Organic Electroactive Molecule-Based Electrolytes for Redox Flow Batteries: Status and Challenges of Molecular Design

Zhong, Fangfang; Yang, Minghui; Ding, Mei; Jia, Chuankun

doi:10.3389/fchem.2020.00451

Cited by 60 publications

(53 citation statements)

References 105 publications

(128 reference statements)

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“…Organic electroactive molecules in both non-aqueous and aqueous RFBs can be considered to be in their infancy since no RFBs has been reported to replace the VRFB. Therefore, several efforts to develop more advanced RFBs with organic electroactive materials toward practical applications are being pursued and put in practice [52].…”

Section: Inorganic Aqueousmentioning

confidence: 99%

Redox Flow Batteries: Materials, Design and Prospects

et al. 2021

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The implementation of renewable energy sources is rapidly growing in the electrical sector. This is a major step for civilization since it will reduce the carbon footprint and ensure a sustainable future. Nevertheless, these sources of energy are far from perfect and require complementary technologies to ensure dispatchable energy and this requires storage. In the last few decades, redox flow batteries (RFB) have been revealed to be an interesting alternative for this application, mainly due to their versatility and scalability. This technology has been the focus of intense research and great advances in the last decade. This review aims to summarize the most relevant advances achieved in the last few years, i.e., from 2015 until the middle of 2021. A synopsis of the different types of RFB technology will be conducted. Particular attention will be given to vanadium redox flow batteries (VRFB), the most mature RFB technology, but also to the emerging most promising chemistries. An in-depth review will be performed regarding the main innovations, materials, and designs. The main drawbacks and future perspectives for this technology will also be addressed.

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Section: Inorganic Aqueousmentioning

confidence: 99%

Redox Flow Batteries: Materials, Design and Prospects

et al. 2021

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“…Recently, there has been a dramatic increase in the global demand for renewable and green energy sources due to the exhaustion and environmental issues associated with conventional energy sources, such as fossil fuels and nuclear energy ( Rego de Vasconcelos and Lavoie, 2019 ; Ashok et al, 2020 ; Lin et al, 2020 ; Subhan et al, 2020 ; Tiwari et al, 2020 ). In this regard, solar energy, a low-cost, renewable, naturally abundant and clean energy source, has attracted enormous research effort as a promising alternative to traditional energy sources ( Subramanyam et al, 2019 ; Zhong et al, 2020 ; Rabaia et al, 2021 ). Among the new-generation photovoltaic devices that convert solar energy into electricity, organic solar cells (OSCs) are being widely investigated owing to their low production cost, facile fabrication procedure, abundance of raw materials, easy scalability, lightweight, excellent flexibility and environmentally friendly nature ( Gusain et al, 2019 ; Lee, 2019 ; Li et al, 2020a ; Shah et al, 2020 ; Shoyiga et al, 2020 ; Liu et al, 2021 ).…”

Section: Introductionmentioning

confidence: 99%

Recent Applications of Carbon Nanotubes in Organic Solar Cells

et al. 2022

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In recent years, carbon-based materials, particularly carbon nanotubes (CNTs), have gained intensive research attention in the fabrication of organic solar cells (OSCs) due to their outstanding physicochemical properties, low-cost, environmental friendliness and the natural abundance of carbon. In this regard, the low sheet resistance and high optical transmittance of CNTs enables their application as alternative anodes to the widely used indium tin oxide (ITO), which is toxic, expensive and scarce. Also, the synergy between the large specific surface area and high electrical conductivity of CNTs provides both large donor-acceptor interfaces and conductive interpenetrating networks for exciton dissociation and charge carrier transport. Furthermore, the facile tunability of the energy levels of CNTs provides proper energy level alignment between the active layer and electrodes for effective extraction and transportation of charge carriers. In addition, the hydrophobic nature and high thermal conductivity of CNTs enables them to form protective layers that improve the moisture and thermal stability of OSCs, thereby prolonging the devices’ lifetime. Recently, the introduction of CNTs into OSCs produced a substantial increase in efficiency from ∼0.68 to above 14.00%. Thus, further optimization of the optoelectronic properties of CNTs can conceivably help OSCs to compete with silicon solar cells that have been commercialized. Therefore, this study presents the recent breakthroughs in efficiency and stability of OSCs, achieved mainly over 2018–2021 by incorporating CNTs into electrodes, active layers and charge transport layers. The challenges, advantages and recommendations for the fabrication of low-cost, highly efficient and sustainable next-generation OSCs are also discussed, to open up avenues for commercialization.

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“…The existing commercial flow battery technologies have limited energy density due to the solubility limits of the electroactive species [21]. The energy losses of the electrochemical cell are caused by electrodes resistance, electrolyte resistance, and the steric impediment of the ion exchange membranes [22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Structure and Population of Complex Ionic Species in FeCl2 Aqueous Solution by X-ray Absorption Spectroscopy

2022

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Technologies for mass production require cheap and abundant materials such as ferrous chloride (FeCl2). The literature survey shows the lack of experimental studies to validate theoretical conclusions related to the population of ionic Fe-species in the aqueous FeCl2 solution. Here, we present an in situ X-ray absorption study of the structure of the ionic species in the FeCl2 aqueous solution at different concentrations (1–4 molL−1) and temperatures (25–80 °C). We found that at low temperature and low FeCl2 concentration, the octahedral first coordination sphere around Fe is occupied by one Cl ion at a distance of 2.33 (±0.02) Å and five water molecules at a distance of 2.095 (±0.005) Å. The structure of the ionic complex gradually changes with an increase in temperature and/or concentration. The apical water molecule is substituted by a chlorine ion to yield a neutral Fe[Cl2(H2O)4]0. The observed substitutional mechanism is facilitated by the presence of the intramolecular hydrogen bonds as well as entropic reasons. The transition from the single charged Fe[Cl(H2O)5]+ to the neutral Fe[Cl2(H2O)4]0 causes a significant drop in the solution conductivity, which well correlates with the existing conductivity models.

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Organic Electroactive Molecule-Based Electrolytes for Redox Flow Batteries: Status and Challenges of Molecular Design

Cited by 60 publications

References 105 publications

Redox Flow Batteries: Materials, Design and Prospects

Redox Flow Batteries: Materials, Design and Prospects

Recent Applications of Carbon Nanotubes in Organic Solar Cells

Structure and Population of Complex Ionic Species in FeCl2 Aqueous Solution by X-ray Absorption Spectroscopy

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