A foldable flexible assembling of cells for a lithium-ion battery including: a separator containing an electrolyte; a series of n physically separated negative electrodes located on the first side of the separator and a series of n physically separated positive electrodes located on the second side of the separator; a first current collector including a layer covering continuously the series of negative electrodes so as to ensure electrical connection between all the negative electrodes; and a second current collector including a layer covering continuously the series of positive electrodes so as to ensure electrical connection between all the positive electrodes.