Cobalt disulfide (CoS) stands as a promising candidate for anode materials in lithium-ion batteries due to its high theoretical capacity, but it faces challenges associated with the shuttle effect of lithium polysulfide during cycling. To address these issues, zeolitic imidazolate framework (ZIF)-derived composites have been extensively explored because of distinct advantages such as the formation of nano-sized particles, heteroatom doping, and highly porous structures. However, ZIF-derived carbon supports primarily consist of ultra-micropores that can impede lithium-ion diffusion. Herein, we aimed to enhance cycling stability by introducing a nitrogen-doped carbon quantum dot (NCQD) solution derived from N-methyl-2-pyrrolidone into cobalt-based ZIF-67 to modify the porosity and dope heteroatoms of CoS nanoparticle-embedded heteroatom-doped carbon composites (CoS/NSC). The mildly acidic NCQD solution resulted in the partial etching of the ZIF-67 structure, along with the deposition of NCQDs as a nitrogen source. Notably, the pore sizes could be adjusted by varying the concentration of the NCQD solution, while retaining the nitrogen functional groups during carbonization. The electrode using CoS/NSC with the 2.8 mL NCQD pre-treatment exhibited enhanced C-rate capability with the capacity of 392 mAh/g at 2.0 A/g. Moreover, the cycling stability was improved, with a capacity retention of 77 % after 100 cycles.

中文翻译：

---

氮掺杂碳量子点对高性能锂离子电池CoS2/介孔碳复合材料的双功能效应


二硫化钴（CoS）由于其高理论容量而成为锂离子电池负极材料的有前途的候选者，但它面临着循环过程中多硫化锂的穿梭效应相关的挑战。为了解决这些问题，沸石咪唑酯骨架（ZIF）衍生的复合材料因其独特的优点（例如纳米颗粒的形成、杂原子掺杂和高度多孔结构）而得到了广泛的探索。然而，ZIF 衍生的碳载体主要由超微孔组成，会阻碍锂离子扩散。在此，我们的目的是通过将源自 N-甲基-2-吡咯烷酮的氮掺杂碳量子点 (NCQD) 溶液引入钴基 ZIF-67 中，以修饰 CoS 纳米颗粒嵌入杂原子的孔隙率和掺杂杂原子，从而提高循环稳定性-掺杂碳复合材料（CoS/NSC）。弱酸性 NCQD 溶液导致 ZIF-67 结构部分蚀刻，同时沉积 NCQD 作为氮源。值得注意的是，可以通过改变 NCQD 溶液的浓度来调整孔径，同时在碳化过程中保留氮官能团。使用 CoS/NSC 并经过 2.8 mL NCQD 预处理的电极表现出增强的倍率性能，在 2.0 A/g 下的容量为 392 mAh/g。此外，循环稳定性得到改善，100次循环后容量保持率为77%。