Ask HN: What is the most important publicly unknown fact in your industry?
I work with (among other things) batteries. As I&#x27;ve gotten a bunch of emails about it, I suppose I am &quot;the battery guy&quot; here.<p>Li-ion battery energy density grows in spurts. Realistically, there have been a few major improvements, with very small incremental improvements in between. For example, in 2001 we were at 180 Wh&#x2F;kg. In just a handful of months we jumped to 260 Wh&#x2F;kg, then to 280 Wh&#x2F;kg as manufacturing processes improved. In the last 11 years, however, improvements have been maybe a few Wh&#x2F;kg per year, and there have been literally zero improvements whatsoever in the past four years, by anyone.<p>Eleven years is a very long time, especially for something that everybody just assumes is constantly silently improving. And it&#x27;s not like the battery industry stopped investing in growth: there are absolutely insane amounts of money invested in battery R&amp;D, since whoever figures out how to make a cheap, energy-dense battery will become absolutely infathomably rich and make Madoff-level growth look like US savings bonds.<p>Bonus fact: nobody really understands lithium-ion batteries. One production run might have substantially higher or lower capacity. Some batteries might explode. Some batteries are high discharge and some are low discharge. The &quot;explanation&quot; for all of these things is &#x27;heat&#x27;.<p>Imagine that happening to any other industry (for example the auto industry.)<p>- &quot;Why did my car just explode!?&quot; &quot;Heat&quot;<p>- &quot;Why does this car last a tenth the lifetime of this car?&quot; &quot;Heat&quot;<p>- &quot;Why does this car go a thousand times faster than any others?&quot; &quot;Heat&quot;<p>- &quot;Why is this entire production run of cars not working?&quot; &quot;Heat&quot;<p>People say &quot;heat&quot; for two reasons: 1) because nobody understands li-ion batteries and 2) because yes, the real answer does have something to do with heat.<p>Batteries are one of the most important industries and critical to every company on HN. But the state of the art of batteries is putting together random metals with a bunch of random chemicals and watching which ones don&#x27;t explode.<p>Imagine talking to the CEO of Boeing: &quot;We just did our millionth test, engines made of cheese and wings made of coconut shells. It crashed during takeoff, of course. We haven&#x27;t had any improvements in over a decade, but we&#x27;re sure we&#x27;ll get there eventually - we&#x27;ve spent billions on research so far.&quot;