Graphite/Copper interfacial conditioning enabling high-yield recovery of graphite and copper from spent graphite electrodes

초록

Graphite and copper current collectors constitute major mass fractions of lithium-ion batteries, yet their selective recovery from individual spent graphite electrodes remains challenging due to persistent binder and interphase residues that stabilize the graphite-copper interface and hinder clean delamination. Here, we present an electrode-level recycling strategy based on interfacial conditioning, in which conductivity-guided aqueous rinsing is coupled with rapid thermal processing (RTP) and surfactant-free high-shear aqueous delamination to enable efficient graphite-Cu separation. We show that the pre-rinsing step is critical because it removes soluble electrolyte/interphase species that would otherwise convert during RTP into water-insoluble residues that impede subsequent delamination. This sequence-dependent interfacial control enables efficient graphite release while preserving nearly bare, intact Cu foils, yielding >97% graphite recovery under optimized conditions. The recycled graphite exhibits reduced impurity content and improved structural ordering, leading to lower polarization, reduced resistance, enhanced rate capability, and improved cycling stability. Stable long-term operation is further demonstrated in a lithium iron phosphate-graphite full cell. By directly addressing the spent graphite-Cu interphase without additional chemical additives or surfactants during the separation step, this work provides a scalable strategy for the high-purity recovery of graphite and copper current collectors from spent graphite electrodes.

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