Structure and electrochemical properties of LiMnBO3 as a new cathode material for lithium-ion batteries

Single-phase lithium manganese borate, LiMnBO3, was obtained at the temperature higher than 850 °C by one-step solid state reaction without using carbon black in the starting materials. The initial specific discharge capacity for the cathode active material was 75.5 mAh/g at the current density of 5 mA/g and the mean fade of capacity was 0.09% per cycle except for the first cycle. The LiMnBO3 compound maintained a specific discharge capacity of 42.3 mAh/g even at the current density of 50 mA/g and the capacity fade per cycle was only 0.2% during 40 cycles. The cyclic voltammograms (CV) curves show that the Mn3+/Mn2+ redox couple situated at 2.23 and 4.13 V can be clearly observed during anodic and cathodic sweeps. Combined the cyclic voltammograms results with the X-ray diffraction patterns of electrodes before and after cycling, where no significant change of the peak currents and the peak potentials during cycling, it was anticipated that the extraction and insertion of Li-ions are totally reversible in this compounds and the hexagonal structure for LiMnBO3 can be maintained after long cycles under high charge and discharge rate.