Electrochemical energy storage is one of the few options to store the energy from intermittent renewable energy sources like wind and solar. Redox flow batteries （RFBs） are such an energy storage system, which has f...Electrochemical energy storage is one of the few options to store the energy from intermittent renewable energy sources like wind and solar. Redox flow batteries （RFBs） are such an energy storage system, which has favorable features over other battery technologies, e.g. solid state batteries, due to their inherent safety and the independent scaling of energy and power content. However, because of their low energy-density, low powerdensity, and the cost of components such as redox species and membranes, commercialised RFB systems like the all- vanadium chemistry cannot make full use of the inherent advantages over other systems. In principle, there are three pathways to improve RFBs and to make them viable for large scale application： First, to employ electrolytes with higher energy density. This goal can be achieved by increasing the concentration of redox species, employing redox species that store more than one electron or by increasing the cell voltage. Second, to enhance the power output of the battery cells by using high kinetic redox species, increasing the cell voltage, implementing novel cell designs or membranes with lower resistance. The first two means reduce the electrode surface area needed to supply a certain power output, thereby bringing down costs for expensive components such as membranes. Third, to reduce the costs of single or multiple components such as redox species or membranes. To achieve these objectives it is necessary to develop new battery chemistries and cell configurations. In this review, a comparison of promising cell chemistries is focused on, be they all-liquid, slurries or hybrids combining liquid, gas and solid phases. The aim is to elucidate which redox-system is most favorable in terms of energy-density, power-density and capital cost. Besides, the choice of solvent and the selection of an inorganic or organic redox couples with the entailing consequences are discussed.展开更多
While redox flow batteries carry a large potential for electricity storage,specifically for regenerative energies,the current technology-prone system-the all-vanadium redox flow battery-exhibits two major disadvantage...While redox flow batteries carry a large potential for electricity storage,specifically for regenerative energies,the current technology-prone system-the all-vanadium redox flow battery-exhibits two major disadvantages:low energy and low power densities.Polyoxometalates have the potential to mitigate both effects.In this publication,the operation of a polyoxometalate redox flow battery was demonstrated for the polyoxoanions[SiW_(12)O_(40)]^(4-)(SiW_(12))in the anolyte and[PV_(14)O_(42)]^(9-)(PV14)in the catholyte.Emphasis was laid on comparing to which extent an upscale from 25 to 1400 cm^(2) membrane area may impede efficiency and operational parameters.Results demonstrated that the operation of the large cell for close to 3 months did not diminish operation and the stability of polyoxometalates was unaltered.展开更多
文摘Electrochemical energy storage is one of the few options to store the energy from intermittent renewable energy sources like wind and solar. Redox flow batteries （RFBs） are such an energy storage system, which has favorable features over other battery technologies, e.g. solid state batteries, due to their inherent safety and the independent scaling of energy and power content. However, because of their low energy-density, low powerdensity, and the cost of components such as redox species and membranes, commercialised RFB systems like the all- vanadium chemistry cannot make full use of the inherent advantages over other systems. In principle, there are three pathways to improve RFBs and to make them viable for large scale application： First, to employ electrolytes with higher energy density. This goal can be achieved by increasing the concentration of redox species, employing redox species that store more than one electron or by increasing the cell voltage. Second, to enhance the power output of the battery cells by using high kinetic redox species, increasing the cell voltage, implementing novel cell designs or membranes with lower resistance. The first two means reduce the electrode surface area needed to supply a certain power output, thereby bringing down costs for expensive components such as membranes. Third, to reduce the costs of single or multiple components such as redox species or membranes. To achieve these objectives it is necessary to develop new battery chemistries and cell configurations. In this review, a comparison of promising cell chemistries is focused on, be they all-liquid, slurries or hybrids combining liquid, gas and solid phases. The aim is to elucidate which redox-system is most favorable in terms of energy-density, power-density and capital cost. Besides, the choice of solvent and the selection of an inorganic or organic redox couples with the entailing consequences are discussed.
文摘While redox flow batteries carry a large potential for electricity storage,specifically for regenerative energies,the current technology-prone system-the all-vanadium redox flow battery-exhibits two major disadvantages:low energy and low power densities.Polyoxometalates have the potential to mitigate both effects.In this publication,the operation of a polyoxometalate redox flow battery was demonstrated for the polyoxoanions[SiW_(12)O_(40)]^(4-)(SiW_(12))in the anolyte and[PV_(14)O_(42)]^(9-)(PV14)in the catholyte.Emphasis was laid on comparing to which extent an upscale from 25 to 1400 cm^(2) membrane area may impede efficiency and operational parameters.Results demonstrated that the operation of the large cell for close to 3 months did not diminish operation and the stability of polyoxometalates was unaltered.
