Probing the failure mechanism of nanoscale LiFePO_4 for Li-ion batteries

摘要

LiFePO_4 is a high power rate cathode material for lithium ion battery and shows remarkable capacity retention, featuring a 91% capacity retention after 3300 cycles. In this work, we use high-resolution transmission electron microscopy and electron energy loss spectroscopy to study the gradual capacity fading mechanism of LiFePO_4 materials. We found that upon prolonged electrochemical cycling of the battery, the LiFePO_4 cathode shows surface amorphization and loss of oxygen species, which directly contribute to the gradual capacity fading of the battery. The finding can guide the design and improvement of LiFePO_4 cathode for high-energy and high-power rechargeable battery for electric transportation.