Abstract
Theoretical investigations of cathode materials LiCoO2, LiMnO2, LiNiO2, LiFeO2, and LiMn1/3Co1/3Ni1/3O2 are performed by density functional theory (DFT), using GGA(+U). Structural properties and stability are evaluated by considering the c axis of unit-cell as a naïve indicator. Calculated force on the transition metal atoms is used as a simple indicator for cycling stability (cycle-ability). Requirement of stability in conditions of relevant atoms is proposed here as a new approach for ab-initio evaluation of cycle-ability. Comparison among the oxide cathodes show the best structural properties, stability and conductivity belong to LiMn1/3Co1/3Ni1/3O2. In terms of energy density, cycle-ability and rate-capability, LiCoO2 is the best. In contrast, relatively, LiMnO2 is not an appropriate cathode. Calculated atomic forces show that LiFeO2 suffers from low cycle-ability. LiNiO2 may suffer from ion diffusion difficulty due to its low highness of the c axis. The conclusions justify reputation of the cathodes and their relevant experimental observations.