Mitigating the voltage decay and improving electrochemical properties of layered-spinel Li1.1Ni0.25Mn0.75O2.3 cathode material by Cr doping

Abstract Layered-spinel composite cathode material Li 1.1 Ni 0.25 Mn 0.75 O 2.3 and Cr doped Li 1.1 Ni 0.25−x Mn 0.75−x Cr 2x O 2.3 (x = 0.005, 0.015, 0.025) have been synthesized. The effect of Cr doping on physical and electrochemical properties are discussed using the characterizations of X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), charge/discharge, cyclic and rate tests. The results show that the Li 1.1 Ni 0.235 Mn 0.735 Cr 0.03 O 2.3 has the best electrochemical performance. Among the pristine and doped samples, the Li 1.1 Ni 0.235 Mn 0.735 Cr 0.03 O 2.3 shows the highest discharge capacity (261.9 mAhg −1 ), first coulomb efficiency (93.17%) and best rate performance (113 mAhg −1 at 10 C rates). Furthermore, the voltage decay of Li 1.1 Ni 0.25 Mn 0.75 O 2.3 can be mitigated after Cr doping effectively. The middle voltage (MDV) of Li 1.1 Ni 0.25 Mn 0.75 O 2.3 after 55 cycles is increased from 3.103 V to 3.220 V in Li 1.1 Ni 0.235 Mn 0.735 Cr 0.03 O 2.3 . Electrochemical impedance spectroscopy (EIS) results show that the R ct of Li 1.1 Ni 0.25 Mn 0.75 O 2.3 electrode decreases after Cr doping.