Simplifying thermal pretreatment of lithium iron phosphate cells: Benefits of whole-cell processing without inert atmospheres

The rapid growth of lithium iron phosphate (LFP) batteries challenges recycling due to their lower material value, making capital and operational cost reduction essential. Current flowsheets rely heavily on thermal treatment under inert atmospheres, which drives cost through complex sealed reactor design requirements, inert gas consumption, and high energy input. This study demonstrates a simplified alternative: thermally treating whole LFP cells in an open rotary kiln. The cell casing acted as a passive barrier, providing an inert micro-environment that limits oxidation. Furthermore, the in-situ volatilization and combustion of electrolyte and separator provided a source of heating for the process. Under best conditions (650 °C, 15 min), 78 % LFP and 69 % graphite were recovered into black mass (<0.3 mm), with limited Cu (3 %) and Al (<1 %) reporting to fines, achieving a black mass of comparable composition to the one obtained through inert atmosphere methods (68.6 % LFP, 30.6 % C, 0.2 % Al, 0.6 % Cu). XRD confirmed preservation of LiFePO 4 , whereas uncased comparative runs oxidized to Li 3 Fe 2 (PO 4 ) 3 . The resulting black mass was compatible with flotation, yielding 96 % LFP grade in underflow and 73 % graphite grade in overflow. This work provides evidence that thermal treatment of whole cells in air can achieve comparable performance to inert atmosphere flowsheets with significantly lower process complexity, supporting the development of more scalable and economically viable industrial LFP recycling systems. • Whole-cell feedstock provides heating and isolation enabling usage of reactors as rotary kilns operated under open atmosphere conditions. • Thermal runaway reactions provide sufficient heat to remove PVDF preparing materials for mechanical separation and flotation. • Casings prevent material oxidation, preserving LFP phase and low Cu and Al content in black mass. • Flotation of the black mass achieved >85 % LFP recovery at >96 % grade and ∼90 % graphite recovery at 74 % grade.