Saccharin Anion Acts as a “Traffic Assistant” of Zn²⁺ to Achieve a Long-Life and Dendritic-Free Zinc Plate Anode

Abstract

Due to the great advantages of low cost, high capacity, and excellent safety, the Zn metal is a promising candidate material for rechargeable aqueous battery systems. However, its practical applications have been restricted by the uncontrollable dendrite growth and electrode side reactions (such as corrosion, passivation, and hydrogen evolution reactions) during the plating process. Herein, we reveal that the dendrite growth would expose the electrode to more highly active tips, exacerbating the passivation of the electrode and the decomposition of the electrolyte by in situ optical microscopies. We propose a low-cost, nontoxic, low-concentration (less than 1 g/L), and effective electrolyte additive, saccharin sodium, which can guide an even Zn deposition without obvious electrode side reactions in the charge/discharge process. The saccharin anion acts as a “traffic assistant” of Zn2+ and demonstrates its great potential for practical application. The assembled Zn symmetrical battery shows an excellent cycling performance at a high current density and capacity (an extremely long cycle life over 3800 h is obtained at 5 mA/cm2 and 8 mA h/cm2, and 20 mA/cm2 and 5 mA h/cm2 show a lifetime over 800 h), and the full cell (coupled to an AC electrode) presents a stable cycle life with a capacity retention of 86.4% even after 8000 cycles at 5 mA/cm2. The saccharin sodium proposed in this work is promising to solve the anode problems in advanced Zn batteries.

Stabilizing Zinc Electrodes with a Vanillin Additive in Mild Aqueous Electrolytes

“…However, introducing massive organic species or highly concentrated salt would compromise the advantages of the intrinsic high safety and low cost of aqueous electrolytes. 29 Alternatively, electrolyte additives (either solute or solvent) with low concentrations are attractive. 30,31 Small amounts of additives such as poly(ethylene oxide), 32 polyacrylamide, 33 and tetrabutylammonium sulfate 34 effective to homogenize Zn deposition.…”

“…For example, “water-in-salt” highly concentrated aqueous electrolytes have been proposed to reduce the water activity and side reactions. , In addition, designing aqueous–organic hybrid electrolytes by coupling with organic solvents (e.g., dimethyl carbonate, dimethyl sulfoxide, and antisolvents) can modulate the Zn 2+ solvation shell to decrease the number of solvating H 2 O molecules, thus alleviating the generation of byproducts. However, introducing massive organic species or highly concentrated salt would compromise the advantages of the intrinsic high safety and low cost of aqueous electrolytes . Alternatively, electrolyte additives (either solute or solvent) with low concentrations are attractive. , Small amounts of additives such as poly­(ethylene oxide), polyacrylamide, and tetrabutylammonium sulfate have been demonstrated to be effective to homogenize Zn deposition.…”

Strategies of regulating Zn2+solvation structures for dendrite-free and side reaction-suppressed zinc-ion batteries

“…The strategies of zinc-philic additives and the corresponding electrochemical performance are summarized in Table 3. 58,87,101,207–209,211,213,216–225 These zinc-philic additives can adsorb onto the zinc anode surface via physical/chemical adsorption to form a protective layer on the anode surface, which can effectively prevent the contact between H 2 O and zinc and guide the uniform zinc deposition. Besides, the adsorbed additive molecules promote the desolvation of Zn(H 2 O) 6 2+ by removing H 2 O molecules from the solvation sheath of Zn 2+ , which can suppress the HER, corrosion, and formation of by-products and zinc dendrites.…”

Highly Strengthened and Toughened Zn–Li–Mn Alloys as Long‐Cycling Life and Dendrite‐Free Zn Anode for Aqueous Zinc‐Ion Batteries

“…For example, optimizing electrolyte formulations, designing additives, and hierarchical Zn microstructures, etc. [24][25][26][27][28][29][30] have been demonstrated to have positive effects on the zinc dendrite inhibition. Besides, Li and co-workers protect the Zn anode with hafnium-oxide to avoid growing dendrites.…”