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Metal sulfides possess tremendous potentials owing to their high specific capacity for sodium storage. However, the huge volume expansion, accompanied with structural collapse and unsatisfied electric conductivity upon continuous cycling, always lead to inferior rate capability and severe cycling fading. In this work, binary metal sulfide (ZnS/SnS2) nanoboxes confined in N/S dual‐doped carbon shell (ZSS@NSC) are fabricated through a facile co‐precipitation method involving the wrapping of polypyrrole, and subsequent in situ sulfidation process. Such a well‐designed heterogeneity between ZnS and SnS2 provides rapid Na+ insertion and enhanced charge transport by creating an electric field at the heterointerface. More significantly, the formation of polypyrrole‐derived N/S dual‐doped carbon is synergistically coupled with the ZnS/SnS2 to create a unique and robust architecture, further strengthening the interconnect function at the heterointerface, which improves electric/ion transfer and mitigates the volume variation during the long‐term cycling process. Herein, this as‐prepared ZSS@NSC exhibits satisfied specific capacity, excellent rate property, and superior cyclic stability (a reversible capacity of 456.2 mAh g−1 with excellent capacity retention of 97.2% after 700 stable cycles at ultrahigh rate of 5 A g−1). The boosted Na‐storage properties demonstrate that the optimized strategy of structure‐engineering has a broad prospect to promote energy storage applications.

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Coating methodology is commonly employed in the enhancement of Ni-rich cathodes for Li-ion batteries as an efficient approach, while its strategy and effect are still great challenges to achieve success in surface modifications for comprehensive electrochemical properties. In this work, the surface of Ni-rich cathode LiNi0.82Co0.15Al0.03O2 (NCA) is modified by intimately coating NASICON-type solid electrolyte LiZr2(PO4)3 (LZP) via a facile approach involving electrostatic attraction. With well-designed architecture and a uniform NASICON-type LZP nanolayer wrapping over the NCA microsphere, the entire electrode demonstrates exceptional Li+ diffusion and conductivity and suppresses the side reaction between electrolyte and electroactive NCA, stabilizing the phase interface with less Li+/Ni2+ cation mixing. As a result, the NCA@LZP can deliver a high reversible capacity of 182 mAh g–1 at 1C in 2.7–4.3 V, maintaining the capacity retention of 84.6% after 100 cycles. More importantly, the structure stability of NCA is enhanced substantially by surface modification of LZP at high cutoff voltage. It achieves a reversible capacity of 204 mAh g–1 and keeps 100.4 mAh g–1 after 500 cycles at 1C in the potential range of 2.7–4.5 V. This effective strategy of using NASICON fast ionic conductor like LZP as a coating layer may provide a new insight to modify the surface of Ni-rich electrode, improving the rate capability and cyclic performance under high voltage.

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Potassium‐ion batteries (PIBs) are promising candidates to substitute lithium‐ion batteries (LIBs) as large‐scale energy storage devices. However, developing suitable anode materials is still a great challenge that has limited the anticipated application of PIBs. Herein, the interlayer expanded SnS2 nanocrystals anchored on nitrogen‐doped graphene nanosheets (SnS2@NC) are synthesized following a facile one‐step hydrothermal strategy. Relying on the exquisite nanostructure with larger interlayer spacing, the K+ ions diffusion and charge transfer will be accelerated. In addition, the intense coupling interaction between nitrogen‐doped graphene nanosheets and SnS2 can endow a sturdy nanostructure, avoiding the collapse and aggregation of SnS2 nanocrystals upon cycling. Based on the above merits, the as‐prepared SnS2@NC anode exhibits improved electrochemical performanc (desirable rate capability of 206.7 mAh g−1 at 1000 mA g−1 and advanced cyclic property of 262.5 mAh g−1, while after 100 cycles at 500 mA g−1). More importantly, multistep reactions of K+ storage mechanism combining with intercalation, conversion and alloying reactions are clearly illustrated by combined in‐situ XRD measurement and ex‐situ TEM detection. This strategy of enhancing K+ storage performances has a great potential for other electrode materials.

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