Affiliation:
1. Battery Science Branch, FCDD-RLA-GD, DEVCOM Army Research Laboratory, Adelphi, MD 20783-1138, USA
Abstract
In this work, dimethoxyethane (DME) and 1,3-dioxolane (DOL) are studied as the co-solvent of an advanced electrolyte for fast charging of Li-ion batteries by using lithium bis(fluorosulfonyl)imide (LiFSI) as a salt and fluorinated ethylene carbonate (FEC) as an additive. It is shown that even when used with LiFSI and FEC, neither DME nor DOL constitute a suitable electrolyte for Li-ion batteries, either because of their inability to form a robust solid-electrolyte interphase (SEI) with graphite (Gr) anodes or because of their oxidative instability against oxygen released from the delithiated LiNi0.80Co0.10Mn0.10O2 (NCM811) and LiNi0.80Co0.15Al0.05O2 (NCA), respectively. However, using 30% FEC as the co-solvent can make 1:1 DME/DOL mixture compatible with high-voltage Li-ion batteries and combining it with conventional ethylene carbonate (EC) and ethyl methyl carbonate (EMC) significantly enhances the fast charging capability of Li-ion batteries. As a result, an advanced electrolyte composed of 1.2 m (molality) LiFSI 1:1:1:2 DME/DOL/EC/EMC + 10% FEC (all by wt.) offers much improved fast-charging performances in terms of capacity and capacity retention for a 200 mAh Gr/NCA pouch cell, compared with a 1.2 m LiFSI 3:7 EC/EMC baseline electrolyte. AC impedance analysis reveals that the significant improvement is attributed to a much reduced charge transfer resistance, while the advanced electrolyte has little effect on the bulk and SEI resistances.
Funder
US Army Research Laboratory
Subject
Electrical and Electronic Engineering,Electrochemistry,Energy Engineering and Power Technology
Cited by
1 articles.
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