Targeted Catalysis of the Sulfur Evolution Reaction for High‐Performance Lithium‐Sulfur Batteries

Abstract The sluggish kinetics of the sulfur evolution reaction (SER) that occur because of the high oxidation barrier of Li₂S causes low sulfur utilization and the poor rate performance of lithium–sulfur batteries. However, the design of the catalysts to solve this problem is still hard to achieve because it is difficult to precisely correlate the catalytic oxidation ability with the electronic structure. Here, a layer transition metal oxide, Na_xTi_0.5Co_0.5O₂, is used as a model catalyst to probe such a correlation because it has a tunable electronic structure and good stability in the working potential window of Li–S batteries. By removing Na⁺, a partial phase change gradually increases the concentration of Co active sites while decreasing the work function with an upshift of the Fermi level, accelerating charge transfer on the catalyst surface and therefore improving its catalytic oxidation activity of Li₂S. In particular, Na_0.7Ti_0.5Co_0.5O₂ with two‐phases coexisting effectively lowers the activation potential of Li₂S, leading to minimum polarization and excellent rate performance, and even at 5.0 C, the assembled cell has a high capacity of 615 mAh g⁻¹. This study indicates a way to optimize the electronic structure to enhance the SER, which is important for promoting the practical use of Li–S batteries.