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Conjugated coordination polymers (CCPs) with extended π–d conjugation, which can effectively promote long‐range delocalization of electrons and enhance conductivity, are superior to traditional metal‐organic frameworks (MOFs) and attracted great attention for potential applications in chemical sensors, electronics, energy conversion/storage devices, etc. However, the precise construction of CCPs is still challenging due to the complex and uncontrollable reactions of CCPs. Herein, two different framework dimensions of CCPs are controllably realized by employing the same ligand (2,3,5,6‐tetraaminobenzoquinone (TABQ)) and the same metal (copper) as center ions. The manipulation of reaction leads to different valences of ligands and metal ions, different coordination geometries, and thereby 1D‐CuTABQ and 2D‐CuTABQ frameworks, respectively. High performance of charge storage is hence achieved involving the storage of both cations and anions, and therein, 2D‐CuTABQ shows a high reversible capacity of ≈305 mAh g−1, good rate capability and high capacity retention (≈170 mAh g−1 after 2000 cycles at 5 A g−1 with 0.01% decay per cycle), which outperforms 1D‐CuTABQ and almost all of the reported MOFs as cathodes for batteries. These results highlight the delicate structural control of CCPs for high‐performance batteries and other various applications. [ABSTRACT FROM AUTHOR]

Redox-active organic materials have shown great potential as electrodes in lithium-ion batteries (LIBs). However, most of them showed a low discharge potential. We report a thianthrene-based small molecule (BDBDT), which could be facilely synthesized, as a high-potential cathode. The BDBDT cathode exhibited good electrochemical performance with a discharge plateau at 3.9 V (vs. Li/Li+) and a discharge capacity of 63 mA h g−1 after 100 cycles at 500 mA g−1 (∼10C). Our results demonstrate that thianthrene-based molecules are promising for the development of high-potential organic electrodes towards rechargeable batteries with high energy and power density. [ABSTRACT FROM AUTHOR]

Aqueous zinc‐ion batteries (ZIBs) are promising for next‐generation energy storage. However, the reported electrode materials for ZIBs are facing shortcomings including low capacity and unsatisfactory cycling stability etc. Herein, hexaazatrinaphthalene‐quione (HATNQ) is reported for aqueous ZIBs. The HATNQ electrodes delivered an ultrahigh capacity (482.5 mAh g−1 at 0.2 A g−1) and outstanding cyclability of >10 000 cycles at 5 A g−1. The capacity sets a new record for organic cathodes in aqueous ZIBs. The high performances are ascribed to the rich C=O and C=N groups that endowed HATNQ with a 2D layered supramolecular structure by multiple hydrogen bonds in plane with π–π interactions out‐of‐plane, leading to enhanced charge transfer, insolubility, and rapid ion transport for fast‐charge and ‐discharge batteries. Moreover, the 2D supramolecular structure boosted the storage of Zn2+/H+, particularly the storage of Zn2+, due to the more favorable O⋅⋅⋅Zn⋅⋅⋅N coordination in HATNQ. [ABSTRACT FROM AUTHOR]

With the development of large-scale energy storage and the electric-vehicle market, the demand for lithium-ion batteries (LIBs) is increasing, resulting in the explosive increase in spent LIBs. The cathode materials of spent LIBs contain multiple transition elements, such as lithium (Li), cobalt (Co), nickel (Ni), and manganese (Mn). The recovery of these metals has significant environmental benefits and high economic value. As a green solvent, deep eutectic solvents (DESs) show great potential in recovering valuable metal elements from spent LIBs. Here, this study proposed a new type of DES formed from betaine hydrochloride and ethylene glycol (betaine hydrochloride and ethylene glycol at a 1 : 5 molar ratio), which can efficiently leach metal elements from spent Ni–Co–Mn lithium batteries (LNCM). The leaching rates of Ni, Co, Mn, and Li can all reach 99% under the conditions of T = 140 °C, t = 10 min and no reductant. Compared with the traditional leaching process, this study provided an economical, green, and efficient approach to recover valuable metals from spent LIBs. [ABSTRACT FROM AUTHOR]

