Sustainable Upcycling of Battery Graphite Scrap via Synergistic Air Oxidation and Ammonia Etching

Abstract

The exponential growth of the lithium-ion battery industry has generated substantial manufacturing scrap, presenting an urgent imperative for sustainable resource recovery.Traditional graphite anode recycling relies heavily on volatile organic solvents and corrosive inorganic acids, posing severe environmental and occupational risks. This study introduces a zero-waste, closed-loop upcycling framework for battery manufacturing scraps utilizing solely pure deionized water, static air, and recoverable aqueous ammonia. By exploiting intrinsic thermodynamic wettability contrasts, complete binder-free aqueous delamination of the active graphite coating from the copper foil is achieved under ultrasonic assistance. Subsequent low-temperature ( 440°C)air pyrolysis simultaneously decomposes the polyvinylidene fluoride binder and oxidizes trace copper impurities. Final purification via room-temperature ammonia leaching selectively extracts copper as [Cu(NH 3 ) 4 ] 2+ , reducing residual copper concentrations to an ultralow 4.65 ppm without generating acidic effluents. Crucially, the synergistic application of thermal air oxidation and mild alkaline etching induces controlled microstructural remodeling. This dual-etching mechanism generates a hierarchical pore structure that nearly doubles the specific surface area (from 4.4 to 8.3 m 2 g -1 ) while introducing topological edge defects. This rationally engineered porosity facilitates a kinetic shift from bulk diffusion to pseudocapacitive charge storage, significantly accelerating solid-state lithium-ion transport. Consequently, the regenerated graphite delivers an initial discharge capacity of 372.71 mAh g -1 , an initial Coulombic efficiency of 93.6%, and robust long-term cycling stability in full-cell configurations, maintaining 80.35% capacity over 800 cycles at a rigorous 2 C rate.This inherently benign methodology transforms hazardous manufacturing waste into high-performance, fast-charging energy storage materials.