Preparation And Electrical Property Research Of Sodium-ion Battery Electrode Composite Materials

A brief review about lithium-ion rechargeable battery and sodium-ion rechargeable battery was presented in this paper. A summary based on recently sodium-ion rechargeable battery relating articles was also introduced in this paper. Advantages and disadvantages of electrode materials were discussed in the following part. The aim of this work is that alleviating the poor intrinsic electronic conductivity of electrode materials by surface modification process. Polymers are promising candidates to achieve better electrochemical performance by coating on the surface of electrode materials. The main research contents are listed as follows:A series of problems, like poor intrinsic electronic conductivity, large deformation under high temperature, low diffusion of Na+ ion and weak rate performance, hampers further development of layered Na2Ti3O7 as sodium-ion rechargeable cathode materials. In this work, mesoporous titanium dioxide was employed as precursor, thermosetting phenolic resin as carbon source, Na2Ti3O7@C composite electrode materials was fabricated finally. The structure of Na2Ti3O7@C composite electrode materials was analyzed by X-ray diffraction technique, scanning electron microscope (SEM) and transmission electron microscope (TEM). The diameter of core-shell like Na2Ti3O7@C composite materials was around 500 nm. A thin carbon layer was coated on the surface of Na2Ti3O7 spheres. Internal carbon net segmented Na2Ti3O7 spheres were coated by a thin carbon shell, provided by SEM and TEM. Nanostructure shortens Na+ion transmission distance, and improves efficiency of the diffusion of Na+ions. Thin carbon shell promotes electrochemical conductivity of composite materials. As a result, an enhanced sodium electrochemical storage performances was achieve. The discharge capacity of the second cycle is about 155 mAh/g and remains in 100 mAh/g even after 100 cycle, much higher than pure Na2Ti3O7, which retains only 60.1 mAh/g.The NASICON Na3V2(PO4)3 is constructed by VO6 octahedron and PO4 tetrahedron through connecting each other by apex angle. forming three dimensional framework. The framework provides fast Na+ ion transmission channels, however, its electricalchemical activity and sodium storage ability are relatively low. Doped polyaniline (PANI), in which π electrons can flow along polymer chains, was considered to solve these problems. Proton acid doped PANI was prepared by chemical oxidation method, and coated on 3 materials subsequently. Corresponding characterizations confirmed this construction. Charge/discharge profiles and cyclling stability were improved after modification of PANI. Temperature shows an important impact on electrochemical ability. Na3V2(PO4)3 calcined under 700℃ carried the best electrochemical performance, and the composite with 0.01 wt% PANI exhibits the most excellent performance, the capacity of 96.5 mAh/g and 62 mAh/g after 20 cycles at 0.2C. This work expands application of conducting polymers, but also exhibits a certain content of references to development of sodium-ion rechargeable battery.