Powerful, long-lasting rechargeable batteries may be key to a future green society — especially if they can become widely used to power electric vehicles.

Many Japanese companies are racing to develop high-quality battery cells for digital devices and vehicles, striving in the process to lower the costs.

What kinds of rechargeable batteries are available and what changes may they bring about? Following are questions and answers regarding such cells:

What kinds of rechargeable batteries are in use and how do they differ from conventional cells?

The past two decades have seen a constant evolution of rechargeable batteries that can power devices for ever-longer periods with just one charge, resulting in wireless gadgets becoming more compact and lighter.

Whereas conventional disposable batteries may be cheaper, they are limited to one use, unlike their more expensive rechargeable counterparts.

Rechargeable lithium-ion batteries in particular have been improved over the past decade and are now the main cell in use. Their volumetric energy density has more than doubled in little more than 10 years since their market debut, according to the Battery Association of Japan.

Other major rechargeable batteries include the nickel-cadmium (NiCad) and nickel-metal hydride types.

Lithium-ion batteries accounted for 69 percent of overall rechargeable cells and 51 percent of all batteries in terms of sales, according to 2009 data from the Ministry of Economy, Trade and Industry.

Because lithium-ion batteries have the potential for further improvement, their manufacturers are in heated competition.

What companies are key play

ers in the battery market?

Sanyo Electric Co., a subsidiary of Panasonic, boasts the world’s largest share of rechargeable batteries, saying it holds 25 percent of the lithium-ion market, 35 percent of the nickel-metal and 35 percent of the NiCad sector.

Other companies, seeing future growth in the electric vehicle market, have been forming alliances with automakers to develop and supply batteries.

In 1996, Panasonic set up a joint venture with Toyota Motor Corp. that makes lithium-ion and nickel-metal hydride batteries for hybrid cars, including the Prius, and plug-in models.

NEC Corp. and Nissan Motor Co. formed a joint venture in 2007 to supply lithium-ion batteries for electric vehicles made by Nissan and its French partner, Renault SA.

In the same year, GS Yuasa Corp. launched a joint venture with Mitsubishi Motors Corp. to make lithium-ion batteries for electric vehicles and another venture in 2009 with Honda Motor Co. to make cells for hybrids.

South Korean firms Samsung and LG Chem Inc. have meanwhile actively invested in recent years in new production plants to supply lithium-ion batteries for U.S. and German automakers.

Amid the fierce competition, the global share of lithium-ion cells produced by Japanese makers slid to 48 percent in fiscal 2008 from 64 percent in fiscal 2003, while the share of batteries produced by South Korean firms grew to 14 percent in 2008 from 10 percent in 2003, according to Sanyo.

How do the rechargeable cells differ and what can they be used to power?

NiCad batteries were created more than 100 years ago by Waldemar Jungner of Sweden. They use nickel oxide hydroxide as anodes and metallic cadmium as electrodes. With their relatively lower internal resistance, they are used in cordless and wireless telephones, electric tools, shavers and emergency lighting, according to the battery association.

Then nickel-metal hydride batteries came along. They are similar to nickel-cadmium cells but more powerful.

Panasonic Corporation Energy Co. and Sanyo began mass-producing them in 1990.

Because nickel-metal hydride batteries use a hydrogen-absorbing alloy for the negative electrode instead of cadmium, they can have larger capacity than an equivalent size nickel-cadmium battery.

They became widely used in cell phones, laptops, camcorders and digital cameras in the 1990s and are still used in small electric devices, including digital cameras

Lithium-ion cells, first mass-produced by Sony Corp. in 1991, are more powerful and lighter than other renewable batteries. Their higher energy density and lower rate of losing their charge make them the cells of choice. They are now commonly found in laptops, cell phones and digital cameras, according to the battery association.

Nickel-metal hydride batteries have been in wide use in electric vehicles, but automakers are shifting to lithium-ion cells. For many years, rechargeable batteries for electric vehicles have been heavy and expensive. But recent vast improvements in lithium-ion cells are making electric vehicles more of a viable option.

Do lithium-ion batteries still have hurdles to overcome?

Lithium-ion cells can overheat and in some cases even ignite. The problem grabbed attention in 2006 when Sony recalled 9.6 million lithium-ion batteries used in laptop computers because of the fire danger.

Lithium-ion batteries have been improved since then and are now used in larger products, including electric vehicles and bicycles. But industry sources say the cells may still have the potential to ignite.

Lithium-ion batteries also are expensive, require rare metals and lose their charge over time.

What does the future hold?

In June 2008, Toyota announced it will develop “next-generation batteries” by 2030 that can outperform lithium-ion cells, which have been widely touted as the expected power source for the green cars of the future.

Although Toyota didn’t elaborate on the types of batteries it plans to develop, the automaker, a pioneer in gasoline-electric hybrids, said it set up a new battery department July 1 with an initial staff of 50 that will be increased to 100 this year and include domestic and overseas experts, and university academics.

How will future competition shape up?

Industry sources expect the lithium-ion battery market to grow rapidly as demand for electric vehicles surges and manufacturers that can stay ahead in terms of technology will be in the best position.

Japanese manufacturers so far lead the lithium-ion cell market, and it will take time for overseas rivals to catch up.

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