Long-Term Anti-freezing Active Organohydrogel Based Superior Flexible Supercapacitor and Strain Sensor

Abstract

Multifunctional conductive hydrogels attract booming attention with the prosperity of flexible and wearable soft devices such as energy storage systems and sensors. However, conventional water-based conductive hydrogels inevitably lose ionic conductivity and mechanical flexibility at subzero temperature, thus restricting their practical utilizations in extremely cold environments. On the other hand, simultaneous realization of high freezing tolerance, toughness, ionic conductivity, and electrochemical property through a simple approach is still a challenge. Herein, a novel long-term anti-freezing and mechanically tough conductive active organohydrogel is designed and prepared by simultaneously introducing poly(vinyl alcohol) (PVA), alizarin red S (ARS), and H 2 SO 4 into a H 2 O/ethylene glycol (EG) binary solvent. Benefiting from the exceptionally low temperature tolerance capability of H 2 O/EG and extra pseudocapacitance contribution of ARS active molecules, even at the temperature as low as −37 °C, the as-fabricated flexible supercapacitor still demonstrates a large electrode specific capacitance (240 F g −1 ), high energy density (21 Wh kg −1 ), excellent cycling stability (only 9% capacitance decay over 5000 cycles), and superior durability (97% capacitance retention after stored for 50 days). More impressively, owing to the excellent strain sensitivity (GF = 2.18) and significant repeatability, the active organohydrogel based antifreezing strain sensor can not only precisely monitor the large-scale and subtle human movements but also efficiently distinguish the directions of the movements under RT or −37 °C. Overall, our investigation of long-term low temperature tolerant active organohydrogels provides a versatile strategy to exploit superior flexible energy storage devices and strain sensors applied in extremely cold environments.

Telemedicine platform for health assessment remotely by an integrated nanoarchitectonics FePS3/rGO and Ti3C2-based wearable device

“…8a ). The relative resistance is defined as ΔR/R 0 , where ΔR = R − R 0 and R 0 and R are the resistance before and after the applied strain, respectively 41 . Applied tensile strain is calculated by ε = (L − L 0 )/L 0 × 100 , where L 0 is initial length and L is length after being stretched 42 .…”

Low-Temperature Wearable Strain Sensor Based on a Silver Nanowires/Graphene Composite with a Near-Zero Temperature Coefficient of Resistance

“…As demonstrated in Figure c, this high GF outperforms the values of any previously reported strain sensors measured under subzero temperatures. ,− ,− As the strain was in the 24–32 and 32–36% regions, the GFs of our sensor at −40 °C reached 782 and 1912, respectively. When the strain exceeded 36%, the GF increased dramatically to 9156, which was among the highest values of any types of strain sensors ,− ,− ,− ,,,,− ,,,− (Table S1). Furthermore, the GFs of the Ag NWs/G/PDMS strain sensor under relatively high strain decreased evidently with increasing temperature.…”

“…Recently, temperature tolerant wearable strain sensors have aroused increasing interest. Conductive hydrogels − are promising candidates for assembling these sensors because they are easy to obtain antifreezing performance by employing water-locking agents such as ethylene glycol (EG) and glycerol , or by incorporating inorganic salts such as NaCl, ZnCl 2 , and CaCl 2 into the hydrogel networks. For example, Liao et al developed an antifreezing organohydrogel by immersing a MXene nanocomposite hydrogel in the EG solution to replace partial water molecules .…”

Sensitive, Stretchable, and Sustainable Conductive Cellulose Nanocrystal Composite for Human Motion Detection

“…(a) Relative resistance responses of PVA/Gly-CNC/PVP/PEDOT after fabricating for 100 days. (b) Comparison of reported maximum gauge factor of PVA-based nanocomposites as a function of applied strain. ,,− …”