Extended π-conjugated N-containing heteroaromatic hexacarboxylate organic anode for high performance rechargeable batteries

Abstract

Organic electrode materials are desirable for green and sustainable Li-ion batteries (LIBs) due to their light-weight, low cost, abundance and multi-electron transfer reactions during battery operation. However, the successful utilization of organic electrodes is hindered by their poor electrical conductivity and low cyclic stability. Herein, a facile synthesis of π-conjugated N-containing heteroaromatic hexacarboxylate (Li6-HAT) compound and its electrochemical performance as an anode material in LIBs is reported. The as-synthesized Li6-HAT electrode renders an ultrahigh initial capacity of 1126.3 mAh g−1 at the current density of 100 mA g−1. Moreover, π-conjugated N-containing heteroaromatic center provide excellent reversibility of (de)lithiation process, resulting in excellent capacity retention. Furthermore, a combination of density functional theory (DFT) calculations, in-situ Fourier transform infrared (FTIR) and ex-situ X-ray photoelectron spectroscopy (XPS) characterization reveal that the π-conjugated nitrogen and carboxyl oxygen act as electrochemically active sites during the charge/discharge process. The current work provides novel insights into the charge storage mechanism of organic electrodes and opens up avenues for further development and utilization of organic electrodes in Li-ion batteries.