Glucose assisted synthesis of hollow spindle LiMnPO4/C nanocomposites for high performance Li-ion batteries

Abstract

Nano-sized hollow spindle LiMnPO4 with a well-developed olivine-type structure was synthesized with the assistance of glucose in dimethyl sulfoxide (DMSO)/H2O under ambient pressure and 108°C. The scanning electron microscopy (SEM) and transmission electron microscope (TEM) images show that the LiMnPO4 particles consist of hollow spindles with a mean width of 200nm, length of 500-700nm, and wall thickness of about 30-60nm. The LiMnPO4/C nanocomposite was obtained by sintering nano-sized LiMnPO4 with glucose at 650°C under an inert atmosphere for 4h. With a coated carbon thickness of about 10 nm, the obtained composite maintained the morphology and size of the hollow spindle. The electrochemical tests show the specific capacity of LiMnPO4/C nanocomposite is 161.8mAhg−1 at 0.05C, 137.7mAhg−1 at 0.1C and 110.8mAhg−1 at 0.2C. The retention of discharge capacity maintains 92% after 100 cycles at 0.2C. After different rate cycles the high capacity of the LiMnPO4/C nanocomposite can be recovered. This high performance is attributed to the composite material's hollow spindle structure, which facilitates the electrolyte infiltration, resulting in an increased solid-liquid interface. The carbon layer covering the hollow spindle also contributes to the high performance of the LiMnPO4/C material as the carbon layer improves its electronic conductivity and the nano-scaled wall thickness decreases the paths of Li deintercalation.