Crucial role of water content on the electrochemical performance of α-Ni(OH)2 as an anode material for lithium-ion batteries

Abstract

In this work, we investigate the influence of water content on the lithium storage performance of α-Ni(OH)2 samples prepared by homogeneous precipitation method and subsequent heat treatment at different temperatures. It is found that the adsorbed water in α-Ni(OH)2 has a decisive impact on the cycling stability and rate capability of the electrode; in contrast, the effect of interlayer water contents is not significant. For example, the α-Ni(OH)2 sample with adsorbed water molecules (heat-treated at 100 °C) delivers a reversible specific capacity of 1115 mAh g−1 at 500 mA g−1 after 30 cycles, while the α-Ni(OH)2 sample after removing the adsorbed molecules (heat-treated at 150 °C) gives a capacity of only 516 mAh g−1 under the same measurement condition. EIS and CV analyses reveal that the adsorbed water molecules in α-Ni(OH)2 decrease the electrochemical reaction resistance, increase lithium ion diffusivity, and greatly enhance the pseudocapacitive charge storage behavior, which lead to superior performance in cycle life and rate capability.