Battery Electrode Engineering Enables Fast Charging LMFP Cells Without Carbon‐Coated Foil

ABSTRACT Lithium manganese iron phosphate (LiMn x Fe 1‐x PO 4 , LMFP) has emerged as a promising Li‐ion battery cathode material due to its high voltage, thermal stability, and cycle life, yet its intrinsically low electronic and ionic conductivity limits high‐rate performance and thus usefulness in fast‐charge applications such as electric vehicles. Here, we evaluate key electrode design aspects, investigating the interplay between calendering density and current collector priming (carbon‐coating) on the fast cycling performance of LMFP cathodes. For electrodes on pristine aluminium, calendering to high density induced particle embedment into the foil (quantified via segmentation of cross‐sectional microscope images), reducing interfacial resistance while enhancing both rate capability and long‐term cycling stability. In contrast, performance of electrodes on C‐coated aluminium exhibited minimal sensitivity to densification. Surprisingly, at sufficiently high calendering pressure (achieving density ≥ 2.5 g cm −3 ), the carbon coating provided no advantage to high‐rate performance, in stark contrast with conventional understanding, and cells manufactured with pristine Al achieved fast charging from 10% to 80% SOC in just over 15 min, a key milestone for this chemistry. These findings establish a mechanistic understanding of how density and interfacial properties govern transport and electrochemical behavior in LMFP cells, providing practical guidance for optimized electrode structures.