Zinc-induced phase reconstruction of cobalt-nickel double hydroxide cathodes for high-stability and high-rate nickel-zinc batteries

Nickel-zinc (Ni-Zn) batteries have received extensive attention in the field of energy storage. However, the unsatisfactory durability greatly impedes their wider commercial application. Herein, a novel and efficient zinc induced phase reconstruction method was reported to boost the electrochemical stability of cobalt-nickel double hydroxide (CoNi-DH) cathode materials for developing high-stability and high-rate Ni-Zn batteries. The inherent mechanism for this phase reconstruction method to achieve the improvement of electrochemical stability was systematically investigated and clarified in this work by combining theoretical calculations and experimental tests. The research results confirmed that the zinc-induced phase reconstruction can produce a new phase of Zn2Co3(OH)(10)center dot 2H(2)O in the mixed-phase of CoNi-DH without sacrificing its hierarchical micro-nano structure. This Zn2Co3(OH)(10)center dot 2H(2)O phase has a much smaller shrinkage of the lattice spacing of host layers during the redox reaction relative to the pure Co(OH)(2) phase, thereby it can inhibit structural damage during the charge-discharge cycle. In addition, the retained hierarchical micro-nano structure can ensure good capacity output. Therefore, the as-fabricated mixed hydroxide electrode and Ni-Zn battery achieve remarkable improvement in the cycling life and exhibit superior rate performance. Moreover, the resultant mixed hydroxide electrode displays good application in the flexible quasi-solid-state Ni-Zn battery.