The Stability of Carbonaceous Electrodes in Ether Based Electrolyte Solutions for Advanced Li Batteries

In this work we have studied the stability and performance of hard carbon in comparison with petroleum coke (soft carbon) as electrode materials for Li-ion batteries in an ethereal and alkyl carbonate based electrolyte solutions. 1 M bis(triflouromethane) sulfonimide lithium salt (LiTFSI) in diethylene glycol dimethyl ether (diglyme)) and a mixture of dimethyl carbonate (DMC)/mono-fluorinated ethylene carbonates (FEC) 4:1 (%v) with 1 M Lithium hexaflourophosphate (LiPF6) where chosen as representative solutions for this study. The motivation for this work is the potential importance of ethereal solutions for high energy density Li-S and Li-O2 batteries and the possibility of using carbons as an alternative to Li metal anodes in these systems. An acceptable performance of hard carbon electrodes in the ether based solutions was demonstrated. In contrast, soft carbon electrodes which preform very well in alkyl carbonates solutions behave poorly in the ethereal solutions. Their failure mechanism was explored and is explained in this report.