An Aqueous Anti‐Freezing and Heat‐Tolerant Symmetric Microsupercapacitor with 2.3 V Output Voltage
Xuting Jin, Li Song, Chunlong Dai, Yukun Xiao, Yuyang Han, Xinqun Zhang, Xiangyang Li, Congcong Bai, Jiatao Zhang, Yang Zhao, Zhipan Zhang, Lan Jiang, Liangti Qu
Abstract
Abstract Symmetric aqueous microsupercapacitors (MSCs) generally show a low working voltage ( ≤ 1 V) and narrow operating temperature window in the vicinity of 25 ° C due to the poor temperature tolerance and instability of conventional aqueous electrolytes under high voltage. It is challenging to develop MSCs that can offer a high‐voltage output (>2 V) under complex ambient temperature. In this work, a symmetric MSC is fabricated by using the anti‐freezing and heat‐tolerant aqueous polyacrylamide polyelectrolyte (HVTT‐PAM‐10.5) and carbon nanotube microelectrodes, which achieves a record high output voltage of 2.3 V and the widest operating temperature window of − 40 to 100 ° C among the aqueous MSCs reported previously. It can deliver an ultrahigh areal energy density of above 4.9 μ Wh cm −2 at temperatures from − 40 to 100 ° C, outperforming the previous carbon‐based MSCs with aqueous electrolytes at room temperature. Additionally, even after 324 000 cycles at − 40 ° C and 10 000 cycles at 100 ° C, the MSC still retains the high capacitance retention of 92.6% and 90.4%, respectively. Impressively, the HVTT‐PAM‐10.5 polyelectrolyte can also be paired with other electrode materials such as CNT/polyaniline to obtain the highest energy density of 48.6 μ Wh cm −2 among all symmetric/asymmetric MSCs with aqueous electrolytes.