Selenium-Doped Carbon Nanosheets with Strong Electron Cloud Delocalization for Nondeposition of Metal Oxides on Air Cathode of Zinc-Air Battery.

The deposition of metal oxides on the air cathode is a well-known problem for metal-air batteries, since it can cover the active surface and block the oxygen gas diffusion pathway, resulting in poor battery performance and serious cell degeneration. Herein, through deliberate selenium doping in nitrogen-doped carbon, a strong electron cloud delocalization among the carbon matrix is realized, which can prevent the air cathode from zinc oxide poisoning during zinc-air battery operation, as confirmed by experimental results and density functional theory simulations. In situ X-ray powder diffraction observation confirms that the increased electron cloud density of the surrounding carbon caused by electron delocalization from selenium atom could repulse the access of zincate ions, effectively prohibiting the oxide deposition on the air cathode. An amazingly long zinc-air battery cycle life reaching 780 cycles is thus obtained.