新型N掺杂多孔石墨类碳材料，用于钾离子电池

摘要：氮掺杂多孔碳材料作为钾离子电池阳极展现出广阔前景，可有效克服因钾离子半径过大导致的倍率性能下降及循环稳定性差等问题。然而，多孔结构与掺杂杂原子的影响导致初始库仑效率（ICE）相对较低，可能限制钾离子电池的未来应用。本文，大连理工大学肖南副教授、北京化工大学邱

1成果简介

氮掺杂多孔碳材料作为钾离子电池阳极展现出广阔前景，可有效克服因钾离子半径过大导致的倍率性能下降及循环稳定性差等问题。然而，多孔结构与掺杂杂原子的影响导致初始库仑效率（ICE）相对较低，可能限制钾离子电池的未来应用。本文，大连理工大学肖南副教授、北京化工大学邱介山教授《Small》期刊发表名为“N-Doped Porous Graphite-Like Carbon Armored with Dense Amorphous Shell Through a Trojan Horse Strategy for High Performance Potassium-Ion Battery Anode”的论文，研究提出通过“Trojan horse”策略，以氧化煤焦油沥青包覆的C3N4作为前驱体，采用由内而外的蚀刻与掺杂工艺，合成了新型氮掺杂多孔石墨状碳材料——其表面包裹着致密非晶外壳。

氮掺杂多孔内部赋予阳极卓越的速率性能（10 A g−1下达156.5 mAh g−1）和优异的可逆容量（0.05 A g−1下达412.3 mAh g−1），其通过外部致密外壳与电解液隔离，从而获得高达62.6%的库仑效率。此外，该集成结构有效降低了壳核相分离风险，实现6000次以上循环的高电流稳定性。本研究为制备性能均衡的碳负极开辟了新路径，可满足未来PIBs产业的需求。

2图文导读

图1、a) The schematic diagram for the fabrication of INOPC-10. The SEM b,c) and TEM d) images for INOPC-10. e–g) The HR-TEM images for INOPC-5, INOPC-10, and INOPC-20 (red dotted box: porous structure).

图2、a) The XRD patterns of the prepared carbon samples. b) The content ratio of graphite-like and amorphous phase calculated from the fitted XRD patterns. c) Nitrogen adsorption-desorption isothermal curves of the prepared carbon samples. d) Pore size distribution of INOPC-10. e,f) The XPS survey and Raman spectra of the prepared carbon samples.

图3、a) Schematic illustration for carbon microcrystalline structure regulation. b) Schematic illustration for the regulation of microcrystalline structure, pore structure, and N-atom distribution of INOPC through adjusting the C3N4 content inside oxidized pitch.

图4、Potassium storage kinetics for the prepared carbon anodes. (a) Rate performances from 0.05 A g−1 to 10.0 A g−1. b) Comparison of the rate capability for INOPC-10 and other reported carbon anodes in PIBs. c) CV curves of the INOPC-10 electrode at different scan rates (0.2–1.0 mV s−1). d) The corresponding fitting line of b-value for the INOPC-10 electrode. e) The capacitive contribution percentage at different scan rates for the INOPC-10 electrode. f) The K-ions diffusion coefficients calculated from GITT curves for the potassiation process.

图5、a) Galvanostatic charge/discharge curves at 0.05 A g−1 for INOPC-10. b) CV curves at the scanning rate of 0.1 mV s−1 for the INOPC-10 electrode. c) Corresponding quantitative charging capacities in different voltage zones at 0.05 A g−1. d) Long cycling performance of INOPC-10 at 2.0 A g−1. e) Comparison of comprehensive potassium storage properties of INOPC-10 and other reported carbon anodes.

图6、a) The selected potential sites in the charge/discharge curves for ex situ Raman spectra. b) Corresponding ex situ Raman patterns for INOPC-10 at various potentials. c) The ID/IG values of INOPC-10 at different potentials. d) Schematic illustration of the K-ion storage mechanism for the INOPC-10 electrode.

图7、a) Schematic illustration of the potassium-ion full battery. b) Normalized charge/discharge profiles of half and full batteries. c) Charge/discharge curves and d) cycling performance of KPB//INOPC-10 full battery at 0.2 A g−1.

3小结

综上所述，我们通过碳化氧化沥青涂覆的C3N4，调控碳基质内部的氮含量、微晶结构及孔隙率，从而实现由内而外的受控蚀刻与氮掺杂。通过调节氧化沥青与C3N4的配比，成功精确合成了具有致密非晶外壳包裹的独特氮掺杂多孔石墨状碳材料。这种新型碳负极展现出高充放电效率（62.6%）、优异的倍率性能（10 A g−1下达156.5 mAh g−1）和卓越的循环稳定性（2 A g−1下经6000次循环后仍保持202.7 mA h g−1）。值得注意的是，当使用 4.0 m KFSI/DME 醚基电解质时，INOPC-10 的 ICE 可进一步提高到 70.2%。系统分析表明，其卓越性能归因于以下因素：

1) 内部氮掺杂多孔石墨状碳促进离子与电子快速传输，实现高速反应动力学从而支撑高倍率性能；

2) 致密非晶壳层阻隔内部多孔结构与电解液直接接触，减少首次充放电循环中SEI膜形成，从而获得高离子选择性电导率；

3) 多孔内部结构可容纳体积膨胀，坚固外壳防止内部粉化，一体化结构避免相分离，从而实现高循环稳定性。

凭借此独特结构，采用INOPC-10负极与KPB正极组装的钾离子全电池展现出优异的循环稳定性和能量密度。本工作为碳阳极材料在聚异丁烯烃（PIBs）体系中兼顾高离子充放电效率与快速稳定钾存储性能提供了可行解决方案。基于简易制备工艺与优异电化学性能，所设计的INOPC-10作为可规模化生产的PIBs电极材料具有广阔应用前景。

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