Lithium Iron Phosphate Coatings Deposited by Means of Inductively-Coupled Thermal Plasma

Lithium-ion batteries have high energy efficiency and good cycling life and are considered as one of the best energy storage device for hybrid and/or electrical vehicle. Still, several problems must be solved prior to a broad adoption by the automotive industry: energy density, safety and costs. To enhance both energy density and safety, the current study aims at depositing binder-free cathode materials using inductively-coupled thermal plasma. In a first step, lithium iron phosphate LiFePO₄ powders are synthesized in an inductively-coupled thermal plasma reactor and dispersed in a conventional polyvinylidene fluoride (PVDF) binder. Then, binder-free LiFePO₄ coatings are directly deposited onto nickel current collectors by solution precursor plasma spraying (SPPS). These plasma-derived cathodes (with and without PVDF binder) are assembled in button cells and tested. Under optimized plasma conditions, cyclic voltammetry shows that the electrochemical reversibility of plasma-derived cathodes is improved over that of conventional sol-gel derived LiFePO₄ cathodes. Further results related to the substitution of iron with manganese in the SPPS precursors (LiMPO4, where M = Fe or Mn) are discussed.