The French high-technology battery specialist, Saft has introduced what it believes is the first rechargeable Li-ion (lithium-ion) cell capable of operating at temperatures of up to +125°C. The company has also released a new D-size primary lithium cell that will operate at temperatures of up to 150°C.
The new VL 25500-125 C-size and VL32600-125 D-size rechargeable cells have been developed primarily for use in the construction of battery 'staves' that power the electronics within sophisticated 'Measurement-While-Drilling' (MWD) tools. These devices are used by the oil exploration industry to provide a variety of sensor information from the drill bit to the surface operators.
MWD tools incorporate onboard alternator technology, driven by the flow of drilling mud. When the mud is flowing the battery will be charged. When the flow stops, such as when drilling is halted, the battery discharges as it supplies power for the MWD electronics. When the flow restarts the battery will recharge itself. The fast-charging, deep-discharge and high cycling capability of the Li-ion electrochemistry will effectively enable the MWD tool to remain in continuous downhole operation.
This application is possibly the most arduous that any battery has to contend with. In addition to high temperatures, the down-hole conditions include very high levels of vibration and shock that severely test the construction and integrity of cell and battery designs.
Saft believes that there are many other applications that might benefit from this development, including battery-powered medical devices that require autoclaving.