华南理工大学熊训辉团队报道了空间位阻工程调节高性能钠离子电池用聚合物衍生硬碳的闭孔形成。相关研究成果于2024年7月5日发表在国际知名学术期刊《德国应用化学》。

闭孔在提高硬碳（HC）阳极的钠储存能力方面发挥着关键作用，然而，在聚合物衍生的HC中，闭孔的形成机制以及分子水平上的有效调节策略仍然缺乏。

该文中，研究人员首次提出了空间位阻效应，通过接枝前体主链内和主链之间的芳环，在聚合物衍生的HC中产生闭合孔。实验数据和理论计算表明，芳香环侧基的空间位阻效应可以增加聚合物前体中的骨架刚度和内部自由体积，从而防止过度石墨化，促进碳化过程中闭合孔隙的形成。

结果，所制备的HC阳极在0.1C下表现出340.3mAh/g的显著增强的放电容量、改进的倍率性能（在5C下为210.7mAh/g）以及增强的循环稳定性（在2C下1000次循环中为86.4%）。

该项工作通过空间位阻工程对闭孔的形成机制提供了新的见解，可以为开发用于钠离子电池的高性能聚合物衍生HC阳极提供线索。

附：英文原文

Title: Steric Hindrance Engineering to Modulate the Closed Pores Formation of Polymer-Derived Hard Carbon for High-Performance Sodium-Ion Batteries

Author: Jianhao Lin, Qingfeng Zhou, Zhishan Liao, Yunhua Chen, Yike Liu, Qiang Liu, Xunhui Xiong

Issue&Volume: 2024-07-05

Abstract: The 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 2C). 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.

DOI: 10.1002/anie.202409906

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202409906