Anode Active Material For Lithium-ion Batteries Research Articles

Carbon-encapsulated gigaporous microsphere as potential Si anode-active material for lithium-ion batteries

A gigaporous carbon microsphere implanted with Si particles and encapsulated by a carbon nanoshell is proposed as an active material for anodes. This material has the advantage of being processable by the economical tape-casting method for electrode fabrication. Because the implanted Si is distributed in a three-dimensional carbon skeleton of the proposed structure, the anode made of this new composite shows excellent conductivity. In addition, the pores in the structure offer the benefit of absorbing the expanded volume of the Si particles during lithiation, which helps to prevent the Si-expansion-caused physical damage of the fabricated anode. The constructed battery shows good cell performance with a highly stable capacity of ∼3300 mAh g−1 and a good retention of ∼90% under a charge/discharge current of 420 mA g−1 for 100 cycles. The good cyclability is found to be correlated with excellent structural integrity and a lower increase in the resistance of the anode after long-term cycling. Moreover, a simple increase in the thickness of the anode is effective in providing a good areal mass loading with high areal capacity of 4–7 mAh cm−2, demonstrating that the anode-active material is practical for lithium-ion batteries.

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 200nm having a porous surface morphology. The average diameter of the pore is 3–5nm. 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 1370mAhg−1 at a rate of 20mAg−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 3.0–0.005V yields 205mAhg−1 after 20cycles. Impedance spectra have been measured on C:TiO2–TiOF2 in both fully discharged (0.005V) and charged states (3V) in the end of 1–10cycles. The charge-transfer resistance (Rct) at 3V remains constant at 350Ω in the range 2–10cycles.