Structure and electrochemical properties of low-cobalt La1−x LixNi3.2 Co0.3Al0.3(0≤x≤0.2) hydrogen storage electrode alloys

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 La-Ni3 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.