In this work, two strategies have been attempted to achieve decent fast-charging performances of Li-ion batteries. The first is to combine lithium bis(fluorosulfonyl)imide (LiFSI) and dimethoxyethane (DME) into an electrolyte… Click to show full abstract
In this work, two strategies have been attempted to achieve decent fast-charging performances of Li-ion batteries. The first is to combine lithium bis(fluorosulfonyl)imide (LiFSI) and dimethoxyethane (DME) into an electrolyte for high ionic conductivity of the bulk electrolyte and the electrolyte-electrode interphases, and the second is to limit charging capacity within 80% state-of-charge (SOC) for stable capacity retention by lowering charging rate without increasing total charging time in the standard constant current-constant voltage (CC-CV) charging protocol. It is found that using 5 wt% fluoroethylene carbonate (FEC) as an additive enables the hybridization of 20 wt% DME into the electrolyte without adverse effects on the initial formation cycles and ongoing cycling in terms of coulombic efficiency and reversible capacity, and adding 2 wt% LiPF6 is beneficial to reducing charge-transfer resistance and stabilizing capacity retention. As a result, decent fast-charging performances are obtained from the 200 mAh graphite/LiNi0.80Co0.15Al0.05O2 pouch cells by using a 1.2 m (molality) LiFSI 3:5:2 ethylene carbonate (EC)/ethylmethyl carbonate (EMC)/DME + 5% FEC + 2% LiPF6 electrolyte (all by wt) and a modified CC-CV charging protocol consisting of CC charging at 4 C for a total of 12 min, which is the charging time equivalent to a 5 C charging protocol.
               
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