How Is Cycle Life of Three-Dimensional Zinc Metal Anodes with Carbon Fiber Backbones Affected by Depth of Discharge and Current Density in Zinc-Ion Batteries?

Jing Li; Qiaowei Lin; Zhi Zheng; Liuyue Cao; Wei Lv; Yuan Chen

doi:10.1021/acsami.2c00344

How Is Cycle Life of Three-Dimensional Zinc Metal Anodes with Carbon Fiber Backbones Affected by Depth of Discharge and Current Density in Zinc-Ion Batteries?

ACS Appl Mater Interfaces. 2022 Mar 16;14(10):12323-12330. doi: 10.1021/acsami.2c00344. Epub 2022 Mar 2.

Authors

Jing Li¹, Qiaowei Lin², Zhi Zheng¹, Liuyue Cao¹, Wei Lv², Yuan Chen¹

Affiliations

¹ School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, New South Wales 2006, Australia.
² Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.

PMID: 35234443
DOI: 10.1021/acsami.2c00344

Abstract

Zinc (Zn) metal is an attractive anode material for aqueous Zn-ion batteries (ZIBs). Three-dimensional (3D) carbon frameworks may serve as lightweight and robust hosts to enable porous Zn electrodes with a long cycle life. However, Zn electrode tests under a low depth of discharge (DOD) and current density often yield unreliable promises. We used 3D Zn electrodes with carbon nanofiber framework (CNF) backbones (Zn@CNF) as model electrodes to reveal how DOD and current density affect their performance. Plasma-treated CNFs provide sufficient surface hydrophilicity and surface area to allow uniform Zn plating/stripping of a thin and uniform Zn coating (5 mAh cm^-2). CNFs only take a small weight fraction (17.5-19.7 wt. %) in the composite electrodes. The 3D structure and graphitic surface efficiently suppress dendrite growth. The cycle life of Zn@CNF can reach 843 h under 10% DOD and 0.5 mA cm^-2 in symmetric cells. However, high DOD and current density are detrimental to the stability of 3D Zn electrodes. The cycle life drops to 60.75 h under 60% DOD and 4 mA cm^-2. Full cells assembled using Zn@CNF as anodes and V₂O₅ as cathodes with an N/P capacity ratio of 2.4 delivered a capacity of 133.4 mAh g^-1 at 0.1 A g^-1. The full cells also showed excellent capacity retention of 92.1% after 260 cycles under 0.5 A g^-1 with a high average DOD_Zn of 15.5%. Our results suggest that 3D Zn electrodes with CNF backbones are promising anodes for ZIBs. Studying Zn metal electrodes under practical DOD and current density is essential to access their potential accurately.

Keywords: 3D framework; Zn metal anode; Zn-ion battery; carbon nanofiber; depth of discharge.