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

• The layered-spinel composite Li1.1Ni0.25Mn0.75O2.3 material has been synthesized and doped with Cr.
• The Cr doped layered-spinel Li1.1Ni0.235Mn0.735Cr0.03O2.3 material shows better performance.
• The voltage decay phenomena of Li1.1Ni0.25Mn0.75O2.3 have been restrained effectively in the Cr doped material.

Layered-spinel composite cathode material Li1.1Ni0.25Mn0.75O2.3 and Cr doped Li1.1Ni0.25−xMn0.75−xCr2xO2.3 (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 Li1.1Ni0.235Mn0.735Cr0.03O2.3 has the best electrochemical performance. Among the pristine and doped samples, the Li1.1Ni0.235Mn0.735Cr0.03O2.3 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 Li1.1Ni0.25Mn0.75O2.3 can be mitigated after Cr doping effectively. The middle voltage (MDV) of Li1.1Ni0.25Mn0.75O2.3 after 55 cycles is increased from 3.103 V to 3.220 V in Li1.1Ni0.235Mn0.735Cr0.03O2.3. Electrochemical impedance spectroscopy (EIS) results show that the Rct of Li1.1Ni0.25Mn0.75O2.3 electrode decreases after Cr doping.