Suchergebnisse

Aqueous hybrid Zn2+/Na+ ion batteries (AHZSIBs) have gained considerable attention for stationary energy storage applications because of their outstanding safety, sustainability, abundance, and low raw material costs. However, the low capacity values (<100 mAh/g) of the Na+ ion deinsertion/insertion cathodes limit the overall capacity storage of AHZSIBs. Herein, we propose a novel concept to extend the charge storage performance of AHZSIBs using electrolyte with redox characteristics. The benefits of using redox aqueous electrolytes such as 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL) and sodium ferrocyanide (Na4[Fe(CN)6]) were investigated in an AHZSB, which consists of Zn metal as an anode and sodium nickel hexacyanoferrate (Na-NiHCF) as the Na+ deinsertion/insertion cathode. The proposed AHZSB using Na4[Fe(CN)6] redox electrolyte provided a capacity (144 mAh/g) that was ~2.94 times higher than AHZSIB using a conventional Na2SO4 electrolyte (49 mAh/g). This capacity enhancement emanated from the faradaic contribution of the Fe2+(CN)64−/Fe3+(CN)63− redox pair present in the electrolyte and Fe2+/Fe3+ redox pair in the lattice of Na-NiHCF. In addition, the TEMPOL-based redox electrolyte also improved the capacity (from 49 to 120 mAh/g) through the combined faradaic contribution of the TEMPOL/TEMPOL+ redox pair dissolved in the electrolyte and the Fe2+/Fe3+ redox pair in the Na-NiHCF lattice. These results confirm the competence of the redox electrolyte in AHZSIB in enhancing the charge storage capacity. We anticipate that this proof-of-concept study will provide a new direction for developing high-capacity storage AHZSIBs. More importantly, this approach can be used in any aqueous/non-aqueous batteries. ; This work was supported by the 2020 Research Fund (1.200070.01) of UNIST (Ulsan National Institute of Science & Technology). This work was also supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) No.2020R1A4A1019568). S.T.S gratefully ...

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. ; MFreeB project has received funding from the 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).

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).