Electrochemical performance of Si-Mn composites in Li-ion battery

The Si-Mn composites were synthesized by ball-milling mixtures of four different atomic ratios of Si/ Mn. The phases of composites were analyzed with X-ray diffraction. Their charge-discharge performance as negative electrodes in Li-ion batteries were tested and the formation of SEI film was studied by differential capacity plots. The results show that materials prepared by ball-milling technology are composites consisting of Si and Mn. The insertion of lithium ions leads to the formation of amorphous Li-Si alloy. The initial reversible capacity and efficiency of Si-Mn composites are increased and the cycle life is enhanced obviously, especially after their heat treatment. The composite of Si:Mn=4:6 exhibits a reversible capacity of 546.0 mAh·g ^-1 and a charge-discharge efficiency of 70%. The reversible capacity maintains at 374.2 mAh·g^-1 after 40 cycles.