{"title":"Electrochemical kinetic evolution of electrically neutral redox mediator in electrolyte toward advanced electrochemical energy storage device","authors":"Zhenheng Sun , Min Cao , Weiwei Gao","doi":"10.1016/j.jpowsour.2025.236700","DOIUrl":null,"url":null,"abstract":"<div><div>As a novel energy storage strategy, redox electrolytes are promising for the high-performance electrochemical energy storage devices with high energy density and power density simultaneously. In comparison to redox mediators in the form of ion-pair reactions, electrically neutral redox mediators with excellent stability exhibit distinctive electrochemical behaviors, which have rarely been systematically explored. In this study, we utilized a typical nitrogen-oxygen radical, 4-hydroxy-2,2,6,6-tetramethyl-piperidinooxy (TEMPO-OH) as an example, combining a novel quasi-steady electrochemical measurement and <em>in-situ</em> Raman spectrum to systematically characterize the distribution, diffusion and reaction of radicals during electrochemical processes, finally establish a model for the evolution of electrochemical kinetics. The diffusion of radicals is driven by concentration polarization, whereby a high radical concentration can effectively enhance the capacity and rate performance. Nevertheless, the charge transfer process based on radical exchange and oxidation persists, gradually extending outwards from the electrode/electrolyte interface. As a result, the radical diffusion path is prolonged, and irreversible capacity loss occurs during long-term electrochemical processes, which is detrimental to the enhancement of electrochemical performance. Our research facilitate the development of advanced electrochemical energy storage devices.</div></div>","PeriodicalId":377,"journal":{"name":"Journal of Power Sources","volume":"640 ","pages":"Article 236700"},"PeriodicalIF":8.1000,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Power Sources","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0378775325005361","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
As a novel energy storage strategy, redox electrolytes are promising for the high-performance electrochemical energy storage devices with high energy density and power density simultaneously. In comparison to redox mediators in the form of ion-pair reactions, electrically neutral redox mediators with excellent stability exhibit distinctive electrochemical behaviors, which have rarely been systematically explored. In this study, we utilized a typical nitrogen-oxygen radical, 4-hydroxy-2,2,6,6-tetramethyl-piperidinooxy (TEMPO-OH) as an example, combining a novel quasi-steady electrochemical measurement and in-situ Raman spectrum to systematically characterize the distribution, diffusion and reaction of radicals during electrochemical processes, finally establish a model for the evolution of electrochemical kinetics. The diffusion of radicals is driven by concentration polarization, whereby a high radical concentration can effectively enhance the capacity and rate performance. Nevertheless, the charge transfer process based on radical exchange and oxidation persists, gradually extending outwards from the electrode/electrolyte interface. As a result, the radical diffusion path is prolonged, and irreversible capacity loss occurs during long-term electrochemical processes, which is detrimental to the enhancement of electrochemical performance. Our research facilitate the development of advanced electrochemical energy storage devices.
期刊介绍:
The Journal of Power Sources is a publication catering to researchers and technologists interested in various aspects of the science, technology, and applications of electrochemical power sources. It covers original research and reviews on primary and secondary batteries, fuel cells, supercapacitors, and photo-electrochemical cells.
Topics considered include the research, development and applications of nanomaterials and novel componentry for these devices. Examples of applications of these electrochemical power sources include:
• Portable electronics
• Electric and Hybrid Electric Vehicles
• Uninterruptible Power Supply (UPS) systems
• Storage of renewable energy
• Satellites and deep space probes
• Boats and ships, drones and aircrafts
• Wearable energy storage systems