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特斯拉对更好电池的不懈追求

Tesla's Quest for Better Batteries

This episode of Real Engineering is brought to you by Brilliant.
本集《Real Engineering》节目由Brilliant为您提供
A problem solving website to teachs you to think like an engineer.
Brilliant是一个解疑答惑型的网站 本网站会教你像工程师一样思考
Tesla has grown rapidly over the past decade,
在过去的10年间 特斯拉发展十分迅速
when it became the first American automotive
成为自1956年福特汽车公司以来
company to go public since Ford in 1956.
首家上市的美国汽车公司
The attraction towards Tesla is undeniable.
特斯拉的吸引力是不可否认的
Their cars are slick,
特斯拉的车型线条流畅
their acceleration is insane
提速能力强劲
and perhaps most importantly
也许更重要的是
their brand represents a movement towards renewable energy.
特斯拉代表着向可再生能源发展的趋势
Tesla has attracted thousands of well intentioned people
特斯拉吸引了成千上万的有志之人
who want to play their part in saving the world,
他们愿为保护环境出自己的一份力
but there have been a niggling questions
但在许多电动汽车车主和电动汽车反对者心中
on the minds of many EV owners and EV naysayers.
一直存在着一个让人头疼的问题
When is that expensive battery going to need to be replaced,
那块昂贵的电池什么时候需要更换
and at what cost.
以及更换所需的费用是多少
As existing Teslas begin to age,
现有的特斯拉汽车正逐渐老化
and more exotic and demanding models of Teslas come to the fore,
同时更具特色 耗电更多的车型涌现出来
like the Tesla Truck and the Roadster 2.
比如特斯拉卡车和第二代敞篷超跑
These issues are going to become more prominent,
电池的问题将变得更加突出
These batteries do NOT come cheap, but they are getting cheaper.
这些电池并不便宜 但它们的价格正在逐渐下降
This chart shows the cost per kilowatt hour for Tesla powerpacks,
这张图表显示了特斯拉电池组每千瓦时的成本
and the market average.
以及市场平均价格
Both dropping dramatically as technology advanced,
随着技术的进步和制造数量的增加
and manufacturing volumes increased.
两者都大幅地下降
But that storage capacity slowly creeps away as the battery is used,
但随着电池的使用 电池的容量会逐渐下降
slowly degrading the range of your electric vehicle.
慢慢降低电动汽车的续航里程
Tesla currently offers a warranty to all Model 3
特斯拉目前向所有Model 3车主
owners that cover it below 8 years or 160,000 kilometres,
提供8年或16万公里以内的保修服务
whichever comes first.
两个条件满足任意一个即可
Guaranteeing a retention of capacity
保修服务是保证在正常使用的情况下
of at least 70 % when used under normal use.
电池的容量不会跌至70%以下
If it falls below that, they will replace your battery for free.
如果下降到70%以下 特斯拉会为你免费更换电池
Finding out what is considered normal use is pretty difficult,
弄清楚什么是“正常使用”其实很难界定
but they seem to be reasonable
但根据客户满意度报告
with it going by customer satisfaction reports.
特斯拉这么做似乎是合理的
From our graph earlier,
根据我们之前的图表
it’s estimated that Tesla is achieving a cost of 150 $ per kwH of battery packs,
特斯拉的电池组每千瓦时的成本据估计达到了150美元
so the 50 kWh battery pack of the base model
所以基本型号的50千瓦时电池组的
would cost around 7,500 dollars to replace,
更换成本约为7500美元
so they must be pretty confident on those numbers.
所以他们对(电池损耗的)相关数据一定很有信心
As a massive recall of the approximately
因为大规模召回目前出货的
193 thousand Model 3s currently shipped would ruin Tesla.
约19.3万辆Model 3将使得特斯拉破产
Ultimately these batteries are unlikely to drop below the warranties guarantee
总而言之 这些电池在16万公里的行驶范围内
in those 160,000 kilometres,
不大可能跌至保修线
but even so improving batteries is obviously just a wise business
但即便如此 改善电池显然是一个明智的商业决策
decision to retain those customers in future.
以便让特斯拉以后留住这些客户
This is just one of a myriad of factors
这仅是影响特斯拉最近
that influenced Tesla’s recent landmark acquisition
以2.18亿美元收购Maxwell技术公司
of Maxwell Technologies for $218 million dollars.
这一里程碑式交易的众多因素之一
A rare Tesla acquisition that sets Tesla up
这是一桩罕见的特斯拉收购案
for not just cheaper batteries, but better batteries.
