Rechargeable batteries based on magnesium, rather than lithium, have the potential to extend electric vehicle range by packing more energy into smaller batteries. But unforeseen chemical roadblocks have slowed scientific progress.

And the places where solid meets liquid – where the oppositely charged battery electrodes interact with the surrounding chemical mixture known as the electrolyte – are the known problem spots.

Now, a research team at the U.S. Department of Energy’s Joint Center for Energy Storage Research, led by scientists at Lawrence Berkeley National Laboratory (Berkeley Lab), has discovered a surprising set of chemical reactions involving magnesium that degrade battery performance even before the battery can be charged up.

The findings could be relevant to other battery materials, and could steer the design of next-generation batteries toward workarounds that avoid these newly identified pitfalls.

The team used X-ray experiments, theoretical modeling, and supercomputer simulations to develop a full understanding of the chemical breakdown of a liquid electrolyte occurring within tens of nanometers of an electrode surface that degrades battery performance. Their findings are published online in the journal Chemistry of Materials.

The battery they were testing featured magnesium metal as its negative electrode (the anode) in contact with an electrolyte composed of a liquid (a type of solvent known as diglyme) and a dissolved salt, Mg(TFSI)2.

While the combination of materials they used were believed to be compatible and nonreactive in the battery’s resting state, experiments at Berkeley Lab’s Advanced Light Source (ALS), an X-ray source called a synchrotron, uncovered that this is not the case and led the study in new directions.

“People had thought the problems with these materials occurred during the battery’s charging, but instead the experiments indicated that there was already some activity,” said David Prendergast, who directs the Theory of Nanostructured Materials Facility at the Molecular Foundry and served as one of the study’s leaders.

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“At that point it got very interesting,” he said. “What could possibly cause these reactions between substances that are supposed to be stable under these conditions?”

Molecular Foundry researchers developed detailed simulations of the point where the electrode and electrolyte meet, known as the interface, indicating that no spontaneous chemical reactions should occur under ideal conditions, either. The simulations, though, did not account for all of the chemical details.

“Prior to our investigations,” said Ethan Crumlin, an ALS scientist who coordinated the X-ray experiments and co-led the study with Prendergast, “there were suspicions about the behavior of these materials and possible connections to poor battery performance, but they hadn’t been confirmed in a working battery.”

Commercially popular lithium-ion batteries, which power many portable electronic devices (such as mobile phones, laptops, and power tools) and a growing fleet of electric vehicles, shuttle lithium ions – lithium atoms that become charged by shedding an electron – back and forth between the two battery electrodes. These electrode materials are porous at the atomic scale and are alternatively loaded up or emptied of lithium ions as the battery is charged or discharged.

In this type of battery, the negative electrode is typically composed of carbon, which has a more limited capacity for storing these lithium ions than other materials would.

So increasing the density of stored lithium by using another material would make for lighter, smaller, more powerful batteries. Using lithium metal in the electrode, for example, can pack in more lithium ions in the same space, though it is a highly reactive substance that burns when exposed to air, and requires further research on how to best package and protect it for long-term stability.

Apple's Chief Operating Officer Jeff Williams is set to meet Terry Gou, the chairman of key iPhone assembler Hon Hai Precision Industry, also known as Foxconn, to discuss production problems with the iPhone X according to Nikkei.

It has been widely reported the Apple is struggling to produce its new iPhone X handset, with reports of several production issues with the 3D camera the handset uses to recognises faces.

However, the latest reports say that the firm should have '2-3 million' handsets at launch, and that the production bottlenecks will be cleared by November.

In a new analyst note from KGI today, Ming-Chi Kuo said although multiple components are holding up production the ‘biggest hurdle’ for iPhone X shipments is actually the flexible printed circuit board for the antenna system.

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He expects 2-3 million iPhone X units to be available at launch.

'On the bright side, Kuo believes that 3D sensor and circuit board production will quickly ramp up in November, allowing Apple to boost supply for eager consumers,' said 9to5Mac.

The firm's suppliers are still struggling to perfect manufacturing of the iPhone X's TrueDepth camera and 3D facial recognition system, according to Japan's Nikkei Asian Review.

Jeff Pu, an analyst with Taipei-based Yuanta Investment Consulting, believes the problems could mean Apple will face even bigger shortages of its flagship handset than previously thought.

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