A 2.4-V asymmetric supercapacitor based on cation-intercalated manganese oxide nanosheets in a low-cost “water-in-salt” electrolyte

• Published in: Ionics Vol. 25; no. 12; pp. 6007 - 6015
• Main Authors: Bu, Xudong, Zhang, Yurong, Su, Lijun, Dou, Qingyun, Xue, Yun, Lu, Xionggang
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.12.2019; Springer Nature B.V
• Subjects: Activated carbon; Asymmetry; Cations; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Electrochemistry; Electrodes; Electrolytes; Energy Storage; Flux density; High voltages; Low cost; Low voltage; Manganese oxides; Molten salts; Nanosheets; Optical and Electronic Materials; Original Paper; Renewable and Green Energy; Sodium perchlorate; Supercapacitors; Asymmetric supercapacitor; Aqueous electrolyte; High voltage; Cation-intercalated manganese oxide
• ISSN: 0947-7047; 1862-0760
• DOI: 10.1007/s11581-019-03141-y

The main challenge for aqueous asymmetric supercapacitors (ASCs) is the relatively low voltage, which significantly diminishes the energy density of the device. Here, cation-intercalated manganese oxide nanosheets Na 0.55 Mn 2 O 4 ·1.5H 2 O (NaMnO) are synthesized via a facile molten salts method. We find that the electrode potential window for NaMnO nanosheets can be extended to 1.2 V using a low-cost and safe superconcentrated sodium perchlorate (NaClO 4 ) “water-in-salt” (WIS) electrolyte. To construct the asymmetric supercapacitor, the as-prepared NaMnO nanosheets and activated carbon (AC) with a potential window of − 1.2–0 V are used as the positive and negative electrode, respectively. A high-voltage 2.4-V NaMnO//AC aqueous ASC in the concentrated NaClO 4 WIS electrolyte is successfully assembled, which exhibited excellent rate performance (the highest power density of 24.0 kW kg −1 ) as well as good cycling stability (94.9% capacitance retention over 20,000 cycles at 5 A g −1 ). This low-cost WIS electrolyte provides new opportunities for developing high-voltage aqueous ASCs with high energy and high power densities.