Bromine Assisted MnO₂ Dissolution Chemistry: Toward a Hybrid Flow Battery with Energy Density of over 300 Wh L⁻¹

Abstract

Mn2+/Mn3+ redox pair has been considered as a promising cathode for high energy density batteries, due to its attractive features of high redox potential, solubility and outstanding kinetics. However, the disproportionation side reaction of Mn3+, which results in accumulation of “dead” MnO2 limits its reversibility and further energy density. Herein, a novel catholyte based on mixture of Mn2+ and Br− was proposed for flow batteries with high energy density and long cycle life. In the design, the “dead” MnO2 can be fully discharged via Br− by a chemical‐electrochemical reaction. Coupled with Cd/Cd2+ as anode, the assembled Bromine‐Manganese flow battery (BMFB) demonstrates a high energy efficiency of 76 % at 80 mA cm−2 with energy density of 360 Wh L−1. The battery assembled with silicotungstic acid as anode could continuously run for over 2000 cycles at 80 mA cm−2. With high power density, energy density and durability, the BMFB shows great potential for large‐scale energy storage.

A Streptomyces Cytochrome P450 Enzyme Catalyzes Regiospecific C2-Guaninylation for the Synthesis of Diverse Guanitrypmycin Analogs

“…The above results implied GutD 1521 as a new nucleobase transferase for the specific C-2–C-8′ connection between the indole and guaninyl units, differing from the previous reported P450s (Figure ). − …”

“…P450 enzymes from the featured biosynthetic pathways catalyze a wide range of interesting chemical transformations, such as intramolecular C–C bond formation, different types of dimerization, aromatization of the DKP ring, and nucleobase transfer reactions. ,, Seven different types of cyclodipeptide–nucleobase linkages have been characterized from CDPS-P450-related nucleobase transfer pathways, including C–C, C–N, and C–O bonds (Figure ). − Additionally, different tryptophan-containing and tyrosine-containing CDPs as well as two nucleobases, guanine and hypoxanthine, have been found as the substrates of these P450 enzymes. − These findings significantly expanded the spectrum of DKP derivatives and highlight the promise of CDPS-related enzymes as unique biocatalysts for novel transformations.…”

A Highly Reversible Low-Cost Aqueous Sulfur–Manganese Redox Flow Battery

“…The triiodide could come from iodine discharge or accumulated MnO 2 oxidation by the mediator effect (eq ). The mediator effect has been carefully examined in our previous study and verified in other following works. ,− …”

Aqueous MnO2/Mn2+ electrochemistry in batteries: progress, challenges, and perspectives

“…117 Besides, the redox mediator strategy is introduced to recover the lost capacity of “dead Mn” and improve the reversibility of the reaction. 98,118–121 The specific operation mechanism of the redox mediator, such as I − /I 3 − , is shown in Fig. 7h.…”