A chemical method for the complete components recovery from the ferric phosphate tailing of spent lithium iron phosphate batteries

Abstract

The extensive application of LiFePO₄ (LFP) batteries will result in a large amount of spent batteries. Recycling of spent LFP batteries has garnered significant attention due to their ability to recover valuable metals and protect the environment. After the selective extraction of lithium from waste LFP batteries, a large amount of solid waste in the form of ferric phosphate tailings were generated. To better address the issue of this ferric phosphate tailing solid waste, we developed an efficient recycling strategy to selectively recover iron phosphate and carbon black from ferric phosphate tailings for achieving the purpose of recycling all components of the spent LiFePO₄/C (LFP/C). First, the ferric phosphate tailing was treated with H₂SO₄ solution. The maximum Fe-leaching ratio was more than 92%, and the Fe-leaching ratio was still above 91% after recycling 4 times. Then, the leaching solution was treated with NaH₂PO₄ to precipitate FePO₄·2H₂O. Following this, the remaining black tailing was treated with alkali liquor, washed with water, dried, and mechanically processed for the filling agent of natural styrene butadiene rubber (SBR). The results showed that adding the remaining black tailing could significantly improve the reinforcement effect of natural SBR. Therefore, the recovery of iron phosphate and carbon black from the ferric phosphate tailings of spent LFP batteries not only avoids the energy consumption and wastage of carbon resources caused by high-temperature treatment of ferric phosphate tailings for the recovery of FePO₄ but also achieves the recovery and reuse of the whole component of ferric phosphate tailings.