Synthesis and Characterization of Lithium Iron Orthosilicate As a Cathode Active Material for Lithium Ion Batteries

Improvements for lithium ion batteries are being researched due to their wide range of applications such as cellular phones, PDAs, and laptops. The potential exists for improving the overall performance of a Li-ion battery by increasing the cathode capacity. Lithium iron orthosilicate, Li₂FeSiO₄, is a leading candidate towards higher capacity cathode materials because Li₂FeSiO₄ potentially has an insertion and extraction of two lithium ions which leads to a theoretical capacity of 320 mAh/g. This work aims to identify a process by which Li₂FeSiO₄ can be synthesized utilizing a microwave reactor and thermal annealing. The necessity and effect of carbon coating was also analyzed through ball milling and annealing Li₂FeSiO₄ with 0, 10, and 20 weight percent sucrose. Characterization of the Li₂FeSiO₄ powder was performed through X-ray diffraction (XRD), scanning electron microscopy (SEM), and surface area analysis before and after the annealing step to determine any morphological changes that occur. XRD characterization showed that a greater amount of Li₂FeSiO₄ was present in post-annealed material due to a morphological change in the structure of the material. The cathode active material was electrochemically tested in 2032 coin cells, opposite a lithium metal anode, using an Arbin battery cycler. A maximum capacity of 70 mAh/g for carbon coated material and 40 mAh/g for non-carbon coated material has been achieved to date.