Electrochemical characteristics and manganese dissolution of spinel Li1.05M0.2Mn1.75O4 (M = Al, Co, and Cr) cathode for rechargeable lithium ion batteries

Electrochemical characteristics of the spinel Li1.05M0.2Mn1.75O4 (M = Al, Co, and Cr) and manganese dissolution from the spinel cathode materials into an electrolyte solution were investigated in order to understand and suppress the dissolution. As we described previously, the dissolution is one of the origins of a significant capacity fading with cycling for rechargeable lithium ion batteries, that is, severe degradation of a carbon anode was caused by deposition of the soluble Mn(II) species released from the spinel. For the purpose of suppressing the manganese dissolution, the lithium-rich spinel, Li1.05Mn1.95O4, was doped with a small amount of Al, Co, and Cr on the Mn 16d site, and the relationship between their cycle performances and Mn dissolution was investigated using 1 mol dm (-3) LiClO4/EC + DMC (volume ratio 1:1) electrolyte solution at 25 and 50degreesC. By doping with Co and Cr, manganese dissolution from the spinel was successfully suppressed rather than Li1.05Mn1.95O4. Furthermore, the substitution with Co and Cr was remarkably effective to the enhancement in cycling behavior due to the structural stabilization and the suppression of manganese dissolution.