Low-carbon recycling of spent lithium iron phosphate batteries via a hydro-oxygen repair route

In this study, we proposed a sequential and scalable hydro-oxygen repair (HOR) route consisting of key steps involving cathode electrode separation, oxidative extraction of lithium (Li), and lithium iron phosphate (LiFePO4) crystal restoration, to achieve closed-loop recycling of spent LiFePO4 batteries. A hydro-oxygen environment (with a cathode electrode : H2O2 ratio of 30 g mL(-1)) was first used to achieve nondestructive separation of the LiFePO4 cathode material and aluminum foil within a short period of time (0.25 min). The selective and high-efficiency extraction of Li from exfoliated LiFePO4 cathode materials was subsequently achieved by mechanochemically coupled oxidation potential regulation (conditions: 10 min, a rotational speed of 1000 rpm, and a LiFePO4 cathode material : H2O2 ratio of 1 : 37.5 g mL(-1)). The LiFePO4 crystals were successfully restored via a solid phase sintering process using the extracted Li and residual iron phosphate framework, and the regenerated LiFePO4 crystal exhibited a considerable specific electrochemical capacity (& SIM;151.2 mA h g(-1), 1C), which is comparable to that of commercial cathode materials. A life cycle assessment demonstrated that the HOR route can significantly reduce carbon emissions by -0.38 kg CO2 eq. and smog release by -0.17 kg O-3 eq. per kg of spent LiFePO4 batteries, thus contributing to a circular economy and global decarbonization.

Automated summary

In this study, a sequential and scalable hydro-oxygen repair (HOR) route was proposed for closed-loop recycling of spent LiFePO4 batteries. The route involves steps such as cathode electrode separation, oxidative extraction of lithium, and restoration of lithium iron phosphate crystals. The HOR route demonstrated efficient separation and extraction of materials, and the regenerated crystals showed comparable electrochemical capacity to commercial cathode materials. Life cycle assessment showed significant reduction in carbon emissions and smog release, contributing to a circular economy and decarbonization.