High power iron phosphate cathodes by atomic layer deposition

Abstract

Amorphous thin films of FePO4 and Fe4(P2O7)3 show excellent power capabilities and good stability as cathode materials in Li-ion batteries. Within our tested range of materials, 10 nm FePO4 shows the best results and can handle specific powers above 1 MW/kg. The thin films are deposited using atomic layer deposition (ALD) and we studied the growth using in situ quartz crystal microbalance (QCM) showing self-limiting growth. Their electrochemical properties were characterized as cathode materials in coin cell batteries using cyclic voltammetry (CV) and galvanostatic cycling (GC), correcting for the roughness of the substrates and addressing contributions from non-Faradaic processes.