Synthesis and electrochemical characterization of Mg-doped Li-rich Mn-based cathode material

Abstract Mg-doped Mn-rich carbonate precursors (Ni 0.15 Co 0.15 Mn 0.7 CO 3 ) and Li-rich Mn-based cathode materials (Li 1.2 Ni 0.12 Co 0.12 Mn 0.56 O 2 ) have been synthesized by a carbonate precipitation method. The influence of Mg substitution for Ni, Co and Mn on the structural and electrochemical performance of Li 1.2 Ni 0.12 Co 0.12 Mn 0.56 O 2 has been investigated. XRD results of Mg-doped Li 1.2 Ni 0.12 Co 0.12 Mn 0.56 O 2 powders show that they exhibit similar XRD patterns as those of Li-rich Mn-based cathode materials. Electrochemical charge/discharge measurements in lithium-ion cells indicate the Mg-doped samples to exhibit lower discharge capacity but superior rate capability. The Mg substituted for Mn with 0.03 is found to be the most effective in improving the electrochemical performance. Li 1.2 Ni 0.12 Co 0.12 Mn 0.536 Mg 0.024 O 2 (Li 1.5 Ni 0.15 Co 0.15 Mn 0.67 Mg 0.03 O 2.5 ) displays a high reversible capacity of 205.4 mA h g −1 at 0.1 C. EIS results show that Mg doping decreases the charge-transfer resistance and enhances the reaction kinetics, which is considered to be the major factor for higher rate performance.