A rechargeable battery is disclosed having electrode and separator structures which are made up of fibre-reinforced composite material, thereby allowing the battery itself to serve as an integral structural component. The utilisation or efficiency of the rechargeable battery is considerably enhanced by rendering at least part of the matrix material of the electrodes and the separator porous, thereby to facilitate improved access to active sites on the electrodes, with the porosity in the separator allowing improved ion transport, both of which enhance cell operation. The porous structure also provides improved electrolyte containment and retention in the event of damage.