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Organic anodes have emerged as a promising energy storage medium in proton ion batteries (PrIBs) due to their ability to reversibly accommodate non‐metallic proton ions. Nevertheless, the currently available organic electrodes often encounter dissolution issues, leading to a decrease in long‐cycle stability. In addition, the inherent potential of the organic anode is generally relatively high, resulting in low cell voltage of assembled PrIBs (<1.0 V). To address these challenges, a novel long‐period stable, low redox potential biphenylzine derivative, [2,2′‐biphenazine]‐7,7′‐tetraol (BPZT) is explored, from the perspective of molecular symmetry and solubility, in conjunction with the effect of the molecular frontier orbital energy levels on its redox potential. Specifically, BPZT exhibited a low potential of 0.29 V (vs SHE) and is virtually insoluble in 2 m H2SO4 electrolyte during cycling. When paired with MnO2@GF or PbO2 cathodes, the resulting PrIBs achieve cell voltages of 1.07 V or 1.44 V, respectively, and maintain a high capacity retention of 90% over 20000 cycles. Additionally, these full batteries can operate stably at a high mass loading of 10 mgBPZT cm−2, highlighting their potential toward long‐term energy storage applications. [ABSTRACT FROM AUTHOR]

Lithium‐sulfur (Li‐S) batteries, with their high theoretical energy density and cost‐effectiveness, have become one of the most promising next‐generation energy storage devices. However, they still face challenges such as the “shuttle effect” caused by the dissolution of polysulfide intermediates and the slow sulfur conversion kinetics. In this study, based on the Co7Fe3 alloy catalyst, additional Co metal is introduced to form a Co7Fe3Co catalyst with a heterostructure through a simple heat treatment process. This catalyst is incorporated into Ketjenblack (KB) to form a sulfur‐infused cathode material (designated as S/KB/Co7Fe3Co). Li‐S batteries using S/KB/Co7Fe3Co as the cathode demonstrate outstanding electrochemical performance, maintaining a reversible specific capacity of over 500 mAh g−1 after 1000 cycles at a current density of 1 C, with a capacity decay rate of 0.046% per cycle. DFT theoretical calculations and experimental results both reveal that the introduction of additional Co effectively regulates the d‐band center of the material, enhancing the adsorption of polysulfide intermediates by Co7Fe3Co and promoting bidirectional catalytic sulfur conversion. This work highlights the importance of the simple construction of heterostructured catalytic materials and their role in improving the performance of Li‐S batteries. [ABSTRACT FROM AUTHOR]

Aqueous redox flow batteries (ARFBs) based on the electrolytes of organic redox-active species with low cost, abundant sources are very attractive for application in large-scale energy storage systems. Herein, we introduce the green and convenient microwave synthesis of a redox-reversible molecule based on an anthraquinone motif, namely 1,3,5,7-tetrahydroxyanthraquinone (1,3,5,7-THAQ), via the dimerization of low-cost 3,5-dihydroxybenzoic acid with high yield and batch production capability. The 1,3,5,7-THAQ presents a high solubility of 1.88 M and a low redox potential of −0.68 V at pH 14, well suited to serving as an anolyte molecule in ARFBs. When paired with a ferrocyanide catholyte, the ARFBs based on 1,3,5,7-THAQ demonstrate a high cell voltage of ∼1.2 V and a maximum output power density of 0.36 W cm−2. Detailed battery tests and post-analyses verify the excellent cycling stability of 1,3,5,7-THAQ without electrochemical dimerization in highly alkaline aqueous environment, which contributes to the ultrahigh capacity retention (95.2% after 1100 cycles at 100 mA cm−2) and low capacity fade rate (∼0.35% per day) of the ARFBs. This work provides an effective paradigm for the design of high performance and low cost ARFBs based on organic redox-active molecules for large-scale and low-cost energy storage applications. • 1,3,5,7-THAQ is easily synthesized via 3,5-dihydroxybenzoic acid dimerization. • 1,3,5,7-THAQ presents a high solubility and a low redox potential at pH 14. • 1,3,5,7-THAQ based flow battery shows a low capacity fade rate of 0.35% day−1. • 1,3,5,7-THAQ based flow battery shows high energy density and long cycling life. [ABSTRACT FROM AUTHOR]