A battery module having first and second battery cells, a u-shaped frame member, a thermally conductive layer, a top cover plate, and first and second side cover plates is provided. The u-shaped frame member has a bottom wall and first and second side walls coupled to the bottom wall that extend upwardly from the bottom wall. The u-shaped frame member defines an interior space that holds the first and second battery cells therein. The first and second battery cells are disposed directly on the thermally conductive layer. The top cover plate is coupled to the first and second side walls to enclose a top open region of the u-shaped frame member. The first side cover plate that is coupled to the top cover plate and the bottom wall to enclose a first side open region of the u-shaped frame member.