Lithium Storage Mechanism: A Review of Perylene Diimide N-Substituted with a 1,2,4-Triazol-3-yl Ring for Organic Cathode Materials

초록

The demand for lithium-ion batteries (LIBs) has increased rapidly. However, commercial inorganic-based cathode materials have a low theoretical capacity and inherent disadvantages, such as high cost and toxicity. Redox-active organic cathodes with a high theoretical capacity, eco-friendly properties, and sustainability have been developed to overcome these limitations. Herein, perylene diimide derivatives N-substituted with 1,2,4-triazol-3-yl rings (PDI-3AT) were developed to apply as a cathode material for LIBs. The PDI-3AT cathode exhibited discharge capacities of 85.2 mAh g–1 (50 mA g–1 over 100 cycles) and 64.5 mAh g–1 (500 mA g–1 over 1000 cycles) with ratios to the theoretical capacities of 84 and 64%, respectively. Electrochemical kinetics analysis showed capacitive behaviors of the PDI-3AT cathode with efficient pathways for lithium-ion transport. Also, the activation step of the PDI-3AT cathode was demonstrated by improving the charge transfer resistance and lithium-ion diffusion coefficient during the initial few charge–discharge cycles. Furthermore, DFT calculations at the B3LYP/6-311+G** level and ex situ analysis of various charge states of the PDI-3AT electrode using attenuated total reflection Fourier transform infrared (ATR FT-IR) analysis, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were conducted for the further study of the lithium-ion storage mechanism. The results showed that the lithiation process formed the lithium enolate (C–O–Li) coordinated with the N atoms of the 1,2,4-triazole ring. It is expected that our study results will encourage the production and use of redox-active perylene diimide derivatives as next-generation cathode materials.

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