An ultrafast rechargeable hybrid potassium dual-ion capacitor based on carbon quantum dot@ultrathin carbon film cathode

• Published in: Rare metals 2024-10, Vol.43 (10), p.5070-5081
• Main Authors: Liu, Zhao-Meng, Wang, Da, Li, Shang-Zhuo, Lai, Qing-Song, Yang, Dong-Run, Zhao, Lu-Kang, Mu, Jian-Jia, Wang, Xuan-Chen, Gao, Xuan-Wen, Luo, Wen-Bin
• Format: Article
• Language: English
• Subjects: Biomaterials; Chemistry and Materials Science; Energy; Materials Engineering; Materials Science; Metallic Materials; Nanoscale Science and Technology; Original Article; Physical Chemistry
• ISSN: 1001-0521; 1867-7185
• DOI: 10.1007/s12598-024-02719-4

Ultrafast rechargeable hybrid potassium dual-ion capacitors (HPDICs) were designed by employing carbon quantum dot@ultrathin carbon film (CQD@CF) as the cathode material. The designed CQD@CF is self-assembled by a simple catalytic graphitization route followed by an acid leaching process. The special composite features a large adsorption interface, a remarkable anion hybrid storage capability and outstanding structure stability. The electrochemical performance of CQD@CF composite is fully tapped in a half-cell system at the operating voltage between 1.4 and 4.5 V, achieving an admirable specific discharge capacity of 128.5 mAh·g −1 at 50 mA·g −1 , an ultra-high capacity retention ratio of 97.97% after cycling 5000 times at 1000 mA·g −1 and a 96.10% high capacity retention ratio after cycling 40,000 times at 5000 mA·g −1 , respectively. Besides, with the support of ex situ TEM and XPS, the structural stability principle and anionic hybrid storage mechanism of CQD@CF electrode are investigated deeply. In the full-cell system, HPDICs with the CQD@CF as cathode and nano-graphite powder as anode also present a 141.5 Wh·kg −1 high energy density, a 5850 W·kg −1 power density and a super-long cycle stability (90.2% capacity retention ratio after cycling 30,000 times at 5000 mA·g −1 ). Graphical Abstract