Structural, Electronic, Thermal, and Dynamical Responses of Layered Oxide Cathode Materials during Lithiation and Delithiation: Insights from Density Functional Theory

The fundamental understanding of cathode materials for the design of efficient, cheaper, and durable lithium-ion batteries is a continuing endeavor. The present study investigated the structural, electronic, thermodynamical, and dynamical responses of a series of transition-metal-based layered cathode materials during lithiation and delithiation employing density functional theory using the PBE and HSE06 functionals. The responses were supported by analysis of the Bader charges, densities of states (DOS), and band gaps of the materials. The process of delithiation generally led to a contraction of the M–O bond lengths and minor alterations in the lattice constants. After delithiation, the absence of Li–O bonds allows the O atoms to form stronger M–O bonds. The durability of LiMO2 cathode materials is closely tied to the nature of the transition metal (M) and the associated volume change during delithiation. Materials with high intercalation voltages, such as Al (5.24 V), Cr (5.30 V), and Zn (4.78 V), exhibit minimal M–O bond length reductions (0.02–0.05 Å) and smaller volume contractions (0.4–5.2%). The patterns in the DOS show how removing Li affects the electronic properties through M 3d and O 2p orbitals, helping to design better battery cathode materials. Moreover, the present findings demonstrate that the partial substitution of Co atoms with Al atoms in the LiCoO2 material can improve its efficiency. The present findings provide a systematic approach for the rational design of economical lithium-ion-based cathode materials.