Trace Fe3+ mediated synthesis of LiFePO4 micro/nanostructures towards improved electrochemical performance for lithium-ion batteries

Various LiFePO4 micro/nanostructures have been solvothermally synthesized using FeSO4 and ethylene glycol (EG) as the reactant and reaction medium, respectively. The LiFePO4 micro/nanostructures including nanoflakes, stacked microsheets, micro-dumbbells and micro-spindles have been selectively fabricated and tuned via adjusting trace Fe3+ obtained from oxidation of the reactant. The content of mediated-Fe3+ in the EG system plays an important role in the formation of the micro/nanostructures as well as the change in the pH value. In this work, the content of mediated-Fe3+ in the precursor solution as a problem worthy of attention was put forward and the evolution process of the LiFePO4 micro/nanostructures has been extensively studied. Among these micro/nanostructures of LiFePO4, the LiFePO4 micro-dumbbells as a cathode material for lithium-ion batteries showed the most excellent electrochemical performance with a discharge capacity of 117 mA h g−1 at a high rate of 10C (1C = 169 mA h g−1), which demonstrates that the exposed crystal plane and morphology of LiFePO4 play critical roles in the electrochemical performance. This work not only provides deeper knowledge into the formation mechanism of LiFePO4 microstructures, but also paves a facile way to prepare scalable LiFePO4 with a high rate performance and high tap density.