Increased cycling rates for thick all active material electrodes via electrolyte modifications

Abstract

Lithium-ion (Li-ion) batteries are the dominant energy storage technology in many applications due to high energy and power density, and research efforts continue towards further advances in their electrochemical properties. One general strategy to increase energy density at the cell level is to increase electrode thickness. However, with increased electrode thickness and loading, ionic transport becomes a limiting factor. All active material (AAM) electrodes provide a route to increase electrode thickness without inactive conductive additives and polymer binders, which results in relative ionic transport advantages due to the absence of these inactive materials in the electrode interstitial regions. AAM electrodes processed herein have mildly sintered LiFePO4 (LFP) and Li4Ti5O12 (LTO) fabricated into AAM electrodes as cathode and anode. These materials were paired and combined with electrolyte systems with solvent additives which increased electrolyte ionic conductivity. The resulting cells had high areal capacities, and the capacity achieved at increasing current density was significantly improved relative to the additive-free electrolyte which was attributed to the improved ionic conductivity with the electrolyte additives.