The characterization and electrochemical performance of Li[Li_0.2Ni_0.4Mn_0.4]O₂ material prepared by a combustion method

A Li[Li_0.2Ni_0.4Mn_0.4]O₂ cathode material for lithium battery was synthesized in de-ionized water, ethanol and ethanol with PEG by a combustion method. XPS analysis shows that Ni and Mn are in 3+ and 4+ oxidation states, respectively. Three materials exhibit a layered hexagonal α-NaFeO₂ structure, and that prepared in ethanol with PEG displays the best homogeneous morphology in a size distribution of 200-400 nm. The electrochemical tests show that the material prepared in ethanol with PEG displays the best cyclic performance and rate capability, such as the discharge capacity of 254 mAhg^-1 in the first cycle at 0.1C and 234 mAhg^-1 after 50 cycles. Capacity retention is more than 90% after 50 cycles for the cell with a charge/discharge pre-cycling treatment (one cycle at 4.5-2.0 V and followed by one cycle at 4.8-2.0 V) compared with that without pre-cycling. EIS measurements demonstrate that pre-cycling treatment leads to form a better SEI layer and the cell assembled with the material prepared in ethanol with PEG has the least R_SEI and R_ct values.