摘要
Fast charging of Li-ion cells faces two aspects of challenges,1)accelerated capacity fade and 2)inferior charging capability.It is commonly believed that the former is due to Li plating and its resultant reactions with electrolyte at the graphite anode,which results in a loss in the inventory of Li+ions and an increase in the cell’s impedance.While the latter is ascribed to the high voltage polarization in relation to the slow transport of Li+ions between two electrodes.However,there are many other hidden facts that essentially affect the fast charging performances of Li-ion cells.This commentary intends,from the view of materials,to uncover these hidden factors,including failure of the solid electrolyte interphase and exfoliation of the graphite structure at the anode,structural degradation of the Ni-rich layered cathode materials,as well as the high solvation and desolvation activation energies of Li+ions in the electrolyte.Meanwhile,some solutions to the fast-charging problems of Li-ion cells are proposed based on the understanding of these hidden factors.
基金
support of the U.S.Army Research Laboratory.
