Suchergebnisse

The active materials constitute the heart of any battery so that unambiguous determination of their intrinsic properties is of essential importance to achieve progress in battery research. A variety of in situ techniques with high lateral resolution has been developed or adapted for battery research. Surprisingly, nanoelectrochemistry is not attracting sufficient attention from the battery community despite the existing examples of relevant in situ and highly resolved spatiotemporal information. Herein, the important role of nanoelectrochemistry in battery research is highlighted to help encourage its use in this field. In the first part, two examples in which the use of nanoelectrochemistry is a must are provided, that is, determination of intrinsic kinetics of active materials and understanding of relationships between particle structure and electrochemical activity. In the second part, pros and cons of three mature nanoelectrochemistry techniques in battery research, that is, particle-on-a-stick measurements, nanoimpact measurements, and scanning electrochemical probe microscopy, are discussed providing representative examples. ; Spanish Government (MINECO) through the Research Challenges Programme (grant RTI2018-099228-A-I00) and Ramón y Cajal award (RYC2018-026086-I) as well as the NanoBat project. NanoBat has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no. 861962.

Aqueous organic redox flow batteries (AORFBs) have recently been attracting much attention due to their potential utilization as a sustainable solution for stationary energy storage. However, AORFBs have still to face various challenges to become a competitive technology to other mature redox flow batteries. Fading of the energy storage capacity upon cycling leading to insufficient lifetime is likely the most pressing issue. Several processes are contributing to this issue. Among the capacity fading promoters, the existence of side reactions such as water splitting and reactions related to oxygen reduction triggers an imbalanced state of charge for the catholyte and anolyte. Herein, a simple electrochemical balancing procedure is proposed and successfully demonstrated through the restoration of the oxidation states of the two half-cell solutions. The results reveal that it is possible to mitigate and even revert the effects of such side reactions, developing a useful method for mitigating the capacity fading and prolonging the cycling performance of AORFBs. In the two case studies, the implementation of this simple charging procedure leads to a remarkable 20-fold reduction of capacity fading (% h−1). The protocol is a general approach for redox flow batteries, easily implementable and inexpensive. ; European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. 726217). The results reflect only the authors' view and the Agency is not responsible for any use that may be made of the information they contain. The authors also acknowledge the financial support by the Spanish Government through the Research Challenges Programme (Grant RTI2018-099228-A-I00). E.V. thanks the MINECO for the financial support (RYC2018-026086-I). A.M.-C. thanks the MINECO for the financial support (RYC2017-22700).

Each battery technology possesses intrinsic advantages and disadvantages, e.g., nickel–metal hydride (MH) batteries offer relatively high specific energy and power as well as safety, making them the power of choice for hybrid electric vehicles, whereas aqueous organic flow batteries (AORFBs) offer sustainability, simple replacement of their active materials and independent scalability of energy and power, making them very attractive for stationary energy storage. Herein, a new battery technology that merges the above mentioned battery technologies through the use of redox-mediated reactions is proposed that intrinsically possesses the main features of each separate technology, e.g., high energy density of the solid active materials, easy recyclability, and independent scalability of energy and power. To achieve this, Ni(OH)2 and MHs are confined in the positive and negative reservoirs of an AORFB that employs alkaline solutions of potassium ferrocyanide and a mixture of 2,6-dihydroxyanthraquinone and 7,8-dihydroxyphenazine-2-sulfonic acid as catholyte and anolyte, respectively. An energy density of 128 Wh L–1 is achieved based on the capacity of the reservoirs leaving ample room for improvement up to the theoretical limit of 378 Wh L–1. This new battery technology opens up new market opportunities never before envisaged, for redox flow batteries, e.g., domestic energy storage and heavy-duty vehicle transportation. ; Spanish Government through the Research Challenges Programme (Grant No. RTI2018-099228-A-I00). E.V. thanks the MINECO for the financial support (RYC2018-026086-I).

Redox-flow batteries, based on their particular ability to decouple power and energy, stand as prime candidates for cost-effective stationary storage, particularly in the case of long discharges and long storage times. Integration of renewables and subsequent need for energy storage is promoting effort on the development of mature and emerging redox-flow technologies. This review aims at providing a critical analysis of redox-flow technologies that can potentially fulfill cost requirements and enable large scale storage, mainly aqueous based systems. A comprehensive overview of the status of those technologies, including advantages and weaknesses, is presented. Compiled data on the market permeability, performance and cost should serve, together with the perspective included, to understand the different strategies to reach the successful implementation, from component development to innovative designs. ; European Union under HIGREEW, Affordable High-performance Green Redox Flow batteries (Grant Agreement no. 875613) and CuBER, Copper-Based Flow Batteries for energy storage renewables integration (Grant agreement no: 875605) projects. Basque Government (GV-ELKARTEK-2020 KK-2020/00078), Spanish MINECO (RTI2018-099228-A-I00 and RYC2018-026086-I (Ramon y Cajal fellowship) E.V.) and CDTI (Centro para el Desarrollo Tecnológico Industrial, CER-20191006) are also acknowledged for funding this work. R.M. thanks the European Research Council (ERC) through "MFreeB" project (grant agreement no. 726217)