SII to Roll Out Heat-resistant Rechargeable Coin Cell

Mar 14, 2014
Hideyoshi Kume, Nikkei Electronics
The "MS920T" lithium-ion (Li-ion) rechargeable coin cell has the maximum operating temperature of 85 degrees C.
The "MS920T" lithium-ion (Li-ion) rechargeable coin cell has the maximum operating temperature of 85 degrees C.
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Seiko Instruments Inc (SII) developed a lithium-ion (Li-ion) rechargeable coin cell that can be used in high-temperature environments.

The maximum operating temperature of SII's previous product is 60°C. This time, the company increased it to 85°C. It plans to start volume production in June 2014.

In a high-temperature environment, the degradation of a Li-ion rechargeable cell accelerates due to heat. When the capacity of the previous product was measured after it was stored at a temperature of 85°C for 60 days, it was 40% of its initial capacity. On the other hand, the capacity of the new rechargeable cell lowered only to 90% or more of its initial capacity, SII said.

Coin cells are widely used for power supply backup of real-time clock in electronic devices such as digital cameras and drive recorders. In recent years, the image qualities of those electronic devices are improving, and they are coming with more and more advanced functions, raising their internal temperatures. Also, they are increasingly being used in high-temperature environments such as car cabins and under direct sunlight.

Therefore, there is now a strong demand for coin cells that can operate in high temperatures, SII said. This time, the company expanded operating temperature range to 85°C by making improvements to sealing technologies and design. It is now shipping samples.

"The demand for the new cell is high, especially in the auto industry," SII said.

The nominal voltage and capacity of the new cell, "MS920T," are 3V and 6.4mAh, respectively. Its internal impedance is 60Ω. It is 9.5mm in diameter and 2.0mm in height. Its mass is 0.45g. Its operating temperature range is -20 to +85°C. SII aims to sell five million units in fiscal 2014.