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

The recovery of metals from spent LiFePO4 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 H4P2O7 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(P2O7)(3) and recovered Li2CO3 were used to regenerate LiFePO4 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 H4P2O7 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.

Automated summary

This study proposed an effective metal recovery method for spent LiFePO4 batteries, using H4P2O7 as a leaching agent to achieve one-step leaching and separation of metals, and then utilizing the separated iron and lithium for regeneration of LiFePO4 cathode material.