The inner cell pressure characteristics of Ni/MH rechargeable battery with Zr-based hydrogen storage alloy electrode modified by high surface area of Ni powder

Abstract

Efforts to improve the surface catalytic activity of electrodes has been made to decrease the internal pressure of a sealed Ni-MH battery in which the low-cost (Zr-Sn)(0.8)Ti-0.2 (Mn-0.7 (V-Fe)(0.5)Cr0.05Ni1.05)(0.9) alloys are used as the anode. To improve the surface catalytic activity of the Zr-based alloy which is closely related to the inner cell pressure behavior in a sealed cell, the electrode was fabricated by mixing the alloy with Cu powder and filamentary Ni powder. By replacing 25% of carbon black by filamentary Ni powder, the inner cell pressure has been suppressed significantly. The main reason for the reduction of inner cell pressure is the increase of overall surface catalytic activity of the Zr-based alloy electrode by addition of the filamentary Ni powder with high surface area. The filamentary Ni powder-mixed electrode has a surface area comparable to that of carbon black. It is assured that the Ni powder plays a role in enhancing a specific surface catalytic activity for the oxygen recombination reaction on the MH surface. (C) 2002 The Electrochemical Society.