Study Of Electrospinning Si/C Composites Storage Capability And Fabrication

With the expansion of the range of human activities, the demand for energy is even more strongly, but the traditional fossil fuels had a profound impact to our environment, caused a lot of environmental pollution. Also human reproduction itself had Side effects, which prompted us to research new energy research. But the use of wind, solar, hydro and tidal energy and other new energy sources is always limited by environmental conditions, we need a way to regulate the discontinuous supply side and the peak change of demand side in the device, lithium ion secondary battery as the representative of the secondary battery is one very important one.In the current commercial lithium-ion battery, the negative electrode is made of graphite, the theoretical capacity of graphite is 372mAh/g, and it has good cycling stability, good electrical conductivity and low cost, but the pursuit of performance for many researchers can not stop chasing higher capacity anode material. As the next generation of potential negative electrode material, the theoretical capacity of silicon reaches 4200mAh/g, but the lithium insertion process will cause 400% volume expansion, which causes silicon material pulverised, Morphology destruction and SEI(surface electrolyte interface) membrane thickening.Moreover, silicon material is poor in conductivity, which will affect battery performance. Current methods for improving the performance of silicon electrode structure focused on the preparation of nano silicon material or the design of complex silicon core-shell restricted volume expansion. However, these methods face a huge obstacle for industrial application because of its complicated steps and laboratory reagents costly.To solve this problem, we first select the cheap 98% purity metallurgical-grade silicon in semiconductor industry, pulverized to the micron level, then use electrospinning method whose equipment is inexpensive and simple to prepare Si/C composites material, a series of structural optimization of material design and preparation was explorated. We designed that the silicon is directly added to the spinning solution to spin, the introduction of silicon dioxide sacrificial layer to create the expansion space for Si, a core-shell double needle-component to create the interior space for Si to expand, double needle electrospinning and electrospraying Si incorporated by nanofiber. After the performance test, we found that the double-needle double-jet electrospinning electrostatic spraying of Si-C material coulombic efficiency can reach 63.01% at first cycle, the capacity retention rate is 71.2% after 100 cycles which is best in the test, Moreover, it has good rate capability, thus pave the way for exploring low cost silicon anode materials for commerical use.