High-Performance Self-Healing Polyurethane Binder Based on Aromatic Disulfide Bonds and Hydrogen Bonds for the Sulfur Cathode of Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries have been the focus of new energy due to their excellent energy density, but the large volume changes in sulfur cathodes and the shuttle of polysulfides seriously hinder their further development. Therefore, solving both the abovementioned problems is the key to the widespread applications of Li–S batteries. Here, a smart self-healing polyurethane binder (PUB) with sulfur fixation ability is successfully developed for sulfur cathodes. In this design, aromatic disulfide bonds are introduced into the PUB matrix and cooperated with hydrogen bonds in the matrix to provide the self-healing property. The PUB can ensure the sulfur cathode an integrated physical structure by autonomously healing the microcracks caused by volume changes. The sulfur-fixing groups in the PUB can effectively absorb the polysulfides in the electrochemical reaction to suppress the shuttling effect. As a result, the Li–S batteries exhibit a high electrochemical capacity of 1269.7 mA h g–1 and a small fading rate of 0.04% per cycle at 2 C for 500 cycles. Hence, the PUB with dual functions of self-repair and sulfur fixation can effectively stabilize the electrode structures of Li–S batteries and guarantee their electrochemical performance.