Abstract
Over recent decades, a new type of electric energy storage system has emerged with the principle that the electric charge can be stored not only at the interface between the electrode and the electrolyte but also in the bulk electrolyte by redox activities of the electrolyte itself. Those redox electrolytes are promising for non-flow hybrid energy storage systems, or redox electrolyte-aided hybrid energy storage (REHES) systems; particularly, when they are combined with highly porous carbon electrodes. In this review paper, critical design considerations for the REHES systems are discussed as well as the effective electrochemical characterization techniques. Appropriate evaluation of the electrochemical performance is discussed thoroughly, including advanced analytical techniques for the determination of the electrochemical stability of the redox electrolytes and self-discharge rate. Additionally, critical summary tables for the recent progress on REHES systems are provided. Furthermore, the unique synergistic combination of porous carbon materials and redox electrolytes is introduced in terms of the diffusion, adsorption, and electrochemical kinetics modulating energy storage in REHES systems.
Highlights
Electrochemical energy storage (EES) devices are becoming increasingly important in our daily life
For energy storage applications requiring high specific power, supercapacitors are more attractive with values typically > 10 kW/kg
P-nitroaniline p-phenylenediamine porous separator quinone redox electrolyte-aided hybrid energy storage reduced graphene oxide sulfonated polyaniline selective permeability diaphragm semi-permeable membrane specific surface area thermally exfoliated graphene 2,2,6,6-tetramethyl-piperidinyl-1-oxyl thin-layer electrochemistry tetrapropylammonium bromide tetrapropylammonium iodide when normalized by the device mass [12]
Summary
Electrochemical energy storage (EES) devices are becoming increasingly important in our daily life. They are applied in small devices such as laptops, tablets, and cell phones, and in larger devices like electric cars to provide efficient and reliable use of energy [1]. Through redox reactions at the positive and negative electrodes, either by conversion-type or insertion/intercalation type reactions, batteries provide a stable operating potential with high specific charge storage capacity [5]. State-of-the-art intercalation-type lithium-ion batteries, for instance, offer a nominal cell voltage of 3.6 V with a specific energy of 20–150 Wh/kg (normalized by the device mass) [4,6,7,8]. For energy storage applications requiring high specific power, supercapacitors are more attractive with values typically > 10 kW/kg
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
