A chemistry and material perspective on lithium redox flow batteries towards high-density electrical energy storage

Abstract

Electrical energy storage system such as secondary batteries is the principle power source for portable electronics, electric vehicles and stationary energy storage. As an emerging battery technology, Li-redox flow batteries inherit the advantageous features of modular design of conventional redox flow batteries and high voltage and energy efficiency of Li-ion batteries, showing great promise as efficient electrical energy storage system in transportation, commercial, and residential applications. The chemistry of lithium redox flow batteries with aqueous or non-aqueous electrolyte enables widened electrochemical potential window thus may provide much greater energy density and efficiency than conventional redox flow batteries based on proton chemistry. This Review summarizes the design rationale, fundamentals and characterization of Li-redox flow batteries from a chemistry and material perspective, with particular emphasis on the new chemistries and materials. The latest advances and associated challenges/ opportunities are comprehensively discussed.

Fiber‐Type Solar Cells, Nanogenerators, Batteries, and Supercapacitors for Wearable Applications

“…Any wearable device requires energy for operation, and a storage device is necessary to supply this energy. There have been tremendous advancements in the field of energy conversion and storage devices in the past few years 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218. A combination of thin and flexible energy harvesting device and a portable storage device remains the best option for powering the wearable devices.…”

Review Article: Flow battery systems with solid electroactive materials

“…59 ). 65 The lower the energy density, the greater the size of the storage tank needed to meet a specific energy requirement. The tank footprint is not necessarily an issue in stationary energy storage, but it makes it challenging for RFBs to penetrate other applications such as transportation, and even within stationary storage applications, the footprint is particularly important where space involves a cost and access premium such as in urban environments.…”

“…75 More comprehensive discussions on organic and/or Li-based RFBs can be found in these recent reviews. 19,22,65,67,76 The second limitation, electroactive material solubility, is a challenge for both aqueous and organic RFBs. The higher the concentration of redox compounds in the electrolyte, the greater the number of electrons that can be exchanged for a given volume or mass of electrolyte and hence the higher the capacity and energy density of the RFB.…”

“…22,73 The voltage has even been reported as high as $3.5 V when paired with a Li metal anode. 65,74 There have also been efforts to construct hybrid organic-aqueous RFBs to take advantage of the low potential achievable at the anode due to the organic electrolyte and suitable potential and high ionic conductivity offered by the aqueous electrolyte on the cathode side. 75 More comprehensive discussions on organic and/or Li-based RFBs can be found in these recent reviews.…”

“…17,64 A few recent reviews provide good discussions on conventional RFBs. 14,19,22,59,[65][66][67] Efforts to improve the performance of RFBs for next generation concepts have largely been focused on improving RFB energy density. RFB energy density is determined by the energy density of the electrolytes, which is relatively low compared to other battery technologies.…”