Strategies for approaching one hundred percent dense lithium-ion battery cathodes

Abstract

Increasing the density and thickness of battery electrodes can lower costs, ease manufacturing, and increase energy density; however, existing electrode architectures cannot simultaneously enable thick and dense electrodes with good power densities. In particle-based architectures, long range lithium-ion transport primarily occurs through the electrolyte, but electrolyte transport pathways disappear as electrode density approaches 100%. The loss of these transport pathways leads to dramatic capacity reductions at moderate discharge rates and has set minimum porosity limits for commercial cells. This work examines transport through three thick and dense cathode architectures to understand the interdependent impact of inter-particle interfaces, continuous diffusion lengths, solid volume fraction, solid diffusivity, cathode thickness, and discharge rate on areal capacity. We demonstrate the advantages of continuous cathode architectures and show how the combination of high diffusivity and continuous solid diffusion pathways can yield 65% increases in areal capacity over a conventional, particle-based electrode at 85% solids volume fraction. We also show that combining these high-diffusivity, continuous cathode architectures with solid electrolytes can overcome some of the inherent limitations of current solid-state battery designs.