A first holder holds a plurality of layers associated with a battery submodule that is being assembled. A first and second pair of actuators, while the plurality of layers is held by the first holder, extend so that the first and second pair of actuators apply pressure to the plurality of layers. While the first and second pair of actuators are extended and applying pressure to the plurality of layers, the first holder retracts. A second holder holds a container associated with the battery submodule that is being assembled and extends so that the container gradually surrounds the plurality of layers. While the container gradually surrounds the plurality of layers, the first and second pair of actuators sequentially retract.