High-Performance Natural Graphite-TiO2 Anode for Lithium-Ion Batteries: Using TiO2 Emulsion as a Solvent of Binder

Abstract

In this study, an attempt has been made to improve the performance of natural graphite anode using TiO 2 nanoparticles. For this purpose, TiO 2 emulsion is used as a solvent of binder in the preparation of graphite anode slurry. In this method, high-performance electrodes have been achieved by combining two graphite and TiO2 nanoparticles constituents into an integrated structure. TiO 2 emulsions with different concentrations of 10%, 20%, and 100% are applied to prepare the binder solvent. The graphite anode made with 10% concentration of TiO 2 emulsion (NG-T10) shows the best performance in comparison with other samples. The Nano-scale images of the scanning electron microscope (SEM) affirm the existence of a uniform coating on the surface of the natural graphite particles for the NG-T10 electrode. Energy-dispersive X-ray (EDX) spectroscopy on the NG-T10 sample clearly indicates the Ti element signal. According to atomic force microscopy (AFM) images, an increment in surface roughness can provide a more effective surface and improve wettability, resulting in better electrochemical performance of NG-T10. The charge-discharge test of the NG-T10 half-cell represents an excellent cycle performance without any capacity degradation during 100 cycles at 0.5 C. However, the value of capacity retention for bare natural graphite (BNG) is 90.7% in the same conditions. The electrochemical impedance spectroscopy (EIS) results indicate that the existence of TiO 2 nanoparticles in NG-T10 improves the resistance of SEI film and charge-transfer resistance. The NG-T10 also enhances the pouch cell capacity at various current densities up to 4 C.