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

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, NaxTi0.5Co0.5O2, 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, Na0.7Ti0.5Co0.5O2 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. Highly stable NaxTi0.5Co0.5O2 is employed as a model catalyst for Li–S batteries to correlate the tunable electronic structure with the catalytic activity for the sulfur evolution reaction (SER). With partially removed Na+, Na0.7Ti0.5Co0.5O2 with abundant active sites and decreased work function largely accelerates the SER due to the lowered activation potential for Li2S resulting in excellent rate performance for the assembled batteries.