Self-discharge study of lignin/graphite hybrid material electrodes
Lianlian Liu, Niclas Solin, Olle Inganäs
Abstract
Lignin has been proposed as electricity storage materials due to the redox activity of quinone (Q) and hydroquinone (QH2) groups, which can be formed in lignin. Scalable and low-cost lignosulfonate (LS)/graphite hybrid material electrodes have been developed. It is important to investigate the self-discharge mechanism for these electrodes since a high self-discharge rate was observed, which results in loss of energy density and power density. In this work, self-discharge measurements and models are applied to clarify the self-discharge mechanism of the LS/graphite electrodes. A combination of diffusion controlled, activation controlled and charge equilibration mechanisms are indicated during the self-discharge process at different charging voltages, due to the faradaic reactions of the Q/QH2 confined in the electrodes. Our work contributes deeper understanding of the structure and the self-discharge mechanisms of the biopolymer/graphite hybrid electrodes.