In Situ Electrochemical Zn2+-Doping for Mn-Rich Layered Oxides in Li-Ion Batteries

Mn-rich layered oxide materials have been considered as promising cathode materials for large scale Li-ion batteries because Mn is more inexpensive than Co and Ni. In this connection, a variety of doped-materials have been examined to improve the electrochemical performance of Mn-rich cathode materials. Doped-materials are conventionally synthesized using solid state synthesis at high temperatures, where most dopants are located at transition metal sites. The amount of redox-active transition metals decreases with increasing the amount of dopants in transition metals sites, resulting in the reduced reversible capacity of doped-materials. This paper demonstrates an in situ electrochemical doping of Zn2+ that is site-selective. Li+ at Li sites in Mn-rich layered oxides is selectively replaced by Zn2+ during cycling. Zn2+ ions in electrolytes are irreversibly inserted to Li sites in delithiated Mn-rich cathode materials during discharge, leading to the formation of Zn2+-doped Mn-rich layered oxides, [Li1–xZn...