Sodium-ion battery

Sodium-ion batteries (SIB) are a type of rechargeable metal-ion battery that uses sodium ions as charge carriers.

Battery-grade salts of sodium are cheap and abundant, much more so than those of lithium. This makes them a cost-effective alternative especially for applications where weight and energy density are of minor importance such as grid energy storage for renewable energy sources such as wind- and solar power

These cells can be completely drained (to zero charge) without damaging the active materials. They can be stored and shipped safely. Lithium-ion batteries must retain about 30% of charge during storage, enough that they could short-circuit and catch fire during shipment.

Moreover, Sodium-ion batteries have excellent electrochemical features in terms of charge-discharge, reversibility, coulombic efficiency and high specific discharge capacity.

In 2014 Aquion Energy offered a commercially available sodium-ion battery with cost/kWh capacity similar to a lead acid battery for use as a backup power source for electricity micro-grids. According to the company, it was 85 percent efficient.

In 2015 researchers announced a device that employed the "18650" format used in laptops, LED flashlights and the Tesla Model S, among other products. Its energy density was claimed to be comparable to lithium iron phosphate battery.

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