Defect-free solvothermally assisted synthesis of microspherical mesoporous LiFePO4/C

Abstract

Recent studies have shown that the power capability of LiFePO₄ is dramatically enhanced by reducing the size of the LiFePO₄ particles to nanometer dimensions. Unfortunately, the resulting intrinsically low tap density of the nano-LiFePO₄ cathode significantly reduces the volumetric energy density, which is a major hurdle for the successful commercialization of this material. Here, we report the facile synthesis of carbon-coated LiFePO₄ (LiFePO₄/C) with a mesoporous microspherical morphology via a solvothermal process, using ethanol as the sole solvent and in the absence of chelating agents. LiFePO₄/C was highly crystalline and exhibited less than 1% anti-site defects, which is important for fast lithium conduction in LiFePO₄. LiFePO₄/C showed an excellent rate performance (86 mAh g⁻¹ at a 20 C rate), a high retention ratio of 100% (140 mAh g⁻¹ at a 1 C rate), and a high tap density (1.2 g cm⁻³). The material is thus suitable for use as a cathode in lithium-ion batteries and for high-power energy storage devices.