Optimizing the charging protocol to address the self-discharge issues in rechargeable alkaline Zn-Co batteries

Wenxu Shang, Wentao Yu, Xu Xiao, Yanyi Ma, Ziqi Chen, Meng Ni, Peng Tan

Research output: Journal article publicationJournal articleAcademic researchpeer-review

Abstract

Aqueous rechargeable Zn-Co batteries feature intrinsic safety and excellent electrochemical performance, and zinc metal is cheap with abundant reserves. However, a key issue, self-discharge, which may be fatal to the application, is always overlooked. Herein, the self-discharge performance is investigated systematically for the first time, and in-depth charge–discharge mechanisms are analyzed. Based on a free-standing Co3O4 electrode, the insufficient utilization of the active material is found under a conventional galvanostatic charging process. Additionally, a dramatic attenuation in the open-circuit voltage is exhibited during the delay, leading to poor capacity retention. Through electrochemical tests and ex-situ characterization, the limited capacity and the severe self-discharge behavior are ascribed to the low amount and poor stability of the high valence state, respectively. Aiming at suppressing the self-discharge behavior, a novel charging protocol is proposed based on a new mechanism, which uses a time-controlling potentiostatic charging after the galvanostatic charging process. Using this strategy, the discharge capacity increases effectively by about 31.8% from 220 to 290 mA h g−1, and the capacity retention ratio after 10 h delay lifts from 72% to 90%. More importantly, the discharge capacity remains 100% after even 2500 cycles. This work puts forward a practical method for the operation of Zn-Co batteries, addresses the limiting issues for application, and greatly facilitates the improvement of this technology. Further, the results also inspire the research of other rechargeable Zn-based batteries.

Original languageEnglish
Article number118366
JournalApplied Energy
Volume308
DOIs
Publication statusPublished - 15 Feb 2022

Keywords

  • Charging protocol
  • High capacity
  • Low self-discharge rate
  • Zn-Co batteries

ASJC Scopus subject areas

  • Building and Construction
  • Mechanical Engineering
  • Energy(all)
  • Management, Monitoring, Policy and Law

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