Electrochemical properties of lithium-rich Li1+x(Mn1/3Ni1/3Co1/3)(1-x)O-2 at high potential

The electrochemical properties of lithium-rich Li-1.1(Mn1/3Ni1/3Co1/3)(0.9)O-2 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 Li-1.1(Mn1/3Ni1/3Co1/3)(0.9)O-2 had an intrinsic critical upper cutoff potential at about 4.3 V vs Li+/Li, beyond which the electrochemical performance of the active material deteriorated significantly. This detrimental impact at high potential (> 4.3 V vs Li+/Li) was related to the oxidative reaction of the electrolyte by the highly delithiated positive electrode material. (c) 2006 The Electrochemical Society.