US - Variation of a sodium-metal halide battery

A research team led by the Department of Energy's Pacific Northwest National Laboratory (PNNL) demonstrated what should be a new design for a grid energy storage battery built with low-cost metals sodium and aluminum. 

According to the Department, design should provide a pathway towards a "safer and more scalable" stationary energy storage system that could help integrate renewable energy into the nation's grid. If it proves able to move from the lab to commercial deployment, the technology could enable low-cost, daily shifting of solar energy into the electrical grid over a 10- to 24-hour period.

Researchers said the novel molten salt battery design has the potential to charge and discharge faster than other conventional high-temperature sodium batteries, operate at a lower temperature and maintain an "excellent" energy storage capacity. 

The energy that a battery can deliver in the discharge process is called its "specific energy density," which is expressed as watt hour per kilogram (Wh/kg). The researchers speculated that it could result in a practical energy density of up to 100 Wh/kg. 

Source: Renewable Energy Source