Battery module, battery pack comprising the same, and vehicle

A battery module with enhanced stability against fire and explosion. The battery module includes a cell assembly having a plurality of secondary batteries, a lower case having an open top and having an accommodation space, an upper case coupled to the lower case to cover the open top of the lower case and having a connection hole perforated to communicate with the accommodation space; an upper cover coupled to the upper case to cover an upper portion of the upper case and configured to form a buffer space spaced apart from the upper case, the upper cover having a discharge hole perforated so that the buffer space communicates with the outside; and at least one partition member extending in a horizontal direction inside the buffer space to form a moving passage extending from the connection hole to the discharge hole and configured to have an adjustable extension length.