Investigations into the origin of pseudocapacitive behavior of Mn sub(3)O sub(4) electrodes using in operandoRaman spectroscopy

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 3; no. 14; pp. 7338 - 7344
• Main Authors: Yang, Lufeng, Cheng, Shuang, Ji, Xu, Jiang, Yu, Zhou, Jun, Liu, Meilin
• Format: Journal Article
• Language: English
• Published: 01.03.2015
• Subjects: Capacitance; Charging; Cycles; Discharge; Electrode materials; Energy storage; Manganese oxides; Phase transformations; Spectroscopy
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c5ta00223k

A detailed understanding of the phase changes of manganese oxides in a pseudocapacitor during cycling is vital to reveal the mechanism by which they store energy and to achieve a rational design of improved electrode materials. Here we report the results of our probing the phase changes of a Mn sub(3)O sub(4) electrode material in a pseudocapacitor during a charging/discharging process using in operandoRaman spectroscopy. Along with enhancing performance, the spinel Mn sub(3)O sub(4) was transformed to a layered birnessite-type MnO sub(2) upon potential cycling and two types of processes were shown to contribute to the energy storage: intercalation/deintercalation of Na super(+) and oxidation/reduction of Mn super(2+). After charging and discharging for similar to 10 000 cycles, the specific capacitance of manganese oxide increased almost 3-fold; and the maximum specific capacitance approached 230 F g super(-1) at a cycling rate of 0.5 A g super(-1).