Battery cell holder of improved connecting reliability and battery module employed with the same

A battery cell holder configured so that a single cylindrical battery cell is mounted therein, the battery cell holder comprising:

• an upper cover comprising a first main body to cover an upper part of the battery cell in a state in which a first electrode terminal of the battery cell is exposed and at least one first extension fastening part extending downward from the first main body;
• and
• a lower cover comprising a second main body to cover a lower part of the battery cell in a state in which a second electrode terminal of the battery cell having a polarity opposite to that of the first electrode terminal is exposed and at least one second extension fastening part extending upward from the second main body, wherein
• an end of the at least one first extension fastening part and an end of the at least one second extension fastening part are fastened to each other in a state in which the battery cell is mounted in the battery cell holder,
• the upper cover and/or the lower cover is provided at an outer side thereof with at least one side fastening part and a coolant flow channel is formed at a space defined between side fastening parts, by which a side of the battery cell holder is fastened to that of another battery cell holder,
• the at least one side fastening part is configured to have a sliding fastening type groove structure formed in a longitudinal direction of the battery cell holder, and
• the sliding fastening type groove structure comprises a hook and a depressed groove corresponding to the hook in a sectional shape perpendicular to the longitudinal direction.