Preparation of 3D spherical Ni/Al LDHs with significantly enhanced electrochemical performance as a superior cathode material for Ni/MH batteries

Abstract

Nickel-based hydroxides with excellent electrochemical performance have been considered as cathode materials for Ni/MH batteries. In this paper, a Ni/Al layered double hydroxides (Ni/Al LDHs) material with three-dimensional (3D) spherical structure is synthesized by a facile stable dual complexation–precipitation method. SEM images show that the obtained Ni/Al LDHs possess 3D spherical structure composed of nanosheets. XRD and CV tests indicate that doping of Al increases the distance between Ni–Al layers, greatly improving the specific capacity of the obtained materials. The electrochemical tests show that the specific capacity of the obtained material with 18% Al is up to 383.4 mAh g−1 at a current density of 1 A g−1. In addition, when the current density is further increased to 10 and 20 A g−1, the specific capacity of this material still maintains 345.0 mAh g−1 and 307.9 mAh g−1, respectively, which implies that this cathode material can provide remarkable power densities. Moreover, the material composed of Ni/Al LDHs keeps 97.6% initial capacity after 5000 cycles at a current density of 10 A g−1, showing an excellent cycling stability and durability.