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Theaflavins (TFs) are a kind of bioactive compound that formed during the fermentation stage of black tea. TFs play a vital role both in the sensory quality and the biological activity of black tea. However, the complex composition of black tea and the low content of TFs in black tea (0.3%–0.7%) make the technology for the preparation of high‐purity TFs a great challenge. This review provides an updated overview for extracting, synthesizing and purifying of TFs. Molecular imprinting technology, an efficient method for extracting bioactive compounds, will be a promising method for the preparation of TFs with high purity. Overall, this review can provide a scientific basis and technical support for the preparation of TFs with high purity and will be helpful for the in‐depth development and further research of TFs. Schematic representation of the synthesis, extraction, and purification method of TFs from black tea and the extraction principle of magnetic molecularly imprinted polymers (MMIPs) for bioactive compounds. MMIPs will be a promising method for the preparation of TFs with high purity.

In this work, a high-performance cathode comprising hydrothermally grown MnCo2O4(MCO) nanowires sandwiched by the subsequently electrodeposited Ni-CoMnS4(NCMS) nanosheets, i.e., MCO@NCMS on Ni foam, is developed. Due to its highly porous and interconnected nanostructure and the synergistic effect of its MCO and NCMS components, an outstanding capacitance of 12,020.8 mF cm−2at 1 mA cm−2is achieved. In addition, this cathode displays remarkable performance in terms of rate capability and cycle stability. Electrochemical analysis shows that the corresponding aqueous asymmetric supercapacitors have a highly competitive energy density of 0.611 mW h cm−2(at 0.800 mW cm−2) and robust cycling performance, i.e., ∼90% retention of the initial capacitance and 100% Coulombic efficiency over 15,000 charge-discharge cycles.

Vanadium-based oxides have garnered significant attention as cathode materials for aqueous zinc-ion batteries (AZIBs) because of their high theoretical capacity and low cost. However, the limited reaction kinetics and poor long-term cycle stability hinder their widespread application. In this paper, we propose a novel approach by coinserting Ni2+and NH4+ions into V2O5·3H2O, i.e., NNVO. Structural characterization shows that the coinsertion of Ni2+and NH4+not only extends the interlayer spacing of V2O5·3H2O but also significantly promotes the transport kinetics of Zn2+because of the synergistic “pillar” effect of Ni2+and NH4+, as well as the increased oxygen vacancies that effectively lower the energy barrier for Zn2+insertion. As a result, the AZIBs with an NNVO electrode exhibit a high capacity of 398.1 mAh g–1(at 1.0 A g–1) and good cycle stability with 89.1% capacity retention even after 2000 cycles at 5.0 A g–1. At the same time, a highly competitive energy density of 262.9 Wh kg–1is delivered at 382.9 W kg–1. Considering the simple scheme and the resultant high performance, this study may provide a positive attempt to develop high-performance AZIBs.

Supercapacitors display promising electrochemical performance with high power density and excellent cycle stability. However, their low energy density limits their advancement in a broader range of applications. To enhance their energy density, we proposed self-assembled spinel NiMn2S4nanoflakes grown on nickel foam which we successfully prepared by a facile hydrothermal method. The NiMn2S4electrode delivers a high capacitance of 2096.7 F g−1at 1.0 A g−1, with an exceptional rate capability (~720.6 F g−1at a very high current density of 100 A g−1) and good cycle stability (~85.1% retention of the initial capacitance after 7000 cycles with the Coulombic efficiency around 100%). The as-fabricated asymmetric supercapacitors based on NiMn2S4nanoflakes//active carbon demonstrate an energy density of 73.6 W h kg−1at 800.5 W kg−1and adequate cycling performance of ~84.6% capacitance retention at 15 A g−1after 10000 cycles. The results reveal that the nanostructured NiMn2S4is an excellent electrode material for high performance energy storage applications.

In this paper, we report a cathode with the good comprehensive electrochemical performance by electrochemically growing MnCoP nanosheets on NiCo2O4nanograss hydrothermally grown on carbon nanotube (CNT)-coated Ni foam. A capacitance of 4787.3 mF cm−2at 1 mA cm−2, high rate performance (3126.2 mF cm−2at 30 mA cm−2), as well as good cycle stability is delivered by the cathode. By employing this cathode, the anode of activated carbon on carbon cloth, and the electrolyte of 2 M KOH aqueous solution, we assembled an aqueous asymmetric supercapacitor, which exhibits an energy density of 0.390 mWh cm−2at 0.825 mW cm−2and good cycle stability of 85.7 % capacitance retention after 20,000 cycles at 10 mA cm−2.