A core-shell composition for gas storage, comprising a hollow or porous core and a shell comprising a nanocomposite. The nanocomposite is composed of an exfoliated layered filler dispersed in a matrix material, which provides high mechanical strength to hold a high pressure gas such as hydrogen and high resistance to gas permeation. Alternatively, the porous core may contain a plurality of cavities selected from the group consisting of shell-hollow core micro-spheres, shell-porous core micro-spheres, and combinations thereof. These core-shell compositions, each capable of containing a great amount of hydrogen gas, can be used to store and feed hydrogen to fuel cells that supply electricity to apparatus such as portable electronic devices, automobiles, and unmanned aerial vehicles where mass is a major concern. A related method of storing and releasing hydrogen gas in or out of a plurality of core-shell compositions is also disclosed.