关键词: 水系锌离子电池, 枝晶, 山梨醇添加剂, 溶剂化调节, 界面调节

Abstract:

The unstable zinc (Zn)/electrolyte interfaces formed by undesired dendrites and parasitic side reactions greatly hinder the development of aqueous zinc ion batteries. Herein, the hydroxy-rich sorbitol was used as an additive to reshape the solvation structure and modulate the interface chemistry. The strong interactions among sorbitol and both water molecules and Zn electrode can reduce the free water activity, optimize the solvation shell of water and Zn²⁺ ions, and regulate the formation of local water (H₂O)-poor environment on the surface of Zn electrode, which effectively inhibit the decomposition of water molecules, and thus, achieve the thermodynamically stable and highly reversible Zn electrochemistry. As a result, the assembled Zn/Zn symmetric cells with the sorbitol additive realized an excellent cycling life of 2000 h at 1 mA·cm^-2 and 1 mAh·cm^-2, and over 250 h at 5 mA·cm^-2 and 5 mAh·cm^-2. Moreover, the Zn/Cu asymmetric cells with the sorbitol additive achieved a high Coulombic efficiency of 99.6%, obtaining a better performance than that with a pure 2 mol·L^-1 ZnSO₄ electrolyte. And the constructed Zn/poly1, 5-naphthalenediamine (PNDA) batteries could be stably discharged for 2300 cycles at 1 A·g^-1 with an excellent capacity retention rate. This result indicates that the addition of 1 mol·L^-1 non-toxic sorbitol into a conventional ZnSO₄ electrolyte can successfully protect the Zn anode interface by improving the electrochemical properties of Zn reversible deposition/decomposition, which greatly promotes its cycle performance, providing a new approach in future development of high performance aqueous Zn ion batteries.

Key words: aqueous zinc ion batteries, dendrite, sorbitol additive, solvation regulation, interface modulation