Prediction Clue on the Fading Capacity of Multi-Walled Carbon Nanotube-Decorated Li<sub>2</sub>(Fe<sub>1–<i>x</i></sub>Ti<sub><i>x</i></sub>)SiO<sub>4</sub>/C High-Performance Cathode Materials
Sivaraj Pazhaniswamy, Abhilash Karuthedath Parameswaran, B. Nalini, Sunkulp Goel, Zdeněk Sofer, Sudheer Kumar Yadav, Christopher Selvin Panneerselvam
Abstract
The key challenges of Li2FeSiO4 are poor conductivity, low Li-ion diffusion, and extreme capacity fading during the charge–discharge process. In this research, a new attempt has been made to combine three key strategies: carbon coating, cation (Ti4+) doping, and the incorporation of multi-walled carbon nanotubes (MWCNTs) to address major electrochemical impediments in the Li2FeSiO4 cathode material. The field emission-scanning electron microscopy and high-resolution transmission electron microscopy analyses demonstrated the homogeneous distribution of spherical Li2Fe0.94Ti0.06SiO4/C nanoparticles entangled in the MWCNT framework. The 5 wt % MWCNT-integrated Li2Fe0.94Ti0.06SiO4/C composite cathode offers an excellent initial specific charge capacity of 240 mA h g–1 and the discharge capacity of 238 mA h g–1, which are higher than those of the bare Li2FeSiO4/C. The sample exhibits an excellent rate capability (124 mA h g–1@15 C) and a good long-term cycle life up to 1000 cycles. The Ti doping at the Fe site of Li2FeSiO4/C prohibits the structural distortion during the charge and discharge processes. The surface charge-transfer performance has improved via carbon coating and incorporation of MWCNTs into the Ti-doped Li2FeSiO4/C nanoparticles. To date, the results of the research have been very enlightening, especially in terms of the rate capability and stability of cycling.