Novel cellulose aerogel coated on polypropylene separators as gel polymer electrolyte with high ionic conductivity for lithium-ion batteries

•A novel HEC aerogel was successfully coated on PP separator by ISISA.•The morphology of HEC aerogel layer shows well-ordered macroporous monoliths.•The HEC aerogel coating separator exhibits the high ionic conductivity.•The high ionic conductivity induces superior electrochemistry performance.

The low ionic conductivity of polypropylene (PP) separators has stymied their use as polymer electrolytes in high-power lithium-ion batteries. To improve the ionic conductivity, we coated PP separators with cellulose aerogel based on hydroxyethyl cellulose (HEC), via ice segregation induced self-assembly (ISISA). The coating was characterized via scanning electron microscopy (SEM), attenuated total reflection–infrared spectra (ATR-IR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). In addition, the electrochemical performances of the separator were evaluated by using a cell consisting of the coated separator, lithium foil as the counter and reference electrodes, and LiFePO4 as the cathode. The porous cellulose aerogel-coated separator exhibited superior dimensional stability, electrolyte uptake, and hence a higher ionic conductivity and better cycling performance, than its non-coated counterpart. Furthermore, the separator was coated without the use of toxic solvents, thereby rendering the preparation process cost effective and highly efficient.