Hydrogen Bonding-Reinforced Hydrogel Electrolyte for Flexible, Robust, and All-in-One Supercapacitor with Excellent Low-Temperature Tolerance

Abstract

Flexible supercapacitors are promising energy storage devices for emerging wearable electronics. However, due to the poor mechanical strength, complicated device manufacturing process, and unsatisfactory low-temperature tolerance, their overall performance for practical applications is hindered. Herein, we report a hydrogen bonding-reinforced, dual-crosslinked poly­(vinyl alcohol), acrylic acid, and H2SO4 (PVA-AA-S) hydrogel electrolyte for all-in-one flexible supercapacitors. The PVA-AA-S hydrogel demonstrates excellent compressive/tensile properties and high ionic conductivity. It tolerates compressive stress of 0.53 MPa and is stretchable up to 500%. The hydrogel-based all-in-one supercapacitor shows promising electrochemical performance under various harsh conditions. The device energy density and power density reach up to 14.2 μWh cm–2 and 0.94 mW cm–2, respectively. Furthermore, it retains nearly 80% capacitance after being stored at −35 °C for 23 days. The excellent performance of the hydrogel electrolyte originates from its abundant strong hydrogen bonding between polymer chains and water molecules.

Dense Hydrogen-Bonding Network Boosts Ionic Conductive Hydrogels with Extremely High Toughness, Rapid Self-Recovery, and Autonomous Adhesion for Human-Motion Detection

“…After the third cycle, the hysteresis loop and the loss factor of PAM-r-MVIC-2 almost remained. The dissipated energy and dissipation coefficient of the 3 rd and 4 th cycles remained around 17 kJ m −3 and 0.16, respectively, indicating a good fatigue resistance and highly deformation-tolerant and fast self-recovery performance [ 32 – 34 ]. The ionic conductive hydrogels with comprehensive mechanical properties demonstrated extraordinary stretchability and excellent toughness under different strains, thus showing a broad application prospect in flexible ionic devices.…”

Electrochemical Supercapacitors: From Mechanism Understanding to Multifunctional Applications

“…Hydrogel‐based electrolytes with abundant hydrogen bonding between hydrophilic polymer chains with water molecules can effectively disrupt ice formation, thus improving the low‐temperature performance of SCs. [ 100,101 ] With dual‐crosslinked PVA‐AA‐H 2 SO 4 hydrogel electrolyte, the specific capacitance of a symmetric SC based on MoN/CNT electrodes can retain 80% of its original value after being stored at −35 °C for 23 days. [ 100 ] Incorporation of fatty species was also attempted to improve the antifreezing properties of PVA hydrogels.…”

“…[ 100,101 ] With dual‐crosslinked PVA‐AA‐H 2 SO 4 hydrogel electrolyte, the specific capacitance of a symmetric SC based on MoN/CNT electrodes can retain 80% of its original value after being stored at −35 °C for 23 days. [ 100 ] Incorporation of fatty species was also attempted to improve the antifreezing properties of PVA hydrogels. [ 102 ] The storage modulus of LiCl‐PVA‐H 2 O hydrogel was increased dramatically when the temperature was reduced from 25 to −40 °C, while the storage modulus of LiCl‐PVA‐H 2 O/ethylene glycol hydrogel remain almost constant.…”

Free-Standing, Flexible Nanofeatured Polymeric Films Prepared by Spin-Coating and Anodic Polymerization as Electrodes for Supercapacitors

“…In these devices, which exhibit high specific energy and power densities and long life cycles, all components, including the electrodes, are flexible. In general, it is well-accepted that polymeric gel electrolytes fulfill the practical conditions required by the electrolyte layers of flexible SCs, especially in terms of electrochemical performance, excellent compressive/tensile properties, simple manufacturing properties, satisfactory tolerance over a wide temperature range [ 28 , 29 , 30 , 31 ]. However, the most suitable format for the electrodes in flexible SCs is still controversial and highly dependent on the final application of the device.…”