The slow oxygen reduction reaction (ORR) of zinc-air battery cathodes has been an obstacle to the commercial application, and one possible solution is to use platinum (Pt) and Pt-based catalysts, but its high cost and scarce availability make it less ideal. In addition, alkaline KOH (or NaOH) is generally used as the electrolyte, but it leads to the generation of carbonates from the dissolution of CO 2 in the electrolyte as well as the spontaneous corrosion of the anodic zinc in strong alkaline media. This has the effect of slowing down the ionic conductivity of the electrolyte and battery life and means a neutral electrolyte should be used instead along with a non-precious metal ORR catalyst.
The team of researchers from the School of Chemistry and Chemical Engineering at Hunan University of Science and Technology prepared a Ni/Co-doped C-N hollow nanotube composite catalysts (C-N, Co/C-N, Ni/C-N and Ni-Co/C-N) in a Ni/Co salt with dicyandiamide and glucose. The composites have a curly tubular structure, resulting in a large active surface area and stability.
This was used for a zinc-air battery in a neutral medium using the prepared sample as the catalyst of the air electrode. The battery delivers the open circuit voltage of 1.13 V and the maximum power density of 65 mW/cm 2. The constant discharge current density of 50, 100 and 150 mA/cm 2 can last 202, 93 and 11 hours respectively and the battery can be repeatedly discharged after replacing the zinc anode, showing the high stability of the cathodic catalyst and broad application prospects as a mobile power source.