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Comment by xoa | Hacker News Reader

>Yeah, there have been lots of "breakthrough battery tech" announcements that didn't lead to commercial products

Although very important to note in these discussions: a lot of them did. Yes, in mass production as as part of a whole battery system vs a single lab cell the gains are almost always far smaller, but small gains add up over time. Energy density has dramatically increased over the last few decades [0] as well as cost dropping and those trends together have combined to make the current electrification acceleration possible. There isn't any need to be overly cynical about this stuff, the progress is real and a tipping point was reached a while ago. With the amount of capital for R&D and production pouring in at this point it's not unreasonable to hope for even more.

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0: https://arstechnica.com/science/2021/05/eternally-five-years...

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Energy density, yes; longevity, no. Obviously making batteries that last (much) longer would not be very profitable, especially to the companies who depend on forced obolescence.

This applies less when selling B2B. Auto companies and power companies are GOING to shop based on reliability, and are GOING to notice when your stuff doesn't last as long as it should.

I'm referring to the battery companies, who won't bother to increase longevity beyond the bare minimum necessary to meet a specification.

While I doubt something like the Phoebus Cartel exists for batteries, when they all have little incentive to make them last longer, you won't find much difference between them. Exceptions include military and aerospace where the costs are also many times higher.

Battery cartel did exist tho

I think that in the super fast growing market you don't lose anything by making your product last longer. The demand would be larger than supply for a long time anyway. OTOH, it's good to get an edge over competition by offering a superior product.

You can mitigate planned obsolescense with recurrent billing, like monthly fees.

Not really. A battery that can last longer at a given operation rate also means you could, for example, charge it faster or draw bigger loads.

> a lot of them did

Really? I haven't noticed much progress over the last 5 to 10 years. What was the biggest breakthrough that has materialized in that time?

>Really? I haven't noticed much progress over the last 5 to 10 years

You don't call doubling to tripling of energy density progress?

https://cleantechnica.com/2020/02/19/bloombergnef-lithium-io...

And it's not about "big breakthroughs" any more than it is for microprocessors. A bunch of lab changes that in production add .5-5% each add up to 10-20% in a generation add up to 2-3x over a decade. That something works in a lab though is still interesting since it shows the possible ceiling we can work towards. Going from that to something that we can make billions of cheaply entails compromises, but the ultimate envelope still matters.

Just like in finance, most (consumer/laymen) people are looking for a big win when it's been shown over and over that small gains compounded over time always come out ahead.

So this got me curious and I started to look at something a bit more concrete: the history of 18650 cell capacity. Currently the highest capacity 18650 that's widely available is 3500 mAh. The first such cell I found is the LG MJ1 which dates back to 2014: https://cdn.shopify.com/s/files/1/0481/9678/0183/files/lg_mj...

I also found a 3200 mAh model from 2012: https://cdn.shopify.com/s/files/1/0481/9678/0183/files/panas...

That's a fair bit less than a 3x improvement over 10 years. Now of course this is a rather crude and unscientific measurement. It's also effectively measuring energy density by volume rather than weight, but volume is more often the limiting factor for Li-ion batteries (e.g. smartphones and EVs are volume limited).

Still, I think this shows why people are skeptical about claimed massive improvements in battery tech: it's hard to find clear evidence of it in actual products people can buy.

So far as I can tell Li Ion batteries have gained about a 1.5x charge per mass improvement in the last 10 years. They may have doubled or trebled over a longer time frame though. If there was a big jump due to a particular technology an extra year or two in the time frame, or shift in the time frame might make a big difference.

I think while the energy density has doubled the amount observed work from a battery seems constant.

Laptops last a few hours, phones last around a day, etc. We’ve used that density to get thinner and lighter devices with slightly more performance that’s hard to observe from everyday tasks.

The outlier is cars, where they’ve crept up as the density has come up.

>I think while the energy density has doubled

Has it really ? I remember the same mAh ratings or slight bumps in phones for many generations. 2016 Samsung galaxy s7 had 3000mah battery - latest ones have like 3700mah ? There have been larger batteries in bigger phones - but I'd like to have a 6000mah battery in a normal form factor.

The only doubling I see is in 10 year period, but phone size grew considerably in that time as well.

And smart watch batteries still suck no matter the price range.

You’re not taking into account the weight of those batteries or their cost as components. A bigger phone might not just have a bigger battery, it might have a bigger cheaper battery with the same capacity. Only looking at the capacity doesn’t tell you anything useful about charge to weight.

This chart is a little suspicious given that iPhone battery density has only increased by 20% in 9 years.

https://twitter.com/Alxbk/status/1181307722991652864

Apple isn't going to be selecting for mass/energy density. That's a major concern for EVs, but for a phone, you would gladly take double the capacity for 3x the mass.

EV battery capacity hasn't exactly been skyrocketing either. When the Tesla Model S was introduced in 2012 the largest battery option was 85 kWh. For the 2015 model year it got a 90 kWh option and 100 kWh for 2016. Today 100 kWh remains the most you can get.

How has the mass changed? If we're talking about a fraction (density) it's pointless to talk about the numerator on its own.

I can't find any indication that the weight of Tesla batteries has changed significantly since the introduction of the 100 kWh pack. In any case weight savings on Tesla batteries seems to have come primarily from improved packaging rather than better chemistries.

Mobile phones mostly optimise for Wh/m³ or for batteries more usually stated Wh/L (stored energy by volume), however that tweet is about Wh/kg (stored energy by weight) which is less relevant to mobile phones. “Density” means one thing that has little to do with energy, “energy density” https://en.wikipedia.org/wiki/Energy_density is a slightly better term but it is also misused. “volumetric energy density” versus “gravimetric energy density” are clearer terms (edit:) for usage in conversations like this, although the more standard industry terms afaik are “energy density” for volumetric and “specific energy” for gravimetric.

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