Synthesis and Characterization of Chelidonic Acid and Chelidamic Acid as Organic Anode Materials for Energy Storage

Organic materials (OMs) have great potential to accept alkaline ions and thus be used in energy storage systems. Owing to their low cost, easy synthesis, and wide applications, a green battery containing an OM without any considerable production of heavy pollutants such as graphite and transition-metal oxides can be expected in the near future. In this study, two new OMs, chelidamic acid (CDA) and chelidonic acid (CDO), were prepared and investigated for energy storage. CDA and CDO have a similar molecular weight and structure but differ in the electronegative heteroatoms, the secondary amine, and the oxygen atom. This research demonstrates that the different heteroatom dramatically dominates the electrochemical behavior of these two materials. After cycling with Li+, composite electrodes containing CDA and CDO exhibited capacities of 740.2 and 562.8 mAh g–1, respectively, for 250 cycles with no capacity decade. The specific surface area of CDA (2.46 m2 g–1) is twice that of CDO (1.23 m2 g–1), implying that the secondary amine changes the three-dimensional structure and leads to an interesting electrochemical activity with Li+. The composite electrodes containing the two OMs, especially those containing CDA, exhibited rate performance (10 C) superior to that of graphite electrodes. Ex situ Fourier transform infrared and X-ray photoelectron spectroscopies were used to investigate the reaction mechanism of these two OMs. CDA and CDO not only provide outstanding capacity, rate performance, and cycle retention with Li+ but also display great potential in applications with other alkaline ions.