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Please note that certain information may have changed since the date of release.

June 10, 2009

Commercialization of mercury-free alkaline button battery (LR) that reduces environmental impact

English summary of product press release for the Japanese market

package design [Package design]

Sony Corporation (Tokyo, Japan) today announced the realization of a mercury-free alkaline button battery (LR), and plans to commercialize six models of those environmentally conscious batteries.

With conventional alkaline button batteries, mercury was added to the anode material in order to prevent the occurrence of Hydrogen gas. Furthermore, as the cathode material used in these batteries was known to have a low rate of Hydrogen gas absorption, making the creation of a totally mercury-free alkaline button battery a significant technological challenge. The mercury-free alkaline button battery announced today, incorporates proprietary Sony technology that mixes absorbent raw material into the cathode for the first time. By combining this with existing technology that prevents Hydrogen gas occurrence on the anode (which Sony originally adopted in its mercury-free silver oxide (SR) button batteries), Sony has succeeded in eliminating the use of mercury in this new batteries.

Sony's development of environmentally conscious batteries

Sony's sales of alkaline button batteries and sliver oxide button batteries total approximately 300 million *1 per year. The development of a new mercury-free alkaline button battery, in addition to Sony's existing silver oxide button batteries, will result in a reduction of approximately 470kg and approximately 68 bottles (500ml per bottle) of mercury per year*2. In general, when mercury is not disposed properly, it can infiltrate the food chain, and mercury has therefore been identified as a material that has of the potential to cause serious damage to the human body and environment. Sony will continue its advancement of environmentally conscious technologies in order to minimize the impact to the environment.

  • *1)Source: Sony FY08 silver oxide and alkaline button battery sales
  • *2)Based on Sony research

New battery line-up

Model Name Size Voltage (V) Launch Date Price
Alkaline button battery
11.6 x 5.4 1.5V Oct.10th,2009 Open
Alkaline button battery
11.6 x 4.2
Alkaline button battery
7.9 x 3.6
Alkaline button battery
11.6 x 3.05
Alkaline button battery
11.6 x 2.05
Alkaline button battery
"LR44-2ECO" (two batteries)
11.6 x 5.4

The function of mercury in conventional alkaline button batteries

Alkaline button batteries use Zinc for their anode, manganese dioxide as the cathode, and an alkaline electrolyte. Zinc, which is the activator in the anode, corrodes when dissolved in alkaline solution. When this happens, it becomes difficult to maintain the capacity of the unused battery. Zinc also causes electrolysis in the electrolyte, generating Hydrogen gas which causes increased inner pressure and expansion of the cell. For this reason, mercury, which is effective in suppressing Zinc corrosion, was added to the battery.

Sony's development of mercury-free button batteries

The anode material used in conventional alkaline button batteries was known for having a low rate of Hydrogen gas absorption compared to silver oxide button battery cells. In order to prevent Hydrogen gas, which causes battery expansion, Sony has developed a further method in addition to the three original countermeasures* it implemented when developing a mercury-free silver oxide button battery. With this additional method, Sony has now succeeded in adopting a newly developed substance that absorbs Hydrogen gas within the battery into the activator in the cathode.

* Three countermeasures to control Hydrogen gas emissions:

  1. Adoption of high quality Zinc alloy powder with improved resistance to corrosion
  2. Addition of anti-corrosion material into anode materials
  3. Adoption of anti-corrosion technology in the collector materials

-Together with the realization of this mercury-free alkaline button battery, Sony also introduced a new package design for its mercury-free alkaline button batteries and mercury-free silver oxide button batteries, and will launch them as its "mercury-free series".

"Mercury-free series"logo
[Estimated market price]
Alkaline button battery"LR44-ECO"  approx. 200 JPY
Alkaline button battery "LR43-ECO"  approx. 200 JPY
Alkaline button battery "LR41-ECO"  approx. 200 JPY
Alkaline button battery "LR1130-ECO"  approx. 200 JPY
Alkaline button battery "LR1120-ECO"  approx. 200 JPY
Alkaline button battery "LR44-2ECO"  
(two batteries)  approx. 400 JPY

*"Estimated market price" is the price that Sony has estimated for the products above.  The actual price will be determined by each retail outlet.

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