Modulation of lithium iron phosphate electrode architecture by magnetic ordering for lithium-ion batteries

Abstract

The structure of lithium iron phosphate (LFP)-based electrodes is highly tortuous. Additionally, the submicron-sized carbon-coated particles in the electrode aggregate, owing to the insufficient electric and ionic conductivity of LFP. Furthermore, because LFP electrodes have a lower specific capacity than high-nickel content positive electrodes, thicker electrodes are required for the LFP active material than NCM at identical areal capacity design. Hence, the ionic resistance of LFP electrodes must be reduced for application in electric-vehicle batteries. Considering the intrinsic magnetic properties of LFP and carbon additive, a one-sided magnetic field is applied to order the particles in the cast slurry. The ordering of LFP and the carbon additive particles facilitates the formation of evenly distributed pores owing to their distinct magnetic properties, which significantly decreases the ionic resistance of the LFP electrode. The modulation of pores and active materials enhances the lithium-ion conduction in the magnetically ordered LFP electrode. From facile lithium-ion conduction in the magnetically ordered LFP electrodes, the rate and cycle performances of graphite/LFP pouch cells are highly improved, and electrolyte decomposition is subsequently decreased.