Research On Preparation And Properties Of Na_xLi_4-xTi₅O₁₂ Anode Materials For Sodium Ion Battery

Currently, various cathode materials have been studied for application in NIBs. In comparison, relative less research has been carried out on the development of anode materials. Recently, Ti-based intercalation compounds have attracted more attention used as anode materials in NIBs due to their relatively low redox potentials of Ti4+/Ti3+. Several Ti-based Na compounds have been shown to reversible intercalate Na+ ions. Li4Ti5O12 is well known as a ‘zero-strain’ anode material for long-life stationary lithium-ion batteries. It has been demonstrated that the Na+ ions insertion into the spinel Li4Ti5O12, and with an excellent reversible capacity.Herein, in our paper, we report the Na-substituted spinel Li4Ti5O12(NaxLi4-xTi5O12, 0≤x≤0.26) anode electrode materials for sodium-ion battery. In general, the ionic radius of Na+(1.02 ?) is larger than that of Li+(0.76 ?). When lithium ions in the spinel Li4Ti5O12 are partially substituted by sodium ions, it will be beneficial to fabricated new anode host materials with a relatively open tunnel structure, which can allow easier transport of sodium ions, leading to better rate capability.We divide the full text into three parts, first, the influence factors in the process of NaxLi4-xTi5O12 material preparation, we can synthesize the material through the ratio of sodium and lithium, the source of sodium and lithium, the temperature of hydrothermal. We can get the best result through X-ray diffraction(XRD) measurements, scanning electron microscopy(SEM) analysis and transmission electron microscopy(SEM) analysis, which shows that the best materials(Na0.11Li3.89Ti5O12) have homogeneous sub-micrometric plate size(200-400 nm). Compared with the Li4Ti5O12 electrode, the Na0.11Li3.89Ti5O12 materials show not only higher specific capacity, but also better cycling stability and rate performance in sodium-ion battery.Secondly, we explore the effects of different binders on the electrochemical properties. The superior rate and excellent long-term cycling stability of Na0.11Li3.89Ti5O12 used as anode for sodium-ion battery are with an appropriate binder(NaAlg), the Na0.11Li3.89Ti5O12 electrode delivers a reversible capacity over 150 mAhg-1 and shows excellent long-term cyclic stability over 500 cycles with a very small capacity decay of 0.033% per cycle.Finally, We use carbon composites to improve the electrical conductivity of the Na0.11Li3.89Ti5O12 material. Through the X-ray diffraction(XRD) measurements, we can find the carbon composites with weak diffraction peaks, the scanning electron microscopy(SEM) analysis shows the compound degree of carbon material and active material. and the electrochemical performance test system indicates that graphene composites can improve the specific capacity of the active material, but the cycle stability is not very ideal, the first charge capacity can be as high as 185.8 mAhg-1, but after 40 cycles, it can only give a relative poor capacity 140.2 mAhg-1, the capacity retention rate is only 75.5%, per charge and discharge cycle capacity attenuation rate is as high as 0.6125%, so it needs to be further improved.