The electrode is one of the main components in redox flow batteries (RFBs), as it provides the reactions sites for redox couples and can influence the cell performance through its effect on cell voltage losses associated with activation overpotential, concentration overpotential and ohmic losses. Extensive research has thus been carried out on material selection, structural design and modification of electrodes as well as electrocatalysis for redox reactions. This review provides an historical overview of the screening and modification of electrode materials together with recent progress in novel electrode architectures, electrode modification and electrocatalysis methods. RFB systems such as iron/chromium, polysulfide/bromine and all vanadium batteries are discussed in detail.

With virtues of high safety, long cycle life, environmental friendly and state of charge easy monitoring, vanadium flow battery has been an effective technique for large scale energy storage. In this paper, its main developers and suppliers, installation capacity, standards, patents and incentive policies are summarized.

Redox flow battery (RFB) is an important type of electrochemical device for large-scale stationary energy storage. The most intriguing advantage of RFB is the decoupled energy storage and power generation of the system. It shows great promises for grid and for distributed energy storage from renewable resources. In this article, the development and prospects of high energy density RFBs are briefly reviewed, with special emphasis on the recently developed redox flow lithium battery.

In this paper, we studied the distribution patents and the technology development of supercapacitors. The patent information in this paper is collected from the patent database of Derwent Innovations Index (DII). We analyzed the publication year, countries, subjects, key applicants by using of TDA and innography. Based on the analysis, we got the present international situation and trend of supercapacitor energy storage technology.

In recent years, aqueous lithium-ion batteries have been widely studied due to their advantages of high power, low environmental pollution, etc. In this paper, we use LiFePO₄ which has better stability in alkali systems as a positive electrode, graphite plate as the negative electrode. The reactivity of the lithium insertion/extraction, zinc deposition/dissolution and the stability of positive electrode material were studied by SEM, XRD, cyclic voltammetry, linear sweep voltammetry and other methods.

State of charge (SOC) indicates the ratio of the schedulable capacity to that of available maximum W·h capacity in an energy storage system, which is necessary parameter for energy storage applications. This study clarified SOC concept framework for all vanadium redox flow battery from both theory and applications, proposed two approaches to determine the maximum W·h capacity. The measured method has high accuracy, containing information relative to vanadium ions transport and water diffusion through membranes, hydrogen emission and oxidization in the negative electrolyte by side-reaction, having promising potential for use in the characterization of the state of charge in practical system. We also elaborated the relationship of the maximum W·h capacity, electrochemical W·h capacity and theoretical W·h capacity. It can be expected that this method can be used to determine the state of charge in vanadium redox flow battery R&D process.

As one of the most feasible large scale energy storage technology of electrical energy, vanadium redox flow battery has been combined with non-continuous renewable power sources such as solar or wind power. In the VFB, the electrolyte is one of the most important components. It is not only the conductor of the ions but also the energy-store medium. The research on thermodynamics of the electrolyte will be of great value to having an adequate understanding of the nature of the electrolyte for providing clues to optimize the overall performance of the VFB. The conductivities of aqueous solution V(Ⅴ) sulfuric acid with various molalities are measured in the temperature range of 278.15~318.15 K. The conductivities of V(Ⅴ) +H₂SO₄+H₂O ternary system was analyzed and the conductivities binary system V(Ⅴ) aqueous solution was obtained by extrapolation, the effects of concentration and temperature on the ionic limiting molar conductivity, stocks radius, the transport number, diffusion coefficient and conductance activation energy were studied and discussed.

Based on Darcy equation, pressure differences at different volume flow rates are measured on the test platform of the electrolyte flow characteristics. The Kozeny-Carman constant is 24.087, evaluated from the linear relationship between pressure differences and flow rates. The accuracy of the calculation is improved. The average value of the relative errors to the experimental data is less than 3%.

Electrolyte of vanadium flow battery (VFB) is the key component of the energy storage unit, which plays an important role in the energy conversion efficiency and cycle stability performance of VFB. Considering the volume ratio of the catholyte and anolyte, also the electrolyte valence state, the effect of the excess of negative active reactant on the electrochemical performance of VFB is systematically investigated. The results show that the increasing the volume of the anolyte with the same catholyte improves the discharge capacity for VFB, but has less effect on the energy conversion efficiency. The increasement of the electrolyte valence lead to a reduced discharge capacity of VFB in some extent, while the energy conversion efficiency increases at first and then decreases, conforming to a parabola law. Increasing of the volume of anolyte and electrolyte valence state result in the excess of the negative active reactant, the latter has more significant effect on the battery performance of VFB. However, the effect of anolyte volume will be enlarged with the existence of exec valence state.

This bimonthly review paper highlights 100 recent published papers on lithium batteries. We searched the Web of Science and found 1573 papers online from June 1,2015 to July 31,2015. 100 of them were selected to be highlighted. Layered oxide and high voltage spinel cathode materials are still under extensive investigations for the structure evolution and modifications. Large efforts were devoted to Si based composite anode material. There are a few papers related to electrolyte additives, solid state electrolyte, Li/S and Li-air batteries, and more papers for analyzing the fading and thermal safety mechanism of the cell.