Peony-shaped micron-sized NiO particles: their excellent electrochemical performances as anode materials of lithium ion batteries (LIBs)

For the first time, peony-shaped micron-sized nickel oxide (NiO) particles are fabricated through a hydrothermal process-assisted air calcination method using nickel acetate tetrahydrate (NAT) and the spent bicycle tires-derived porous carbon particles as the starting materials. Firstly, porous carbon particles (PCPs) are prepared via an air calcination-acid pickling-air drying method using the spent bicycle tires as the raw materials. Then, the products prepared using PCPs and NAT with a mass ratio of 3:10, 3:20, and 3:30 are, respectively, nominated as sample a, b, and c. XRD and XPS analyses reveal that, besides the amorphous carbon materials, NiO as the main product exists in all prepared samples. Interestingly, as exhibited by the SEM images, a large piece of luxuriant flower assembled by many smaller and broken petals, well-defined peony-shaped micron-sized particles, and a large piece of luxuriant flower wove by a large number of larger petals are displayed clearly in sample a, b, and c, respectively. When being used as electrode materials of LIBs, the initial discharge capacity (DC) value at 100 mA g(-1) delivered by sample b is as high as 1013 mAh g(-1) and, even after 20 cycles, the DC value is still maintained to be 518 mAh g(-1). Most importantly, the DC value of sample b at 1 A g(-1) after 50 cycles is still kept to be 138.7 mAh g(-1), almost 2.8 times larger than that of the commercial graphite (50.1 mAh g(-1)), presenting an excellent high rate performance. This work is very favorable not only to the development of NiO-based LIBs anode materials due to the superior electrochemical performance, but also to the further exploration of NiO related research fields owing to the special peony-shaped morphology.

Automated summary

Micron-sized nickel oxide (NiO) particles in the shape of peony flowers were successfully fabricated through a hydrothermal process-assisted air calcination method. These particles exhibited excellent electrochemical performance, which is significant for developing anode materials for lithium-ion batteries and further research in the field of NiO.