Interfacial Chemistry Modulation via Amphoteric Glycine for a Highly Reversible Zinc Anode

Zn metal is thermodynamically unstable in aqueous electrolytes, which induces dendrite growth and ongoing parasitic reactions at the interface during the plating process and even during shelf time, resulting in rapid battery failure and hindering the practical application of aqueous Zn ion batteries. In this work, glycine, a common multifunctional additive, is utilized to modulate the solvation shell structure and enhance the interfacial stability to guard the reversibility and stability of the Zn anode. Apart from partially replacing the original SO42- in the contact ion pair of Zn2+[H2O]5 center dot OSO32- complexes to suppress the formation of Zn4(OH)6SO4 center dot xH2O byproducts at the interface, glycine molecules can also form a water-poor electrical double layer on the zinc metal surface during resting and be further reduced to build in situ a ZnS-rich solid electrolyte interphase (SEI) layer during cycling, which further suppresses side reactions and the random growth of Zn dendrites in the whole process. As expected, the cycle life of the symmetrical cells reaches over 3200 h in glycine-containing electrolytes. In addition, the Zn//NVO full cell shows exceptional cycling stability for 3000 cycles at 5 A g-1. Given the low-cost superiority of glycine, the proposed strategy for interfacial chemistry modulation shows considerable potential in promoting the commercialization progress of aqueous batteries.

Automated summary

In this study, glycine is used as an additive to modulate the solvation shell structure and enhance the interfacial stability of aqueous Zn ion batteries. The results show that the cycle life of the symmetrical cells reaches over 3200 h in glycine-containing electrolytes, and the Zn//NVO full cell exhibits exceptional cycling stability for 3000 cycles at 5 A g-1. Therefore, the proposed strategy for interfacial chemistry modulation, represented by glycine, has considerable potential in promoting the commercialization progress of aqueous batteries.