Electrochemical characteristics of LaNi_(4,5)Co_(0.5) alloy composite hydrogen storage material at high discharge rates

摘要

Electrochemical hydrogen storage behavior ofLaNi_(4.5)Co_(0.5) powder composite electrode cycled in 6M KOH solution at increased discharge rates is discussed. Galvanostatic charging/discharging technique has been applied to determine high rate discharge ability (HRD) after N = 15 and N = 60 cycles. The anodic plots for both tested options are typical: electrode potential nearly linearly (with very low slope) increases with electrode discharge and then sharply jumps towards E_(end)= -0.5V (HgO/Hg) after electrode full dehydrogenation. Maximum discharge capacity (298 mAh·g~（-1） at -0.5C/+0.5C i.e. -186/+186 mA-g~（-1）) has been achieved after N = 31 cycles. The HRD markedly decreases with electrode cycling. After 15 cycles the HRD falls to 46.8 % at discharge rate of 5C. TheSEM examinations reveal severe structural deterioration of the electrode, especially evident after 60 cycles at the greatest discharge rates.