Flow battery

A flow battery, comprising:

• a first non-aqueous electrolyte liquid;
• a first electrode in contact with the first non-aqueous electrolyte liquid;
• a second electrode which serves as a counter electrode of the first electrode;
• and
• a lithium ion conductive film which separates the first electrode and the second electrode from each other,
• wherein
• the first non-aqueous electrolyte liquid contains:
• lithium ions;
• and
• at least one kind of first redox material selected from the group consisting of biphenyl, phenanthrene, stilbene, triphenylene, anthracene, acenaphthene, acenaphthylene, fluorene, fluoranthene, o-terphenyl, m-terphenyl, and p-terphenyl;
• the lithium ion conductive film comprises a composite body;
• the composite body contains a lithium ion conductive polymer and polyvinylidene fluoride;
• the lithium ion conductive polymer includes an aromatic ring into which a lithium salt of an acidic group has been introduced;
• and
• the lithium ion conductive polymer and the polyvinylidene fluoride have been mixed with each other homogeneously in the composite body.