Carbonyl Compounds as Electrochemically Active Materials for Li-ion and Na-ion Batteries

Abstract

Li ion batteries (LIB) are currently the dominant energy storage system in portable electronic devices (EV), electric vehicles and energy storage systems (ESS). With market saturation of battery for small device, global Li-ion battery market has a great interest in the large energy storage system. The conventional cathode materials for Li-ion batteries are inorganic materials based on cobalt source. However, the cobalt source is expensive, limited mineral resources and toxic. Furthermore, the price of lithium carbonate as a lithium source for the cathode material is fluctuated due to the geographically-restricted carbonate source. Because of these reasons, current inorganic materials are inadequate for the post Li ion battery market. So, new alternatives are required and organic electrode materials are suggested as a promising electrode material. The organic electrode material have advantages which are cheap, sustainability and structural flexibility. But, they suffer from problems of dissolution in electrolyte and low conductivity. In this study, the topics will deal with the solution about the problem of both dissolution and low conductivity and the utilization about merit of structural flexibility. To solve drawbacks about dissolution and low conductivity, the carbon composite method was facilitated by using a mesoporous carbnon having a conductivity and a confinement effect in their pore. the π-π interaction-dependent vapour pressure of phenanthrenequinone can be used to synthesize a phenanthrenequinone-confined ordered mesoporous carbon. Intimate contact between the insulating phenanthrenequinone and the conductive carbon framework improves the electrical conductivity. This enables a more complete redox reaction take place. The confinement of the phenanthrenequinone in the mesoporous carbon mitigates the diffusion of the dissolved phenanthrenequinone out of the mesoporous carbon, and improves cycling performance. To utilize the structural flexibility of the organic material, the possibility which enables to change the reduction potential was demonstrated. By correlating the practical reduction potential and the theoretical LUMO energy, possibility to change the reduction potential was suggested. Experimented nine organic molecules matched with trend between LUMO level and reduction potential. Results were categorized into three part. They are affected by the factors of the polar effect and the expansion of pi conjugation. LUMO level could be decreased through the stronger electron withdrawing group or the longer pi conjugated and it affect to reduction potential increasing.