Synthesis and Electrochemical Properties of Hierarchical Porous (Nickel/Cobalt)‐Carbonate‐Hydroxide Structures

Abstract

Abstract Hierarchical porous Ni 3 (CO 3 )(OH) 4 and (Ni x Co 1‐ x ) 6 (CO 3 ) 2 (OH) 8 ⋅ H 2 O ( x =0, 1/3, 1/2, and 2/3) structures have been synthesized via a hydrothermal route. The chloride ions in the precursor play an important role in the morphology of (Ni,Co) 6 (CO 3 ) 2 (OH) 8 ⋅ H 2 O. The formation mechanism and growth process of urchin‐like (Ni,Co) 6 (CO 3 ) 2 (OH) 8 ⋅ H 2 O structure was investigated by adjusting the reaction time. The electrochemical properties of the products depend on the chemical composition and surface property. Ni 3 (CO 3 )(OH) 4 exhibits higher specific capacitance at a low current density due to its porous structure and larger specific surface area. However, its rate property and cycle stability are much poorer. Co 6 (CO 3 ) 2 (OH) 8 ⋅ H 2 O nanorod‐assembled structure possesses better cyclic performance but lower specific capacitance. (Ni,Co) 6 (CO 3 ) 2 (OH) 8 ⋅ H 2 O electrodes behave improved rate property and cycle stability in comparison with Ni 3 (CO 3 )(OH) 4 , and higher specific capacitance than Co 6 (CO 3 ) 2 (OH) 8 ⋅ H 2 O, which can be attributed to the synergistic effect of bimetal species and unique surface property.