Sodium-ion batteries could light path to new power cells (Nikkei Asian Review)
SHIGEYUKI YAMAGUCHI, Nikkei staff writer
TOKYO -- Research is continuing apace on sodium-ion batteries, cells that could deliver more juice to gadgets much more cheaply than current power cells.
A group led by Shinichi Komaba, a professor at Tokyo University of Science, has developed technology that increases the charge capacity of the cell by five to seven times per unit of weight, compared with conventional batteries. Although the results are preliminary, the new battery's quick-charge characteristics are comparable to the lithium-ion batteries used to power most portable devices today. The research group is working to further enhance the cell's performance, and it hopes to bring the technology to market in five to 10 years.
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Batteries work by moving ions between two electrodes, one positive and one negative. With sodium-ion batteries, sodium ions inside the cell move from the negative electrode to the positive electrode through an electrolyte; electrons follow this ion path, which generates the electric current to power whatever is hooked up to the battery. When the battery is charging, ions and the corresponding electrons flow in the opposite direction, returning to the negative electrode.
Research into sodium-ion batteries has been going on since the 1980s, but as capacity increased, battery life dwindled. From the middle of the last decade, however, this started to change, as the electrolytes and the materials comprising the electrodes were tweaked. Little by little, better materials for charging and discharging have been discovered and other problems overcome.
The basic makeup of sodium-ion batteries is the same as that of their lithium-ion counterparts. The main drawback of lithium is its rarity. It is most commonly found in South America, but only in small deposits. Sodium, on the other hand, can be readily collected from seawater and other sources, which would make sodium-ion batteries far less expensive if they can be perfected.
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