Lithium-ion batteries provide juice for cellphones, laptops and other rechargeable devices. Most function fine, but lithium-ion batteries can occasionally fail spectacularly, causing explosions and fire. Most recently, Samsung announced a recall of its Galaxy Note 7 phone because the phone’s batteries were overheating and exploding. One factor that contributes to this problem is the formation of deposits called dendrites, which grow from the lithium electrode. If these dendrites get large enough, they can contact the battery’s second electrode and short-circuit the battery.
What looks like the liquid android from 1991’s Terminator 2: Judgment Day stuck in the spin cycle is actually the insides of a lithium-ion battery. But this new imagery is more than just a creepy picture. It might be a way to monitor rechargeable batteries in real time, preventing loss of performance and runaway explosions.
To understand the growth process inside batteries, a team of scientists at New York University, led by Alexej Jerschow, developed a magnetic resonance imaging (MRI) technique to see inside the batteries as they are charging. The MRI actually images the electrolytes between the lithium electrodes (these electrolytes allow charge to move through the battery). Electrolytes become distorted around dendrites, the researchers found, and by imaging the distortions, the scientists could track the growth of dendrites in 3D. They reported their findings in September in the journal Proceedings of the National Academy of Sciences.
By devising a method that provides a detailed view inside a lithium-ion battery while it is running, researchers have come up with a way to gather reconnaissance information about processes that could trigger disastrous battery failure. Under some charging conditions, lithium can accumulate on a battery’s anode, leading to uncontrolled growth of needlelike metal dendrites that can cause hazardous short circuiting. Lithium metal, an ideal anode material based on its exceptional charge-storage capacity, carries a high dendrite risk. So manufacturers use lower-capacity carbon anodes, which are safer but not fully dendrite-proof.
Researchers at Argonne National Laboratory in Illinois used nuclear magnetic resonance (NMR) spectroscopy in 2001 to first study the movement of lithium ions within a battery from the outside, but this work does not offer the level of detail provided by the new technique.
MRI also proved more accurate than NMR. Scanning electron microscopy, another tool that has been used to study batteries, requires cutting a battery open, which exposes the battery to air, altering the surfaces. MRI is non-destructive, so you can take a functioning battery and take an image of it, much like one can take an MRI of the human body.
Did you know?
• It is physically impossible for you to lick your elbow.
• The microwave was invented after a researcher walked by a radar tube and a chocolate bar melted in his pocket.
• The leg bones of a bat are so thin that no bat can walk.
• Rats multiply so quickly that in 18 months, two rats could have over a million descendants.
For more trivia see: www.um.edu.mt/think
Sound bites
• Pluto’s ‘heart’ of water: Ever since NASA’s New Horizons spacecraft flew by Pluto last year, evidence has been mounting that the dwarf planet may have a liquid ocean beneath its icy shell. Now, by modelling the impact dynamics that created a massive crater on Pluto’s surface, a team of researchers has made a new estimate of how thick that liquid layer might be. The study, led by Brown University geologist Brandon Johnson and published in Geophysical Research Letters, finds a high likelihood that there’s more than 100 kilometres of liquid water beneath Pluto’s surface. The research also offers a clue about the composition of that ocean, suggesting that it likely has a salt content similar to that of the Dead Sea.
https://www.sciencedaily.com/releases/2016/09/160924222428.htm
• A smoker’s curse: Smoking can cause damage to your DNA, even years after you quit. Many of the negative effects associated with smoking cigarettes can disappear over time after a person quits. But a new study out last week says the habit causes damage to your DNA that can last for decades. The study found compelling evidence that smoking has a long-lasting impact on our molecular machinery, an impact that can last more than 30 years. To come to this conclusion, researchers from medical institutions across the US analysed blood samples taken from nearly 16,000 people during prior studies. They found that people who smoked had a pattern of methylation changes that affected more than 7,000 genes.
www.newsy.com/videos/smoking-can-cause-damage-to-your-dna-even-after-you-quit/