The first synthesis of MnO@Mn O nanoparticles embedded in an N-doped porous carbon framework (MnO@Mn O /NPCF) through pyrolysis of mixed-valent Mn clusters is reported. The unique features of MnO@Mn O /NPCF are derived from the distinct interfacial structure of the Mn clusters, implying a new methodological strategy for hybrids. The characteristics of MnO@Mn O are determined by conducting high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and electron energy loss spectroscopy (EELS) valence-state analyses. Due to the combined advantages of MnO@Mn O , the uniform distribution, and the NPCF, MnO@Mn O /NPCF displays unprecedented lithium-storage performance (1500 mA h g at 0.2 A g over 270 cycles). Quantitative analysis reveals that capacitance and diffusion mechanisms account for Li storage, wherein the former dominates. First-principles calculations highlight the strong affiliation of MnO@Mn O and the NPCF, which favor structural stability. Meanwhile, defects of the NPCF decrease the diffusion energy barrier, thus enhancing the Li pseudocapacitive process, reversible capacity, and long cycling performance. This work presents a new methodology to construct composites for energy storage and conversion.

A novel nitrogen/oxygen co-doped carbon sponge (NOCS) is directly applied as a monolithic binder-free electrode for supercapacitors. It exhibits a high specific capacitance and excellent electrochemical cyclability.

Na + /Na. For full cells, the cathodes were made of 80 wt% Prussian blue, 10 wt% acetylene black, and 10 wt% poly(vinylidene fuoride) coated on aluminum foil with the thickness of 10 µm. The anodes were activated for three cycles at 200 mA g −1 before assembled full cells.

Although the preparation of hierarchical structures of transition‐metal oxides (TMOs) has been intensively studied in recent years, it is still a great challenge to synthesize hierarchical multicomponent TMOs. Herein, we report a versatile method to fabricate three‐component TMOs, namely MnO2@NiO/NiMoO4 nanowires@nanosheets hierarchical porous composite structures (HPCSs). Through a combination of a chemical‐solution‐based route and subsequent calcination, the as‐prepared MnOOH@NiMo precursor is topotactically transformed to MnO2@NiO/NiMoO4 HPCSs without notable structural variation. Ultrathin NiO/NiMoO4 nanosheets become interconnected into a honeycomb analogue with plentiful mesopores. Comparative results demonstrate the vital role of hexamethylenetetramine (HMT), and the solvent system in the formation of the MnOOH@NiMo precursor. When examined as electrode materials for electrochemical capacitors, MnO2@NiO/NiMoO4 HPCSs, with an areal mass loading as high as 5 mg cm−2, deliver a specific capacitance of 918 F g−1 at a current density of 1.0 A g−1 and maintain good cycling stability, which displays better electrochemical performance than electrodes composed of a single component. Note that a high‐voltage asymmetric supercapacitor is configured with MnO2@NiO/NiMoO4 HPCSs (still as high as 2 mg cm−2) against activated carbon, and exhibits outstanding cycling stability with a high energy density of 26.5 Wh kg−1 and a power density of 401 W kg−1. These analytical and experimental results clearly confirm the advantages of distinctive 3D multicomponent hierarchical architectures for engineering high‐performance electrochemical capacitors.

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The general synergistic effect of TiO2‐based heterostructures has been discovered to improve the sodium storage of anodes, involving conversion, alloying, and insertion mechanism materials. Herein, metal sulfides (MS2, M = Sn2+, Co2+, Mo2+), metallic Sb and Sn, as well as, carbon nanotubes (CNTs) are chosen as the model examples from the three kinds. The electrochemical testing demonstrates a better performance of heterostructrues involving TiO2 than the pristine anode components. The introduction of TiO2 into the MS2 and Sb or Sn systems induces a built‐in electric field as the charge transfer force at the heterojunctions, greatly reducing the ion transfer resistance and promoting interfacial electron transfer. In the CNT/TiO2 structure, the chemical growth of TiO2 nanoparticles on the outer surface of CNTs makes the interface more compact than the physical blending case, offering better improvement of electrochemistry. The synergy should work via the growth of heterostructures, relying on the interface effects, which always plays the promotion role through the formation of driving force or grain boundaries and/or condense phase interface to facilitate charge transfer at the interface during the storage process. Therefore, the construction of reasonable heterostructures can endow materials with intriguing electrochemical performance based on the synergistic effect.

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A NiCo2O4@MnO2/NF/MnO2 sandwich with robust adhesion can prevent NiCo2O4 from falling off from the conductive substrate, so the electrode material indicates a satisfactory cycling stability.