Highly efficient tin fluoride nanocomposite with conductive carbon as a high performance anode for Li-ion batteries

Abstract

High capacity anode materials with long cycle life are required for next-generation high energy density lithium-ion batteries. Herein, SnF2/C nanocomposite is prepared using facile ball-milling method with the advantages of high capacity and stable cycling. The nanocomposite is prepared with significant particle size reduction and wrapped with a thick carbon layer as confirmed from scanning and transmission electron microscopies. The SnF2/C nanocomposite electrode demonstrates 768 mA h g−1 in the 100th cycles with a good retention of 90%. The prepared SnF2/C nanocomposite exhibits specific capacities of 974, 798, 743, 693, 632, and 565 mA h g−1 at rates of 0.1, 0.2, 0.5, 1.0, 2.0, and 5.0 C, respectively, demonstrating high rate capability. SnF2/C anode recovers a specific capacity of 765 mA h g−1 at 0.1 C after testing at high rates. Lithium diffusivity into SnF2/C nanocomposite is calculated to be 1.2 × 10−15 cm2 s−1 at the pristine state and 7.6 × 10−15 cm2 s−1 after 100 cycles using electrochemical impedance spectroscopy. The high performance of the nanocomposite is investigated using ex-situ X-ray diffraction and transmission electron microscopy. The obtained ex-situ results indicate that the nanocomposite undergoes both conversion and alloying reactions during the discharge-charge process.