Redox flow batteries, which have been developed over the last 40 years, are used to store energy on the medium to large scale, particularly in applications such as load levelling, power quality control and facilitating renewable energy deployment. Various electrode materials and cell chemistries have been proposed; some of the successful systems have been demonstrated on a large-scale in the range of 10 kW–10 MW. Enhanced performance is attributable to the improvements in electrodes, separator materials and an increasing awareness of cell design. This comprehensive review provides a summary of the overall development of redox flow battery technology, including proposed chemistries, cell components and recent applications. Remaining challenges and directions for further research are highlighted.

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Progress in redox flow batteries, remaining challenges and their applications in energy storage

Effect of degree of sulfonation and casting solvent on sulfonated poly(ether ether ketone) membrane for vanadium redox flow battery

A green SPEEK/lignin composite membrane with high ion selectivity for vanadium redox flow battery

In order to understand the properties of low vanadium permeability anion exchange membranes for vanadium redox flow batteries (VRFBs), quaternary ammonium functionalized Radel (QA-Radel) membranes with three ion exchange capacities (IECs) from 1.7 to 2.4 mequiv g(-1) were synthesized and 55-60 μm thick membrane samples were evaluated for their transport properties and in-cell battery performance. The ionic conductivity and vanadium permeability of the membranes were investigated and correlated to the battery performance through measurements of Coulombic efficiency, voltage efficiency and energy efficiency in single cell tests, and capacity fade during cycling. Increasing the IEC of the QA-Radel membranes increased both the ionic conductivity and VO(2+) permeability. The 1.7 mequiv g(-1) IEC QA-Radel had the highest Coulombic efficiency and best cycling capacity maintenance in the VRFB, while the cell's voltage efficiency was limited by the membrane's low ionic conductivity. Increasing the IEC resulted in higher voltage efficiency for the 2.0 and 2.4 mequiv g(-1) samples, but the cells with these membranes displayed reduced Coulombic efficiency and faster capacity fade. The QA-Radel with an IEC of 2.0 mequiv g(-1) had the best balance of ionic conductivity and VO(2+) permeability, achieving a maximum power density of 218 mW cm(-2) which was higher than the maximum power density of a VRFB assembled with a Nafion N212 membrane in our system. While anion exchange membranes are under study for a variety of VRFB applications, this work demonstrates that the material parameters must be optimized to obtain the maximum cell performance.

Optimized anion exchange membranes for vanadium redox flow batteries.

Sulfonated poly(ether ether ketone)/mesoporous silica hybrid membrane for high performance vanadium redox flow battery

Preparation and characterization of sulfonated poly(ether sulfone)/sulfonated poly(ether ether ketone) blend membrane for vanadium redox flow battery

The invention relates to vanadium redox flow battery field, in particular to a preparation method of sulfonated polymer composite film for vanadium redox flow battery. The preparation method adopts polymer as raw material to prepare sulfonated polymer through concentrated sulfuric acid sulfonation; polysulfonate additives with different proportions are added and stirred for certain time to obtain film forming solution; the sulfonated polymer composite film is prepared through film forming methods of casting method, coating method and dipping method. The composite film prepared through the invention has good vanadium resistance, proton conductivity, mechanical property, chemical stability and film-forming. The preparation method is simple and feasible, has low cost, easy industrialized production and environmental protection, and is widely applicable to vanadium redox flow battery field.

Preparation method of sulfonated polymer composite film for vanadium battery

The invention relates to the field of vanadium redox flow battery (VRB), in particular to a method for preparing an organic-inorganic composite proton exchange membrane for the VRB. The preparation method comprises the following steps: preparing a sulfonated polymer by sulfonation of concentrated sulfuric acid by taking a polymer as a raw material; adding heteropoly acid in different proportions,stirring and dissolving to obtain membrane forming liquid; taking the diaphragm of a polypropylene lithium ion battery as a reinforcing membrane; and preparing a sulfonated polymer/heteropoly acid/polypropylene composite membrane by using membrane forming methods such as a tape casting method, a pasting method, a latex dipping method and the like. The composite membrane prepared by the invention has the advantages of good vanadium resistance performance, swelling performance, proton conductivity, mechanical performance, chemical stability, individual VRB performance and the like. The preparation method of the invention has the advantages of simplicity, easy operation, low cost, easy industrial production, environmental protection and the like and can be widely applied to the field of VRB.

Method for preparing organic-inorganic composite proton exchange membrane for vanadium battery

The invention relates to the field of all-vanadium redox flow battery diaphragms, in particular to a method for preparing a perfluorosulfonic composite proton exchange membrane which is suitable for an all-vanadium redox flow battery. By the method, the problems of poor stability, complex processes, high cost and the like of a proton exchange membrane in the prior art are solved. The method comprises the following steps of: dissolving perfluorosulfonic resin serving as a raw material by using a polar solvent to form perfluorosulfonic resin solution; and in a polypropylene nickel-metal hydride battery; mixing a diaphragm serving as a reinforcing membrane and the perfluorosulfonic resin solution; and preparing a perfluorosulfonic/polypropylene (PP) perfluorosulfonic composite proton exchange membrane by membrane-forming methods such as a substep casting method, a pasting method, a gum dipping method and the like. The prepared composite membrane has the advantages of excellent vanadium resistant performance, proton conductivity, mechanical performance, chemical stability, performance of a single vanadium redox battery (VRB) and the like. The preparation method has the advantages of low cost, simplicity in industrial production and the like, is simple, practicable and environmentally-friendly, and can be widely applied in the field of all-vanadium redox flow batteries.

Method for preparing perfluorosulfonic composite proton exchange membrane

The invention relates to the field of a full-vanadium redox flow battery diaphragm, in particular to a preparation method of a perfluorinated sulfonic acid resin/sulfonated polyether ether ketone type composite diaphragm suitable for a full-vanadium redox flow battery, which solves the problems of poor diaphragm stability, poor vanadium resistance, complex process and high price of the prior art.Perfluorinated sulfonic acid resin and sulfonated polyether ether ketone are used as raw materials, the perfluorinated sulfonic acid resin is dissolved in an organic solvent to prepare perfluorinatedsulfonic acid resin solution, and the sulfonated polyether ether ketone is sulfonated and is then dissolved in the organic solvent to prepare sulfonated polyether ether ketone solution. The perfluorinated sulfonic acid resin solution and the sulfonated polyether ether ketone solution are mixed to prepare mixed solution. The composite diaphragm is prepared with the diaphragm of a polypropylene nickel-metal hydride battery as a reinforcing film and the mixed solution via step-by-step casting, slurry coating, gumming and other film-forming methods. The composite diaphragm prepared in the method can be widely applied in the field of the full-vanadium redox flow battery.

Jianguo Liu

Papers

Preparation and characterization of sulfonated poly(ether sulfone)/sulfonated poly(ether ether ketone) blend membrane for vanadium redox flow battery

Preparation method of sulfonated polymer composite film for vanadium battery

Method for preparing organic-inorganic composite proton exchange membrane for vanadium battery

Method for preparing perfluorosulfonic composite proton exchange membrane

Preparation method of perfluorinated sulfonic acid resin/sulfonated polyether ether ketone type composite diaphragm