Tunable oxygen vacancy concentration in vanadium oxide as mass-produced cathode for aqueous zinc-ion batteries
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Tunable oxygen vacancy concentration in vanadium oxide as mass-produced cathode for aqueous zinc-ion batteries Yehong Du1, Xinyu Wang1,2 (), and Juncai Sun1 () 1 2
Institute of Materials and Technology, Dalian Maritime University, Dalian 116026, China Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Nankai University, Tianjin 300071, China
© Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Received: 6 August 2020 / Revised: 4 September 2020 / Accepted: 10 September 2020
ABSTRACT Oxygen vacancy (Vö) is important in the modification of electrode for rechargeable batteries. However, due to the scarcity of suitable preparation strategy with controllable Vö incorporation, the impact of Vö concentration on the electrochemical performances remains unclear. Thus, in this work, Vö-V2O5-PEDOT (VöVP) with tunable Vö concentration is achieved via a spontaneous polymerization strategy, with the capability of mass-production. The introduction of poly(2,3-dihydrothieno-1,4-dioxin) (PEDOT) not only leads to the formation of Vö in V2O5, but it also results in a larger interlayer spacing. The as-prepared Vö-V2O5-PEDOT-20.3% with Vö concentration of 20.3% (denoted as VöVP-20) is able to exhibit high capacity of 449 mAh·g−1 at current density of 0.2 A·g−1, with excellent cyclic performance of 94.3% after 6,000 cycles. It is shown in the theoretical calculations that excessive Vö in V2O5 will lead to an increase in the band gap, which inhibits the electrochemical kinetics and charge conductivity. This is further demonstrated in the experimental results as the electrochemical performance starts to decline when Vö concentration increases beyond 20.3%. Thus, based on this work, scalable fabrication of high-performance electrode with tunable Vö concentration can be achieved with the proposed strategy.
KEYWORDS aqueous zinc-ion battery, oxygen vacancy, tunable, vanadium oxide, mass-produced
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Introduction
High safety and low-cost battery technologies are important in our current society so as to power various applications such as portable electronics, energy storage grid, or even hybrid electric vehicles [1]. Even though lithium-ion batteries (LIB) are typically able to deliver high energy density, the depleting Li resource and the growing concern with regards to the safety issues due to the flammable organic electrolytes are slowly stifling the appeal of LIB [2, 3]. Rechargeable aqueous zinc-ion batteries (ZIBs) are widely considered as a promising alternative in the stationary energy storage grid for renewable energy due to its enhanced safety, ease of assembly, and environmental benignity [4, 5]. In addition, water-based electrolyte possesses superior ionic conductivity as compared to its organic counterparts, which in turn results in high rate capability [6, 7]. As such, due to this multitude of advantages, the motivation for developing high performing ZIBs are tremendous. However, in the development of high performing ZIBs, one of the g
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