Quasi-solid-state supercapacitors based on wide-temperature eutectogels

• Published in: Journal of energy storage Vol. 59; p. 106414
• Main Authors: Zhang, Jijian, Li, Jing, Zuo, Danying, Xu, Jin, Zhang, Hongwei
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.03.2023
• Subjects: Deep eutectic solvent; Gel polymer electrolyte; Supercapacitor; Wide temperature; Supercapacitor; Wide temperature; Deep eutectic solvent; Gel polymer electrolyte
• ISSN: 2352-152X; 2352-1538
• DOI: 10.1016/j.est.2022.106414

Carbon-based supercapacitors possess fast charge-discharge rate, superior power density, and excellent cyclic lifespan, but it is subject to some problems, such as low operating potential window and energy density. To address these issues, a ternary deep eutectic solvent with a freezing point below −85.6 °C was firstly prepared using lithium perchlorate trihydrate and urea and then used as a reaction solvent to take part in a free radical polymerization reaction to prepare eutectogels. The optimized eutectogel showed an ionic conductivity of 20 mS cm−1 at room temperature and could be still stretched and twisted even at −40 °C. The quasi-solid-state supercapacitor composed of a eutectogel and carbon electrodes demonstrated a stable voltage window of 0–2.0 V, an energy density of 10.76 Wh kg−1 at a power density of 465 W kg−1 and excellent cycling stability with ∼105 % capacitance retention after 10,000 cycles. The flexible quasi-solid-state supercapacitors with such a eutectogel not only could be operated from −40 to 60 °C, but also exhibited a moderate bendability. Moreover, the damaged flexible quasi-solid-state supercapacitor could be still charged and drive a mini-fan for ⁓60 s. Therefore, the eutectogels displayed a promising potential for enhancing the energy density of carbon-based supercapacitors and should also provide instructive guidance for the preparation of wide-temperature gel polymer electrolytes. A carbon-based supercapacitor using an eutectogel can be operated from −40 to 60 °C. [Display omitted] •A ternary DES with a freezing point below −85.6 °C is prepared.•A eutectogel based on the DES has an ionic conductivity of 20 mS cm−1.•A quasi-solid-state device with a eutectogel shows enhanced energy density.•A flexible device with a eutectogel can run even at −40 °C.