Antimatter can be made, at great expense. Producing antimatter uses vast amounts of energy, far more than it can release in matter-antimatter annihilation reactions, so antimatter is not an efficient means of energy storage. It might be economical for uses which demand incredibly high energies per unit mass, such as space propulsion.

This section is about the scientific aspects of batteries and storage cells.

Capacitors use electric fields (rather than chemical changes, motion, or potential energy) to store energy, and charge and discharge faster than batteries. Ratings are usually in Farads (Coulombs per Volt).

Compressed Air Energy Storage (CAES) puts large quantities of air into an underground cavern or mine during off-peak (low electric demand) periods. At a time of day when demand is greater, this air is expanded through a turbine to generate electricity. To improve efficiency, the air may be heated with natural gas. CAES has been called "the only proven technology to store electric energy on an industrial scale of hundreds of MW’s" (http://www.espcinc.com/CAES_AI.htm)

Flywheels store and release kinetic energy (mass in motion) in this context, they apply to devices which may be used to store electrical energy by attaching a motor-generator to a high-speed rotating weight.

This category is for sites about energy storage systems that use liquid nitrogen. When liquid nitrogen heats up it evaporates and expands, creating pressure if confined. Such pressure can be used to run engines and drive vehicles. It results in fair efficiencies, with low emissions overall.

The pumping of water from a lower to higher elevation to store energy (potential). Discharge works much like a hydroelectric dam.

Science or technology related to superconductors or magnets useful for energy storage. Superconductors go from little, to practically zero, resistance, at some low (critical) temperature. It is then possible to put large amounts of electricity (current) through a relatively small wire, with few losses (heat). With magnetic material near the wire, this energy is stored as an electromagnetic field. Most Superconducting Magnetic Energy Storage (SMES) systems can provide large amounts of power for a relatively short time

Thermal Storage generally uses the phase change of a substance (example: ice instead of water) to save energy. Classically, a chiller might make ice at night, for use as air conditioning during the day. Less well known is the use of Epsom Salt decahydrate to store heat at room-temperature. If you know of a site to describe this, please submit.