Stable high-voltage aqueous pseudocapacitive energy storage device with slow self-discharge. (October 2019)

• Record Type: Journal Article
• Authors: Avireddy, Hemesh; Byles, Bryan W.; Pinto, David; Delgado Galindo, Jose Miguel; Biendicho, Jordi Jacas; Wang, Xuehang; Flox, Cristina; Crosnier, Olivier; Brousse, Thierry; Pomerantseva, Ekaterina; Morante, Joan Ramon; Gogotsi, Yury
• Is Part Of: Nano energy. Volume 64(2019)
• Publication Date: 2019-10
• Subjects: Water-in-salt electrolyte -- High-voltage supercapacitor -- Titanium carbide MXene -- Manganese oxide; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2019.103961
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: We demonstrate an asymmetric supercapacitor in a potassium acetate-based water-in-salt electrolyte, where 2-D titanium carbide MXene and manganese oxide were used as negative and positive electrode materials, respectively. Use of water-in-salt electrolyte enables the assembled asymmetric device to be operated up to a cell voltage of 2.2 V, which overcomes the limited cell voltage issue in aqueous pseudocapacitors (1.2 - 1.4 V). This cell shows excellent rate capability (~48%) between 5 and 100 mV s -1 and good stability (~93%) throughout 10, 000 charge-discharge cycles (at 1 A g -1 ) and 25 h voltage-hold at 2.2 V, which is competitive when compared with the performance of known asymmetric supercapacitors designed with activated carbon electrodes and fluorinated-imide based water-in-salt electrolytes. Moreover, our device shows slower self-discharge and ~32% higher volumetric energy density than activated carbon-based supercapacitors and is promising for applications where volumetric energy density is critical. Graphical abstract: Image 1 Highlights: First association of a MXene material along with a MnO2 tunnel structure in a quickly-rechargeable asymmetric device. An aqueous fully pseudocapacitive cell with voltages (2.2 V) close to that of organic electrolytes. Cell shows excellent rate capability when compared to existing cells based in water-in-salt electrolytes. Excellent stability throughout 10, 000 cycles and 25 h Voltage-Hold, unlike existing cells based in water-in-salt electrolytes. The asymmetric cell exhibits lower self-discharges than activated carbon based electrodes.