Atomic layer deposition-enabled ultrastable freestanding carbon-selenium cathodes with high mass loading for sodium-selenium battery

摘要

AbstractMelt diffusion followed by vapor deposition is judiciously combined with atomic layer deposition (ALD) to construct Al2O3–coated (Se/porous N-doped carbon nanofibers)@Se composite (denoted SC@Se-Al2O3) materials for sodium-selenium (Na-Se) batteries. High mass loading, ultrastable and free-standing carbon-selenium cathode is conveniently achieved by tailoring both the Se content and the thickness of deposited Al2O3layer. Importantly, in contrast to only 176 mAh g?1of the electrode without Al2O3deposition after 660 cycles, the composite with a Se content of 67wt% and a 3-nm Al2O3thickness retains a reversible capacity of 503 mAh g?1after 1000 cycles with no capacity fading at 0.5Ag?1. These findings clearly suggest that ALD strategy provides a viable, controllable and effective means of tuning the electrode performance towards high mass loading of active materials and long cycle life of the resulting battery for energy storage applications.Graphical abstractCarbon-selenium composites with high Se conte