Improved electrochemical activity of nanostructured Li2FeSiO4/MWCNTs composite cathode

Electrochemical activity of nano Li2FeSiO4 material with the Pmn21 symmetry is reported against lithium. Small amount of carboxylic group impurity distributed heterogeneously over the Li2FeSiO4 surface is concluded with Fourier transformed infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis. The electrode material with Pmn21 symmetry is prepared by simple sol-gel technique and further modified with multi-walled carbon nanotubes (MWCNTs) to achieve better electron passage to the particle-particle boundaries. Our strategy helps to improve the electrochemical performance and storage capacity to a level compared to bare material. The Li2FeSiO4/MWCNT composite electrode delivered first discharge capacity of 240 mAh g−1 at 16.5 mA g−1, when it is cycled between 1.5 V- 4.8 V at 20°C. This indicates more than one lithium is extracted. The voltage plateau of second charge is different and lower than that of first charge plateau whereas first and second discharge plateaus are almost similar, structural rearrangement involving the lithium and iron exchange between their sites and pre-activation during first oxidation step are the possible reasons for this phenomenon. Since silicates are inexpensive compared to other electrode materials, we have undertaken this work to improve the electrochemical activity and power performance by nanosizing of particle and adding MWCNTs as conductive additives.