Structural and electrochemical properties of Li0.44+xMn1−yTiyO2 as a novel 4V positive electrode material

The specific capacity of Li 0.44 Mn 1− y Ti y O 2 (0 y 3 –LiOH salt at a low temperature. High-purity specimens of the lithium-inserted Li 0.44+ x Mn 1− y Ti y O 2 have been successfully prepared. We have conducted a systematic experimental study of the structural and electrochemical properties of these compounds. The inserted lithium content, x , in Li 0.44+ x Mn 1− y Ti y O 2 increases together with the substituted Ti content, y . The initial charge capacity increases from 130 mAh g −1 ( y = 0) to 145 mAh g −1 ( y = 0.22) for the Li 0.44+ x Mn 1− y Ti y O 2 compounds. The maximum discharge capacity that has been achieved is 180 mAh g −1 in the case of Li 0.72 Mn 0.78 Ti 0.22 O 2 between 2.5 and 4.8 V with a fixed current density of 30 mA g −1 ( C /6) at 30 °C. The discharge capacity at the 4 V plateau region (about 100 mAh g −1 ) in the lithium-inserted Li 0.55 MnO 2 has been improved to twice that in as-prepared Li 0.44 MnO 2 (about 50 mAh g −1 ). The structural differences between Li 0.44 MnO 2 and Li 0.55 MnO 2 are discussed based on XRD Rietveld analysis results.