特斯拉因此拥有了更加优质和廉价的电池
That will be lighter, have greater range
这种电池更轻 续航更久
and live a longer life.
并且使用寿命也更长
It wouldn’t be the first time an automotive company
这不是汽车公司第一次
underestimated their battery degradation.
低估他们的电池退化
When the Nissan Leaf debuted in 2010,
2010年尼桑聆风首次亮相时
the battery production they needed simply did not exist,
聆风所需要的电池还未生产
and neither did the technical expertise required to design battery packs.
设计电池组所需的相关技术也不存在
In those days lithium ion batteries cost about 400 dollars
那时候 笔记本级别的锂离子电池
per kWh for laptop grade batteries,
每千瓦时的价格约为400美元
and up to 1000 dollars per kWh for ones
而电动汽车所需要的寿命长的电池
with the longevity needed for an electric vehicle.
每千瓦时的价格高达1000美元
To minimise costs
为了将成本降到最低
Nissan decided to start production of their own batteries,
尼桑决定开始生产他们自己的电池
and opted for a small 24 kWh battery,
他们选择了24千瓦时的小容量电池
giving it a range of just over 100 kilometres.
导致电池的续航能力仅仅有100公里
Suitable for city driving, and that’s about it.
它只适合城市驾驶 仅此而已
But customers soon realised
但客户很快意识到
that this paltry range was dwindling quickly.
电池不多的容量正在急剧缩减
Within just 1-2 years of driving,
在仅仅1-2年的时间内
the Leafs battery capacity was dropping up to 27.5 percent
聆风的电池容量在正常使用的情况下
under normal use.
下降到了27.5%
Despite careful in-house testing
尽管进行了仔细的内部测试
Nissan overlooked some crucial test conditions when
尼桑在开发电池时忽略了一些
developing their battery,
关键性的测试条件
and because of this they made some crucial design errors.
因此他们犯了一些关键性的设计错误
To learn why this degradation happens,
要了解电池为什么会发生这种退化
we first need to understand how lithium ion batteries work.
我们首先需要了解锂离子电池是如何工作的
A lithium ion battery, like all batteries,
像所有的电池一样
contains a positive electrode, the anode,
锂离子电池包括正极和负极
and a negative electrode, the cathode, separated by an electrolyte.
又称阳极和阴极 它们由电解质隔开
Batteries power devices by transporting positively charged ions
电池通过在阳极和阴极之间传输正离子
between the anode and cathode,
来给设备供能
creating an electric potential between the two sides of the battery
由此电池两侧将会产生电势差
and forcing electrons to travel through the device
使得电子从用电设备穿过来供能
it is powering to equalise the electric potential.
电子将会平衡掉正离子产生的电势
Critically,this process is reversible for lithium ion batteries,
重点是 对于锂离子电池来说这个过程是可逆的
as the lithium ions are held loosely,
因为作用在锂离子上的束缚力并不强
sitting into spaces in the anode and cathodes crystal structure.
锂离子处于阳极和阴极晶体结构之内
This is called intercalation.
这叫做嵌入
So, when the opposite electric potential is applied to the battery
当相反的电势作用在电池上
it will force the lithium ions to transport back across the electrolyte bridge
电势差会使得锂离子 通过电解质返回
and lodge themselves in the anode once again.
并且将锂离子再一次 镶嵌在阳极上
This process determines a huge amount of the energy storage capabilities of the battery.
这个过程决定锂电池有着极大的储能能力
Lithium is a fantastic material for batteries,
锂是极好的电池材料
with an atomic number of 3,
锂的原子序数为3
it is the 3rd lightest element
它是第三轻的元素
and the lightest of the metals.
也是最轻的金属
Allowing it’s ions to provide fantastic energy
对于任意体量的电池
to weight characteristics for any battery.
它都能提供优质的能量
But, the energy capacity of the battery is not determined by this
但是 电池容量不仅决定于此
it is determined by
还在于
how many lithium ions can fit into these spaces in the anode and cathode.
在阴极和阳极之中可以容纳多少锂离子
For example, the graphite anode requires 6 carbon atoms
举个例子 石墨阳极需要6个碳原子
to store a single lithium ion,
才能存留1个锂原子
to form this molecule (LiC6).
二者结合成了六碳化锂化合物(LiC6)
This gives a theoretical maximum battery capacity of 372 mAh per gram.
这决定了电池的理论最大容量是372毫安每克
Silicon however can do better.
