| The development of high-performance rechargeable lithium-ion batteries (LIBs) is one of the most important challenges that the modern society faces. LIBs can store more energy than nickel-metal hydride, nickel-cadmium, or lead acid batteries. Long cycle life, high specific energy density, good thermal stability, low self-discharge rate and no memory effect also make LIBs superior to their competitors. The demand for increased energy density and power density for LIBs has led to a search for electrode materials that have higher capacities and longer cycling life than those commercially available. Electrospinning is a continuous process that can fabricate one-dimensional nanostructures with a series of distinctive properties, such as large specific surface areas and superior mechanical properties. Due to these unique properties, a combination of electrospinning and carbonization is an efficient, simple and inexpensive way to fabricate nanofiber anodes for LIBs. In this work, we focus our research on fabricating electrospun Si/C composite nanofibers to combine the advantages of carbon (long cycle life) and silicon (high storage capacity) materials and improving the electrochemical performance of Si/C composite nanofibers as anode materials for high-performance rechargeable LIBs. The processing-structure-performance relationships for Si/C nanofiber electrodes prepared from electrospun Si/polyacrylonitrile (PAN) precursors were established. To improve the homogeneity of the composite nanofiber anodes, the effect of different surfactants on the morphology and electrochemical performance of Si/C composite nanofibers made from electrospun Si/PAN precursors was investigated. One challenge of preparing high-capacity, long-cycle life electrospun Si/C nanofiber anodes is the relatively low conductivity of Si nanoparticles and CNF matrix. Hence we investigated the effect of multi-walled carbon nanotubes (CNTs) on the morphology and electrochemical performance of Si/CNT/C nanofiber composite anodes. To improve the cyclability of Si/C composite nanofibers, it is important to control the interfacial properties. We investigated the interfacial stability of Si/C composite nanofiber anodes by employing electrolyte additive, which showed promising results. In addition, we used atomic layer deposition (ALD) alumina coating to improve the structure integrity and control the SEI stability of Si/C composite nanofiber anodes. Results indicate that Si/C nanofiber anodes with increased reversible capacity and enhanced capacity retention were achieved. Therefore, this technology opens up new opportunities to develop high-performance electrode materials for next-generation LIBs, which are one of the promising power sources for consumer portable devices and electric vehicles, and meet the developing challenge of the sustainable energy sources and reduce the consumption of fossil fuels. |
