Tan Wen, Wang Lina, Liu Kun, Lu Zhouguang, Yang Fan, Luo Guangfu, Xu Zhenghe
Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, P. R. China.
Shenzhen Key Laboratory of Interfacial Science and Engineering of Materials, Key University Laboratory of Highly Efficient Utilization of Solar Energy and Sustainable Development, Shenzhen, 518055, P. R. China.
Small. 2022 Sep;18(39):e2203494. doi: 10.1002/smll.202203494. Epub 2022 Aug 27.
Potassium-ion batteries (PIBs) have been regarded as a competitive alternative for lithium-ion batteries, owing to the natural abundance, low cost, and similar rocking-chair working mechanism of potassium element. However, it is challenging to simultaneously prepare suitable potassium ion anode materials of low voltage plateau, high capacity, and long cycle life. In this work, onion-like soft carbon (OLSC) of high heteroatom content is prepared by using solvent-sensitive self-assembly properties of asphaltene molecules. The OLSC electrode exhibits a low voltage plateau because of a high degree of graphitization. Meanwhile, it possesses excellent cycling stability and rate capability due to the high stability of the onion-like structure and fast transport of potassium ions, the latter of which is caused by heteroatom-induced expanded interlayers as found by first-principle calculations. Compared with existing carbon materials, the OLSC synthesized in this study exhibits a high reversible capacity of 466 mAh g at 20 mA g , a reversible capacity of 222 mAh g and capacity retention of 95% after 1600 cycles at 1 A g . This work connects the nanostructure of carbon materials and electrochemical performance and provides new insights in improving carbon-based anodes for PIBs.
钾离子电池（PIBs）因其钾元素的天然丰度、低成本以及类似摇椅式的工作机制，被视为锂离子电池具有竞争力的替代品。然而，同时制备出具有低电压平台、高容量和长循环寿命的合适钾离子负极材料具有挑战性。在这项工作中，利用沥青质分子的溶剂敏感自组装特性制备了高杂原子含量的洋葱状软碳（OLSC）。由于高度石墨化，OLSC电极呈现出低电压平台。同时，由于洋葱状结构的高稳定性和钾离子的快速传输，它具有优异的循环稳定性和倍率性能，后者是由第一性原理计算发现的杂原子诱导的层间距扩大所导致。与现有的碳材料相比，本研究合成的OLSC在20 mA g 时表现出466 mAh g 的高可逆容量，在1 A g 下1600次循环后可逆容量为222 mAh g ，容量保持率为95%。这项工作将碳材料的纳米结构与电化学性能联系起来，并为改进PIB的碳基负极提供了新的见解。
