Simulated discharge overpotential distributions for sintered electrode batteries in rechargeable coin cell form factors

摘要

Sintered electrode lithium-ion batteries contain only electroactive material which has undergone a mild thermal treatment to improve particle connectivity and thus electrode mechanical strength. These electrodes can be made very thick, and due to the lack of inactive binders or conductive additives there are ion transport advantages relative to equivalent thickness and porosity composite electrodes. In this study, the discharge of sintered electrode full cells was simulated at the cell level for three different form factors: CR2032, CR2025, and CR2016. Simulations also include relatively high and low rates of discharge and two different electrolytes. Using the simulations, overpotential distributions enable analysis of the contributors to resistance in the cell analyzed for the different regions of the anode, cathode, and separator. Overpotential sources include electronic overpotential, ionic overpotential, interfacial overpotential, and OCV overpotential. As the total thickness increases, the main overpotential contribution shifts from interfacial to ionic, with both originating from the electrodes. In all cases a higher conductivity electrolyte dramatically increases total capacity delivered at higher discharge rates.