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.