Beyond slurry cast: Patterning of a monolithic active material sheet to form free-standing, solvent-free, and low-tortuosity battery electrodes

Abstract

Commercial lithium-ion battery electrodes today are manufactured by slurry casting active material powder onto a metal current collector foil. This manufacturing process has become embedded over recent decades but limits commercial cell performance. This paper presents patterning of a monolithic active material sheet as an alternative to slurry casting. The concept is proven experimentally by laser drilling a pyrolytic graphite sheet to increase the gravimetric active material capacity from 10 mA h g⁻¹ to 450 mA h g⁻¹, when used as a negative lithium-intercalation electrode. Cell-level calculations show that, without changing the chemistry, a pyrolytic graphite sheet electrode with a hexagonal array of 5 μm diameter, 20 μm pitch channels could increase the gravimetric energy density of a LGM50 cell by 22% to 322 W h kg⁻¹. By moving beyond slurry casting, patterned monolithic electrodes could enable batteries with lower cost, reduced energy intensity, and enhanced performance.