In an embodiment, the gas storage device includes a cylinder with opposing ends. An endcap is present at each end. The cylinder and the endcaps form an enclosure. Each endcap includes a connector. A diaphragm is located in the enclosure. The diaphragm includes an annular sidewall. The device includes an inner chamber defined by an inner surface of the sidewall, and a storage space between an interior surface of the cylinder and an outer surface of the sidewall. A metal hydride composition is located in the storage space.