Enhanced electrochemical performance of LiAlO2-LiMnPO4/C composite using LiAlO2 from AAO synthesis by hydrothermal rout

Abstract

Lithium aluminate (LiAlO2) has been successfully synthesized by a hydrothermal reaction based on using the anodic alumina (AAO) as the template and explored as the compound materials in LiMnPO4/C lithium battery. LiAlO2 nanoplate porous structure is inherited from anodic aluminum oxide (AAO) structure and serves as substrates to grow LiMnPO4 nanocrystals, which provide a high surface area with a porous structure. The morphology, structure, and electrochemical properties of the samples were analyzed. The instruments used in this process are X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscope (HRTEM), and charge-discharge test system. The crystallization transition process of the precursor after hydrothermal reaction was researched by thermal gravity analysis. The specific surface area and pore volume of LiAlO2 are 118.6 m2/g and 0.89 cm3/g, which were confirmed by the method of nitrogen adsorption. Moreover, the 10% content LiAlO2-LiMnPO4/C has the excellent electrochemical performance, and its first discharge capacity is 144 mAh/g at 0.1 C, compared with the LiMnPO4/C electrode (121 mAh/g at 0.1 C). The LiAlO2 can obstruct the direct contact of electrode and electrolyte, thus reducing their direct contact areas of cathode at charged state, owing to the fact that LiAlO2 around the active surfaces of LiMnPO4 grains acts as an ionic conductive wiring.