The Effect of Li x Ni2-x O2/Ni with Modification Method on Activity and Durability of Alkaline Water Electrolysis Anode

Water electrolysis requires durability during a fluctuating power supply in power-to-gas application with renewable energies. The previously developed lithiated NiO modified Ni (LixNi2-xO2/Ni) has a high catalytic activity and durability during potential cycling, whereas the relatively high surface oxide resistance due to preparation of the oxidation at high temperature with a LiOH coating. In order to improve the catalytic activity, we proposed optimization of the oxide layer by thermal decomposition with various precursor coatings. The oxide layers prepared with acetate and nitrate precursors were dense and porous, respectively. The initial activity obtained from the acetate precursor electrode was higher than that of the nitrate precursor and the oxidation with the LiOH coating. Although the nitrate precursor electrode suffered from the same degradation as the Ni anode during potential cycling, the activity of the acetate precursor electrode as well as the oxidized electrode with the LiOH coating increased, and the activity for the former was almost the same as the initial Ni anode after 20,000 cycles. The lower preparation temperature of the acetate precursor would suppress the formation of the electron resistive nickel oxide between the base nickel and lithiated NiO, which was observed for the oxidized electrode with the LiOH coating as well. While the double-layer capacitance and redox peak around 1.3 V vs. RHE of the Ni and the nitrate precursor electrode significantly increased with Ni(IV) formation during potential cycling, those of the acetate precursor electrode slightly increased without any Ni(IV) formation. Therefore, the dense LixNi2-xO2 prepared with acetate has a good electric conductivity and catalytic activity with a high durability during potential cycling as the anode of an alkaline water electrolyzer for renewable power sources.