Facile introduction of polyether chains onto polypropylene separators and its application in lithium ion batteries

• A novel and facile way is proposed to prepare PEO modified separators.
• Mussel-inspired dopamine is used as a transitional interface.
• This method is universal for modifying the surfaces of other materials.
• Affinity between separator and liquid electrolyte is effectively improved.
• PEO modified separators show enhanced electrochemical performances.

In this work, polyether chains such as polyethylene glycol (PEG) chains were grafted onto polypropylene (PP) separators based on mussel-inspired dopamine coating. This method was proved to be also effective to modify other separators, such as polyethylene (PE) and polyvinylidene fluoride (PVDF) separators. Meanwhile, considering the extensive utilization of polyether chains in other fields, e.g., water treatment, biomedical, and so on, this work provided a facile and effective way for introducing polyether chains onto the surfaces of the other kinds of materials. Compared to the virgin PP separators, the introduction of polyether chains onto PP separators enhanced the affinity between the separator and liquid electrolyte. The PEG modified PP separators show higher ambient ionic conductivity, up to 0.99×10−3 S cm−1. Also, the PEG chains effectively decreased the interface resistance and enhanced the interfacial stability, which was beneficial for high performances of separators for lithium ion batteries (LIBs).