Anion-chemistry-enabled positive valence conversion to achieve a record-high-voltage organic cathode for zinc batteries

作者：Chen, Ze; Cui, Huilin; Hou, Yue; Wang, Xiaoqi; Jin, Xu; Chen, Ao; Yang, Qi; Wang, Donghong; Huang, Zhaodong; Zhi, Chunyi^*

来源：Chem, 2022, 8(8): 2204-2216.

DOI：10.1016/j.chempr.2022.05.001

• HIGH-PERFORMANCE
• ION
• POLYMERS
• SPECTRA
• SODIUM
• ANODE
• RISE

Chalcogens undergoing positive valence conversions show great potential to achieve a high discharge voltage in batteries; however, such reactions with high reversibility are difficult to achieve because element O/S/Se are inherently electron acceptors. Herein, by incorporating the chalcogens with the unique triphenylphosphine-based structure (strong electron-withdrawing groups), a high-potential triphenylphosphine selenide organic cathode (TP-Se) is developed. Facilitated by a Zn2+/trifluoromethanesulfonate (OTF-) hosting mechanism, the (TP-Se)(-) to (TP-Se)(0) to (TP-Se)(+) conversion is realized. The dual-ion Zn||TP-Se batteries exhibit a flat discharge plateau at 1.96 V and a superior discharge capacity. Benefiting from the stable triphenylphosphine molecular structures and optimized hybrid electrolytes, excellent cycling performance is also attained (up to 85.3% capacity retention after 4,300 cycles). Moreover, the ZnkTP-Se battery also delivers a remarkable rate performance. The system is attractive due to its high discharge voltage, which is higher than ever reported for organic cathodes of zinc batteries.