Mg doped Li2FeSiO4/C nanocomposites synthesized by the solvothermal method for lithium ion batteries

• Published in: Dalton transactions : an international journal of inorganic chemistry 2017-10, Vol.46 (38), p.1298-12915
• Main Authors: Kumar, Ajay, Jayakumar, O. D, Jagannath, Bashiri, Parisa, Nazri, G. A, Naik, Vaman. M, Naik, Ratna
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c7dt03177g

A series of porous Li 2 Fe 1− x Mg x SiO 4 /C ( x = 0, 0.01, 0.02, 0.04) nanocomposites (LFS/C, 1Mg-LFS/C, 2Mg-LFS and 4Mg-LFS/C) have been synthesized via a solvo-thermal method using the Pluronic P123 polymer as an in situ carbon source. Rietveld refinement of the X-ray diffraction data of Li 2 Fe 1− x Mg x SiO 4 /C composites confirms the formation of the monoclinic P 2 1 structure of Li 2 FeSiO 4 . The addition of Mg facilitates the growth of impurity-free Li 2 FeSiO 4 with increased crystallinity and particle size. Despite having the same percentage of carbon content (∼15 wt%) in all the samples, the 1Mg-LFS/C nanocomposite delivered the highest initial discharge capacity of 278 mA h g −1 (∼84% of the theoretical capacity) at the C/30 rate and also exhibited the best rate capability and cycle stability (94% retention after 100 charge-discharge cycles at 1C). This is attributed to its large surface area with a narrow pore size distribution and a lower charge transfer resistance with enhanced Li-ion diffusion coefficient compared to other nanocomposites. Despite having the same carbon content, Li 2 Fe 0.99 Mg 0.01 SiO 4 /C delivered the highest initial discharge capacity and also exhibited the best rate capability and cycle stability.