic active flake edges enable high areal sulfur loading up to 10 mg cm-2 and areal capacity up to 9.7 mA h cm-2 at 3.2 mA cm-2 current density.