Dataset Information

Hierarchical Carbon Micro/Nanonetwork with Superior Electrocatalysis for High-Rate and Endurable Vanadium Redox Flow Batteries.

ABSTRACT: Vanadium redox flow batteries (VRFBs) are receiving increasing interest in energy storage fields because of their safety and versatility. However, the electrocatalytic activity of the electrode is a pivotal factor that still restricts the power and cycling capabilities of VRFBs. Here, a hierarchical carbon micro/nanonetwork (HCN) electrode codoped with nitrogen and phosphorus is prepared for application in VRFBs by cross-linking polymerization of aniline and physic acid, and subsequent pyrolysis on graphite felt. Due to the hierarchical electron pathways and abundant heteroatom active sites, the HCN exhibits superior electrocatalysis toward the vanadium redox couples and imparts the VRFBs with an outstanding energy efficiency and extraordinary stability after 2000 cycles at 250 mA cm^-2 and a discharge capacity of 10.5 mA h mL^-1 at an extra-large current density of 400 mA cm^-2. Such a micro/nanostructure design will force the advancement of durable and high-power VRFBs and other electrochemical energy storage devices.

SUBMITTER: Ling W

PROVIDER: S-EPMC6299713 | biostudies-literature | 2018 Dec

REPOSITORIES: biostudies-literature

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Hierarchical Carbon Micro/Nanonetwork with Superior Electrocatalysis for High-Rate and Endurable Vanadium Redox Flow Batteries.

Ling Wei W Deng Qi Q Ma Qiang Q Wang Hong-Rui HR Zhou Chun-Jiao CJ Xu Jian-Kai JK Yin Ya-Xia YX Wu Xiong-Wei XW Zeng Xian-Xiang XX Guo Yu-Guo YG

Advanced science (Weinheim, Baden-Wurttemberg, Germany) 20181031 12

Vanadium redox flow batteries (VRFBs) are receiving increasing interest in energy storage fields because of their safety and versatility. However, the electrocatalytic activity of the electrode is a pivotal factor that still restricts the power and cycling capabilities of VRFBs. Here, a hierarchical carbon micro/nanonetwork (HCN) electrode codoped with nitrogen and phosphorus is prepared for application in VRFBs by cross-linking polymerization of aniline and physic acid, and subsequent pyrolysis ...[more]

PMID: 30581714

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Project description:A core component of energy storage systems like vanadium redox flow batteries (VRFB) is the polymer electrolyte membrane (PEM). In this work, the frequently used perfluorosulfonic-acid (PFSA) membrane Nafion™ 117 and a novel poly (vinylidene difluoride) (PVDF)-based membrane are investigated. A well-known problem in VRFBs is the vanadium permeation through the membrane. The consequence of this so-called vanadium crossover is a severe loss of capacity. For a better understanding of vanadium transport in membranes, the uptake of vanadium ions from electrolytes containing Vdimer(IV-V) and for comparison also V(II), V(III), V(IV), and V(V) by both membranes was studied. UV/VIS spectroscopy, X-ray absorption near edge structure spectroscopy (XANES), total reflection X-ray fluorescence spectroscopy (TXRF), inductively coupled plasma optical emission spectrometry (ICP-OES), and micro X-ray fluorescence spectroscopy (microXRF) were used to determine the vanadium concentrations and the species inside the membrane. The results strongly support that Vdimer(IV-V), a dimer formed from V(IV) and V(V), enters the nanoscopic water-body of Nafion™ 117 as such. This is interesting, because as of now, only the individual ions V(IV) and V(V) were considered to be transported through the membrane. Additionally, it was found that the Vdimer(IV-V) dimer partly dissociates to the individual ions in the novel PVDF-based membrane. The Vdimer(IV-V) dimer concentration in Nafion™ was determined and compared to those of the other species. After three days of equilibration time, the concentration of the dimer is the lowest compared to the monomeric vanadium species. The concentration of vanadium in terms of the relative uptake λ = n(V)/n(SO3) are as follows: V(II) [λ = 0.155] > V(III) [λ = 0.137] > V(IV) [λ = 0.124] > V(V) [λ = 0.053] > Vdimer(IV-V) [λ = 0.039]. The results show that the Vdimer(IV-V) dimer needs to be considered in addition to the other monomeric species to properly describe the transport of vanadium through Nafion™ in VRFBs.

Dataset Information

Hierarchical Carbon Micro/Nanonetwork with Superior Electrocatalysis for High-Rate and Endurable Vanadium Redox Flow Batteries.

Publications

Hierarchical Carbon Micro/Nanonetwork with Superior Electrocatalysis for High-Rate and Endurable Vanadium Redox Flow Batteries.

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