Zinc Plating on Inkjet-Printed Ti3C2Tx MXene: Effect of Electrolyte and PEG Additive

Abstract

Zinc-ion batteries (ZIBs) are currently being studied as an alternative to lithium-ion batteries (LIBs). The nucleation and growth of the zinc deposition mechanism is a critical field of research in ZIBs, as it directly affects the battery efficiency and lifespan. It is of paramount importance in mitigating the formation of porous, dendritic Zn structures that may cause cell inefficiency and, eventually, short-circuiting failures. Interfacial engineering plays a key role in providing reversible plating and stripping of metallic Zn in ZIBs through the proper regulation of the electrode–electrolyte interface. In this work, we investigated the behavior and characteristics of Zn plating on inkjet-printed Ti3C2Tx MXene-coated substrates according to the different electrolyte compositions. Specifically, ZnCl2 and ZnSO4 solutions were employed, evaluating the effect of a relatively low-molecular-weight polyethylene glycol (PEG400) addition to the electrolyte as additive. Electrochemical analyses demonstrated higher deposition kinetics in chloride-based electrolytes rather than sulfate ones, resulting in lower nucleation overpotentials. However, the morphology and microstructure of the plated Zn, investigated via scanning electron microscopy (SEM) and X-ray diffraction (XRD), revealed that the electrolytic solution played a predominant role in the Zn crystallite formation rather than the Ti3C2Tx MXene coating. Specifically, the preferential Zn [002] orientation could be favored when using additive-free ZnSO4 solution, and a PEG addition was found to be an efficient texturing agent only in ZnCl2 solution.