Co9S8/CNTs microspheres as superior-performance cathodes in aqueous ammonium-ion batteries

Coated Co 9 S 8 /carbon nanotube (Co 9 S 8 /2CNTs) microspheres were constructed and successfully applied to aqueous ammonium-ion batteries. The introduction of carbon nanotubes in the Co 9 S 8 microspheres increased the electronic conductivity, shortened the diffusion distance for NH 4 + ions and improved the buffering ability against volume changes in the cycling processes. As a result, Co 9 S 8 /2CNTs microspheres had a reversible capacity of 112 mA·h/g at 0.1 A/g. In addition, the ammonium ion energy storage mechanism accompanied by the formation of reversible phase transition product CoSO 4 ·6H 2 O and establishment/breaking of intermolecular hydrogen bonds in Co 9 S 8 /2CNTs was investigated.