The Research Progress Of Silicon Suboxides (SiO_x) And Its Composites Material In Lithium-ion Batteries

The first Li-ion battery was invented by Sony since 1990,it widely used in the military,aerospace and civilian.The dependence for Li-ion battery will be increasing,at same time,also the requirement of the energy density and cycle life becoming increasingly high.The graphitewhich was mainstream anode materials could not meet the more and more high requirement of energy density,it's theoretical specific capacity only 372 mAh/g.So,choosing the new type anode materials to replace absolutely or partly mainstream commercial graphite was one of the important research route for researchs.Si-based was current one of the hottest research anode materials,its specific capacity can reach up to 4200 mAh·g-1(Li22Si5),which is the highest of all anode materials currently.Meanwhile,the lowness of lithiation/delithiation and richness in natural resources makes Si-based become a research focus by domestic and international scholar in recent years.However,the volume of material changes a lot with the changes in the process of cycling(ca.300%),which affects the batteries,cycling performance,thereby limiting its development and usage.Compared with pure Si,the special Si-O network structure of SiOx make the material to have smaller volume change and the specific capacity is several times higher than graphite,hence SiOx have more commercial potential.In this paper,SiOx was fabricated by chemical vapor synthsis,also the electrochemical performance,structure and morphology of SiOx was research.From the test result,it was indicate that the volume exoansion of SiOx was so large in early cycle test,the capacity will decaying quickly.In order to alleviate the inherent problems of SiOx materials which have large volume expansion in process of inserction/extraction Li+,carbon coated process with four carbon sources(asphalt,citric acid,glucose and phenol resin)was ues for suppression of volume expansion.Different carbon sources have different effect on SiOx/C electrochemical performance.From the test,phenolic resin was appropritate for SiOx that SiOx/C electrochemical performance was improved significantly.While SiOx/C(citric acid),for example,it's improved the electrochemical performance of SiOx/C that carbonsources was increased.Binder is one of important component of lithium-ion battery electrode material,due tothe volume expansion of SiOx with the process of insertion/extraction,it is a approach that choosing appropriater binder has been shown to effectively suppress the volume expansion and improve the cycle performance.The three kinds of binders was used in this study:PVDF,LA132 and PAA.SiOx electrode composed of SiOx(80 wt%),binder(10 wt%)and conductive carbon black(10 wt%).The SiOx electrode with different binders was performed by electrochemical test and physical characterization.The failure condition of SiOx electrochemical properties was analysis,also,it was evaluated that impact of different binders for SiOx.The analysis and characterization methods of SEM,EIS,XRD and differential capacity plots,the PAA which have no obvious crystallization most suitable for SiOx,also,it is prove that amorphous or little crystalline binder have physical or chemical reaction with-OH of SiOx and formed class network constitute.The expansion pulverization of SiOx power limited in original domain and maintained electronic and ionic conductivity effectively,improved cycle performance of materials.Therefore,the binders which have functional group-OH and a low degree of crystallization is also likely to apply to SiOx material.