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  • This video was made possible by Anker – more on that later.

  • Over the last twenty years, a slew of ever-lighter, ever-more-powerful rechargeable batteries

  • has enabled the rise of smartphones, miniature high definition cameras, drones, commercially

  • competitive electric cars, wireless headphones, and so on.

  • It seems like we're moving towards a future where the entire planet is battery-powered,

  • but there are two big factors that will come into play: 1) how light and energy dense we

  • can make batteries, and 2) whether we'll even be able to physically manufacture enough

  • batteries.

  • This video covers part 1 of this question, and Brian of Real Engineering is covering

  • part 2 – we'll link to his video at the end.

  • Ok, so batteries have been getting better and better, and nowadays, they can store over

  • twice as much energy per kilogram as in the 1990s , which means they're half the weight

  • for the same energy stored.

  • Hence all the drones and smart phones.

  • So what's the limit to this trend?

  • Batteries are, in principle, fairly simple: take two partially dissolved metals, one whose

  • atoms want to dissolve more and give up electrons, and one whose atoms want to deposit back on

  • the solid bit but need spare electrons to do so.

  • When you put these two together connected with a wire or some other conductor , they'll

  • satisfy each others' wants, either dissolving more or depositing more, and sending the electrons

  • to each other along the wire.

  • Voilá: electricity!

  • And if you force electricity backwards through the wire they'll reverse their dissolving

  • and depositing, otherwise known asre-charging”.

  • The intrinsic limits to how lightweight batteries can be are imposed by two factors: the weight

  • of the two materials you use, and how much energy they give off per electron traded.

  • So you want the lightest materials that produce the most energy per electron.

  • Metals from the left side of the periodic table, like lithium, sodium and beryllium,

  • really want to lose electrons, while atoms from the right side like fluorine, oxygen,

  • and sulfur really want electrons.

  • And atoms close to the top are lighter weight, so we can just slap together lithium and fluorine

  • and make a perfect battery, right?

  • Unfortunately, nolithium and fluorine are way too reactiveone of the only well-documented

  • practical uses of a lithium fluorine reaction I could find was incredibly powerful and dangerous

  • rocket fuel.

  • In practice, the electrochemistry of batteries is incredibly complicated, and requires combining

  • metals that work well together chemically, electrically, and controllably at normal temperatures

  • and pressures . For example, oxygen is a gas, sulfur is a horrible conductor, and sodium

  • needs to be moltenchallenges to using any of them to make batteries.

  • The current standard for lightweight, rechargeable and commercially safe batteries uses lithium

  • and graphite on one side, with a variety of options for the other side, often cobalt oxide

  • . Lithium atoms are what either dissolve or deposit in order to transfer electrons, hence

  • the namelithium ion”, while the other materials are dead weight along for the ride

  • – I mean, they play important chemical roles, but they greatly increase the weight-per-electron

  • transferred.

  • So how much lighter will batteries get?

  • Theoretical calculations put the minimum possible weight for lithium ion batteries at around

  • half what they currently are . A lighter candidate currently being developed

  • is the lithium-sulfur battery , which has a similar amount energy-per-electron as lithium-ion

  • batteries, but lithium and sulfur are lighter than lithium and cobalt, oxygen and carbon

  • , so a battery with equivalent capacity can in principle weigh around a third as much

  • . Even better, lithium-oxygen batteries , while

  • still an incredibly far-off technology, are theoretically four times lighter than lithium

  • sulfur batteries.

  • But that's pretty close to the limit for chemical-reaction-based batteriesthere

  • aren't really any materials that give off more energy per electron for a given weight

  • than lithium on the dissolving side and fluorine on the depositing side , and a lithium-fluorine

  • batteryas dangerous and impossible as it is – is limited to only be about 10%

  • lighter than a lithium-oxygen battery . So the theoretical lower limit for batteries,

  • period, is about 5% of current weights.

  • But that's an incredible long-shot, everything-works-out, perfect world scenario.

  • More likely is that we end up combining pretty-good batteries with supercapacitors, fuel cells,

  • hydropower and other mechanical energy storage types, and airplanes will probably always

  • have to use some sort of hydrocarbon fuel.

  • Or maybe we'll finally figure out fusion.

  • Ok, so here's an example of the amazing battery technology we have available today

  • : this battery pack is crazy small and light – it's basically eight of these with

  • some clever circuitry – and it has enough energy to charge a smartphone 10 times, which

  • is equivalent to running this LED lightbulb for 10 hours.

  • The makers of this ridiculous battery pack, Anker, are sponsoring this video and also

  • running a ridiculous contest where they're giving away ten prizes of two thousand dollars

  • plus one of their battery packsthey're asking for video submissions about a time

  • that running out of power was awkward or unpleasantyou know, like how Apollo 13 almost ran

  • out of batteries, or how I only made it halfway through mowing the lawn last week.

  • You can find out more about Anker's batteries and the contest by going to the links in the

  • video description.

  • And one aspect of batteries I haven't mentioned at all yet is power delivery - aka, how quickly

  • they can charge your devices – this battery pack is smart enough to detect what you've

  • got plugged in in order to optimize charging time.

  • And of course don't forget to check out Brian's video about whether or not it's

  • even possible to make enough batteries to power the planet.

This video was made possible by Anker – more on that later.

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B2 lithium battery fluorine lighter sulfur electron

Will Batteries Power The World? | The Limits Of Lithium-ion

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    Summer posted on 2021/02/18
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