The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202105178.-1), the batteries still exhibit ≈80% capacity retention over 100 cycles, showing great potential for practical application.

Iron-based phosphate materials have been employed as cathodes for sodium-ion batteries (SIBs) because of their low cost and environmental friendliness, but the electrochemical performance of this kind cathode is far from that of a practical application. On one hand, the huge volume expansion during sodium-ion insertion/extraction restricts its cycle life. On the other hand, the relativity low capacity and working potential result in a low energy density. Herein, we report a new NASCION-phase iron-based phosphate material with a formula of Na 3 Fe 2 (PO 4 )(P 2 O 7 ), which possesses a theoretical capacity of 119 mAh g −1 and an average working potential of 3.1 V versus Na/Na + , along with a small volume change during Na-ion insertion/extraction in SIBs. Moreover, the reduced graphene oxide has been introduced during synthesis to enhance the electrochemical performance. The composite cathode exhibits an initial reversible specific capacity of 110.2 mAh g −1 at 0.1 C and maintains a specific capacity of 89.7% after 6400 cycles at 20 C.

The catalysis of covalent organic frameworks (COFs) in Li–S chemistry is largely blocked by a weak chemical interaction and low conductivity. Herein, a new kind of diketopyrrolopyrrole (DPP)-based COF is in situ fabricated onto the carbon nanotube (CNT) surface (denoted as COF@CNT) to uncover the electrocatalysis behavior by its strong chemical interaction and highly conductive property. We declare that the electrocatalytic activity of DPP-COF can be maximized by introducing an appropriate content of CNT (66 wt %); the analyses including density functional theory calculations, X-ray photoelectron spectroscopy, Fourier transform infrared, and Raman show that the DPP moiety can mediate the conversion of polysulfides contributed by a CO/C–O bonding conversion. Hence, the modified battery shows a 0.042% decay rate over 1000 cycles and achieves a desirable capacity of 8.7 mAh cm–2 with 10 mg cm–2 sulfur loading and lean electrolyte (E/S = 5). This work will inspire the rational design of COF@support hybrids for various electrocatalysis applications.