Cycling Performance of Zinc-Nickel Rechargeable Battery Using Segmentation of Electrolyte

Abstract

An aqueous rechargeable battery (ARB) shows a high safety and a potential of high cycleability, which have been demonstrated with nickel-hydrogen batteries (NHB) used in electrified vehicles such as HEV and PHEV and electronic devices. A zinc-nickel secondary battery (ZNB) is one of the promising candidates of next-generation ARB which could have higher energy density and power density than NHB, although the zinc anode for secondary uses is still suffering from the issues on dendrite growth and non-uniform redistribution of zinc and zinc oxide, because they result in an internal short circuit and a poor capacity retention.In this paper, we introduce a novel zinc anode with segmentation of electrolyte (SoE) developed in our recent works. The concept of SoE is to segment the space of the electrolyte between the anode and the cathode. The electrolyte is KOH solutions containing zincate ions that are the intermediate of redox reaction between zinc and zinc oxide, and SoE gives the limited space for zincate ions, within which they can move free but the concentration change is suppressed in the limited space so that the non-uniform reaction distribution during charge and discharge is also inhibited.Our ZNB using SoE technology presented the excellent cycling performance at 1 C of charge-discharge rate for 5,500 cycles, in which the charge and discharge voltages hardly changed and the discharge capacity was 90% or more of the initial one during the cycles [1]. Comparison to ZNB using non-woven separator further indicated that SoE technology is beneficial to improve the cycling performance on cell voltage and capacity retention and ZNB with SoE is unnecessary to use non-woven separator. SoE is expected to solve the zinc anode problems of ZNB, i.e., both zinc dendrite and non-uniform distribution of zinc/zinc oxide, and may be applied to other zinc rechargeable battery such as zinc-air battery.This work was financially supported by DOWA Holdings, Co. Ltd.Ref. [1] M. Morimitsu, Patent No. WO-A1-2021/049609. Figure 1