Structural and electrochemical investigation of nanostructured C:TiO2-TiOF2 composite synthesized in plasma by an original method of pulsed high-voltage discharge

The efficiency of an original method of pulsed high-voltage discharge in synthesis of nanomaterials for Li-ion batteries has been demonstrated. A nanostructured C:TiO2-TiOF2 composite has been synthesized in plasma in the course of destruction of titanium electrodes and polytetrafluoroethylene wire. Physicochemical characterization of composite was carried out by means of infrared spectroscopy, energy-dispersive X-ray analysis, scanning electron microscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. It has been established that as-synthesized C:TiO2-TiOF2 consists of nanocrystallites of sizes ranging from 40 to 200 nm having a porous surface morphology. The average diameter of the pore is 3-5 nm. Carbon has the function of matrix containing ab embedded nanocomposite consisting of TiO2 and TiOF2 particles. Electrochemical properties of the nanostructured porous C:TiO2-TiOF2 composite were investigated in view of its application as an anode-active material for lithium-ion batteries. The initial high specific capacity of the composite is equal up to 1370 mA h g−1 at a rate of 20 mA g−1. It is higher (due to the TiO2 presence) in comparison with advanced TiOF2 anode materials. Galvanostatic charge-discharge cycling of the Li/C:TiO2-TiOF2 half-cell in the range of 3.0-0.005 V yields 205 mA h g−1 after 20 cycles. Impedance spectra have been measured on C:TiO2-TiOF2 in both fully discharged (0.005 V) and charged states (3 V) in the end of 1-10 cycles. The charge-transfer resistance (Rct) at 3 V remains constant at 350 Ω in the range 2-10 cycles.