Electrochemical properties of Li-rich ternary cathode material Li1.20Mn0.44Ni0.32Co0.04O2 and its oxygen-deficient phase

As the cathode material of lithium-ion batteries, Li-rich ternary layered oxides usually suffer from high first cycle irreversible capacity, low rate capability, and structural instability during charge-discharge. Recent studies show that Ni-rich Li1.20Mn0.44Ni0.32Co0.04O2 material has good structural stability. In this paper, the electrochemical performance of Li1.20Mn0.44Ni0.32Co0.04O2 and its oxygen-deficient phase Li1.20Mn0.44Ni0.32Co0.04O1.83 are studied by the first-principles calculations. The results show that, for the pristine phase Li1.20Mn0.44Ni0.32-Co0.04O2, the theoretical delithiation capacity is 380 mAh/g and the highest charging voltage platform is 4.99 V. The O ions are found to participate in the charge compensation significantly. Ni ions can only contribute 118 mAh/g of the delithiation capacity, and the remaining charging capacity is contributed by O ions. For the oxygen-deficient phase Li1.20Mn0.44Ni0.32Co0.04O1.83, the highest voltage platform is reduced by 0.21 V, O ions are also found to participate in the charge compensation obviously. Compared to the pristine phase, transition metal (TM) ions in the oxygen-deficient phase exhibit higher chemical activity, while the contribution of O ions to charge compensation is relatively reduced. The oxygen-deficient phase has a slightly higher theoretical ca-pacity (392 mAh/g) than the pristine phase.