Modeling electrochemical properties of LiMn$$_{1-x}$$Co$$_{x}$$BO$$_3$$ for cathode materials in lithium-ion rechargeable batteries

In this work, we report first-principle calculations of the electrochemical properties of lithitated and delithiated LiMn$$_{1-x}$$ 1 - x Co$$_{x}$$ x BO$$_3$$ 3 ($$x = 0$$ x = 0 , 0.25, 0.5, 0.75, 1) crystals based on the density functional theory (DFT) with the generalized gradient approximation (GGA) and also considering the on-site Coulomb interaction, the so-called Hubbard correction. We found that the top of the valence band and the bottom of the conduction band of these crystals are mainly formed by the hybridization of the 3d orbitals of mixed Mn$$_{1-x}$$ 1 - x Co$$_{x}$$ x ions and oxygen 2p orbitals. We observed a band gap narrowing with an increase of cobalt concentration and that the Hubbard correction implies a better theoretical description of their electronic structures. When considering the delithiated materials, our calculations show a metallic behavior for intermediate cobalt concentrations ($$x = 0.25$$ x = 0.25 , 0.5, 0.75), which is a good quality for cathodic materials, as it improves the battery discharge process. We also obtained high (4.14 V vs. Li$$^+$$ + /Li$$^0$$ 0 and 4.16 V vs. Li$$^+$$ + /Li$$^0$$ 0 ) open circuit voltage (OCV) values at cobalt concentrations of $$x = 0.5$$ x = 0.5 and 0.75, where we believe that if these high OCV values are accompanied by a high charge storage capacity, these compounds can become promising and useful cathode materials. Finally, our results are in accordance with previous calculations and also with experimental results.