How to recycle used lithium iron phosphate battery

XueleiLi of Tianjin University of Technology designed a green recycling process for recycling lithium iron phosphate batteries. The specific process steps are shown below. The biggest feature of this step is the low cost, high efficiency and environmentally friendly recycling for the characteristics of lithium iron phosphate materials. The process not only realizes the recovery and regeneration of the positive LFP material and the negative graphite material, but also recovers materials that are difficult to recover such as electrolyte.

XueleiLi and other first lithium iron phosphate batteries were discharged and disassembled. The residual electrolyte was treated with low concentration of NaOH. According to the physical characteristics of solvent density, solubility and boiling point in the electrolyte, DMC was realized. Separation of DEC and EC, etc., the solvent salt LiPF6 is decomposed in an aqueous solution, as shown in the following formula, and then it can be recovered by filtration.

After the positive LFP material separated in this process is mixed with a certain Li2CO3, the regenerated LFP material can be obtained by heat treatment at different temperatures in an Ar/H2 atmosphere. In order to ensure good performance of recycled and recycled LFP materials, XueleiLi performed LFP regeneration experiments at 600, 650, 700, 750 and 800 degrees Celsius, and performed performance tests using button-type half- cells.

We can see that the capacity of LFP material without regeneration treatment is about 143mAh/g, and the capacity of LFP material after 650 °C treatment is increased to 147mAh/g, but after other temperature treatment, LFP The capacity of the material has declined to varying degrees.

At the same time, we also noticed that the initial efficiency of the regenerated material was significantly lower than that of the non-regenerated LFP material, which was mainly caused by the presence of heterogeneity in the regenerated LFP. XueleiLi's study showed that the initial efficiency of the LFP material could be improved by appropriately extending the heat treatment time.

Studies on the electrochemical properties of regenerated LFP show that heat treatment can significantly improve the cycle performance of LFP materials, while heat treatment also significantly improves the rate performance of LFP materials.

XueleiLi proposed a method for recycling lithium iron phosphate battery, which combines the structural stability of lithium iron phosphate material, without the traditional method of acid treatment and recovery of valuable elements, but directly regenerating it, using lower The cost of obtaining high-performance recycled LFP materials, the process also achieves the recovery of electrolyte and other materials, greatly reducing the environmental pollution caused by the lithium iron phosphate battery recycling process.

As a large number of lithium iron phosphate power batteries are scrapped and enter the recycling stage, the battery recycling market has experienced explosive growth. In order to avoid secondary pollution to the environment during recycling, we need to adopt a more green recycling method. XueleiLi's research provides us with useful lessons.

The page contains the contents of the machine translation.