Separator, electrochemical cell, stack and apparatus

A separator comprising:

• a frame;
• and
• a flow-channel wall on the frame, the flow-channel wall defining a supply-area, an exhaust-area, and a groove-area, the groove-area comprising a first groove group between the supply-area and the exhaust-area, the first groove group comprising (A) a first supply-side connection groove in which the side of the supply-area has a larger opening than the side of the exhaust-area;
• and (B) a first exhaust-side connection groove in which the side of the exhaust-area has a larger opening than the side of the supply-area, wherein
• the flow-channel wall is provided at the exhaust-area-side end of the first supply-side connection groove, and
• the separator satisfies at least one of the following:
• (i) a height of the end portion of the flow-channel wall on the exhaust-area side of the first supply-side connection groove is lower than a height of a portion of the flow-channel wall that is located between the first supply-side connection groove and the first exhaust-side connection groove;
• (ii) a thickness of the end portion of the flow-channel wall on the exhaust-area side of the first supply-side connection groove is thinner than a thickness of the portion of the flow-channel wall which is located between the first supply-side connection groove and the first exhaust-side connection groove;
• (iii) the frame on the end side of the first supply-side connection groove on the supply-area side is elevated so that a depth at the end portion of the first supply-side connection groove on the exhaust-area side is shallower than a depth at the end portion of the first supply-side connection groove on the supply-area side;
• (iv) the flow-channel wall located on the end portion of the first supply-side connection groove on the exhaust-area side, has a through hole;
• and
• (v) the flow-channel wall located on the end portion of the first supply-side connection groove on the exhaust-area side, is split.