A Double‐Charged Organic Molecule Additive to Customize Electric Double Layer for Super‐Stable and Deep‐Rechargeable Zn Metal Pouch Batteries

• Published in: Advanced functional materials 2024-02, Vol.34 (8), p.n/a
• Main Authors: Hu, Nan, Lv, Wensong, Chen, Wenjian, Tang, Huan, Zhang, Xiaoyan, Qin, Hongyu, Huang, Dan, Zhu, Jinliang, Chen, Zhengjun, Xu, Jing, He, Huibing
• Format: Article
• Language: English
• Subjects: A double‐charged organic molecule; aqueous zinc metal batteries; Charging; Diffusion layers; Electric double layer; Electrochemical analysis; electrolyte additive; Electrolytic cells; Organic chemistry; Solvation
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202311773

The electrochemical performance of aqueous zinc metal batteries (AZMBs) is highly dependent on the electric double layer (EDL) properties at Zn electrode/electrolyte interface. Herein, a novel reconfigured EDL is constructed via a double‐charged theanine (TN) additive for super‐stable and deep‐rechargeable AZMBs. Experiments and theoretical computations unravel that the positively charged TN not only serves as preferential anchor to form a water‐poor Helmholtz plane onto the Zn anode, but also its anionic end could coordinate with Zn2+ to tailor the solvation structure in the diffusion layer and further reconstruct the inner H‐bonds networks, thus effectively guiding uniform Zn deposition and suppressing the water‐induced side reactions. Consequently, the Zn//Zn cells acquire outstanding cycling stabilities of nearly 800 h at a high depth of discharge of 80%. Moreover, the Zn//VOX full cells deliver substantial capacity retention (94.12% after 1400 cycles at 2 A g−1) under practical conditions. Importantly, the designed 2.7 Ah Zn//VOX pouch cell harvests a recorded energy density of 42.3 Wh Kgcell−1 and 79.5 Wh Lcell–1, with a remarkable capacity retention of 85.93% after 220 cycles at 50 mA g−1. This innovative design concept to reshape the EDL chemistry would inject fresh vitality into developing advanced AZMBs and beyond. A double‐charged organic molecule additive of theanine fosters the customized electric double layer structure with a regulated Zn anode interface in the Helmoze plane, tailored Zn2+ solvation chemistry and reconstructed inner H‐bonds networks in the diffusion layer, rendering the high‐performance Zn metal anodes.