Dielectric Polarization of a High-Energy Density Graphite Anode and Its Physicochemical Effect on Li-Ion Batteries

Abstract

The high energy density graphite anode for the commercial LIBs has critical problems on Lition kinetics due to decreases both in electrode porosity and electrolyte permeability. To overcome issues, interfaces of graphite particles in the anode are polarized using poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP) with the high dielectric constant (epsilon = 8.4), high solubility with lithium salt, and ability to trap a large amount of liquid electrolyte. The PVDF-HFP treatment promoted electrolyte permeability into the graphite electrode with a high mass loading of 13.8 mg cm(-2) and a density of 1.7 g cc(-1) (a current density over 5 mA cm-2) which particularly leads to an improvement of capacity retention from 77% of a bare electrode to 95% over 40 cycles. These achievements were of the lithium-ion kinetics but also to the stable formation of a solid electrolyte into ere attributed not only to the enhancement erface (SEI) layer on the graphite surface.