Regeneration and utilization of graphite from the spent lithium-ion batteries by modified low-temperature sulfuric acid roasting.

[Display omitted] • Modified low-temperature sulfated roasting is used to recycle spent graphite. • The purity of recycled graphite reached 99.55% and the recovery rate exceeds 94%. • Economical products Na 2 SO 4 and NaF can be obtained by treating wastewater and gas. • The valuable metal recovery rates are all over 99%. • The generated graphite shows excellent columbic efficiency and capacity retention. Recycling spent graphite in spent lithium-ion batteries (LIBs) is crucial for lacking high-quality graphite and environmental protection. Here, an environmentally friendly and economical modified method based on sulfate roasting was proposed to recycle spent graphite via low temperature roasting at 250 °C with sodium fluoride as an assistant additive. Recycling leads to graphite with a high purity of 99.55 % and chemical structures for energy storage. Batteries manufactured in regenerated graphite deliver a high initial charge capacity of 333.9 mAh/g with an initial columbic efficiency of 85.71% and excellent capacity retention of 91.2% after 400 cycles. In addition, the waste produced in the method could be well treated, and by-products 177 g of sodium sulfate would be collected per 1 kg spent graphite and NaF, equivalent to 78.95% of the added amount obtained through wastewater and exhaust gas, respectively. The regenerated sodium fluoride will be re-applied to the recovery spent graphite. The loop-closed method shows great promise for the industrial-scale recycling of spent graphite for energy storage applications. [ABSTRACT FROM AUTHOR]