Battery Module, Battery Pack, Device Using Battery Module as Power Source, and Method of Manufacturing Battery Module

A battery module, a battery pack, a device using a battery module as a power source, and a method of manufacturing a battery module are provided. The battery module includes: at least two battery cells; a connecting piece configured to electrically connect two battery cells of at least two battery cells; and a protective layer including a first protective portion configured to cover the connecting piece. A melting point of the first protective portion is greater than that of the connecting piece.