Hong Zhensheng, Zhen Yichao, Ruan Yurong, Kang Meiling, Zhou Kaiqiang, Zhang Jian-Min, Huang Zhigao, Wei Mingdeng
Fujian Provincial Key Laboratory of Quantum Manipulation and New Energy Materials College of Physics and Energy, Fujian Normal University, Fuzhou, Fujian, 350117, China.
Fujian Provincial Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Xiamen, 361005, China.
Adv Mater. 2018 May 28:e1802035. doi: 10.1002/adma.201802035.
Heteroatom-doping is a promising strategy to tuning the microstructure of carbon material toward improved electrochemical storage performance. However, it is a big challenge to control the doping sites for heteroatom-doping and the rational design of doping is urgently needed. Herein, S doping sites and the influence of interlayer spacing for two kinds of hard carbon, perfect structure and vacancy defect structure, are explored by the first-principles method. S prefers doping in the interlayer for the former with interlayer distance of 3.997 Å, while S is doped on the carbon layer for the latter with interlayer distance of 3.695 Å. More importantly, one step molten salts method is developed as a universal synthetic strategy to fabricate hard carbon with tunable microstructure. It is demonstrated by the experimental results that S-doping hard carbon with fewer pores exhibits a larger interlayer spacing than that of porous carbon, agreeing well with the theoretical prediction. Furthermore, the S-doping carbon with larger interlayer distance and fewer pores exhibits remarkably large reversible capacity, excellent rate performance, and long-term cycling stability for Na-ion storage. A stable and reversible capacity of ≈200 mAh g is steadily kept even after 4000 cycles at 1 A g .
杂原子掺杂是一种很有前景的策略，可调整碳材料的微观结构以提高电化学存储性能。然而，控制杂原子掺杂的位点是一个巨大的挑战，迫切需要对掺杂进行合理设计。在此，通过第一性原理方法探索了两种硬碳（完美结构和空位缺陷结构）的硫掺杂位点和层间距的影响。对于层间距为3.997 Å的前者，硫倾向于掺杂在层间，而对于层间距为3.695 Å的后者，硫则掺杂在碳层上。更重要的是，开发了一步熔盐法作为一种通用的合成策略来制备具有可调微观结构的硬碳。实验结果表明，孔隙较少的硫掺杂硬碳比多孔碳具有更大的层间距，这与理论预测吻合良好。此外，层间距较大且孔隙较少的硫掺杂碳在钠离子存储方面表现出显著的大可逆容量、优异的倍率性能和长期循环稳定性。即使在1 A g下循环4000次后，仍能稳定保持约200 mAh g的稳定可逆容量。
