Combining Ester Solvent-Containing Electrolytes with All-Active Material Electrodes for High Current Density Lithium-Ion Batteries

Lithium (Li)-ion batteries are a leading rechargeable energy storage technology due to their high volumetric and gravimetric energy density. Increasing the electrode thickness is one method to increase the energy density at the cell level, regardless of the specific cell chemistry. All-active material (AAM) electrodes, fabricated via hydraulic compression and mild sintering of only electroactive material (no binders or conductive additives), provide a robust route to achieve thick Li-ion electrodes. The removal of additives also facilitates improved ion transport in the electrode microstructure, which reduces tortuosity and improves the retention of electrochemical capacity at increased cycling rates. However, due to the high thickness of the electrodes, ionic overpotentials are still typically the largest source of cell polarization. To mitigate that polarization and improve retention of capacity at increasing current density, herein, AAM electrodes were combined with high-conductivity ester-based electrolytes. Relative to prior reports with the same or higher areal loadings of the Li-ion electrodes, the delivered capacity was retained at relatively higher rates of charge.