Influence of Nickel Foam Pore Structure on the High-Rate Capability of Nickel/Metal-Hydride Batteries

The influence of nickel foam pore structure on the high-rate capability of nickel/metal-hydride (Ni/MH) batteries was studied to develop a substrate suitable for high-power use. Three types of nickel foam substrates with different pore structures were used for preparing the sealed cells. Among the three prepared sealed cells, the cell using the substrate with a smallest pore diameter and largest surface area exhibited the best high-rate discharging performance. The electrochemical impedance measurement also showed a close relationship between the charge-transfer resistance and the pore structure of the substrate. The contact area between the current collector and the active material is considered to significantly affect the contact resistance and the charge-transfer resistance. The pore-size reduction and the enlargement of the surface area of the substrate were revealed to be effective in improving the high-rate performance of Ni/MH batteries.