Structure, Electrode Voltage and Activation Energy of LiMn_xCo_yNi_1-x-yO₂Solid Solutions as Cathode Materials for Li Batteries from First-Principles

Abstract

Layered transition-metal oxides, LiMn x Co y Ni 1-x-y O 2 , have been considered as potential cathode materials for lithium batteries with high energy density. The crystal structures, reversible potentials and activation energies of LiMn x Co y Ni 1−x−y O 2 are studied by means of density functional theory (DFT) calculations within generalized gradient approximation (GGA) and projector-augmented-wave (PAW) method. The larger cell volume with increasing Ni content benefits the capacity of the cathode materials. Sufficient amount of Ni content in the LiMn x Co y Ni 1-x-y O 2 is beneficial for stabilizing the electrode voltage. Ni substitution is always beneficial to Li diffusion, whereas existence of Mn ions may hinder Li motion by increasing the activation energy. All these first-principles results reveal some general trends for the synergistic effects of TM ions and may guide finding optimal compositions in future experiments.

Electrode potential and activation energy of sodium transition-metal oxides as cathode materials for sodium batteries: A first-principles investigation

“…The lattice parameters (a and c) for NaMO 2 crystals of O3 type from present calculations are shown in Table 1, along with previous experimental data and DFT results [19,[44][45][46][47][48][49]. Our calculations are basically in agreement with the experimental results, with a deviation less than 3%.…”

“…Calculated AEP is defined as the average value of the nine steps. Experimental AEP within reversible ionic (de)intercalation content are listed and other computational values for LiCoO 2 [49], NaCoO 2 and NaNiO 2 [44] are given in parentheses for comparison when available. DU denotes the drop of U values from low x region (0 6 x 6 1/9) to high x region (8/9 6 x 6 1).…”

“…As a reference, we also carried out comparative calculations on LiCoO 2 crystal. The performance of DFT first-principles calculations on LiCoO 2 crystal has already been assessed in our previous publication [49].…”

Doped Nanoscale NMC333 as Cathode Materials for Li-Ion Batteries

“…Intensive studies for the replacement of LCO were conducted by formulating layered oxides with multi-components of the system Li M O 2 ( M = Ni, Mn, and Co); then, the new lamellar compounds LiNi 1-y Mn y O 2 (NMO), LiNi 1−y Co y O 2 (NCO), and LiNi y Mn z Co 1 −y −z O 2 (NMC) were successively proposed [8,9,10,11,12,13]. The performance of LiNi x Mn y Co 1 −x −y O 2 as cathode material relies on the distribution of the transition-metal (TM) cations.…”

First-principles study of native point defects in LiNi1/3Co1/3Mn1/3O2and Li2MnO3

“…Although the DFT + U correction has shown improved results for redox potential 15 and oxidation energy 16 in transition metal oxides, it was reported that the GGA method is also appropriate for thermodynamic calculations such as formation energy and phase diagram. [17][18][19][20][21] The GGA + U also results in significant errors in the calculated energies of metallic phases of element materials. 20 For clarity, we calculated the total energy difference between E tot (V Ni ) and E tot (bulk) in NCM, which is the main part in the calculation of formation energy (eqn (1)), in each of the GGA and GGA + U schemes, and obtained the difference of 0.38 eV for V ni in NCM, where U-parameters of Ni, Co, and Mn atoms were fitted to the experimental value of open circuit voltage (3.7 V vs. Li + /Li) of NCM.…”