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Effects of a High-Concentration LiPF6‑Based Carbonate Ester Electrolyte for the Electrochemical Performance of a High-Voltage Layered LiNi0.6Co0.2Mn0.2O2 Cathode
journal contribution
posted on 2019-12-10, 14:50 authored by Qi Liu, Hongliang Xu, Feng Wu, Daobin Mu, Lili Shi, Lei Wang, Jiaying Bi, Borong WuLithium-ion battery electrolytes are key components contributing
to the Li+ transference and the formation of solid electrolyte
interface (SEI) film. A high-concentration LiPF6-based
EC/DMC electrolyte is employed to investigate the electrochemical
performance of layered LiNi0.6Co0.2Mn0.2O2 cathode material at the high voltage of 4.6 V. Cyclic
voltammetry tests indicate that the 6.5 M EC/DMC-LiPF6 high-concentration
electrolyte enjoys a stronger oxidation resistance compared with 1
M diluted electrolyte. It is indicated that the highest occupied molecular
orbital (HOMO) energy of nEC-Li+ and nDMC-Li+ solvation complexes is reduced with the Li+ concentration
increase, suggesting that the high Li+ concentration enhances
the oxidation resistance of the solvent molecules by the density functional
theory (DFT) method. X-ray photoelectron spectroscopy (XPS) tests
demonstrate that the SEI film is different from that of the diluted
electrolyte on the cathode surface by using the high-concentration
electrolyte. The composite cathode of LiNi0.6Co0.2Mn0.2O2 exhibits a 161.3 mAh/g reversible capacity
at the rate of 0.2C (1C = 180 mA g–1) after 100
cycles by using the high-concentration electrolyte, while a 138.6
mAh/g lower capacity is exhibited in the diluted electrolyte. The
improvement of cycling performance should be attributed to the prevention
of the interface side reactions on the cathode.
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Cyclic voltammetry testsLiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode materialXPSCarbonate Ester ElectrolyteLiNi 0.6 Co 0.2 Mn 0.2 O 2 exhibitsHigh-Voltage Layered LiN i 0.6 Co 0.2 Mn 0.2 O 2 Cathode Lithium-ion battery electrolytesECoxidation resistanceinterface side reactionsHOMOhigh-concentration electrolyteSEIDFThigh-concentration LiPF 6X-ray photoelectron spectroscopy
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