Researchers have paid much concentration on sodium-ion batteries (SIBs) due to the low-price and huge supplies of Na source compared to lithium ion batteries (LIBs). Although the fundamental principle of electrochemical reaction of sodium is similar to that of lithium, Na-ion with larger ionic radius and molar mass than Li-ion has make it full of difficulty to explore high performance sodium storage materials. Various nanostructured electrode materials have been designed to alleviate the volume expansion during Na-ion intercalation/disintercalation for improving the sodium storage. Cobalt selenide (CoSe2) nanomaterial is a promising anode material for SIBs due to its stable chemical properties, environmental friendliness and the marcasite structure similar to FeSe2. The cycle life and rate capability would be enhanced by building electronic conductivity framework of 3D interconnecting carbon nanofibers via electrospinning, which can alleviate the volume variation during charge-discharge process and sustain the high electrical conductivity and fast Na-ions diffusion throughout the electrode.
In view of this, Prof. Mingqiang Zhu's group (Huazhong University of Science and Technology) reported a practicable electrospinning method to build self-standing and flexible CoSe2@carbon nanofibers. The structures of CoSe2/CNFs are shown in Figure 1. The CoSe2/CNFs electrode exhibits an excellent cycling stability (430 mAh g-1 at a current density of 200 mA g-1), rate capability (224 mAh g-1 at a current density of 15 A g-1) and even a capacity of 370 mAh g-1 at a current density of 2 A g-1 after 1000 cycles (Figure 2). The prominent electrochemical performance suggests that the CoSe2/CNFs electrode has great potential for practical applications, particularly in high performance energy storage devices.
This work (Long cycle life and high rate capability of three dimensional CoSe2 grain-attached carbon nanofibers for flexible sodium-ion batteries) is published on the Nano Energy, 2019, 58, 715-723 (https://www.sciencedirect.com/science/article/pii/S2211285519300825?via%3Dihub). Dr. Hong Yin is the first author, Prof. Ming-Qiang Zhu and Dr. Chong Li are the corresponding authors.
This work was supported by the National Natural Science Foundation of China and the China Postdoctoral Science Foundation.
Figure 1 The microstructure of CoSe2/CNFs nanofiber.
Figure 2 Na storage performance of the CoSe2/CNFs electrode
