A monodispersed nano-hexahedral LiFePO4 with improved power capability by carbon-coatings

A monodispersed nano-sized hexahedral LiFePO4 of regular angularity was prepared through hydrothermal process. Different carbon precursors were employed to create carbon-coating layers onto the nano-particles to improve the electrochemical performances of the material. Structure and morphology of the LiFePO4 material without and with carbon-coating layer were studied using a combination of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. It confirms that carbon-coating plays an important role inhibiting the agglomeration of the nanoparticles. A uniform carbon-coating layer of higher graphitization degree was developed on the LiFePO4 particles with sucrose precursor. The electrode exhibits discharge capacities of 148.3 mA h g−1, 138.7 mA h g−1, 117.8 mA h g−1 at 0.1 C, 1 C and 10 C, respectively. Very close Li ion diffusion coefficient of around 8 × 10−14 cm2 s−1 for all the LiFePO4/C composites with different carbon sources implies that the improved power capability is mainly attributed to the small particle size and low contact resistance between the LiFePO4 nanoparticles.