Li Shuo, Zhang Guoli, Li Qianrui, He Tianshun, Sun Xiaoqi
Department of Chemistry, Northeastern University Shenyang 110819 China
National Frontiers Science Center for Industrial Intelligence and Systems Optimization, Northeastern University 3-11 Wenhua Road Shenyang 110819 China.
Chem Sci. 2024 Oct 10;15(43):17971-8. doi: 10.1039/d4sc04685d.
Small quinone molecules are promising cathode materials for aqueous zinc batteries. However, they experience fast capacity decay due to dissolution in electrolytes. Herein, we introduce a simple methyl group to a naphthoquinone (NQ) cathode and demonstrate a facile self-saturation strategy. The methyl group exhibits hydrophobic properties together with light weight and a weak electron-donation effect, which allows a good balance among cycling stability, capacity and voltage for cathode materials. The resulting menadione (Me-NQ) presents around one-third solubility of NQ. The former thus rapidly reaches saturation in the electrolyte during cycling, which suppresses subsequent dissolution. Thanks to this process, the Me-NQ cathode preserves 146 mA h g capacity after 3500 cycles at 5 A g, far exceeding 88 mA h g for NQ. Me-NQ also delivers a stabilized capacity of 316 mA h g at 0.1 A g with only 0.05 V lower average redox voltage than NQ. The co-storage of Zn and H with the redox reactions on the carbonyl sites of Me-NQ is revealed.
小分子醌是水系锌电池中很有前景的阴极材料。然而，由于它们在电解质中溶解，其容量会快速衰减。在此，我们将一个简单的甲基引入萘醌（NQ）阴极，并展示了一种简便的自饱和策略。甲基具有疏水特性，重量轻且电子给体效应弱，这使得阴极材料在循环稳定性、容量和电压之间实现了良好的平衡。由此得到的甲萘醌（Me-NQ）的溶解度约为NQ的三分之一。因此，前者在循环过程中能迅速在电解质中达到饱和，从而抑制后续溶解。得益于这一过程，Me-NQ阴极在5 A g下循环3500次后仍保持146 mA h g的容量，远高于NQ的88 mA h g。Me-NQ在0.1 A g下也能提供316 mA h g的稳定容量，其平均氧化还原电压仅比NQ低0.05 V。研究揭示了在Me-NQ的羰基位点上，锌和氢与氧化还原反应的共存储现象。
