Ethylene glycol-assisted nanocrystallization of LiFePO4 for a rechargeable lithium-ion battery cathode

Abstract

Hydro- and/or solvo-thermal nanocrystallization of lithium iron phosphate (LiFePO₄) has been well recognized as an effective pathway to improve its electrochemical performances. Herein, it is reported that high-performance LiFePO₄ single-crystalline nanoparticles have been successfully prepared by the additive-free solvothermal reaction and subsequent glucose-assisted calcination. In comparison with the similar hydrothermal reaction, the presence of ethylene glycol can unexpectedly induce the formation of gel-like intermediates at the time interval of 0.5 h, resulting in LiFePO₄ nanoparticles with a three-dimensional (3D) lattice structure and an amorphous nanocoating for a reaction time of 2 h. Interestingly, the lattice structure of growing LiFePO₄ crystals can be thoroughly damaged under the irradiation of an electron beam. Furthermore, after the continuous crystal growth and subsequent heat-treatment, nanocrystalline LiFePO₄ can achieve a discharge capacity of ∼165 mAh g⁻¹ at 0.1 C in assembled LiFePO₄/Li half-cells, proving a successful nanocrystal-forming engineering of LiFePO₄ for a lithium-ion battery cathode.