Study on the surface modification of metal hydride electrodes with cobalt

A novel method has been applied to the surface modification of the metal hydride (MH) electrode of the MH/Ni batteries. Both sides of the electrode were plated with a thin cobalt film about 0.15 μm using vacuum evaporate plating technology and the effect of the electrode on the performance of the MH/Ni batteries was examined. It was found that the surface modification could enhance the electrode conductivity and decrease the battery ohmic resistance. After surface modification, the discharge capacity at 5C (8.5 A) was increased by 115 mAh and discharge voltage was increased by 0.04 V, the resistance of the batteries was also decreased by 18%. The batteries with modified electrode exhibited satisfactory durability. The remaining capacity of the modified batteries was 93% of the initial capacity even after 500 cycles. The inner pressure of the batteries during overcharging was lowered and the charging efficiency of the batteries was improved.