[thedoc (OP)]

German scientists have designed a high-efficiency, low-cost lithium-sulphur battery...

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[evan_au]

But does this new design suffer the thermal runaway that has dogged early Lithium-ion batteries? They sometimes caught fire inside laptops, cellphones and aeroplanes.

When temperatures got high (eg during rapid charging), the electrode decomposed, releasing the stored chemical energy as heat, causing the temperature to rise further....

[Laurie]

evan_au Yep, you're right, that has been a problem with Li-ion batteries for a while.

When lithium-ion batteries are recharged, ions move through the electrolyte that separates the battery’s two electrodes. This charge flow also draws material from the electrolyte and results in the formation of lithium dendrites on the positive electrode (anode) of the battery. These dendrites can grow so large that they span the distance between the electrodes; the moment the dendrite reaches the cathode, the battery fails.

In this new Li-Sulphur battery, the anode (that would normally be lithium) has been replaced with a silicon-carbon compound which is much more stable at these higher temperatures. The cathode (which is cobalt in a Li-ion battery) is made with sulphur, surrounded by porous carbon - the sulphur will eventually leak into the electrolyte at high temperatures, but it'll do so much more slowly, and more predictably, than the cobalt in Li-ion batteries.

Hope that helps