Li Xuechun, Wang Huanlei, Zhang Wenzhe, Wei Wenrui, Liao Ranxia, Shi Jing, Huang Minghua, Liu Shuai, Shi Zhicheng
School of Materials Science and Engineering, Ocean University of China, Qingdao 266100, China.
Nanoscale. 2021 Feb 4;13(4):2389-2398. doi: 10.1039/d0nr08628b.
The development of carbon materials for potassium storage is limited by their low specific capacity and poor cycling stability due to the sluggish kinetics of K ions. Herein, fucoidan-derived oxygen-rich carbon nanosheets are reported as a fantastic anode for potassium ion batteries. Attributed to its 2D porous sheet-like structure (morphology engineering), rich oxygen doping (defect engineering), and dilated graphitic layer in an amorphous structure (structure engineering), a competitive capacity of 392 mA h g-1 at 0.05 A g-1 and a long cycling span over 2500 cycles at 2 A g-1 was achieved for the carbon anode, outperforming most of the reported carbons. The kinetic analyses reveal that rich active sites and a porous nanosheet structure account for the superb rate performance and cycling stability of the material. Ex situ X-ray photoelectron spectroscopy measurements demonstrate that the introduction of C[double bond, length as m-dash]O greatly promotes K+ adsorption, and that the improvement of the C[double bond, length as m-dash]O bonds during cycling contributes to enhancement in the capacity. The fabricated potassium ion hybrid capacitor displays an exceptional energy/power density of 193 W h kg-1/22 324 W kg-1, and a promising cycling stability with 99.3% capacity retention over 2000 cycles. This work provides a large-scale synthesis strategy for preparing oxygen-rich carbon nanosheets for advanced potassium ion storage.
由于钾离子动力学缓慢，用于钾存储的碳材料的发展受到其低比容量和较差循环稳定性的限制。在此，报道了岩藻依聚糖衍生的富氧碳纳米片作为钾离子电池出色的负极材料。由于其二维多孔片状结构（形貌工程）、丰富的氧掺杂（缺陷工程）以及非晶结构中扩张的石墨层（结构工程），该碳负极在0.05 A g-1下实现了392 mA h g-1的竞争容量，在2 A g-1下循环超过2500次，性能优于大多数已报道的碳材料。动力学分析表明，丰富的活性位点和多孔纳米片结构是该材料优异倍率性能和循环稳定性的原因。非原位X射线光电子能谱测量表明，C=O的引入极大地促进了K+的吸附，并且循环过程中C=O键的改善有助于容量的提高。所制备的钾离子混合电容器展现出193 W h kg-1/22 324 W kg-1的优异能量/功率密度，以及在2000次循环中容量保持率为99.3%的良好循环稳定性。这项工作为制备用于先进钾离子存储的富氧碳纳米片提供了一种大规模合成策略。
