Panasonic's new battery, EVOLTA
Panasonic's new battery, EVOLTA
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Matsushita Electric Industrial Co Ltd will start shipping its new long-lasting alkaline battery cell, EVOLTA, April 26, 2008.

The new battery cell has a discharge performance almost 1.3-2 times higher than that of the company's existing alkaline battery cell. When compared, based on the discharge modes set by JIS and ANSI, it is the longest-lasting AA battery cell in the world, the company said.

In a comparative test conducted by the company using two AA cells, EVOLTA could flash a strobe light 277 times, while the existing alkaline and oxyride battery cells could set off 203 and 255 flashes, respectively. The recommended use period for all models of EVOLTA was prolonged from 5 to 10 years because the battery life was extended.

To develop EVOLTA, the company made some improvements to the structure, materials and manufacturing method of the existing alkaline battery cell. As for structural improvements, the company increased the volume by thinning down the gasket in the sealing portion and eliminating the washer.

The thickness of the battery body is also reduced by 17% to increase the capacity of active materials, while the thickness of the sealing portion was increased for higher strength.

As for the new material of the positive electrode, the company added titanium oxyhydroxide (TiO(OH)2) to the normal materials, graphite and manganese dioxide (MnO2). The reaction is enhanced to the inner side of the MnO2 particle by the effect of TiO(OH)2, thereby increasing the amount of discharge.

In order to enhance the reaction of zinc on the negative electrode, the amount of fine particle was increased to enlarge its total surface area. Although the details are yet to be announced, the company employed a new inhibitor (corrosion inhibitor for zinc) that can prevent zinc from being contaminated by impurities without disturbing the reaction.

To improve the manufacturing method, the company reduced the variation in the density of the positive electrode pellet by making uniform the density of the "pelletization mixture" used to form the pellet. And, at the time of forming the negative electrode, the density of the electrode material is increased and made uniform by degassing under a reduced pressure.

Also, the company increased the amount of electrolyte in the battery cell by the absorption utilizing the difference in pressure.

There is no manufacturer's suggested retail price, but the expected market price for both a pack of four AA cells and a pack of four AAA cells will be about ¥590 (US$5.57). A pack of two D cells and a pack of two C cells are expected to be about ¥570 and ¥420, respectively. The prices will be approximately 15% higher compared with the existing alkaline battery cells, the company said.

The company thus far sold a total of about 700 million long-lasting oxyride battery cells throughout the world since its release in 2004. When it is used in a low power device, however, the oxyride battery cell lasts less time than existing alkaline battery cells in some cases. EVOLTA features a better performance than that of the oxyride or existing alkaline battery cell in a wider power range.

The company plans to promote the sales of EVOLTA as its flagship. For the time being, it will continue manufacturing the oxyride battery cells because some electric appliances are powered by this type of battery.

However, it is likely that the company will focus on the sales of affordable alkaline battery cells and expensive but high-performance EVOLTA, because the prices of EVOLTA and the oxyride battery cells only differ by about 3-5%.