and thus do not allow water to enter the battery optionally a water resistant composite material or thin layer of silicon 120 may be used to fill the interstitial voids between the glass balls fig5 is a fragmentary top plan view of the flexible battery structure illustrated in fig4 as viewed from the cathode side 108 the marginal peripheral seam having a length l surrounds the periphery of the battery structure 100 referring now to fig6 a schematic cross section of another alternate embodiment of the flexible battery structure embodying the present invention is illustrated therein and is generally designated 200 the battery structure 200 includes a cathode 202 cathode active material layer 204 electrolyte or separating layer 206 anode active material layer 208 and an anode 210 the construction of the battery structure of fig6 is similar to that shown in fig4 with the exception that a caliber 212 made of a water resistant material is inserted between the overlapping end portions 214 of the cathode substrate 202 and the end portion 216 of the anode substrate 210 defining the marginal peripheral seam a water resistant composite material 218 may also be inserted into the marginal peripheral seam along.