| With the development of modern science and technology, lithium ion battery has become anindispensable important part in people’s life.Currently used in actual production application of lithium ionbattery cathode materials are carbon materials, which has advantages like low electrode potential, longcycle life, high cycle efficiency, and so on. But because of its low capacity (six carbon atoms supporting alithium ion, theoretical capacity of372mAh g-1), causing poor performance. As the informationization ofpeople’s modern life, the existing functionality indicators of lithium ion battery cathode materias have beendifficult to meet the needs of various fields, so the development of new anode materials have become oneof research focuses in this field[1,2].Silicon has been recognized as an alternative anode material for lithium ion batteries (LIBs) and hasdrawn much attention since it has advantages of high theoretical capacity (4200mAh g-1), low insertionpotential and high relative abundance. While the huge volume change (300%) during repeatedcharge/discharge in cycling and the resulting short cycle life still hinder its widespread application[3,4].Recently, great efforts have been paid on material design, such as nanostructured Si and Si-basedcomposite electrodes. They have shown improved performances, presumably due to the small sizes thatenable fast Li+transportation and facile strain relaxation. Among these materials, Si/C composites are moreattractive due to the conductive and ductile features of carbon, which is effective in improving conductivityand buffering the volume changes of Si during repeated charge-discharge cycles. Many Si/C compositeanode materials have been studied by scientists and engineers. Such as Xu[5]et al. dissolved PVDF powderin N-methyl pyrrolidone (NMP) and then added nanosized silicon powder to prepare core/shellsilicon@carbon. At a high current density of1000mA g-1, the composite still has a reversible capacity of450mAh g-1, which showed excellent electrochemical performance. Wang[6]et al. prepared silicon/carbonnanocomposite by a simple route using phenolic resin as a precursor. They dissolved phenolic resin inacetone under continuous stirring and then nano-Si was added into the above solution with ultrasonicstirring. The Si/C nanocomposite exhibits a reversible capacity of678mAh g!-1after50cycles as well as excellent capacity retention at high rates. Despite the substantial progress in improving the cyclingperformance of Si, the poor safety and performance issues are still restricting the practical application ofSi/C composite. Because the alloyed mechanism of two-phase separation is difficult to produce fast lithiumion migration channels, be bounding to lose a large capacity in repeated cycling at high rates and bringing asecurity risk. And the cycling performance of Si/C composite is to be further improved.Nano-transition metal oxides have become the important direction for anode materials since they havesignificantly improved specific capacities and rate performances. Among many transition metal oxides,TiO2has attracted much attention for its many advantages such as low price, non-toxic, and pollution-freenatures. Particularly, nano-TiO2has little structure change in repeated charge-discharge, and demonstrateslow polarization, good reversibility and safety performance[7].In this present work, the TiO2/C/Si composite was prepared by a simple hydrothermal method.Satisfactorily, cycling stability and rate capability are obtained due to the synergy effect of carbon andTiO2.In this paper, we prepared through TiO2/C/Si and TiO2/Si composites through different precursors andconditions of hydrothermal method, and did a series of work of the study of materials, specific as follows.1. TiO2/C/Si composite was synthesized by a simple hydrothermal which used Tetrabutyl titanate asthe titanium source. A series of characterization of physical properties and electrochemical properties haveproved that compared with the pure Si, TiO2and C/Si composite, TiO2/C/Si composite has greatlyimproved the cycle of material properties and improve the mass specific capacity.2. TiO2/Si composite was synthesized by hydrothermal which used Isopropyl titanate as the titaniumsource. A series of characterization of physical properties and electrochemical properties have proved thatcompared with the pure Si and TiO2, TiO2/Si composite has greatly improved the cycle of materialproperties and improve the mass specific capacity. |
