Affiliation:
1. School of Environment and Energy South China University of Technology Guangzhou 510006 P. R. China
2. School of Materials Science and Engineering South China University of Technology Guangzhou 510640 China
3. School of Intelligent Manufacturing Huzhou College Huzhou 313000 China
4. Department of Mechanical Engineering The Hong Kong Polytechnic University Kowloon Hong Kong SAR 999077 China
Abstract
AbstractThe closed pores play a critical role in improving the sodium storage capacity of hard carbon (HC) anode, however, their formation mechanism as well as the efficient modulation strategy at molecular level in the polymer‐derived HCs is still lacking. In this work, the steric hindrance effect has been proposed to create closed pores in the polymer‐derived HCs for the first time through grafting the aromatic rings within and between the main chains in the precursor. The experimental data and theoretical calculation demonstrate that steric‐hindrance effect from the aromatic ring side group can increase backbone rigidity and the internal free volumes in the polymer precursor, which can prevent the over graphitization and facilitate the formation of closed pores during the carbonization process. As a result, the as‐prepared HC anode exhibits a remarkably enhanced discharge capacity of 340.3 mAh/g at 0.1 C, improved rate performance (210.7 mAh/g at 5 C) as well as boosted cycling stability (86.4 % over 1000 cycles at 2 C). This work provides a new insight into the formation mechanisms of closed pores via steric hindrance engineering, which can shed light on the development of high‐performance polymer‐derived HC anode for sodium‐ion batteries.