Hybrid annealing method synthesis of Li[Li0.2Ni0.2Mn0.6]O2 composites with enhanced electrochemical performance for lithium-ion batteries

Abstract

A lithium rich composite cathode electrode material Li[Li_0.2Ni_0.2Mn_0.6]O₂ was synthesized using the hybrid annealing method. Compared with the traditional annealing method, the hybrid annealing method added a cool treatment to the annealing process. Based on detailed characterizations from X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS), it is suggested that a good layer structure (axis ratio of c/a > 5.0), appropriate particle size of about 100 nm, and high lithium ion diffusion coefficient around 3.98 × 10⁻²⁴ cm² s⁻¹ are attained when the annealing temperature drops to 100 °C. Because of the above reasons the sample showed a high discharge capacity and excellent cycle stability. The first discharge capability and capacity retention after 60 cycles are 287.3 mA h g⁻¹ and 96.1%, respectively. The reasons for the electrochemical enhancement are systematically investigated.