Liu Zhaomeng, Wang Jue, Lu Bingan
School of Physics and Electronics, Hunan University, Changsha 410082, China.
College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China.
Sci Bull (Beijing). 2020 Aug 15;65(15):1242-1251. doi: 10.1016/j.scib.2020.04.010. Epub 2020 Apr 6.
The investigation on the cathode material of potassium ion batteries (PIBs), one of the most promising alternatives to lithium ion batteries, is of great significance. Potassium vanadium fluorophosphate (KVPOF) with a high working voltage is an appealing cathode candidate for PIBs, while the poor cycling performance and low electronic conductivity dramatically hinder the application. Herein, a plum pudding model inspired three-dimensional amorphous carbon network modified KVPOF composite (KVPOF@3DC) is successfully designed in this study to tackle these problems. In the composite, KVPOF particles are homogeneously wrapped by a layer of amorphous carbon and bridged by cross-linked large area carbon sheets. As the cathode for PIBs, the KVPOF@3DC composite exhibits a high average operating voltage about 4.10 V with a super-high discharge capacity of 102.96 mAh g at 20 mA g. An excellent long cycle stability with a capacity retention of 85.4% over 550 cycles at 500 mA g is achieved. In addition, it maintains 83.6% of its initial capacity at 50 mA g after 100 cycles at 55 °C. The design of KVPOF@3DC with plum pudding structure provides facilitative electron conductive network and stable electrode/electrode interface for electrode, successfully innovating an ultra-stable and high-performance cathode material for potassium ion batteries.
作为锂离子电池最有前景的替代方案之一，对钾离子电池（PIB）阴极材料的研究具有重要意义。具有高工作电压的氟磷酸钾钒（KVPOF）是一种有吸引力的PIB阴极候选材料，但其较差的循环性能和低电子导电性极大地阻碍了其应用。在此，本研究成功设计了一种受李子布丁模型启发的三维非晶碳网络修饰的KVPOF复合材料（KVPOF@3DC）来解决这些问题。在该复合材料中，KVPOF颗粒被一层非晶碳均匀包裹，并由交联的大面积碳片桥接。作为PIB的阴极，KVPOF@3DC复合材料在20 mA g下表现出约4.10 V的高平均工作电压和102.96 mAh g的超高放电容量。在500 mA g下经过550次循环后，实现了85.4%的容量保持率，具有优异的长循环稳定性。此外，在55℃下以50 mA g循环100次后，其初始容量保持83.6%。具有李子布丁结构的KVPOF@3DC的设计为电极提供了便利的电子导电网络和稳定的电极/电极界面，成功地创新了一种用于钾离子电池的超稳定、高性能阴极材料。
