Abstract
The cathode material LiNi1/3Co1/3Mn1/3O2 for lithium-ion battery has a better electrochemical property than LiCoO2. In order to improve its electrochemical performance, Na-doped LiNi1/3Co1/3Mn1/3O2 is one of the effective modifications. In this article, based on the density functional theory of the first-principles, the conductivity and the potential energy of the Na-doped LiNi1/3Co1/3Mn1/3O2 are calculated with Materials Studio and Nanodcal, respectively. The calculation results of the band gap, partial density of states, formation energy of intercalation of Li+, electron density difference, and potential energy of electrons show that the new cathode material Li1−xNax Ni1/3Co1/3Mn1/3O2 has a better conductivity when the Na-doping amount is x = 0.05 mol. The 3D and 2D potential maps of Li1−xNaxNi1/3Co1/3Mn1/3O2 can be obtained from Nanodcal. The maps demonstrate that Na-doping can reduce the potential well and increase the removal rate of lithium-ion. The theoretical calculation results match well with experimental results. Our method and analysis can provide some theoretical proposals for the electrochemical performance study of doping. This method can also be applied to the performance study of new optoelectronic devices.
Highlights
Since Sony introduced commercial lithium-ion batteries (LIBs) that used LiCoO2 as cathode, LIBs have been used in electric vehicles (EVs), hybrid electric vehicles (HEVs), and mobile electronic devices for their good cycle performance, long life, less self-discharge, high specific capacity, and working voltage [1]
The Na-doped layer-structure Li1−xNaxNi1/3Co1/3Mn1/3O2 is studied theoretically with density functional theory of firstprinciples; the results show that the electrochemical performance of Li1−xNaxNi1/3Co1/3Mn1/3O2 is affected by the proportion of Na-substitution and the best proportion of Nasubstitution in LiNi1/3Co1/3Mn1/3O2 is in agreement with that of experiments [15]
The results show that its band gap is decreasing when x increases, and Na-doping can effectively improve the conductivity of LiNi1/3Co1/3Mn1/3O2
Summary
Since Sony introduced commercial lithium-ion batteries (LIBs) that used LiCoO2 as cathode, LIBs have been used in electric vehicles (EVs), hybrid electric vehicles (HEVs), and mobile electronic devices for their good cycle performance, long life, less self-discharge, high specific capacity, and working voltage [1]. LiNi1/3Co1/3Mn1/3O2, LiNi0.5Co0.2Mn0.3O2, and LiNi0.4Co0.2Mn0.4O2 [2, 3] are often studied by scholars and experts. Their precursors are made by hydroxide coprecipitation reaction combined with solid-phase sintering step [4]. LiNi1/3Co1/3Mn1/3O2 is considered a promising cathode material for commercial LIBs due to its low price, high conductivity, excellent cycle performance, high reversibility, and stable structure [5]. The commercial LiNi1/3Co1/3Mn1/3O2 has already reached its theoretical limit, with poor
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