Conversion Of Rice Husks To Prepare Silicon Carbide For Lithium-ion Battery Anodes Via High Temperature Molten Salt Electrochemistry

High temperature molten salt electrolysis has many advantages and is an important means for material synthesis.The lithium-ion batteries with high power and energy densities are currently the crucial factor to the development of electric vehicles.Graphite,as the most widely used anode material,is not enough to meet the market demand due to the low specific capacity.Since the abundant resources and outstanding performance,silicon materials have been developed and paid attention as a new generation of lithium-ion battery anode materials.However,it also has many problems.At present,nanocrystallization and silicon-carbon composite are the focus of research in this field.Rice husk,as a kind of natural silicon-carbon composite biomaterial resource,is a biological product that captures carbon dioxide from the atmosphere and absorbs silicic acid from the soil,and with high annual output and low price,thus can supply green,sustainable,and hierarchically porous C-SiO2 feedstocks..In this paper,C-SiC composites were directly synthesized by high temperature molten salt electrochemical method and carbothermal reduction method using C and SiO2 in rice husks.The effects of carbonization conditions and electrolysis variables of rice husk on the morphology,structure and electrochemical properties of C-SiC composites were studied.The products were characterized by XRD and SEM.The results show that C-SiC composites can be prepared by high temperature molten salt electrolysis of rice husks,and SiC mainly exists in the form of nanowires.The C-SiC composite,obtained under 2.4V from electrolysis of carbonized rice husks with a carbon-to-silicon ratio of 4.2,has excellent electrochemical performance,it can deliver a gravimetrical capacity of over 1000 mAh/g at a current density of 1000 mA/g after 400 cycles.In the process of preparing C-SiC material by molten salt electrolysis,increasing the contact area between C and SiO2 in the electrolysis precursor is beneficial to promote the formation of SiC.The electrochemical performance of C-SiC materials prepared by high temperature carbothermal reduction of rice husks is much lower than that of C-SiC composites obtained by salt electrolysis.