Researchers at the University of Texas at Austin are proposing a novel approach to suppress the “polysulfide shuttle” in Li-S batteries—a freestanding, three-dimensional graphene/1T MoS₂ (3DG/TM) heterostructure with highly efficient electrocatalysis for lithium polysulfides (LiPSs).

Cells with 3DG/TM exhibit outstanding electrochemical performance, with a high reversible discharge capacity of 1181 mAh g^-1 and a capacity retention of 96.3% after 200 cycles. An open-access paper on their work is published in the RSC journal Energy & Environmental Science.

The 3DG/TM heterostructure is constructed by a few-layered graphene nanosheets sandwiched by hydrophilic, metallic, few-layered 1T MoS₂ nanosheets with abundant active sites.

The metallic 1T MoS₂ nanosheets are hydrophilic with rich active sites and high electronic conductivity that is six orders of magnitude higher than that of 2H MoS₂.

The conversion process of LiPSs on a graphene surface with 1T MoS₂. The 3DG/TM heterostructures work as a highly efficient electrocatalyst for LiPSs conversion. He et al.

The porous 3D structure and the hydrophilic feature of 1T-MoS₂ are beneficial for electrolyte penetration and Li-ion transfer, and the high conductivities of both graphene and 1T MoS₂ nanosheets facilitate electron transfer.

These attributes lead to a high electrocatalytic efficiency for LiPSs due to excellent ion/electron transfer and sufficient electrocatalytic active sites.

Resources

• Jiarui He, Gregory Hartmann, Myungsuk Lee, Gyeong S. Hwang, Yuanfu Chen and Arumugam Manthiram (2018) “Freestanding 1T MoS₂/Graphene Heterostructure as a Highly Efficient Electrocatalyst for Lithium Polysulfides in Li-S Batteries” Energy Environ. Sci. doi: 10.1039/C8EE03252A