硅的性能更好
A single silicon atom can bind 4.4 lithium ions,
一个硅原子能结合4.4个锂离子
giving it a theoretical maximum battery
其理论最大容量为
capacity 4200mAh per gram.
4200毫安每克
This seems great, and can provide increases in battery capacity,
看起来很不错 电池容量能有着巨大的提升
but it also comes with drawbacks.
但这样也有一些缺点
As those 4.4 lithium ions lodging themselves
电池在充满的过程中
into the silicon crystal lattice causes a
随着4.4个锂离子被固定在硅晶格中
volume expansion of 400% when charging from empty to full.
硅电极的体积会增大四倍
This expansion creates stress
体积的增加对电池内部造成压力
within the battery that damages the anode material,
并会破坏阳极材料
that will eventually destroy it’s battery capacity over repeated cycles.
最终在一次次的使用循环中 电池彻底失去储电能力
Battery designers are constantly looking
电池工程师们一直在想办法
for ways to maximise this energy density of their batteries
希望在不牺牲电池寿命的前提下
while not sacrificing longevity of the battery.
最大化电池的能量密度
So what exactly is being damaged in the batteries
究竟是电池中的哪一部分被破坏
that causes them to slowly wither away?
导致了电池容量慢慢的消耗呢?
When researchers began investigating
研究人员开始调查
what caused the Nissan Leaf’s rapid battery degradation,
导致尼桑聆风电池快速退化的原因
they began by opening the battery and unrolling the batteries contents.
他们打开了电池 研究电池的内部结构
they found that the electrode coatings had become coarse over their life
他们发现在使用过程中电极的涂层慢慢变得粗糙
clearly a non-reversible reaction was occurring within the cell
这明显是一个不可逆的反应
but the change was expected.
同时也是预料之中的
In fact the chemical process that caused it
事实上造成这个现象的化学反应
is vital to the operation of the battery.
对电池的使用来说极为重要
When a battery is charged for the very first time
当电池首次充电时
a chemical reaction occurs at the electrolyte electrode interface
在锂离子和电子结合的地方 电解质和电极之间的固液相界面上
where electrons and ions combine.
会发生化学反应
This causes the formation of a new layer
在电解质-电极界面上
between the electrode and electrolyte
会形成一个薄层
called the solid electrolyte interphase.
叫做固体电解质层
The name is exactly what it suggests,
顾名思义
it’s a layer formed by the liquid electrolyte reacting
这是由于电解液和电子反应
with electrons to form a solid layer.
而形成的一层固体膜
Thankfully, this layer is permeable to ions,
这层膜允许通过离子
but not electrons.
而电子无法通过
So it initially forms a protective layer over the electrode
所以它形成之初是一层对于电极的保护
that allows ions to enter and insert themselves via intercalation,
因此它仅允许离子通过和嵌入
but it is impermeable to electrons.
电子则不可通过
Preventing further reaction with the electrolyte.
这避免了电极与电解液的进一步反应
At least that’s the idea under normal conditions.
至少正常情况下是这样的
The problem is, under certain conditions
问题是在某种情况下
this layer can grow beyond just a thin layer of protective coating
这层膜不仅仅会长成为一层保护薄层
and result in the permanent lodgement of the lithium
它还会导致用来储存能量的锂
that provides the battery with its energy storage.
被永久禁锢在保护层里
This process is not entirely well understood
这个过程不是很好懂
and is outside the scope of this video,
也超出了本视频的科普范围
but we can identify some factors that increase the rate of this formation.
但我们可以确定一些加快导致这种局面产生的因素
The expansion of the silicon electrode battery
早先我们提到的硅电极电池的膨胀
we mentioned earlier causes the fracture of the SEI layer,
会造成固体电解质膜的破裂
exposing fresh layers of electrode to react with the electrolyte.
电极上新形成的膜被暴露出来与电解液反应
Charging rate and temperature can also accelerate the thickening of this layer.
充电速率和温度都会加速膜的形成
NASA performed their own in depth study of this effect,
NASA 完成了他们对这个效应的深度研究
and released a report in 2008 titled
并于2008年发表了标题为
“Guidelines on Lithium-ion Battery Use in Space Applications”
《锂离子电池在航空航天领域的应用指南》的文章
sharing their findings.
并分享了他们的发现
The temperature that the battery is charged and discharged
电池在充放电时的温度
at plays a massive role in the batteries performance.
会对电池的性能产生极大的影响
Lowering the temperature lowers chemical activity,
降低温度可以削弱化学反应
but this is a double edged sword.
但这是一把双刃剑
Lowering the chemical activity negatively affects the batteries ability to store energy.
