Recycling bacteria for the synthesis of LiMPO₄ (M = Fe, Mn) nanostructures for high-power lithium batteries

In this work, a novel waste-to-resource strategy to convert waste bacteria into a useful class of cathode materials, lithium metal phosphate (LiMPO₄; M = Fe, Mn), is presented. Escherichia coli (E. coli) bacteria used for removing phosphorus contamination from wastewater are harvested and used as precursors for the synthesis of LiMPO₄. After annealing, LiFePO₄ and LiMnPO₄ nanoparticles with dimensions around 20 nm are obtained. These particles are found to be enveloped in a carbon layer with a thickness around 3-5 nm, generated through the decomposition of the organic matter from the bacterial cell cytoplasm. The battery performance for the LiFePO₄ is evaluated. A high discharge capacity of 140 mAh g^-1 at 0.1 C with a flat plateau located at around 3.5 V is obtained. In addition, the synthesized particles display excellent stability and rate capabilities. Even under a high C rate of 10 C, a stable discharge capacity of 75.4 mAh g^-1 can still be achieved.