B-axis oriented alignment of LiFePO4 monocrystalline platelets by magnetic orientation for a high-performance lithium-ion battery

Lithium-iron phosphate (LiFePO4) monocrystalline platelets (LFP-P) with ac facet-preferred growing were obtained by a solvothermal method. Based on its anisotropy, a LiFePO4 cathode (LFP-PM) with the b axis-oriented aligning was prepared by magnetic orientation. The structure, morphology and magnetic performance of the LFP-P were studied by X-ray diffractometry, scanning-electron microscopy, transmission-electron microscopy and superconducting quantum-interference device technologies. The LFP-P exhibited paramagnetic behavior and its b axis had the largest magnetic susceptibility, which made the LFP-P stack parallel to the magnetic field. It resulted in a higher lithium-ion diffusion coefficient of the LFP-PM (1.6855 × 10−11 cm2 s−1) compared with that of the LiFePO4 cathode (LFP-PU) prepared without magnetic orientation (1.2538 × 10−11 cm2 s−1). The faster lithium-ion diffusion was contributed to a higher reversibility at 0.1 mV s−1 and higher discharge capacities of the LFP-PM at high rates ≥2 C. For the first time, LiFePO4 monocrystalline platelets were made to align along b axis through magnetic orientation. It was proved to be an effective means of enhancing high rate performance.