Phase evolution of an alpha MnO2-based electrode for pseudo-capacitors probed by in operando Raman spectroscopy

• Published in: Nano energy 2014-10, Vol.9, p.161-167
• Main Authors: Cheng, Shuang, Yang, Lufeng, Chen, Dongchang, Ji, Xu, Jiang, Zhong-jie, Ding, Dong, Liu, Meilin
• Format: Article
• Language: English
• Subjects: Alpha MnO2; Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Energy; Energy accumulation; Energy storage behavior; Energy. Thermal use of fuels; Exact sciences and technology; Fullerenes and related materials; In operando Raman; Infrared and raman spectra and scattering; Materials; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Physics; Pseudo-capacitors; Transport and storage of energy
• ISSN: 2211-2855
• DOI: 10.1016/j.nanoen.2014.07.008

In operando Raman spectroscopy has been used to monitor the phase changes of non-stoichiometric α-MnO2, α-Mn0.98O2, electrode materials in a pseudo-capacitor during the charging/discharging process. Results indicate that the α-Mn0.98O2 can be converted to MnO2 and Mn3O4 when placed in electrolyte exposed to laser for the Raman measurements. Both the phases contribute to the energy storage process through reversible phase transformation which involves hydrated cations M+, protons H+ and Mn2+ intercalation/deintercalation during the charging/discharging process. [Display omitted] •Alpha MnO2-based pseudo-capacitor cell with high capacitance was assembled.•Lattice change was monitored via in situ Raman during the charging/discharging process.•M+, H+ from electrolyte and Mn2+ from active material contribute to energy storage.