Outstanding Catalytic Effects of 1T'-MoTe<sub>2</sub> Quantum Dots@3D Graphene in Shuttle-Free Li-S Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 34351124.
- Also identified by DOI 10.1021/acsnano.1c03011.
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Abstract
It is still challenging to develop sulfur electrodes for Li-S batteries with high electrical conductivity and fast kinetics, as well as efficient suppression of the shuttling effect of lithium polysulfides. To address such issues, herein, polar MoTe<sub>2</sub> with different phases (2H, 1T, and 1T') were deeply investigated by density functional theory calculations, suggesting that the 1T'-MoTe<sub>2</sub> displays concentrated density of states (DOS) near the Fermi level with high conductivity. By optimization of the synthesis, 1T'-MoTe<sub>2</sub> quantum dots decorated three-dimensional graphene (MTQ@3DG) was prepared to overcome these issues, and it accomplished exceptional performance in Li-S batteries. Owing to the chemisorption and high catalytic effect of 1T'-MoTe<sub>2</sub> quantum dots, MTQ@3DG/S exhibits highly reversible discharge capacity of 1310.1 mAh g<sup>-1</sup> at 0.2 C with 0.026% capacity fade rate per cycle over 600 cycles. The adsorption calculation demonstrates that the conversion of Li<sub>2</sub>S<sub>2</sub> to Li<sub>2</sub>S is the rate-limiting step where the Gibbs free energies are 1.07 eV for graphene and 0.97 eV for 1T'-MoTe<sub>2</sub>, revealing the importance of 1T'-MoTe<sub>2</sub>. Furthermore, <i>in situ</i> Raman spectroscopy investigation proved the suppression of the shuttle effect of LiPSs in MTQ@3DG/S cells during the cycle.