Electrochimica Acta, Vol.109, 684-693, 2013
Effect of surface modifiers in improving the electrochemical behavior of LiNi0.4Mn0.4Co0.2O2 cathode
Surface modification of LiNi0.4Mn0.4Co0.2O2 (442) compound with certain metal oxides viz., Al2O3, Bi2O3 and In2O3 has been attempted with a view to improve the structural and cycling stability, especially upon high voltage and high rate cycling conditions. In addition to HF scavenging effect, the protective metal oxide inter-connect layer restricts the number of oxide ion vacancies eliminated during the initial cycling of cathode, resulting in the reduced irreversible capacity loss of the first cycle. Among the surface modified cathodes, Bi2O3 coated LiNi0.4Mn0.4Co0.2O2 cathode exhibits appreciable specific capacity values of 196 mAh g(-1) (Q(dc1)) and 175 mAh g(-1) (Q(dc100)) with 89% capacity retention, thus evidencing the superiority of Bi2O3 modifier in improving the electrochemical behavior of pristine LiNi0.4Mn0.4Co0.2O2 cathode. Further, suitability of Bi2O3 coated LiNi0.4Mn0.4Co0.2O2 cathode for high voltage (5.0 V) and high rate (3 C) lithium intercalation and de-intercalation applications has been demonstrated up to 100 cycles. Based on the extent of improvement in electrochemical behavior, the cathodes under investigation could be arranged in the order: Bi2O3 coated > Al2O3 coated > In2O3 coated > uncoated LiNi0.4Mn0.4Co0.2O2 oxide. (C) 2013 Elsevier Ltd. All rights reserved.
Keywords:Surface modification;Irreversible capacity loss;Rate capability;Extended potential window;Lithium batteries