title: Neutral pH Gel Electrolytes for V2O5·0.5H2O-Based Energy Storage Devices.
abstract: Gel electrolytes are considered to be promising candidates for the use in supercapacitors. It is worthy to systematically evaluate the internal electrochemical mechanisms with a variety of cations (poly(vinyl alcohol) (PVA)-based Li+, Na+, and K+) toward redox-type electrode. Herein, we describe a quasi-solid-state PVA-KCl gel electrolyte for V2O5·0.5H2O-based redox-type capacitors, effectively avoiding electrochemical oxidation and structural breakdown of layered V2O5·0.5H2O during 10 000 charge-discharge cycles (98% capacitance retention at 400 mV s-1). With the gel electrolyte, symmetric V2O5·0.5H2O-reduced graphene oxide (V2O5·0.5H2O-rGO) devices exhibited a volumetric capacitance of 136 mF cm-3, which was much higher than that of 68 mF cm-3for PVA-NaCl and 45 mF cm-3for PVA-LiCl. Additionally, hybrid full cells of activated carbon cloth//V2O5·0.5H2O-rGO delivered an energy density of 102 μWh cm-3and a power density of 73.38 mW cm-3over a wide potential window of 2 V. The present study provides direct experimental evidence for the contribution of PVA-KCl gel electrolytes toward quick redox reactions for redox-type capacitors, which is also helpful for the development of neutral pH gel electrolytes for energy storage devices.
authors.affiliation: School of Chemical Engineering, Sungkyunkwan University , Suwon 16419, Republic of Korea.
authors.forename: Aniu
authors.initials: A
authors.lastname: Qian
authors.affiliation: School of Chemical Engineering, Sungkyunkwan University , Suwon 16419, Republic of Korea.
authors.forename: Kai
authors.initials: K
authors.lastname: Zhuo
authors.affiliation: School of Chemical Engineering, Sungkyunkwan University , Suwon 16419, Republic of Korea.
authors.forename: Padmanathan
authors.initials: P
authors.lastname: Karthick Kannan
authors.affiliation: School of Chemical Engineering, Sungkyunkwan University , Suwon 16419, Republic of Korea.
authors.forename: Chan-Hwa
authors.identifier: http://orcid.org/0000-0003-2808-1001
authors.initials: CH
authors.lastname: Chung
keywords: cyclic stability; electrochemistry; gel electrolyte; hybrid supercapacitors; vanadium oxide hydrates