This invention relates to an improvement in battery packs. The invention intends to provide a highly flexible battery pack and an electronic device assembly using the same. The battery pack of the invention includes an elastic sheet and at least one coin battery embedded in the elastic sheet. In a preferable embodiment of the invention, the electronic device assembly includes a laminate of the battery pack and a flexible electronic device. The electronic device is driven by power supplied through positive and negative terminals of the battery pack. In another preferable embodiment of the invention, the electronic device assembly includes the battery pack and a device embedded in the elastic sheet of the battery pack, and the device is driven by power supplied by the at least one coin battery.
