Porous SiO2 as a separator to improve the electrochemical performance of spinel LiMn2O4 cathode

• A porous hydrophilic SiO2 is developed for battery separator applications.
• After the electrolyte infiltrated, the SiO2 separator exhibits high ionic conductivities.
• The cell using the SiO2 separator shows excellent electrochemical properties.
• The SiO2 separator can alleviate the LiMn2O4 capacity fading at high temperature.

Porous SiO2 separator is prepared by pressing followed by sintering process. The SiO2 separator has a high porosity of 45% and good mechanical strength. After the liquid electrolyte is infiltrated, the separator exhibits quite high ionic conductivities, and the ion conductivity reaches 0.35 mS cm−1 at −20 °C. More importantly, the hydrophilic SiO2 separator has an advantage over the polymer separator in the electrolyte infiltration and retention. The LiMn2O4/Li cell using the SiO2 separator shows higher discharge capacity, rate capacity, and better low-temperature properties than that using the commercial polymer separator. Furthermore, the SiO2 separator can alleviate the capacity fading of the LiMn2O4 at high temperature, implying that the SiO2 separator is very promising to be applied in the lithium-ion batteries.