Synergistically Improving the Stability and Operating Potential of Organic Cathodes for Sodium‐Ion Battery

Tailoring the organic cathode: By introducing chlorine substitution and thiourea linker in the perylene polyimide skeleton, we have discussed an approach to simultaneously tweak the reduction potential and address the solubility issues of organic electrodes for sodium-ion batteries.

Abstract

Establishing a sustainable energy solution is one of the most important issues in achieving a greener community. Given the geographically limited cobalt resources, the rising concerns about the growth of electric vehicle sectors driven by lithium-ion batteries consisting of cobalt-based cathodes have pushed the research community to probe alternate avenues. In this endeavor, employing organic electrodes can open the road to green and sustainable batteries. Among many new emerging candidates, polyimides are still being considered as cathode candidates owing to their tunability. This work envisaged tailoring the reduction potential and enhancing the cycling stability of a perylene polyimide-based organic cathode through a dual modification strategy. The influence of the twist induced by chlorine functionality at the bay position of perylene diimide and the role of the linker is systematically summarized. The correlation between the reduction potentials and the electron-withdrawing ability of the four-chlorine bay-substituent was supported by HOMO-LUMO energy levels and orbital iso-surface studies of the monomers. The accompanying thiourea linker group has significantly increased the cycling stability for 200 cycles at 1 A g⁻¹ current density. This approach can be expanded to other organic battery chemistries for significantly enhanced electrochemical performance.

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