Theoretical Assessment of the First Cycle Transition, Structural Stability and Electrochemical Properties of Li2FeSiO4 as a Cathode Material for Li-ion Battery

Lithium iron orthosilicate (Li2FeSiO4) with Pmn21 space group is theoritically investigated as a chathode material of Li-ion batteries using density functional theory (DFT) calculations. PBE-GGA (+USIC), WC-GGA, L(S)DA (+USIC) and mBJ+LDA(GGA) methods under spin-polarization ferromagnetic (FM) and anti-ferromagnetic (AFM) procedure are used to investigate the material properties, including structural parameters, theoretical reaction voltage (TRV), magnetic state and electerical properties (based on density of states, DOS).  Theoretical structural assessments carried out in this research imply electrochemical reversibility and structural stability of Li2FeSiO4.  Based on DFT calculations, switch between magnetic states are proposed to account for the experimentally observed extra oxidation voltage in the first cycle.