LiFePO4 spray drying scale-up and carbon-cage for improved cyclability

Abstract The growing market for electrical vehicles requires inexpensive, long-lasting batteries. LiFePO 4 (LFP) melt-synthesized from ore concentrate fits this role, but the manufacturing process requires additional steps that includes grinding large ingots into a nanoparticle suspension followed by a dessication step. Spray drying, rather than tray drying, creates a mesoporous powder that enhances wettability. Adding lactose and high-Mw polyvinyl alcohol (PVA) to the suspension of nanostructures followed by pyrolysis, creates a carbon-cage that interconnects the cathode nanoparticles, imparting better capacity ( LiFePO 4 /C: 161 mA h g−1 at 0.1C), discharge rate (flat plateau, 145 mA h g−1 at 5C), and cyclability (91% capacity retention after 750 cycles at 1C). Particle size affects battery stability; PVA increases the suspension's viscosity and alters the powder morphology, from spherical to hollow particles. A model describes the non-Newtonian suspension's rheology changing: shear, temperature, LFP and PVA loading. Carbon precursors prevent the nanoparticles from sintering during calcination but lactose gasifies 50% of the carbon, according to the chemical and allotropic composition measurements (CS analyzer, XPS, and Raman). The carbon-cage imparts microporosity and we correlate the SEM and TEM powder's morphology with N 2 physisorption porosimetry. Ultrasonication of the suspension fragments the PVA chain, which is detrimental to the final cathode performance.