Effect of reductive cyclic carbonate additives and linear carbonate co-solvents on fast chargeability of LiNi0.6Co0.2Mn0.2O2/graphite cells

Abstract

For application to electric vehicles, the fast charging of lithium-ion batteries is required. However, lithium-ion batteries are faced with undesirable Li plating causing the capacity fading with low Coulombic efficiency at high charge rates. Here, we present the effects of solid electrolyte interphase structures of the graphite anode and linear carbonate solvents on fast charging capability of LiNi0.6Co0.2Mn0.2O2/graphite full cells. To control the nature of the interfacial layer on the graphite anode affecting the Li plating behavior, we exploit three kinds of additives, ethylene carbonate, fluoroethylene carbonate and vinylene carbonate, as anode solid electrolyte interphase formers. In addition, the effect of ethyl methyl carbonate and dimethyl carbonate on the solvation and transport of high concentrations of Li ions de-intercalated from the LiNi0.6Co0.2Mn0.2O2 cathode in a full cell at high charge rates is explored in fluoroethylene carbonate-based electrolytes. Our investigation reveals that the combination of fluoroethylene carbonate and dimethyl carbonate in the electrolyte enables fast-charging LiNi0.6Co0.2Mn0.2O2/graphite full cells showing the excellent capacity retention of 79% after 1000 cycles at a high charging current density of 6 mA cm−2, corresponding to 2C, and a discharge rate of 1C without Li plating on the graphite anode.