As ideal cathode catalysts for proton exchange membrane fuel cells (PEMFCs), the oxygen reduction reaction (ORR) activity and durability of Pt‐based alloys can be improved further. This study presents the catalyst with Au doping on the surface of an ordered PtFe alloy (Au‐PtFe/C) utilizing a synergistic process of microwave reduction and chemical replacement, as well as the reorganization of a Pt‐rich surface using acid etching and high temperature annealing. Physical characterization indicated that the oxygen binding energy on the surface of Au‐PtFe/C was more effective at promoting the ORR reaction than commercial Pt/C, which contributes significantly to its enhanced activity. Further electrochemical tests revealed that the Au‐PtFe/C catalyst exposes abundant active sites for ORR, with mass and specific activity up to 12 and 8 times that of commercial Pt/C, respectively. Additionally, the catalyst demonstrated remarkable durability following 10,000 cycles of accelerated durability tests (ADT) in acidic circumstances. In PEMFC test, the single cell with an Au‐PtFe/C cathode also performed admirably when compared with commercial Pt/C. Owing to its facile synthesis, low cost, and exceptional performance, this bimetal‐doped ordered Pt‐based alloy has the capability to be a promising component in fuel cells commercialization. [ABSTRACT FROM AUTHOR]

The oxidation of π–d‐conjugated coordination polymers (CCPs) accompanied with anion insertion has the merits of increasing the capacity and elevating the discharge voltages. However, previous reports on this mechanism either required more investigations or showed low capacity and poor cyclablity. Herein, triphenylene‐catecholate‐based two‐dimensional CCPs are constructed by employing inactive transition‐metal ions (Zn2+) as nodes, forming Zn‐HHTP. Substantial characterizations and theoretical calculations indicate the successive storage of cations and anions by redox reactions of only ligands, leading to a high reversible capacity of ≈150 mAh g−1 at 100 mA g−1 and a remarkable capacity retention of 90 % after 1000 cycles. On the contrary, as a control experiment, the analogous CCPs (Cu‐HHTP) with Cu2+ nodes, where both ligands and metal ions undergo redox reactions, accompanied by the storage of only Na+ cations, show a much poorer cyclability. These results highlight the importance of redox reactions of only ligands for long‐term cycle life and the insight into the storage mechanisms deepens our understanding on CCPs for the further design of CCPs with high performance. [ABSTRACT FROM AUTHOR]

Low‐cost and highly safe zinc‐manganese batteries are expected for practical energy storage and grid‐scale application. The electrolyte adjustment is further combined to boost their performance output; however, the mechanism behind the electrochemical contrast caused by electrolyte composition remains unclear, which has held back the development of these systems. Hence, new insight into the electrochemical activation of manganese‐based cathodes, which is induced by the aqueous zinc‐ion electrolyte, is provided. The relationship between the desolvation of Zn2+ from [Zn(OH2)6]2+‐solvation shell and the electrolyte/electrode interfacial reaction to form Zn4SO4(OH)6·4H2O phase or its analogues is established, which is the key for the electrochemical activation. Further electrolyte optimization promotes the cycling stability of Zn/LiMn2O4 battery with a long life span over 2000 cycles. This work illuminates the confused direction in exploring electrolyte for zinc‐manganese batteries. [ABSTRACT FROM AUTHOR]

• The modification strategy with PDA@nano-TiO 2 was designed to enhance electrochemical performance of spinel LNMO. • PDA@TiO 2 -LNMO cathode showed high reversible capacities and good capacity retention. • The excellent performance was attributed to PDA@nano-TiO2 as protective layer and good conductor for Li+ diffusion. The surface modification of LiNi 0.5 Mn 1.5 O 4 cathode material with PDA@TiO 2 enable it gain the high reversible capacities and good capacity retention. [Display omitted] Improving the cycling performance without sacrificing its capacity is challenging for high-voltage LiNi 0.5 Mn 1.5 O 4 cathode due to the trade-off nature among the key properties. A self-polymerization process of dopamine was utilized to grow polydopamine (PDA)-nano titanium dioxide assembly. PDA@TiO 2 composite was demonstrated to be integrated with the particles of high-voltage spinel LiNi 0.5 Mn 1.5 O 4 cathodes via wet chemical method. PDA@TiO 2 decorated LNMO improved the long-term cycling performance and rate capability by suppressing detrimental side reactions in balancing the interfacial stability and Li+ diffusion kinetics of LNMO and consequently providing efficient conductive pathways. As a result, 2% PDA@TiO 2 modified LNMO cathode exhibited the high reversible capacity of 117 mAh g−1 after 1000 cycles with good capacity retention of 90.7% at 1 C, and superior rate capability (78.5 mAh g−1 at 5 C) at room temperature. Remarkably, a significant improvement in cycling stability at an elevated temperature (50 °C) was obtained for the PDA@TiO 2 -LNMO composite, giving a capacity retention of 93% after 100 cycles at 1 C. The mechanism of performance improvement could be attributed to the maintenance of the structural stability of LNMO cathode materials and the enhanced kinetics of the remarkable lithium-ion diffusion through the protective effect of PDA@TiO 2 decorating. [ABSTRACT FROM AUTHOR]