In a paper published in the Journal of the Electrochemical Society, a team from Argonne National Laboratory reports identifying a fluorinated carbonate compound as an electrolyte additive capable of stabilizing the new fluorinated electrolyte/electrode interphase in a high-voltage spinel LiNi0.5Mn1.5O4/graphite cell.
The Argonne team is working on a larger DOE-funded project to develop advanced electrolyte materials that can significantly improve the electrochemical performance of high-voltage, high-energy Li-ion cathode materials without sacrificing safety.
Specifically, the Argonne-led project is developing electrolyte materials that can tolerate high charging voltage (>5.0 V vs Li+/Li) with high compatibility with anode materials providing stable cycling performance for high voltage cathodes including 5-V LiNi0.5Mn1.5O4 (LNMO) and high energy LMR-NMC cathodes recently developed for high-energy high-power lithium-ion battery for PHEV and EV applications.
Conventional alkyl carbonates/LiPF6 tend to be oxidized around 4.5 V; therefore, the development of high voltage electrolytes is needed to support the higher voltage systems.
The analysis of the new additive found that it actively participates in passivation formation on the graphite anode, making it an effective additive for enabling all-fluorinated electrolytes supporting reversible Li+ intercalation chemistry in a LiNi0.5Mn1.5O4/graphite cell.
Libo Hu, Zheng Xue, Khalil Amine and Zhengcheng Zhang (2014) “Fluorinated Electrolytes for 5-V Li-Ion Chemistry: Synthesis and Evaluation of an Additive for High-Voltage LiNi0.5Mn1.5O4/Graphite Cell” J. Electrochem. Soc. volume 161, issue 12, A1777-A1781 doi: 10.1149/2.0141412jes