Characterization of yttrium substituted LiNi0 33Mn0 33Co0 33O2 cathode material for lithium secondary cells

LiNi0 33-xMn0 33Co0 33YxO2 materials ate synthesized by Y3+ substitute of Ni2+ to improve the cycling performance and rate capability The influence of the Y3+ doping on the structure and electrochemical properties are investigated by means of X-ray diffraction (XRD) scanning electron microscope (SEM) cyclic voltammetry (CV) electrochemical impedance spectroscopy (EIS) X-ray photoelectron spectroscopy (XPS) and galvanostatic charge/discharge tests LiNi0 Mn-33(0) 33Co0 33O2 exhibits the capacity retentions of 89 9 and 87 8% at 20 and 4 0 C after 40 cycles respectively After doping the capacity retentions of LiNi0 305Mn0 33Co0 33Y0 025O2 are increased to 972 and 959% at 20 and 4 0 C respectively The discharge capacity of LiNi0 305Mn0 33Co0 33Y0 025O2 at 5 0 C remains 757% of the discharge capacity at 0 2 C while that of LiNi0 33Mn0 Co-33(0) O-33(2) is only 47 5% EIS measurement indicates that LiNi0 305Mn0 Co-33(0) Y-33(0) O-025(2) electrode has the lower impedance value during cycling It is considered that the higher capacity retention and superior rate capability of Y-doped samples can be ascribed to the reduced surface film resistance and charge transfer resistance of the electrode during cycling (C) 2010 Elsevier Ltd All lights reserved