Deng Wentao, Cao Yongjie, Yuan Guangming, Liu Gonggang, Zhang Xiang, Xia Yongyao
College of Materials Science and Engineering, Hunan Province Key Laboratory of Materials Surface & Interface Science and Technology, Central South University of Forestry and Technology, Changsha 410004, China.
Department of Chemistry, Fudan University, Shanghai 200433, China.
ACS Appl Mater Interfaces. 2021 Oct 13;13(40):47728-47739. doi: 10.1021/acsami.1c15884. Epub 2021 Sep 29.
Micropores and defects, like oxygen-containing groups, as active sites for sodium-ion storage in hard carbon have attracted considerable attention; nevertheless, most oxygen doping or oxidizing processes inevitably introduce undesired oxygen groups into a carbon framework, leading to deteriorated initial Coulombic efficiency (ICE). Here, precise carbonyl groups and closed micropores are together introduced into biomass-derived hard carbon to enhance the Na-ion storage performance. The hard carbon delivers a large reversible capacity of 354.6 mA h g at 30 mA g, a high ICE (88.7%), as well as ultra-long cycling stability (277 mA h g at 0.3 A g over 1000 cycles; 243 mA h g at 1 A g over 5000 cycles). The rate capability and cycling stability of hard carbon in carbonate- and diglyme-based electrolytes are contrasted to demonstrate the superiority of diglyme. Cyclic voltammetry at varied scans and galvanostatic intermittent titration techniques are carried out to clarify the disparity between the two different electrolyte systems. Furthermore, the as-prepared hard carbon is utilized as the anode for sodium-ion full cells exhibiting an energy density of 166.2 W h kg at 0.2 C and a long-cycle life (47.9% retention over 200 cycles at 1 C).
微孔和缺陷，如含氧基团，作为硬碳中钠离子存储的活性位点已引起了广泛关注；然而，大多数氧掺杂或氧化过程不可避免地会在碳骨架中引入不需要的氧基团，导致初始库仑效率（ICE）下降。在此，将精确的羰基和封闭的微孔共同引入生物质衍生的硬碳中，以提高钠离子存储性能。该硬碳在30 mA g下具有354.6 mA h g的大可逆容量、高ICE（88.7%）以及超长循环稳定性（在0.3 A g下1000次循环后为277 mA h g；在1 A g下5000次循环后为243 mA h g）。对比了硬碳在碳酸盐基和二甘醇二甲醚基电解质中的倍率性能和循环稳定性，以证明二甘醇二甲醚的优越性。进行了不同扫描速率下的循环伏安法和恒电流间歇滴定技术，以阐明两种不同电解质体系之间的差异。此外，所制备的硬碳被用作钠离子全电池的负极，在0.2 C下表现出166.2 W h kg的能量密度和长循环寿命（在1 C下200次循环后保留47.9%）。
