In-vehicle lithium ion battery member

An in-vehicle lithium ion battery member produced by molding a resin composition containing (a) a polyphenylene ether resin and (c) olefinic polymer constituted from an olefin,

• the resin composition having a critical strain in a chemical resistance evaluation of 0.5% or more and a Charpy impact strength at 23° C. of 20 kJ/m2 or more,
• wherein
• a sea-island phase structure having a sea phase containing the (a) component and island phases containing the (c) component and present in the sea phase is formed in a morphology image of the in-vehicle lithium ion battery member, and
• in a second processed image obtained through a binarization of the morphology image,
• a number per unit area of second black portions that are black after the binarization and have an area of 4.92×10−4 μm2 or more is 8/μm2 or more, and
• in a case where AW2 (μm2/μm2) represents an occupied area per unit area by second white portions that are white after the binarization, and L2 (μm/μm2) represents a length per unit area of a total peripheral length which is a sum of peripheral lengths of second non-small portions having an area of 15×10−4 μm2 or more among the second black portions, the length L2 relative to the occupied area AW2 (L2/AW2) is 7 μm−1 or more.