Highly Reversible Zinc Metal Anode in a Dilute Aqueous Electrolyte Enabled by a pH Buffer Additive

Wei Zhang; Yuhang Dai; Ruwei Chen; Zhenming Xu; Jianwei Li; Wei Zong; Huangxu Li; Zheng Li; Zhenyu Zhang; Jiexin Zhu; Fei Guo; Xuan Gao; Zijuan Du; Jintao Chen; Tianlei Wang; Guanjie He; Ivan P Parkin

doi:10.1002/anie.202212695

Highly Reversible Zinc Metal Anode in a Dilute Aqueous Electrolyte Enabled by a pH Buffer Additive

Angew Chem Int Ed Engl. 2023 Jan 26;62(5):e202212695. doi: 10.1002/anie.202212695. Epub 2022 Dec 7.

Authors

Wei Zhang¹, Yuhang Dai², Ruwei Chen¹, Zhenming Xu³, Jianwei Li¹, Wei Zong¹, Huangxu Li⁴, Zheng Li⁵, Zhenyu Zhang², Jiexin Zhu², Fei Guo², Xuan Gao¹, Zijuan Du¹, Jintao Chen¹, Tianlei Wang¹, Guanjie He^{1

2}, Ivan P Parkin¹

Affiliations

¹ Christopher Ingold Laboratory, Department of Chemistry, University College London, London, WC1H 0AJ, UK.
² Electrochemical Innovation Lab (EIL), Department of Chemical Engineering, University College London, London, WC1E 7JE, UK.
³ Jiangsu Key Laboratory of Electrochemical Energy Storage Technologies, College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, P. R. China.
⁴ Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong, 999077, P. R. China.
⁵ School of Metallurgy and Environment, Central South University, Changsha, 410083, P. R. China.

Abstract

Aqueous zinc-ion batteries have drawn increasing attention due to the intrinsic safety, cost-effectiveness and high energy density. However, parasitic reactions and non-uniform dendrite growth on the Zn anode side impede their application. Herein, a multifunctional additive, ammonium dihydrogen phosphate (NHP), is introduced to regulate uniform zinc deposition and to suppress side reactions. The results show that the NH₄ ⁺ tends to be preferably absorbed on the Zn surface to form a "shielding effect" and blocks the direct contact of water with Zn. Moreover, NH₄ ⁺ and (H₂ PO₄ )^- jointly maintain pH values of the electrode-electrolyte interface. Consequently, the NHP additive enables highly reversible Zn plating/stripping behaviors in Zn//Zn and Zn//Cu cells. Furthermore, the electrochemical performances of Zn//MnO₂ full cells and Zn//active carbon (AC) capacitors are improved. This work provides an efficient and general strategy for modifying Zn plating/stripping behaviors and suppressing side reactions in mild aqueous electrolyte.

Keywords: Additive; Aqueous Electrolyte; Dendrite Growth; Zinc Anode; pH Buffer.

Abstract

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