Maximizing Electrostatic Polarity of Non‐Sacrificial Electrolyte Additives Enables Stable Zinc‐Metal Anodes for Aqueous Batteries

Abstract

Although additives are widely used in aqueous electrolytes to inhibit the formation of dendrites and hydrogen evolution reactions on Zn anodes, there is a lack of rational design principles and systematic mechanistic studies on how to select a suitable additive to regulate reversible Zn plating/stripping chemistry. Here, using saccharides as the representatives, we reveal that the electrostatic polarity of non‐sacrificial additives is a critical descriptor for their ability to stabilize Zn anodes. Non‐sacrificial additives are found to continuously modulate the solvation structure of Zn ions and form a molecular adsorption layer (MAL) for uniform Zn deposition, avoiding the thick solid electrolyte interphase layer due to the decomposition of sacrificial additives. A high electrostatic polarity renders sucrose the best hydrated Zn2+ desolvation ability and facilitates the MAL formation, resulting in the best cycling stability with a long‐term reversible plating/stripping cycle life of thousands of hours. This study provides theoretical guidance for the screening of optimal additives for high‐performance ZIBs.

Multifunctional Cellulose Nanocrystals Electrolyte Additive Enable Ultrahigh‐Rate and Dendrite‐Free Zn Anodes for Rechargeable Aqueous Zinc Batteries

“…The local electronegativity of Zn‐CNC‐COOH (−3.72 eV), Zn‐CNC‐OH (−3.59 eV), and CNC (−3.15 eV) showed a higher extremum than H 2 O (−2.59 eV), suggesting the potential effect of CNCs on the reconfiguration of solvation sheath. The strong interaction between CNCs and Zn 2+ could lead to replace one or more H 2 O molecules within the [Zn(H 2 O) 6 ] 2+ ion, thus diminishing the amount of H 2 O within the inner solvation sheath of the [Zn(H 2 O) 6 ] 2+ ion and promoting the Zn 2+ desolvation [26] . Furthermore, the strong interaction between −COOH and Zn 2+ is demonstrated, surpassing even the strength of interaction between −OH and Zn 2+ , indicating that CNCs with more negative MEP, rich and densely clustered oxygen‐contained functional groups would contribute to the strongest attractive potential to Zn 2+ ions and facilitate Zn 2+ desolvation, resulting in rapid diffusion kinetics.…”

“…The primary contributing factor to this predicament lies in the limited single‐role function and barren optimization capabilities of the current electrolyte additives [20,25] . Meanwhile, the majority of these additives are inappropriate for environmentally sustainable or commercially viable large‐scale applications due to their toxicity, flammability, instability, and readily sacrificable [20,24a,26] . The development of a multifunctional electrolyte additive that encompasses multiple mechanisms of action and exhibits superior optimization performance is crucial for the realization of high‐rate and long‐life Zn anodes for AZIBs [1a,20,27] .…”

An effective descriptor for the screening of electrolyte additives toward the stabilization of Zn metal anodes

“…4g and Table S2, ESI †). 38,[43][44][45][46][47][48][49][50][51] The interfacial kinetics of the Zn anode was evaluated by the rate performance of symmetric cells (Fig. 4e).…”

Trehalose in Trace Quantities as a Multifunctional Electrolyte Additive for Highly Reversible Zinc Metal Anodes

“…Saccharides, as one of the trace organic additives, have proven effective in enhancing the stability of Zn anodes by modulating solvation structures and establishing robust electrode–electrolyte interfaces, while avoiding the demerits that existed in organic solvent additives. , Despite the demonstrated effectiveness of saccharide additives in addressing the stability issues of Zn anodes, substantial challenges persist, and limited research has been conducted regarding practical application aspects. These include achieving high areal capacity at a high Zn utilization rate, ensuring functionality under low-temperature conditions, and assessing the viability of saccharide electrolyte additives in pouch cells. − Trehalose (TRE, C 12 H 22 O 11 ), as a natural sugar, possesses the unique ability to bond strongly with water molecules, safeguarding organisms under extreme conditions, and setting it apart from other saccharides. , Examining the molecular structure, TRE is abundant in hydroxyl groups, facilitating the formation of hydrogen bonds between TRE and water molecules while reducing H 2 O reactivity (Figure a). , Additionally, the presence of lone-pair electrons on oxygen atoms allows for achievable coordination between TRE and Zn 2+ , effectively modulating the solvation structure. , Therefore, TRE presents itself as a promising electrolyte additive for AZIBs.…”