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

Abstract

<p>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 × 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.</p>