Lithium-ion capacitors with 2D Nb2CTx (MXene) – carbon nanotube electrodes
Version 2 2024-06-06, 09:00Version 2 2024-06-06, 09:00
Version 1 2016-05-30, 14:46Version 1 2016-05-30, 14:46
journal contribution
posted on 2024-06-06, 09:00authored byA Byeon, AM Glushenkov, B Anasori, P Urbankowski, J Li, BW Byles, B Blake, KL Van Aken, S Kota, E Pomerantseva, JW Lee, Ying (Ian) ChenYing (Ian) Chen, Y Gogotsi
There is a growing interest to hybrid energy storage devices, such as lithium-ion capacitors, in which battery-type electrodes are combined with capacitor-type ones. It is anticipated that the energy density (either gravimetric or volumetric) of lithium-ion capacitors is improved if pseudocapacitive or fast insertion materials are used instead of conventional activated carbon (AC) in the capacitor-type electrode. MXenes, a new family of two-dimensional transition metal carbides, demonstrate metallic conductivity and fast charge-discharge behavior that make them suitable for this application. In this study, we move beyond single electrodes, half-cell studies and demonstrate three types of hybrid cells using Nb2CTx-carbon nanotube (CNT) films. It is shown that lithiated graphite/Nb2CTx-CNT, Nb2CTx-CNT/LiFePO4 and lithiated Nb2CTx-CNT/Nb2CTx-CNT cells are all able to operate within 3 V voltage windows and deliver capacities of 43, 24 and 36 mAh/g (per total weight of two electrodes), respectively. Moreover, the polarity of the electrodes can be reversed in the symmetric Nb2CTx-CNT cells from providing a positive potential between 0 and 3 V to a negative one from -3 to 0 V. It is shown that the volumetric energy density (50-70 Wh/L) of our first-generation devices with MXene electrodes exceeds that of a lithium titanate/AC capacitor.