Artificial Cathode-Electrolyte Interphases on Ni-Rich LiNi0.8Co0.1Mn0.1O2 by Carbon Nanotubes Modified LiF for Enhanced Cycleability

Abstract

The high energy density of nickel-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) was hindered the wide usage of this material, by the lack of interface stability which will reduce its long cycle electrochemical performance. In this paper, lithium fluoride nanoparticles were used as artificial cathode-electrolyte interphase to protect the NCM811 from vigorous SEI formation. Since the conductivity of lithium fluoride will reduce the electrode’s electron mobility, 1 wt% multi-wall carbon nanotubes were added to mitigate this issue. Scanning electron microscope and energy disperse spectroscopy represent that the lithium fluoride and multi-wall carbon nanotubes were both evenly dispersed throughout the electrode. After cycled at the same higher c-rates, the specific capacity retention at C/5-rate of the Pristine NCM811 decreased from 92.76 % to 86.55 % (158.7 mAh g−1) while the LiF 5 wt% + MWCNTs 1 wt% modified NCM811 decreased from 96.04 % to 91.77 % (182.6 mAh g−1). The outstanding electrochemical performance is mainly attribute to the artificial cathode-electrolyte interphase, which protects the cathode from side reactions and the consumption of electrolyte. The pulse measurements were also carried out after 50th cycle of 1 C-rate, and the total voltage change of the Pristine sample was up to 1.5336 V at maximum current rate of 10 C, while that of LiF 5 wt% + MWCNTs 1 wt% modified sample was only 0.3408 V, revealing that the artificial cathode-electrolyte interphase could reduce the polarization generated during cycles and the good conductivity by adding MWCNTs.

Keywords

• ni-rich cathode material
• artificial cathode electrolyte interface
• lif
• multiwalled carbon nanotube