Effect of alkaline treatment for the alloys on the hydrogen absorbing reaction by using AC impedance method

LaNi5-xMx (M = Al. Co, x = 0, 0.3, 0.5) electrodes were treated by immersin g them in boiling alkaline solution to remove the oxide films front the all oy surface. The electrodes treated by immersing them in a boiling 6 mol dm( -3) KOH solution for 2 h were activated rapidly. and the capacity was incre ased 10 similar to 67%. The hydrogen absorbing reaction of the treated elec trodes has been investigated using the AC impedance method and MPS, and has been compared with the non-treated electrode. From these results, it was f ound that the oxide films on the alloy surface were removed and the number of Ni clusters on the alloy surface was increased by the alkaline treatment . Therefore, the hydrogen absorbing reaction in which the diffusion of hydr ogen atoms into the alloys follows the formation of hydrogen atoms was impr oved.