Lithium batteries at minus 70 degrees is invented

Chinese scientists have developed a lithium battery capable of operating at minus 70 degrees Celsius, which could one day be used in extremely cold regions on earth and even in outer space.

The new battery, developed by xia yongyao's team at fudan university in China, USES ethyl acetate, which has a low freezing point and conducts electricity at extremely low temperatures, as an electrolyte, and two organic compounds, PTPAn cathode and PNTCDA anode, as electrodes, according to research published in the latest edition of joule, an American journal of energy science.

Electrolyte is a chemical medium in which ions move between two electrodes, but the electrochemical reaction at the junction of electrolyte and electrode is difficult to be sustained at low temperature.

Unlike the electrodes used in conventional lithium-ion batteries, the electrodes use organic compounds that do not rely on an "implantation process," the researchers said, which does not require lithium ions to be embedded into the electrode's molecular matrix, slowing the implantation process at low temperatures.

"The ethyl acetate electrolyte and the organic polymer electrode allow the rechargeable battery to operate at extremely low temperatures of minus 70 degrees Celsius," xia said.

Conventional lithium-ion batteries perform at 50 percent of their optimal level at minus 20 degrees Celsius and 12 percent of their optimal level at minus 40 degrees Celsius. Extremely cold regions such as Russia and Canada have temperatures below -50c. In space, temperatures can drop as low as -157 degrees Celsius.

Mr. Xia said the new batteries are plentiful, cheap and environmentally friendly compared with the electrode materials used in traditional lithium-ion batteries, which he expects to cost about a third as much.

But the researchers acknowledge that the main challenge in getting the batteries into production is that they don't have as much energy per unit mass as commercial lithium-ion batteries, and that the manufacturing process needs to be optimized. Still, xia believes it has significant application potential.

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