Designing dense thick sulfur cathodes to gain high-volumetric/areal-capacity lithium-sulfur batteries (LSBs) in lean electrolytes is extremely desired. Nevertheless, the severe Li2 S clogging and unclear mechanism seriously hinder its development. Herein, an integrated strategy is developed to manipulate Li2 S redox kinetics of CoP/MXene catalyst via electron-donor Cu doping. Meanwhile a dense S/Cu0.1 Co0.9 P/MXene cathode (density = 1.95 g cm-3 ) is constructed, which presents a large volumetric capacity of 1664 Ah L-1 (routine electrolyte) and a high areal capacity of ≈8.3 mAh cm-2 (lean electrolyte of 5.0 µL mgs -1 ) at 0.1 C. Systematical thermodynamics, kinetics, and theoretical simulation confirm that electron-donor Cu doping induces the charge accumulation of Co atoms to form more chemical bonding with polysulfides, whereas weakens CoS bonding energy and generates abundant lattice vacancies and active sites to facilitate the diffusion and catalysis of polysulfides/Li2 S on electrocatalyst surface, thereby decreasing the diffusion energy barrier and activation energy of Li2 S nucleation and dissolution, boosting Li2 S redox kinetics, and inhibiting shuttling in the dense thick sulfur cathode. This work deeply understands the atomic-level manipulation mechanism of Li2 S redox kinetics and provides dependable principles for designing high-volumetric-energy-density, lean-electrolyte LSBs through integrating bidirectional electro-catalysts with manipulated Li2 S redox and dense-sulfur engineering.
Keywords: Cu-doped CoP/MXene; Li2S redox kinetics; dense sulfur cathodes; lithium-sulfur batteries; volumetric capacity.
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