Family Tree for Aqueous Organic Redox Couples for Redox Flow Battery Electrolytes: A Conceptual Review

Redox flow batteries (RFBs) are an increasingly attractive option for renewable energy storage, thus providing flexibility for the supply of electrical energy. In recent years, research in this type of battery storage has been shifted from metal-ion based electrolytes to soluble organic redox-active compounds. Aqueous-based organic electrolytes are considered as more promising electrolytes to achieve “green”, safe, and low-cost energy storage. Many organic compounds and their derivatives have recently been intensively examined for application to redox flow batteries. This work presents an up-to-date overview of the redox organic compound groups tested for application in aqueous RFB. In the initial part, the most relevant requirements for technical electrolytes are described and discussed. The importance of supporting electrolytes selection, the limits for the aqueous system, and potential synthetic strategies for redox molecules are highlighted. The different organic redox couples described in the literature are grouped in a “family tree” for organic redox couples. This article is designed to be an introduction to the field of organic redox flow batteries and aims to provide an overview of current achievements as well as helping synthetic chemists to understand the basic concepts of the technical requirements for next-generation energy storage materials.

Improved Dielectric Properties and Energy Storage Densities of BaTiO3 Doped PVDF Composites by Heat Treatment and Surface Modification of BaTiO3

The dielectric properties of barium titanate/polyvinylidene fluoride (BT/PVDF) composites are investigated. The doped BT particles are prepared by using simple heat treatment. It is found that 1000 ℃ is the optimal temperature for the doped BT particles to improve the dielectric properties of BT/PVDF composites. Besides, we also find that the breakdown strength of the BT/PVDF composites can be significantly enhanced when the surface of the doped BT particles are pre-modified with phthalic acid or KH550. In particular, the BT/PVDF composites doped with KH550 modified BT particles have the maximum energy storage density of 4.08 J/cm3, which is 81.33 % higher than that of BT/PVDF composites doped with BT particles and without any treatment. Therefore, we can conclude that heat treatment and surface modification of doped BT particles could become new approaches to enhance the energy storage performance of the BT/PVDF composites, which has a good application prospect in the field of dielectric energy storage materials.

Enhanced Electrochemical Performance of Biomass Porous Carbon Adsorption Congo Red

Biomass porous carbon has received widespread attention due to its application as electrode material for supercapacitors and adsorbent for difficult-to-degrade organic dyes. In this paper, biomass porous carbon KGL is prepared using ginkgo leaves as the precursor and KOH as the activator. Capitalizing on the adsorption property of porous carbon, an azo dye Congo red (CR) is confined into the nanopores of KGL to fabricate the KGL/CR electrode. The result suggests that KGL has good adsorption performance for organic dye and KGL/CR has excellent capacitance performance. When the CR concentration is 500 mg L-1, the adsorption capacity of KGL is 495 mg g-1. KGL/CR-500 displays elevated specific capacitance of 393 F g-1 at 1 A g-1 and excellent rate performance (76.3% capacitance retention at 10 A g-1). The capacitance retention after 10000 cycles maintains 99%. The symmetric supercapacitor has power density of 699.8 W kg-1 at an energy density of 16.4 Wh kg-1 and can power a light emitting diodes (LED). Our work provides the information that one is the treatment of organic dye wastewater, the other is development of electrochemical energy-storage materials, and may be expanded to the resource-utilization of other versatile effluent containing the redox groups.

Electrospun Nanofibers for Drug Delivery Applications

Nanofiber systems with various composition and biological properties have been extensively studied for various biomedical applications. The electrospinning process has been regarded as one of the versatile techniques to prepare nano to microfibers. The electrospun nanofibers are being used especially in textile industries, sensors, filters, protective clothing, energy storage materials, and biomedical applications. In the last decade, electrospun nanofibers have been highly investigated for drug delivery systems to achieve a therapeutic effect in specifically targeted sites. Various drugs or biomolecules can be easily loaded into the electrospun nanofibers by direct or indirect methods. The proper selection of polymers (or blends of various polymers), drugs, solvents to prepare the composite nanofibers with desired morphology are the tools in enhancing the bioavailability, stability, and bioactivity of drugs.

High valence state metal-ion doped Fe-Ni layered double hydroxide for oxygen evolution electrocatalyst and asymmetric supercapacitors

Delicate design of nanostructures consisting of multiple components is an important strategy for energy storage materials. In this work, cobalt-doped nickel-iron layered double hydroxide (Fe-Ni3Co2 LDH) assembling from one-dimensional (1D)...

Effect of Surfactant Type on Synthesis and Characteristics of Nanonickel Hydroxide

Nickel hydroxide has a vital role in various applications, especially as a support material for energy storage materials. Nickel hydroxide can be synthesized through the hydroxide precipitation method. However, the product formed by this method may be large or more than 100 nm because the agglomeration step can occur easily. This present work aims to study the effect of surfactant types in the synthesis and characterization of nickel hydroxide nanoparticle. Nickel sulfate (NiSO4) solution was used as a precursor solution, while 5M sodium hydroxide (NaOH) solution was used as a precipitation agent. The surfactants studied were alkyl benzene sulfonate (ABS), sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and polyvinylpyrrolidone (PVP). The nickel hydroxide synthesis process was carried out at 50 oC for 1 hour. The surfactant concentration used was at the critical micelle concentration (CMC), where the CMC for ABS, SDS, CTAB, and PVP were 0.01; 0.05; 3; and 0.5 %w/v, respectively. The synthesis of nickel hydroxide nanoparticle was carried out successfully precipitated almost 100% of Ni2+ ions. The product characterization that has been carried out shows that ABS surfactant produces the best nickel hydroxide nanoparticle product where the particle size is 3.12–4.47 nm.

Anthracene modified graphene for C60/C70 fullerenes capture and construction of energy storage materials

Graphene functionalized with dianthracene malonate was synthesized and used subsequently for construction of covalently bound graphene-fullerene hybrid nanomaterials. For this purpose, novel approach of Diels–Alder reaction of C60/C70 fullerene cores with anthracene moieties previously introduced onto graphene surface was successfully employed. Structure and composition of obtained graphene and its derivatives were characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and FT-IR spectroscopy. Obtained results revealed that both C60 and C70 fullerenes were found to be capable of formation desired Diels–Alder adducts, yielding products of different morphology. Capacitive properties of the synthesized energy storage nanomaterials were determined by means of cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) measurements, revealing that functionalization of graphene with C60 moieties enhances its energy storage properties.