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Maxell Introduces a Zero-Mercury, Zero-Lead Added Silver-Oxide Cell; Reducing Environmental Impact While Maintaining Current Product-life Levels |
Hitachi Maxell, Ltd. is pleased to announce the introduction of an environmentally advanced silver-oxide cell that successfully reduces the mercury and lead in the cathode material to zero, while maintaining a product-life comparable to conventional silver-oxide cell products. The new cell will be available from mid-2005, and Maxell plans to replace all of its silver-oxide cells with the new zero-mercury, zero-lead added type by mid-year 2007.
Following European battery regulations*, sales of batteries with 5 ppm or more of mercury is prohibited. However, button-type cells such as silver-oxide cells have received special exemption from the regulations since it has been technically difficult to maintain long product life without mercury and lead as an anti-corrosive. Given the global effort to reduce the environmental impact- of such products, Maxell has been committed to developing silver-oxide cells not using these types of anti-corrosives.
Silver-oxide cells are the primary long-life cells used in wristwatches, and use silver-oxide for the cathodeelectrode, zinc for the anode electrode and an alkaline solution for the electrolyte. In conventional silver-oxide cells, small amounts of mercury and lead are used as an anti-corrosive. An anti-corrosive improves long-term reliability, while reducing the gas generation that follows the corrosion of the zinc in theanodeand as a result of the local cell between the zinc and the surface area of the collector which contacts the zinc.. Maxell has been able to achieve zero-mercury, zero-lead using an original new cathode anti-corrosion technology, along with a corrosion-resistant zinc alloy.
Maxell introduced the first silver-oxide cells for use in quartz wristwatches in Japan in 1976. Since, Maxell has been providing high-capacity, high-reliability silver-oxide cells while responding to increasing demand from the major watch manufacturers for smaller, thinner watches. With the major application of these cells being precision wristwatches, the need for very high reliability has always taken precedence over environmental concerns such as reducing the use of mercury and lead, but with the new development, both requirements have been met. Reliability of the new cells over periods exceeding ten years has been verified.
Maxell also draws on an ongoing commitment to developing and commercializing environmentally friendly products. Last year, Maxell introduced "New Dynamic" alkaline batteries- the first in the industry with a four-year expiry month and year of recommended use, double that of earlier products. It helps to reduce the environmental impact caused by disposing of batteries which had exceeded an expiry month and year of recommended use. Looking forward, Maxell will continue to pursue its corporate ethos of "High-quality, environmentally conscious business", and focus ever more on developing technologies designed to reduce the environmental impact of its own products, and products used daily by consumers around the world.
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Required by European Battery directive. According to the "Restriction of the use of certain of Hazardous Substances in Electrical and Electronic Equipment (RoHS) Directive" European environmental regulation, from July 1, 2006, the sale in the European Union of products containing mercury, lead, cadmium, hexavalent chromium, or brominated fire retardants will be prohibited. However, due to the technical difficulty of creating button-type batteries such as silver-oxide cells without mercury, such products have been exempted in accordance with the European Battery directive. |
・Major Characteristics
| 1. |
Original cathode collector anti-corrosion technology realizes high leak resistance |
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To handle storage and usage over long periods of time, Maxell succeeded in giving the cathode collector resistance to corrosion by adding a special additive to the material used in the batteryanode. With this new technology, it became possible to lengthen the life of silver oxide cells without reducing their resistance to leakage (13 patents pending). |
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| 2. |
Use of a corrosion-resistant zinc alloy suppresses corrosion reaction speed by 50% |
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By using a corrosion-resistant alloy in the anode, the corrosion reaction speed has been reduced to less than 50% of that for the current zinc with mercury cathode, even while stored in an alkaline solution. |
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| 3. |
Prevention of gas generation achieved through optimization of cathode collector. |
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By optimizing the state of the surface of the anode collector, a reduction in gas generation has been achieved. |
・Silver-oxide cell structure comparison
New silver-oxide cell
(zero-mercury, zero lead)
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Silver-oxide cell
(conventional) |
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