Evolution of spent LiFePO4 powders into LiFePO4/C/FeS composites: A facile and smart approach to make sustainable anodes for alkaline Ni-Fe secondary batteries

In recent years, how to properly recycle increasing spent LiFePO4 batteries is becoming an extremely thorny subject, which is related to not only a severe environmental pollution but also a serious waste of valuable resources. Here, for the first time, a sustainable and smart approach is established for manufacturing LiFePO4/C/FeS composites from spent LiFePO4 powders as novel anode materials for alkaline Ni-Fe secondary battery. The LiFePO4/C/FeS composites are prepared via a facile ball milling method by using spent LiFePO4 and commercial FeS as raw materials. When serving as host anode material for Ni-Fe battery, the LiFePO4/C/FeS (40 wt%) composite exhibits attractive anodic performance in alkaline solution, with a high specific discharge capacity of ～232.9 mAh g−1 (639.1 mAh g−1Fe) at 0.2C, prominent high-rate capabilities (～150.7 mAh g−1 (413.5 mAh g−1Fe) still retains even at a high rate up to 5C) and excellent cyclic stability (with retention of as high as 75.9% of its highest capacity after 300 cycles at 1C). Meaningfully, our study proposes a sustainable and economical approach to produce advanced anodes for alkaline Ni-Fe secondary batteries, simultaneously providing an attractive and facile way to recycle spent LiFePO4 materials in large scale.