A Low‐Cost Quasi‐Solid‐State “Water‐in‐Swelling‐Clay” Electrolyte Enabling Ultrastable Aqueous Zinc‐Ion Batteries

Abstract

The poor reversibility of Zn metal anodes arising from water‐induced parasitic reactions poses a significant challenge to the practical applications of aqueous zinc‐ion batteries (AZIBs). Herein, a novel quasi‐solid‐state “water‐in‐swelling‐clay” electrolyte (WiSCE) containing zinc sulfate and swelling clay, bentonite (BT), is designed to enable highly reversible Zn metal anodes. AZIB full cells based on the WiSCE exhibit excellent cyclic stability at various current densities, long shelf life, low self‐discharge rate, and outstanding high‐temperature adaptability. Particularly, the capacity of WiSCE‐based AZIB full cells retains 90.47% after 200 cycles at 0.1 A g−1, 96.64% after 2000 cycles at 1 A g−1, and 88.29% after 5000 cycles at 3 A g−1. Detailed density functional theory calculations show that strong hydrogen bonds are formed between BT and water molecules in the WiSCE. Thus, water molecules are strongly confined by BT, particularly within the interlayers, which significantly inhibits water‐induced parasitic reactions and greatly improves cyclic stability. Compared to the state‐of‐the‐art “water‐in‐salt” electrolytes, the WiSCE can provide a significantly higher capacity at the full‐cell level with a substantially reduced cost, which is promising for the design of next‐generation high‐performance AZIBs. This work provides a new direction for developing cost‐competitive AZIBs as alternatives to grid‐scale energy storage.

The role of Mn in widening the potential window of solid solution derived electrodes for aqueous supercapacitors

“…It has been reported that GPE with limited free water can slow down the dissolution and side reactions of active substances, helping to improve the reversible capacity and stability of the electrode. 52–54 Thus, for practical application, we use PVA–KOH gel electrolyte as a model to assemble quasi-solid-state SSCs (as shown in Fig. S10b†).…”

Conductive Gels for Energy Storage, Conversion, and Generation: Materials Design Strategies, Properties, and Applications

“…To address this issue, the utilization of water-in-salt and hydrate melt electrolytes has been proposed, which partially mitigates the problem but does not eliminate it entirely. Additionally, it is essential to consider the complex and costly preparation process associated with these electrolytes [113,114].…”

Suppressing Dendrite Growth and Side Reactions via Mechanically Robust Laponite-Based Electrolyte Membranes for Ultrastable Aqueous Zinc-Ion Batteries

“…Effective strategies that can enhance the cyclic stability of AZIBs include anode modification, − separator functionalization, and electrolyte engineering. , From the perspective of water molecules, they exist in the bulk electrolyte phase or at the electrode/electrolyte interfaces. Moreover, regulating the water activity in aqueous electrolytes through additives has shown great potential to enhance the cyclic stability of AZIBs. , As summarized in Table S1, electrolyte additives, including organic molecules, − inorganic salts, − metal oxide particles, − and carbon materials, have been added to the baseline electrolytes (e.g., 1–3 M ZnSO 4 ). However, the water activity and how it is affected by the additive-water interactions in these engineered electrolyte systems have not been thoroughly understood.…”

“…Moreover, regulating the water activity in aqueous electrolytes through additives has shown great potential to enhance the cyclic stability of AZIBs. 7,21 As summarized in Table S1, electrolyte additives, including organic molecules, 22−24 inorganic salts, 25−27 metal oxide particles, 28−30 and carbon materials, 31 have been added to the baseline electrolytes (e.g., 1−3 M ZnSO 4 ). However, the water activity and how it is affected by the additive-water interactions in these engineered electrolyte systems have not been thoroughly understood.…”