Desgin And Electrochemical Properties Of The Compoaite Materials Based On Carbon Nanofibers

At present,the cathode materials are basically sodium-based compounds and lithium-based compounds.The two materials have better performance in charge and discharge process of the reverse reaction,when they have more surface area and higher stability.The electrospinning nanofibers not only own the above advantages,but also because of they can connect each other into fiber network with many hole to provide a highly efficient architecture to fabricate high performance cathodes for advanced the batteries,which is helpful to improve to transfer ions and electrons,the specific surface of the active substance,the ion utility ratio and the capacity to increase.In this paper,the ideal fiber with battery material is prepared by changing the relevant parameters of electrospinning,is designed for excellent electrochemical performance.First of all,we use the electrospinning technology to discuss the different forms of the fibers synthesized by electrospinning under different conditions by changing the different conditions such as polymer type,polymer concentration,calcination temperature and time.The effects of different morphologies on the properties of the fibers were compared.Secondly,we have reported a large-scalable approach to construct a freestanding alluaudite Na_2+2xFe_2-x?SO₄?₃@porous carbon-nanofiber?PCNF?hybrid film,which is constructed by combining the electrospinning and electrospraying techniques.Taking the advantage of the highly porous and conductive framework,and a super flexible and stable architecture,the freestanding hybrid film achieves fast electron/ion transport capability and superior cycling stability.It is capable of high rate ultralong-term cycling,which retains more than 95%of the initial capacity after five hundred cycles at high rates of 40C and 5C.Therefore,the present work not only introduces a facile and large-scalable synthetic mechanism for alluaudite sulfate,but also provides a highly efficient architecture to fabricate high performance cathodes for advanced sodium ion batteries.Finally,we further design the structure of the nanofiber,to prepare the aligned NaV₃?PO₄?₃@C hybrid nanofiber with he highly porous which is different of the random arranged.The well aligned nanofiber achieves higher capacity retentions and a highly efficient architecture of 95.9%and 94.2%at both low?1 C?and high?10 C?rates,as compared with the random aligned referenceand the low-carbon aggregated reference samples.It seems more promising because of their high theoretical energy density as a new material for NIBs.