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.

Combining the strength of heterostructure engineering with the properties of quantum materials, quantum‐scale heterostructure will open up a new stage for material design. Herein, a kind of anode material with heterostructures made of Bi/TiO2 quantum dots embedded into N‐doped carbon nanosheets (Bi/TiO2 HQDs⊂NC) is reported. Importantly, unique electronic states, structural distortions and defects, and functionalities can be integrated in the quantum‐scale heterostructure, giving rise to opportunities for reducing the ion‐diffusion resistance and facilitating interfacial charge transport at interface during the storage process. The integrated design greatly reduces the migration energy barrier of Na+, promotes the electron/Na+ transportation, buffers the volume variation of electrodes upon cycling, heightens the electric conductivity and electrochemical reactivity of the hybrids, and provides rich active interfacial sites for sodium uptake. Due to these merits, these Bi/TiO2 HQDs⊂NC hybrid nanosheets manifest excellent sodium storage properties in terms of a high reversible capacity of 299.1 at 0.2 A g−1 with an ultrahigh rate capability up to 20 A g−1 with a capacity of 132.7 mAh g−1 and an ultralong cycle life over 10 000 cycles.

Sodium-ion batteries (SIBs) have recently attracted great interest and been considered an ideal alternative toward lithiumion batteries due to the low cost and abundance of sodium resources on the earth. [1][2][3] However, the intrinsic larger radius (1.06 Å) of Na + than that of Li + (0.76 Å), leads to a sluggish kinetics and grievous volume expansion during Na + insertion and extraction as well as low reversible capacity and fast capacity fading for SIBs. [4,5] The key to widespread application for SIBs is to seek a suitable electrode material which is expected to simultaneously possess high theoretical capacity, low volume expansion, and excellent electric conductivity. [6] To date, considerable efforts have been devoted to developing suitable anode materials for SIBs, such as transition metal dichalcogenides (M = Mo and W), [7,8] alloying compounds (Sb, Sn, and SnO 2 ), [9][10][11] titanates, [12] and 2D metal carbides. [13] It is found that most Sodium-ion batteries (SIBs) are considered a prospective candidate for large-scale energy storage due to the merits of abundant sodium resources and low cost. However, a lack of suitable advanced anode materials has hindered further applications. Herein, metal-semiconductor mixed phase twinned hierarchical (MPTH) MoS 2 nanowires with an expanded interlayer (9.63 Å) are engineered and prepared using MoO 3 nanobelts as a selfsacrificed template in the presence of a trace amount of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O as initiator. The greatly expanded interlayer spacing accelerates Na + insertion/extraction kinetics, and the metal-semiconductor mixed phase enhances electron transfer ability and stabilizes electrode structure during cycling. Benefiting from the structural merits, the MPTH MoS 2 electrode delivers high reversible capacities of 200 mAh g −1 at 0.1 A g −1 for 200 cycles and 154 mAh g −1 at 1 A g −1 for 2450 cycles in the voltage range of 0.4-3.0 V. Strikingly, the electrode maintains 6500 cycles at a current density of 2 A g −1 , corresponding to a capacity retention of 82.8% of the 2nd cycle, overwhelming the all reported MoS 2 cycling results. This study provides an alternative strategy to boost SIB cycling performance in terms of reversible capacity by virtue of interlayer expansion and structure stability.

A multifunctional separator composed of different dimensional ZnO and graphene is fabricated via a vacuum filtration method, which can provide sufficient active sites to adsorb polysulfides, thus enhancing the cycling stability and rate performance of lithium–sulfur batteries.

Herein, NbN nanocrystals immobilized on N-doped carbon nanosheets to functionalize a polypropylene (PP) membrane (NbN@NC/PP) with a thin coating of only 4 µm are designed and synthesized. The functional modifier layer allows for sulfur-involved transformations and also lithium plating behaviors. On the one hand, the sulfur cell with NbN@NC/PP separator exhibits excellent cycling stability and rate capacity. The good electrochemical performance partially results from the strong chemical interactions between NbN and lithium polysulfides via the formation of NbS and NLi bonds, which is proven by the first-principles calculations and X-ray photoelectron spectroscopy analyses. The formation of tiny nanoscrystals (<2 nm) and clusters tends to maximize the surface of NbN to interact with polysulfides and enable the effective catalysis over the sulfur-involved reactions. The higher exchange current density and Li + diffusion coefficient of NbN@NC/ PP cells experimentally verify that the introduction of NbN indeed catalytically accelerates the reaction kinetics. On the other hand, the performance of Li// Li symmetric cells demonstrates that the NbN@NC modifier layer can well induce homogeneous lithium deposition. This work confirms the application potential of NbN in lithium-sulfur batteries and encourages the exploration of prospective nitrides to engineer high performance next-generation batteries.