Effect of alkali-treatment of hydrogen storage alloy on the degradation of Ni/MH batteries

Study on a low-cobalt Ml0.8Mg0.2Ni3.2Co0.3Al0.3 alloy

“…It can be seen that Mg increases in amount on the alloy surface after cycled. This indicates that Mg dissolves ÿrst and then deposits again as an oxide on the alloy surface during cycling process, which is the same as an other easily oxidized element of Mn [20]. The total amount of the easily oxidized elements in the low-Co alloy does not increase because of the Mn-free content, so the degree of oxidation of Ml0:8Mg 0:2 Ni3:2Co0:3Al0:3 shown in Table 5 is not higher than that of MmNi3:55Co0:75Mn0:4Al0:3.…”

Effects of pretreatment on MlNi4.00Co0.45Mn0.38Al0.3 hydrogen storage alloy powders and the performance of 6 Ah prismatic traction battery

“…The formation of micro-voids is due to the deposition of the metal oxides and hydroxides on the alloy surface, which leads to the formation of the porous surface by corrosion and etching of the alloy surfaces. Meanwhile, this porous surface with enriched Ni and Co atoms can also raise the oxidation resistance of alloy [43,46,47].…”

“…Corrosion is dependent on the composition of alloys and can be controlled by the surface treatment of the alloy powder. The structure changes caused by alkali-treatment on alloy surface can i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 7 ( 2 0 1 2 ) 1 2 3 8 4 e1 2 3 9 2 enhance the corrosion resistance and suppress the change in negative electrode [43,46,47]. Thus, the improved cycling performance should be attributed to the enriched Ni and Co layers, which can prevent the hydrogen storage alloy from being oxidized and inhibit the corrosion and pulverization of alloy powders.…”

Phase structure and electrochemical properties of La0.67Mg0.33Ni3.0−xCox (x=0.0, 0.25, 0.5, 0.75) hydrogen storage alloys

“…Partial substitution of Ni by Co was very effective to enhance the cycle life of LaNi 5 alloy [17][18][19][20][21][22][23][24]. However, effect of substitution of Ni with Co on the structure and electrochemical properties of La 0.67 Mg 0.33 Ni 3.0 alloy is not clear.…”