Rational Design and General Synthesis of S‐Doped Hard Carbon with Tunable Doping Sites toward Excellent Na‐Ion Storage Performance

• Published in: Advanced materials (Weinheim) Vol. 30; no. 29; pp. e1802035 - n/a
• Main Authors: Hong, Zhensheng, Zhen, Yichao, Ruan, Yurong, Kang, Meiling, Zhou, Kaiqiang, Zhang, Jian‐Min, Huang, Zhigao, Wei, Mingdeng
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 19.07.2018
• Subjects: Carbon; Doping; hard carbon; Interlayers; Ion storage; Materials science; Microstructure; Molten salts; rational design; sodium‐ion batteries; rational design; doping; sodium-ion batteries; hard carbon
• ISSN: 0935-9648; 1521-4095; 1521-4095
• 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−1 is steadily kept even after 4000 cycles at 1 A g−1. Two kinds of S‐doped hard carbon with different microsctructures are synthesized by a universal synthetic strategy. It is demonstrated that S‐doping hard carbon with fewer pores exhibits a larger interlayer spacing than that of porous carbon, and an excellent Na‐ion storage performance with a stable capacity of ≈200 mAh g−1 after 4000 cycles at 1 A g−1 is displayed.