Local Lattice Distortion Activate Metastable Metal Sulfide as Catalyst with Stable Full Discharge-Charge Capability for Li-O2 Batteries.

The direct lattice strain, either distortion, compressive, or tensile, can efficiently alter the intrinsic electrocatalytic property of the catalysts. In this work, we report a novel and effective strategy to distort the lattice structure by constructing a metastable MoSSe solid solution and thus, tune its catalytic activity for the Li-O2 batteries. The lattice distortion structure with inequivalent interplanar spacing between the same crystals plane were directly observed in individual MoSSe nanosheets with transmission electron microscopy and aberration-corrected transmission electron microscopy. In addition, in situ transmission electron microscopy analysis revealed the fast Li+ diffusion across the whole metastable structure. As expected, when evaluated as oxygen electrode for deep-cycle Li-O2 batteries, the metastable MoSSe solid solution deliver a high specific capacity of ∼730 mA h g-1 with stable discharge-charge overpotentials (0.17/0.49 V) over 30 cycles.