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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,
这段视频是由Anker赞助播出，稍后会详细介绍。在过去二十年里，一系列更轻、
ever-more-powerful rechargeable batteries has enabled the rise of smartphones, miniature high definition cameras, drones,
更强大的可充电电池使智能手机、微型高清相机、无人机、
commercially competitive electric cars, wireless headphones, and so on.
具有商业竞争力的电动汽车、无线耳机等等的崛起变成可能。
So are we moving towards a future where the entire planet is battery-powered?
所以未来，我们将步入一个由电池供电的世界吗？
There are two big factors that will determine that possibility. 1) how light and energy dense we can make batteries,
两大因素决定了这种可能性。1. 我们制造的电池能有多轻以及能储存多少能量
and 2) whether we'll even be able to physically manufacture enough batteries.
以及2. 我们是否能够生产足够的电池。
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.
本期视频将讲述该问题的第一部分，第二部分由Real Engineering的Brian讲述——我们会把视频链接放在最后。
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,
电池已经变得越来越好了，现在，每公斤电池能储存的能量是90年代的两倍多，
which means they're half the weight for the same energy stored.
这意味着只用一半的重量就能储存同样的能量。
Hence all the drones and smart phones. So what's the limit to this trend? Batteries are, in principle, fairly simple:
因此才有了所有的无人机和智能手机。理论上，电池是相当简单的：
take two partially dissolved metals, one whose atoms want to dissolve more and give up electrons,
取两个半溶解金属，一个的原子想溶解更多并放弃电子，
and one whose atoms want to deposit back on the solid bit but need spare electrons to do so.
另一个的原子想要变回固态位元，但需要多余的电子来实现。
When you put these two together connected with a wire or some other conductor,
当你将两个金属放在一起，并接通一根电线或一些其他导体，
they'll satisfy each others' wants, either dissolving more or depositing more, and sending the electrons to each other along the wire. Voila: electricity!
它们会满足彼此的希望，要么溶解，要么析出，并通过电线来传导电子。看，是电！
And if you force electricity backwards through the wire, they'll reverse their dissolving and depositing, which we call "re-charging".
如果你强制让电子倒回去，它们会重置之前的溶解和析出，我们称之为“充电”。
The intrinsic limits to how lightweight batteries can be are imposed by two factors:
对电池重量和容量的本质限制是由两个因素造成的：
the weight of the materials you use, and how much energy they give off per electron traded.
你所使用的材料的重量，以及每个电子交易释放的能量。
So you want the lightest materials that produce the most energy per electron.
你想要一种最轻的材料，其每个电子能产生最多的能量。
Metals from the left side of the periodic table, like lithium, sodium and beryllium, really want to lose electrons,
周期元素表周边的金属，如锂、钠和铍，非常想失去电子，
while atoms from the right side like fluorine, oxygen, and sulfur really want electrons.
而右边的原子，如氟、氧和硫，则需要电子。
And atoms close to the top are lighter weight, so we can just slap together lithium and fluorine and make a perfect battery, right?
接近顶层的原子重量更轻，所以我们可以锂和氟结合在一起就能制造出完美的电池，对吧？
Unfortunately, no – lithium and fluorine are just way too reactive –
不是。锂和氟的反应太过强烈
one of the only well-documented practical uses of a lithium fluorine reaction I could find was incredibly powerful and dangerous rocket fuel.
我所能找到的唯一一种氟锂反应的实际应用是一种强大而危险的火箭燃料。
In practice, the electrochemistry of batteries is incredibly complicated, and requires combining metals that work well together chemically,
在实践中，电池的电化学过程极其复杂，需要在正常温度和压力下，
electrically, and controllably at normal temperatures and pressures.
让金属结合在一起，且要在化学、电性和可控性上运行良好。
For example, oxygen is a gas, sulfur is a horrible conductor, and sodium needs to be molten – challenges to using any of them to make batteries.
例如，氧是气体，硫是一种可怕的导体，钠需要熔化——使用它们中的任何一种来制造电池都是一种挑战。
The current standard for lightweight, rechargeable and commercially safe batteries uses lithium and graphite on one side,
目前轻量级可充电商用安全电池的标准是一侧使用锂和石墨，
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,
另一侧有各种选择，通常是氧化钴。锂可以为了转移电子而溶解或析出，
hence the name "lithium ion", while the other materials are dead weight along for the ride –
因此被称为“锂离子”，而其他材料只是路人——
I mean, they play important chemical roles, but they greatly increase the weight-per-electron transferred. So how much lighter will batteries get?
我的意思是，它们发挥着重要的化学作用，但是它们极大地增加了每转移电子的重量。
Theoretical calculations put the minimum possible weight for lithium ion batteries at around half what they currently are.
根据理论计算，锂离子电池最轻约为目前重量的一半。
A lighter candidate currently being developed is the lithium-sulfur battery, which has less energy-per-electron than lithium-ion batteries,
目前正在研发的一个更轻的候补是硫化锂电池，能量储存比锂离子电池少，
but lithium and sulfur are lighter than lithium and cobalt, oxygen and carbon,
但硫和锂比锂和钴、氧和碳轻，
so a battery with equivalent capacity can in principle weigh around a third as much.
所以同等容量的电池原则上只有其重量的三分之一。
Even better, lithium-oxygen batteries, while still an incredibly far-off technology, are theoretically four times lighter than lithium sulfur batteries.
甚至更胜一筹，锂氧电池虽然仍是一种非常遥远的技术，但理论上其重量是锂硫电池的四分之一。
But that's pretty close to the limit for chemical-reaction-based batteries –
但这相当接近于物理电池的极限了——
there aren't really any materials that give off more energy per electron for a given weight
没有任何材料可以比锂溶解和氟析出
than lithium on the dissolving side and fluorine on the depositing side, and a lithium-fluorine battery –
提供更多的单位输出能量，并且氟锂电池——
as dangerous and impossible as it is – is limited to only be about 10% lighter than a lithium-oxygen battery.
既危险又不可能做出来——而且只比锂氧电池轻10%。
So the theoretical lower limit for batteries, period, is about 5% of current weights.
所以电池的理论下限就是目前重量的约5%。
But that's an incredible long-shot, everything-works-out, perfect world scenario.
机会渺茫，但每次的成功，都将使这个世界变得完美。
More likely is that we end up combining pretty-good batteries with supercapacitors, fuel cells, hydropower and other mechanical energy storage types,
更有可能的是，我们最终会把性能优良的电池与超级电容器、燃料电池、水力发电和其他机械能存储类型结合起来，
and airplanes will probably always have to use some sort of hydrocarbon fuel. Or maybe we'll finally figure out fusion.
而且飞机可能会一直使用某种碳氢燃料。或许我们最终会找到核聚变的方法。
