Preformed Anodes for High-Voltage Lithium-Ion Battery Performance: Fluorinated Electrolytes, Crosstalk, and the Origins of Impedance Rise

Abstract

Preformation of graphite electrodes, in a highly fluorinated electrolyte, show exemplary performance when incorporated into LiNi0.5Mn0.3Co0.2O2//graphite cells (NMC//Gr) containing a traditional organic electrolyte. NMC//Gr cells, using preformed graphite electrodes, showed enhanced capacity and power retention as well as improved coulombic efficiencies. The increased performance was only observed with the use of specific electrolytes during the preforming step, where graphite electrodes, when preformed with the baseline organic carbonate electrolyte, did not show the same benefits. The identity of the preforming electrolyte was also observed to influence electrode crosstalk, where compounds generated at one electrode can affect the opposite electrode. The work herein presents both physical and electrochemical evidence of electrode crosstalk and reveals the beneficial effect of the preforming procedure in limiting the associated degradation mechanisms thereof. The insights gained may lead to new methodologies for the design of electrochemically robust interfaces that can enable high-voltage, lithium-ion batteries.