Transition metal carbonate precursors as cathode materials for lithium ion batteries: first principles study

Lithium-ion batteries (LIBs) are frequently regarded as the best batteries ever made due to their significant energy density, low lithium reduction potential, and small size. LIBs are structurally comprised of functional parts of cathodes, anodes, separator, and electrolyte. Cathode materials are among the best possibilities of achieving the remarkable energy densities for LIBs due to their capacitance value exceeding 250 mAh/g. This study investigates the structural, electronic, mechanical and thermodynamic properties of two candidate materials: Ni0.2Mn0.5Co0.2CO3 and Ni0.2Mn0.5Co0.2O2 by means of DFT-based computational simulations. In particular, structural parameters, density of states, elastic constants and phonon dispersion curves were calculated to mimic their stability. From our results we found that the density of states reveal no energy band gap at the Fermi line for both materials, which indicate metallic characteristic. We also note that from the phonon dispersions, Ni0.2Mn0.5Co0.2CO3 shows no negative vibrations along the high Brillouin zone as compared to Ni0.2Mn0.5Co0.2O2 which displayed negative vibration. This implies that Ni0.2Mn0.5Co0.2CO3 is vibrationally stable while Ni0.2Mn0.5Co0.2O2 is unstable.