A 2.6 V Flexible Supercapacitor Based on Al-MnO<sub>2</sub>-Na<sub>2</sub>SO<sub>4</sub>//AC-KOH with High Specific Energy
Jian Yan, Chao Liu, Jiaojiao Yang, Zhen Wang, Wenxuan Yao, Lulu Huang, Jiewu Cui, Jiaqin Liu, Xiaoye Hu, Yucheng Wu
Abstract
In this work, we have synthesized Al-doped MnO 2 nanoparticles (Al-MnO 2 ) by rapid coprecipitation followed by hydrothermal and heat treatment. Al-MnO 2 shows a specific capacitance of 301.8 F g –1 at 1 A g –1 in a sample of 14% Al-MnO 2 -260 °C. The specific capacitance still remains at 206 F g –1 at 20 A g –1 . It also shows a good cycling stability with no capacitance degradation after 5000 cycles. More importantly, a new type of supercapacitor, Al-MnO 2 |PVA-Na 2 SO 4 //PVA-KOH|AC, has been designed using a Na 2 SO 4 -poly(vinyl alcohol)//cation exchange membrane//KOH-poly(vinyl alcohol)-based decoupled electrolyte. This device exhibits a specific capacitance of 68.9 F g –1 at 1 A g –1, corresponding to 64.7 Wh kg –1 at 1300 W kg –1 . It also delivers a good capacitance retention of ∼84% after 5000 cycles. The cell voltage is up to 2.6 V, which could light up a green light-emitting diode. The PVA-based decoupled gel electrolyte offers good processability to assemble flexible and foldable devices, which is important for mass production in manufacturing. These results clearly indicate that such high-voltage flexible supercapacitors with high specific energy are very promising in future wearable electronics.