A collaborative diagnosis on mesocarbon microbeads electrodes in dual-carbon cells with non-metal electrolytes. (1st September 2018) - Li, Jiayu
Abstract: Dual-carbon cells are a promising candidate for new energy storage devices. Recently, a 4V asymmetric capacitor based on non-metal electrolytes has been proposed. Two kinds of mesocarbon microbeads（MCMB）samples with different treatments (potassium hydroxide activated MCMB and graphitized MCMB, labeled as AMCMB and GMCMB, respectively) have served as electrode materials in this study. The charge storage behaviors of MCMB electrodes are studied by in situ X-ray diffraction (XRD), in situ dilatometry and conventional electrochemical measurements. (−)AMCMB/GMCMB(+) is synergistically diagnosed as a superior electrode collocation from the viewpoint of structural changes, which consists of adequate activation (7.65% irrecoverable expansion) for AMCMB and suitable stretch (13.67% recoverable expansion) for GMCMB. The intercalation-induced activation of AMCMB is indiscernible in XRD patterns but becomes conspicuous as dilatometric responses. A quantitative correlation between the two in situ measurements is established in the research of GMCMB electrodes. Expansions in the two dimensions are closely related to the type and size of intercalated ions, the shrinkage behavior of electrodes is especially synchronous in the discharging process. These findings guide the design of advanced cells and emphasize the necessity combining in situ characterizations. Highlights: Asymmetric dual-MCMB cells with non-metal electrolytes as novel energy devices. Structural changes in MCMB are collaboratively traced by in situ XRD and dilatometry. Relationship of expansion from crystal structure to electrode level is established.