“Bowling Collision Effect” of CoMo₆ Polyoxometalate Units Enables Wide Temperature Range from −20 to 60 °C and Dendrite Mitigation Li‐S Batteries

Abstract

To improve the performance of Lithium-Sulfur (Li-S) batteries, the reaction catalysts of lithium polysulfides (LiPSs) reactions should have the characteristics of large surface area, efficient atomic utilization, high conductivity, small size, good stability, and strong adjustability. Herein, Anderson-type polyoxometalate ([TMMo₆O₂₄]^n-, TM = Co, Ni, Fe, represented by TMMo₆ POMs) are used as the modified materials for Li-S battery separator. By customizing the central metal atoms, this work gains insights into the layer-by-layer electron transfer mechanism between TMMo₆ units and LiPSs, similar to the collision effect of a bowling ball. Theoretical analysis and in situ experimental characterization show that the changes of CoMo₆ units with moderate binding energy and lowest Gibbs free energy result in the formation of robust polar bonds and prolonged S─S bonds after adsorption. Hence, the representative Li-S battery with CoMo₆ and graphene composite modified separator has a high initial capacity of 1588.6 mA h g^-1 at 0.2 C, excellent cycle performance of more than 3000 cycles at 5 C, and uniform Li⁺ transport over 1900 h. More importantly, this work has revealed the inherent contradiction between the kinetics and thermodynamics, achieving a stable cycle in the temperature range of -20 to 60 °C.