Electrochemical Properties of Lithium-Rich Li[sub 1+x](Mn[sub 1∕3]Ni[sub 1∕3]Co[sub 1∕3])[sub 1−x]O[sub 2] at High Potential

Abstract

The electrochemical properties of lithium-rich Li1.1(Mn1∕3Ni1∕3Co1∕3)0.9O2Li1.1(Mn1∕3Ni1∕3Co1∕3)0.9O2 positive electrode material were carefully investigated to understand its performance limitations as an advanced positive electrode material for lithium-ion batteries. The experimental evidence on the initial irreversible capacity loss, the capacity retention, and the ac impedance data consistently demonstrated that Li1.1(Mn1∕3Ni1∕3Co1∕3)0.9O2Li1.1(Mn1∕3Ni1∕3Co1∕3)0.9O2 had an intrinsic critical upper cutoff potential at about 4.3V4.3V vs Li+∕LiLi+∕Li , beyond which the electrochemical performance of the active material deteriorated significantly. This detrimental impact at high potential ( 4.3V4.3V vs Li+∕LiLi+∕Li ) was related to the oxidative reaction of the electrolyte by the highly delithiated positive electrode material.