Enhanced electrochemical performance of LiMnBO3 with conductive glassy phase : a prospective cathode material for lithium-ion battery

LiMnBO3 has been identified as a promising cathode material for next-generation lithium-ion batteries. In this study, LiMnBO3 along with glassy lithium borate material (LiMnBO3 (II)) is synthesized by sol-gel method. X-ray diffraction (XRD) analysis depicts the existence of LiBO2 glassy phase along with m-LiMnBO3 phase. Transmission electron microscopy (TEM) analysis confirms the presence of LiBO2 glassy phase. An enhanced electrical conductivity of 3.64 x 10(-7) S/cm is observed for LiMnBO3 (II). The LiBO2 glassy phase is found to promote the Li reaction kinetics in LiMnBO3 (II). The synthesized LiMnBO3 (II) delivers a first discharge capacity of 310 mAh g(-1) within a potential window of 1.5-4.5 V at C/10 rate. Further, a discharge capacity of 186 mAh g(-1) at the 27th cycle shows a better cycle performance. The enhanced capacity is due to the presence of LiBO2 glassy phase and more than one Li-ion transfer in the lithium-rich stoichiometry of LiMnBO3 (II). Density functional theory calculation reveals the exact electronic structure of m-LiMnBO3 with a band gap of 3.05 eV. A charge transfer mechanism is predicted for delithiation process of m-LiMnBO3.
QC 20170713