本文要点：
含水锌碘电池(AZIBs)由于其高理论容量、增强的安全性和成本效益而作为下一代储能系统受到关注。然而，它们的实际应用受到挑战的阻碍，例如缓慢的反应动力学和持续的多碘穿梭效应。
为了解决这些限制，作者开发了一类新的共价有机框架(COFs ),其特征在于沿孔壁具有不同密度和分布(N1-N4)的富电子氮位点。这些氮位点增强了碘物种的限制和传质。
实验和理论研究表明，COF结构中氮位点的连续和优化分布显著降低了内阻，提高了氧化还原活性。
此外，与其他多孔材料相比，N4-COF表现出优异的性能，这是由于其高密度和活性位点的战略性排列。
I2@N4-COF阴极在1 C下实现了348 mAh g⁻1的显著比容量，几乎是I2@N1-COF的1.8倍，同时还保持了优异的循环稳定性。
多孔框架与N4-COF结构中对齐的氮位点的这种集成不仅增强了碘的氧化还原行为，而且为开发高性能AZIB电极提供了有前途的设计策略。
Scheme 1.Schematic illustration for the synthesis of the Nx-COF, and molecular structure of corresponding build blocks.
Figure 1. a) FT-IR spectra of N4-COF and corresponding synthetic monomers; b) PXRD patterns of N4-COF; c) The solid-state 13C CP/MAS NMR spectra of N4- COF; d) Nitrogen adsorption/desorption isotherms of N4-COF; e) The pore size distribution of N4-COF; f) The SEM image of N4-COF.
Figure 2.a) Thermogravimetric analysis of N4-COF, I2 and I2@N4-COF; b) The Raman spectra of N4-COF and I2@N4-COF; c) Expanded XPS spectra of I 3d of I2@N4-COF; d) Expanded XPS spectra of N 1s of N4-COF and I2@N4-COF.
Figure 3. a) The GCD curves of Zn/I2@Nx-COF at 1 C; b) Comparison of the CV curves of Nx-COF at 0.1 mV s-1 scan rate; c) Nyquist plots of Zn/I2@Nx-COF battery at 30 ºC; d) Rate capability of I2@Nx-COF; e) Long-term performance of the Zn-I2 batteries with I2@Nx-COF at 10 C.
Figure 4. a) The CV curves of I2@N4-COF at different scan rates; b)The fitting results of cathodic and anodic peaks at different scan rates of the I2@N4-COF electrode; c) Proportion of surface and diffusion-controlled capacities at different scan rates; d) Nyquist plots of Zn/I2@N4-COF battery at different temperature.
Figure 5a) The possible active nitrogen site of N4-COF; b) The interaction energies of different active nitrogen sites in the N4-COF structure with I- 3; c) The illustration of the differential charge of site 4 in the N4-COF structure interacting with I- 3 (Cyan and yellow areas correspond to the respective charge depletion and accumulation); d) Comparison of the DOS of I- 3 and I2@N4-COF; e) The TDOS of Nx-COF; f) Diagrams of the electron cloud densities of HOMO and LUMO orbitals for Nx-COF.
Figure 6. The plots of nitrogen content in Zn/I2@Nx-COF versus discharge specific capacity at rates of 0.25, 1, and 5 C, respectively (where, the k denotes the average slope of the change in discharge specific capacity with nitrogen content for the two adjoining materials at different rates).
https://doi.org/10.1002/anie.202423265