降低化学反应活跃度也会削弱电池的存储能力
Which is why batteries have lower ranges in cold countries,
这就解释了为何电池在寒冷地带有着更久的续航
but lowering the chemical activity
但降低活跃度
also decreases the formation rate of that SEI layer.
也会降低固态电解质膜的形成速率
This is one of reason the Nissan Leaf’ s battery
这也是尼桑聆风在短短两年时间里
lost a huge amount of capacity over just 2 years in many countries.
在许多国家都出现较高的电池损耗率的原因
Nissan performed most of its testing in stable laboratory conditions,
尼桑的大多数测试实验都是在稳定的实验室条件下进行的
not over a range of possible temperatures.
并未考虑到所有可能的温度影响
Because of this they failed to realise the disastrous effect
因此他们没能认识到
temperature would have on the life of the battery,
温度对电池寿命带来的灾难性影响
and failed to include a thermal management system,
他们也没有在尼桑车上加装热感系统
which is common place in any Tesla.
而这在特斯拉的车上是标配
This of course reduces the energy density of the battery.
这无疑减少了电池的能量密度
Adding tubing, the glycol needed to exchange heat,
增加管道系统 在其中充入乙二醇用以换热
along with the heat pumps and valves
再配上热管理系统需要的
needed to make a thermal management system,
热泵和阀门
not only adds weight,
这不仅会增加重量
but it draws energy away from the battery to operate.
在运行时也会消耗电池的能量
But it plays a vital part in maintaining the performance of the battery.
只是这些措施对于保持电池的性能极为必要
Nissan’s choice to not include a thermal management system,
尼桑不打算增加热管理系统
even in the 2019 version,
即使是2019款的新车也没有
makes it a poor choice for anyone living in anything but a temperate climate.
这使得只有生活在温和适宜环境的人才会考虑购买尼桑聆风
Of course, just cycling the battery through it’s charged and discharged states
当然由于不断的充放电导致的电池循环
is one of the biggest factor in degrading the battery.
是电池容量减少的最重要的因素之一
Every time you cycle the battery
在每一个充放电的循环
you are giving the SEI layer opportunities to grow.
固态电解质膜也会得到增长
Minimising the number of times a cell is cycled will increase it’s life,
减少充放电的次数可以延长电池的寿命
and maintaining an ideal charge and discharge voltage of about 4 volts
将充放电电压保证在四伏左右
minimises any resistive heating that
也会减少电阻热的生成
may cause an increase in chemical activity.
以避免化学反应过度活跃
This is where Maxwell technologies comes into play.
该到Maxwell公司的技术起作用了
Maxwell has two primary technologies that Tesla will be taking advantage of.
Maxwell公司有两项特斯拉想要应用的技术
The first is what Maxwell are known for, their ultracapacitors.
其一众所周知 是他们的超级电容器
Ultracapacitors serve the save fundamental job as batteries,
超级电容器和电池一样有着基本的储存能力
to store energy,
都可以存储电能
but they function in an entirely different way
但它们存储能量的方式不同
and are used for entirely different purposes.
并且用于完全不同的目的
The fundamental difference between a capacitor and a battery
电容器和电池最根本的区别在于
is that a battery stores energy through chemical reactions,
电池是通过发生化学反应来储能
as we saw for lithium ion batteries earlier
就像早先我们所介绍的锂离子电池
this is done through insertion into the crystal lattice.
它是通过把离子嵌入晶格来储能
Capacitors instead store their energy by ions clinging onto the surface of the electrode.
电容器则是将离子吸附在电极表面来储能
This is a standard ultracapacitor schematic.
这是一张标准的超级电容器原理图
On each side we have an aluminium current collector
每一侧都有一个铝集电器
with thin graphite electrodes on each,
上面有一层薄薄的石墨电极
separated by an electrolyte and an insulating separator
中间由电解质和隔离板隔开
to prevent the passage of electrons.
以阻止电子的通过
In an uncharged state ions float in the electrolyte.
在未充电状态下 离子在电解质中游离不定
When a voltage is applied during charging,
充电时 电压作用在电极上
ions drift towards their opposite charge and
离子会移向其相反电荷的方向
cling to the surface, holding the charge in place.
并依附在表面上 将电荷固定在此
When a device is then connected to the capacitor
当装置与电容器相连
this charge can quickly leave while the ions drift back into the electrolyte.
