Synthesis of graphene and recovery of lithium from lithiated graphite of spent Li-ion battery

Recycling of spent Li-ion batteries is crucial for achieving sustainable development of battery industry. Current recycling processes mainly focus on valuable metals but less attention has been paid to spent graphite, which generally ends up as secondary waste. In this study, a process for preparing graphene and recovering Li in anode as a by-product from spent graphite was developed. The key point was to re-charge the spent LIBs to generate lithium graphite intercalation compounds. The lithium graphite intercalation compounds were then subjected to a hydrolysis procedure and graphene could be produced through ultrasonic treatment via the expansion/micro-explosion mechanism. Experimental results demonstrated that 1-4 layered graphene could be efficiently produced when spent Li-ion batteries with beyond 50% capacity were re-charged. The prepared graphene showed high quantity containing few defects (I_D/I_G = 0.33, C/O = 13.2 by energy dispersive spectroscopy and C/O = 8.8 by X-ray photoelectron spectroscopy). In addition, Li was simultaneously recovered in the form of battery-grade lithium carbonate in the above process. Economic analysis indicated that the graphene production cost was extremely low ($540/ton) compared to that of commercial graphene.