NaOH-assisted low-temperature roasting to recover spent LiFePO4 batteries

Decreasing the operating temperature of pyrometallurgical methods for recycling spent lithium-ion batteries (LIBs) is key to reducing energy consumption and cost. Herein, a NaOH-assisted low-temperature roasting approach is proposed to recover spent LiFePO4. During roasting, NaOH acts as an oxidizing agent to oxidize Fe (II) to Fe3O4 at 150 degrees C, thus collapsing its stable olivine structure while PO43-capturing Li+ and Na+ to form Li2NaPO4 and LiNa5(PO4)2. The obtained Fe3O4 is then separated, and the resulting Li salt can be further recovered as Li3PO4 with a Li recovery efficiency of 96.7 % and a purity of 99.9 %. Economic and environmental analysis based on the EverBatt model shows that this low-temperature strategy reduces energy consumption and greenhouse gas (GHG) emissions, thus increasing the potential profit. Overall, NaOH-assisted low-temperature roasting is a prospective strategy that broadens the application of NaOH as an oxidant and opens up a new avenue for decreasing the temperature of recovering spent LiFePO4 by pyrometallurgy.

Automated summary

This study proposes a low-temperature roasting method assisted by NaOH for recycling spent LiFePO4, achieving efficient Li recovery and purity improvement at lower temperatures with reduced energy consumption and greenhouse gas emissions.