Lin Terri C, Yan Yan, King Sophia C, Lai Chun-Han, Tolbert Sarah H
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States.
Department of Materials Science and Engineering, University of California, Los Angeles, California 90095, United States.
ACS Appl Mater Interfaces. 2020 Jul 29;12(30):33775-33784. doi: 10.1021/acsami.0c08709. Epub 2020 Jul 20.
Fast-charging cathodes with high operating voltages are critical to the development of high energy and power density lithium-ion batteries. One route to fast-charging battery materials is through the formation of nanoporous networks, but these methods are often limited by the high calcination temperatures required for synthesis. Here, we report the synthesis of carbon-coated nanoporous LiVPOF with excellent rate capabilities that can be stably cycled up to 4.6 V in standard LiPF electrolytes. During charge and discharge at 30C, 110 mAh/g (70% of theoretical capacity) was obtained, and only 9% of capacity was lost after 2000 cycles at 20C. These materials also showed excellent stability, with little self-discharge, an open-circuit voltage of 4.2 V, and a discharge capacity of 139 mAh/g obtained after holding for 12 h. Rate capabilities were further demonstrated in a proof-of-concept full cell made with a nanostructured NbO. These devices were able to deliver 200 mAh/g at 1C and 100 mAh/g at 30C. Finally, operando X-ray diffraction and electrochemical kinetics were further used to provide insight into the nature of fast charging in these materials.
具有高工作电压的快速充电阴极对于高能量和功率密度锂离子电池的发展至关重要。实现电池材料快速充电的一种途径是通过形成纳米多孔网络，但这些方法通常受到合成所需的高煅烧温度的限制。在此，我们报道了具有优异倍率性能的碳包覆纳米多孔LiVPOF的合成，该材料在标准LiPF电解质中可稳定循环至4.6V。在30C充放电时，获得了110mAh/g（理论容量的70%），在20C下循环2000次后容量仅损失9%。这些材料还表现出优异的稳定性，自放电小，开路电压为4.2V，静置12h后放电容量为139mAh/g。在由纳米结构NbO制成的概念验证全电池中进一步展示了倍率性能。这些器件在1C时能够提供200mAh/g的电量，在30C时能够提供100mAh/g的电量。最后，利用原位X射线衍射和电化学动力学进一步深入了解了这些材料中快速充电的本质。
