Effect of temperature on the electronic/ionic transport properties of porous LiNi0.5Mn1.5O4 with high voltage for lithium ion batteries

Porous spinel LiNi0.5Mn1.5O4 microspheres were successfully synthesized by a facile method with microspheres MnCO3 template, and characterized by XRD and SEM. The as-synthesized porous LiNi0.5Mn1.5O4 microspheres exhibit high rate capability and good cycle performance, with the specific discharge capacity of 125.5, 125.4, 121 and 97.6 mA h/g at 1, 2, 3 and 5 C, respectively, and the capacity retention of 85.6% at 5 C after 100 cycles, which are attributed to the porous structure. It is found that the EIS features of spinel LiNi0.5Mn1.5O4 cathode are related to the temperature, and the middle to high frequency arc is observed in the Nyquist diagram at temperatures below zero, which is attributed to the electronic properties of the electrode material. In 1 mol/L LiPF6-EC:DEC:DMC electrolyte solutions, the energy barriers for the ion jump related to migration of lithium ions through the SEI film of the spinel LiNi0.5Mn1.5O4 cathode are determined to be 16.89 kJ/mol, the thermal activation energy of the electronic conductivity to be 0.348 eV, and the intercalation-deintercalation reaction activation energies to be 0.619 eV, respectively.