Sustainable treatment of dye wastewater for high-performance rechargeable battery cathodes

Currently, energy scarcity and environmental pollution are two severe challenges facing humanity. On one hand, significant efforts are being devoted to the development of sustainable, cheap, high-performance rechargeable battery cathodes. On the other hand, organic dyes are one of main contaminating components in plant effluents, damaging the ecological balance of surrounding areas as well as wasting a lot of valuable chemical raw materials. In this study, we rationally designed a strategy to simultaneously address these two issues. After carefully studying the chemical structure of dye molecules, we find that two types of widely-used dyes including phenothiazine dyes and anthraquinone derivatives with intrinsic redox centers can be effectively decolorized by adsorption removal with mesoporous carbon and directly resource-utilized for lithium-ion battery electrode materials. For example, the composite based on mesoporous carbon hosting methylene blue dye achieves an outstanding specific capacity of 107 mAh g^-1 even at a high current of 3 A g^-1 and long-term cycling stability with 82% initial capacity retention after 1000 cycles, which is comparable to the classic LiFePO₄ material, and superior to many recently-reported organic cathode materials. Our strategy therefore “kills two birds with one stone”, enabling the development of high-performance battery cathodes based on organic dyes in combination with effective valorization of dye-containing wastewaters.