Preparation Of Helical Silicon,Silicon Carbide Nanomaterials And Their Application In Lithium Ion Battery

The growing demand for portable electronic devices and electrical vehicles has stimulated significant interest in developing lithium-ion batteries?LIBs?with high energy.Silicon and silicon carbide nanomaterials are considered as promising alternatives.However,there are still many problems in practical applications.Therefore,this paper reasonably designs and prepares novel helical silicon and silicon carbide nanomaterials via the sol-gel method,and studied its performance as a lithium ion battery anode material.In the first part of this work,a couple of bola-type amphipathic valine derivatives were designed and synthesized.Their self-assembly behaviors were also studied.Using their self-assemblies as the templates and tetraethoxysilane?TEOS?as the precursor,the single-handed helical silica nanotubes were prepared via sol-gel method.Silicon nanomaterials were prepared via magnesiothermic reduction using the silica and magnesium powder composites.They have been used as anode material for lithium-ion batteries.The results are shown as follows:?1?The self-assembly behavior of bola-type amphipathic valine derivatives is driven by stacking of the carbonyl groups.?2?Circular dichroism?CD?analysis indicates that the silicon nanomaterials possess optical activity,the CD signals are derived from chiral molecular imprinting.?3?The prepared silicon nanomaterials have been sued as anode material for lithium-ion batteries.The initial discharge specific capacity is 3871.4 mA h g^-1and still reach1491.2 mA h g^-1after 50 cycles at a current density of 0.6 mA g^-1,which shows high reversible specific capacity and better cycle stability than commercial silicon nanomaterials.In the second part of this work,using two different amphiphilic compounds which based on valine and a kind of bola-type amphiphilic alanine derivatives respectively,two different single-handed helical resorcinol-formaldehyde resin/silica composite nanomaterials were prepared via sol-gel method.Then they were carbonized at a high temperature of 1400?to prepare single-handed helical carbon/silicon carbide composite nanomaterials respectively.They have been also used as anode material for lithium-ion batteries.The results are shown as follows:?1?The morphology,nitrogen content,carbon content,and specific surface area of single-handed helical carbon/silicon carbide composite nanomaterials are different.?2?They sued as anode material for lithium-ion batteries,the specific capacity values were all higher than 500 mA h g^-1after 500 cycles at a current density of 0.3 mA g^-1,which Shows higher specific capacity than graphite and better cycle stability than commercial silicon nanomaterials.