Structure and electrochemical properties of low-cobalt La_(1-x)Li_xNi_(3.2)Co_(0.3)Al_(0.3) (0≤x≤0.2) hydrogen storage electrode alloys

摘要

The structure and electrochemical properties of a new low cobalt hydrogen storage electrode alloys La1-xLixNi3.2Co0.3Al0.3 (0≤x≤0.2) were investigated with a different additions of Li in replacement of La. With the increase of Li contents the maximum discharge capacity increases from 240 mAh·g-1(x=0) to 328.4 mAh·g-1(x=0.1) and the cycle stability is improved correspondingly. The capacity decay can remain 28.6% (x=0.2) after 230 charge/discharge cycles. The high rate discharge(HRD) ability of the alloys(x≤0.1) is improved and the best HRD is 34.1%(x=0.1) under the discharge current density 1200 mA·g-1. It is found that the prepared alloys are basically composed of LaNi5 as matrix phase and LaNi3 as second phase(x≤0.1). But the abundance of LaNi3 phase dramatically decreases with increasing x. When x=0.2, a new phase Al(NiCo)3 is formed.