Annealing atmosphere dependant properties of biosynthesized TiO₂ anode for lithium ion battery application

The present work demonstrates the synthesis of in situ carbon incorporated TiO₂ nanoparticles (Bio-TiO₂/C) and bare Bio-TiO₂ from low cost and eco-friendly materials, wherein Bengal gram beans (Cicer arietinum L.) extract containing bio-molecules is used as complexing agent to stabilize and engineer Bio-TiO₂/C used as anode for lithium ion battery application. The influence of annealing atmosphere (argon and air) on the formation of carbon anchored biosynthesized TiO₂ nano-spheres is investigated systematically. Interestingly, selective formation of TiO₂/C nano-spheres is observed in argon atmosphere, while annealing in air leads to the formation of carbon free TiO₂ nanoparticles. The gram bean extract containing biomass helps to inhibit the aggregation, leading to uniform size distribution of TiO₂ nanoparticles. These biomasses convert into carbon after calcination of as prepared Bio-TiO₂ in argon atmosphere (Bio-TiO₂/C), and in air calcinations, these biomasses are completely oxidised and form bare Bio-TiO₂. The resulting products TiO₂/C and TiO₂ are characterized using thermogravimetry analyzer, X-ray diffraction, transmission electron microscopy, Raman spectrophotometer, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Furthermore, the prepared TiO₂/C and TiO₂ are investigated as electrodes for lithium ion battery. The charge/discharge performance of TiO₂/C shows an initial reversible capacity of 208 mA h g⁻¹ at a current density of 33 mA g⁻¹, which is higher than TiO₂ nanoparticles (197 mA h g⁻¹). The cycling study exhibit TiO₂/C based electrode retaining about 100 % of reversible capacity after 60 cycles at same current density, which is 3 % higher than the TiO₂ nanoparticles based electrode.