Fluorinated electrolytes for 5-V Li-ion chemistry: Dramatic enhancement of LiNi0.5Mn1.5O4/graphite cell performance by a lithium reservoir

• Li reservoir combined with a fluorinated electrolyte improves high voltage cell performance.
• Conventional electrolyte with Li reservoir also shows improvement but it is short-lived.
• Lithium reservoir can be delivered by Li metal, SLMP or electrochemically prelithiation.

A fluorinated electrolyte was galvanostatically charged and discharged for 100 cycles at an elevated temperature (55 °C) with a LiNi0.5Mn1.5O4 cathode coupled with a graphite anode in the presence of a lithium reservoir. The incorporation of the lithium reservoir was able to compensate for the loss of the active lithium from the LiNi0.5Mn1.5O4 cathode due to the electrolyte oxidative decomposition. Our experimental data demonstrate for the first time that lithium compensation is an efficient way to enhance the performance of high voltage LiNi0.5Mn1.5O4/graphite cell at a high temperature (55 °C).