Made By Monkeys

A frustrated design engineer whose company uses a proprietary lithium-ion battery made in China complained recently here in the Made by Monkeys blog about significant problems with those batteries swelling up.

Bloated batteries sound like fodder for yet another “Made in China” recall story – and it’s not inconceivable that some manufacturing defect could turn out to be the culprit in this case.

But when it comes to lithium ion batteries, it turns out that how you charge one can mean the difference between a well-functioning device and one that bears a resemblance to a certain top criminal underlord in the galaxy.

Prized by design engineers for its enviable strength-to-weight ratio and high modulus, titanium has made its way in recent years into all sorts of high-tech products from turbine engines to bicycle frames.

Now, a new toothbrush with a titanium dioxide core in its handle has hit the market in Europe and the US. Developed by the Osaka-based Shiken Corp., the Soladey toothbrush leverages the electrochemical behavior of titanium dioxide to reportedly reduce bacteria in your mouth. Studies have shown that exposure to UV light induces antibacterial activity in titanium dioxide (TiO2).

The recent brouhaha in this blog over the underwhelming performance of lithium ion batteries and the care that must be taking when charging them reminded me of a case in Design News that involved an explosion of near-Hindenburg-like proportions

Oh I know what you're thinking -- it's those incredibly thermodynamically unstable lithium ion batteries up to their old tricks again. Wrong!! This culprint in this case was a lead acid battery for a lift truck.

Let's just say the sucker really got shredded, as noted by Myron Boyajian, the forensic engineer who was called in to investigate the case on behalf of the singed plaintiff:

"If a lead-acid battery could discharge and charge with perfect electrochemical efficiency, there would be no emission of hydrogen or oxygen gas, just the quiet conversion of the plate material, one of lead and the other of lead oxide, both to lead sulfate while the sulfuric acid electrolyte changed to water while discharging; and the reversal of this process during charging.
One hundred percent efficiency, like perfection, is only to be hoped for. Excess or rapid charging/discharging, plate age and condition, excessive temperature, and other reasons may cause hydrogen and oxygen gas to be emitted from a lead-acid battery."

And kapow!

The announcement last month that 46 million Nokia-branded lithium-ion (Li-ion) batteries made by Matsushita Battery Industrial could potentially short circuit and overheat was just the latest in a spate of product advisories and recalls of the technology over the past two years.

But it’s not as if Li-ion batteries are at the early point in their life cycle when you would expect these sorts of problems to crop up. Sony invented the technology back in 1990. So why is it failing now?

The theories behind the technology’s recent spotty performance are complex and varied, which makes fixing the problem a perplexing engineering challenge.