Application of H4P2O7 as leaching acid in one-step selective recovery for metals from spent LiFePO4 batteries

The recovery of metals from spent LiFePO 4 batteries is arousing increasing concern due to its great market consumption, environmental impact, and wastage of valuable metallic resources. This work proposed an effective recycling approach for metals and promoted a simplified regenerative process. The innovative use of H 4 P 2 O 7 as a leaching agent achieves the leaching of metals and their separation in one step. Under a modified leaching condition, the leaching efficiency of Li is close to 100%, and the precipitation amount of Fe is more than 97%. Then, the separated Fe in the form of Fe 4 (P 2 O 7 ) 3 and recovered Li 2 CO 3 were used to regenerate LiFePO 4 cathode material. It delivers an initial capacity of 167.8 mAh g −1 at 0.1 C and remains 91.31% after 100 cycles; the dynamic property and cycling stability are comparable to the unused commercial material. The application of H 4 P 2 O 7 achieves separation of Li and Fe metals in parallel with leaching process with higher leaching efficiency and selectivity for the metals than the conventional leaching acids in hydrometallurgy technology.