A battery pack includes a plurality of cylinder-type battery cells, each cylinder-type battery cell including a first end and a second end having different polarities. The battery pack also includes a conductive plate having a bendable portion located between a first half portion and a second half portion. The first half portion is fixedly connected to the first end of at least a first cylinder-type battery cell and the second half portion is fixedly connected to the second end of at least a second battery cell so that the conductive plate connects at least two cylinder-type battery cells in series. A width of the bendable portion is narrower than a width of the rest of the conductive plate and the conductive plate is in a bent configuration bent about the bendable portion such that the first half portion and the second half portion are aligned.