The influences of SO42− from electrolytic manganese dioxide precursor on the electrochemical properties of Li-rich Mn-based material for Li-ion batteries

A series of layered Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 cathode materials, of which manganese source was electrolytic manganese dioxide, with different contents of SO 4 2− were successfully synthesized via ball-milling process and solid-state sintering method. The obtained materials were characterized by XRD, XPS, SEM-EDS, C-S, ICP, and HR-TEM. All the obtained materials presented well-ordered layered structure. When the content of SO 4 2− was below 1.30 wt%, the electrochemical properties and structural stabilities at low rate for the layered materials with SO 4 2− were not changed dramatically, while when the content of SO 4 2− increased to 5.85 wt%, the initial discharge capacities decreased dramatically from 248.24 to 209.23 mAh g −1 at 10 mA g −1 . And the pristine sample shows excellent cyclic property and rate capability. It delivered the discharge capacity of 175.25 mAh g −1 after 100 cycles with the highest capacity retention of 90.67% at 200 mA g −1 . Particularly, the treated Li-rich Mn-based materials with the highest amount of SO 4 2− exhibited the best cyclic stability and it delivers the highest capacity retention of 95.17% after 100 cycles at 200 mA g −1 . However, its discharge capacities were much lower than the pristine material. As a result, the addition of SO 4 2− could promote side reactions between electrode and electrolyte and deep-degree corrosion of electrode materials to affect the electrochemical properties and structural stabilities of the Li-rich Mn-based materials.