Improvement of Electrochemical Properties of AB_5-Type Hydrogen Storage Powder by N_2 Gas Atomization

摘要

N_2 gas and N_2-Ar mixed gas atomization followed by acid surface treatment has been applied to improve electrochemical properties of AB_5-type hydrogen storage alloy powder. Increasing N_2 content of mixed gas, powder shape became more irregular from the original spherical shape. Under auxiliary electrical conductivity of nickel powder addition in electrodes, discharge capacity of atomized powder was not varied while high rate dischargeability was improved with increasing N_2 content of atomizing gas. Without nickel powder of electrodes, N_2 atomized powder showed higher activation efficiency and discharge capacity than other atomized powder made with mixed gas or Ar gas and cast-pulverlized powder. It was considered that irregular shape of the powder promoted electrical conductivity in electrodes and catalytic nickel concentrated layer of powder surface was enhanced by surface treatment combined with N_2 gas atomization.