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Flexible Zinc‐Ion Hybrid Fiber Capacitors with Ultrahigh Energy Density and Long Cycling Life for Wearable Electronics
Author(s) -
Zhang Xinshi,
Pei Zengxia,
Wang Chaojun,
Yuan Ziwen,
Wei Li,
Pan Yuqi,
Mahmood Asif,
Shao Qian,
Chen Yuan
Publication year - 2019
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201903817
Subject(s) - materials science , power density , capacitor , energy storage , nanotechnology , electrolyte , electrode , flexible electronics , optoelectronics , voltage , electrical engineering , power (physics) , chemistry , physics , quantum mechanics , engineering
Emerging wearable electronics require flexible energy storage devices with high volumetric energy and power densities. Fiber‐shaped capacitors (FCs) offer high power densities and excellent flexibility but low energy densities. Zn‐ion capacitors have high energy density and other advantages, such as low cost, nontoxicity, reversible Faradaic reaction, and broad operating voltage windows. However, Zn‐ion capacitors have not been applied in wearable electronics due to the use of liquid electrolytes. Here, the first quasisolid‐state Zn‐ion hybrid FC (ZnFC) based on three rationally designed components is demonstrated. First, hydrothermally assembled high surface area and conductive reduced graphene oxide/carbon nanotube composite fibers serve as capacitor‐type positive electrodes. Second, graphite fibers coated with a uniform Zn layer work as battery‐type negative electrodes. Third, a new neutral ZnSO 4 ‐filled polyacrylic acid hydrogel act as the quasisolid‐state electrolyte, which offers high ionic conductivity and excellent stretchability. The assembled ZnFC delivers a high energy density of 48.5 mWh cm −3 at a power density of 179.9 mW cm −3 . Further, Zn dendrite formation that commonly happens under high current density is efficiently suppressed on the fiber electrode, leading to superior cycling stability. Multiple ZnFCs are integrated as flexible energy storage units to power wearable devices under different deformation conditions.