离子会返回到电解质中 电荷也会因此离开
The key limiting factor for ultracapacitors
超级电容器关键的限制因素在于
is the surface area available for this to happen,
电极上可供发生此反应的面积有限
and nanotechnology has allowed for amazing advances in the field.
纳米技术使得这一领域的重大突破成为可能
This is what the inside of a ultracapacitor looks like,
这是超级电容器的内部的样子
it contains hundreds of layers of these electrode pairs.
它里面有着数百层的同样的电极对
But even with this enormous surface area,
但即使有着如此大的表面积
ultracapacitors simply can not compete with
在能量密度上
batteries when it comes to energy density.
超级电容器还是无法和电池相比
Even Maxwell’s best ultracapacitors have an energy density of just 7.4 Wh/kg
即使是Maxwell最好的超级电容器 能量密度仅仅7.4千克每千瓦时
while the best guess for Tesla’s current energy density is about 250 Wh/kg.
而特斯拉电池的能量密度据估已达到250千克每千瓦时
Counter to what corporate owned tech channels may tell you,
相反的 从公司的技术频道你可以发现
ultracapacitors are not intended
超级电容器被设计出来
to be a replacement for batteries.
不是为了取代电池
They are intended to work in conjunction with batteries.
他们是为了与电池相连接
Ultracapacitors strength is their ability to
超级电容器的长处在于
quickly charge and discharge
它可以快速地充放电
without being worn down.
而自身则不会有什么损耗
This makes them a great buffer to place between the motors and the battery.
这使得它可以成为车辆与电池之间良好的缓冲器
Their high discharge rate will allow
它有着很高的放电率
them to give surges of electricity to the motors when rapid acceleration is needed,
这使得它可以在汽车急加速的时候提供极大的电流
and allow them to charge quickly when breaking.
在人们休息时 它可以使得电池快速充电
Saving the battery from unnecessary cycles
电池可以从不必要的循环中解脱出来
and boosting its ability to quickly provide current
而当加速的时候
when needed for acceleration.
电池又可以快速提供大电流
This is going to be a massively important technology for two upcoming Tesla vehicles.
对特斯拉即将发布的两款车型来说 这项技术意义重大
The Tesla Roadster, which will boast an acceleration of 0-60 in just 1.9 seconds,
特斯拉敞篷跑车的车速从零加速到六十仅需1.9秒
which a normal battery would struggle to
这样大的放电率
achieve the discharge rate needed without damaging itself.
普通电池很难在不损害自身的情况下做到
The second vehicle is the Tesla Truck.
第二款车是特斯拉卡车
I have made a video in the past noting
我之前有做过相关视频
that the Tesla Truck is going to be limited in
里面提到由于其所配备的重型电池
its range and cargo hauling ability as a result of the heavy batteries it will need,
特斯拉卡车的续驶里程和运载能力将会被削减
as trucks are limited in weight to about 40 metric tonnes in most countries.
因为在大多数国家卡车的总重都不得超过40吨
This ultracapacitor technology will boost its
超级电容器技术
ability to regain energy from breaking significantly,
可以显著改善电池突然中断后的供电恢复能力
and thus allow its battery capacity to decrease,
因此允许电池采用更小的容量
in turn allowing the truck to swap batteries for cargo.
也就是说卡车可以在需要时更换电池
The second technology Maxwell has been toting
Maxwell持有的第二项技术是干式涂层电池
as their next big breakthrough is dry coated batteries.
这被视为他们在电池领域的一大突破
This is a manufacturing advancement
这是一项制造领域的突破
that Maxwell claims will reduce the cost of manufacturing.
Maxwell宣称它会降低生产制造的成本
A factor Tesla has been working fervently to minimize
随着特斯拉超级工厂的建成和扩展
with the growth of the gigafactory.
特斯拉迫切希望减少制造领域的成本
So what are dry coated batteries.
那什么是干式涂层电池呢
Currently in order to coat their current collectors with the electrode material
现如今 为了将电极材料包裹在集电器上
Tesla in partnership with Panasonic’s patented technology,
特斯拉与松下合作以使用他们的专利技术
must first dissolve the electrode material
首先需要使电极材料溶解于溶剂中
in a solvent which is then spread over current collector,
之后溶液会将集电器全部包裹
both are then passed through an oven for drying,
它们将会被送进烤炉烘干
where the solvent evaporates leaving just the electrode material behind.
当溶液蒸发后 剩下的就只有电极材料了
This adds cost of the manufacturing procedure
这增加了两项制造成本
as the solvent is lost in the process,
一是溶液的蒸发
and the baking process takes energy.
二是烘烤的成本
On top of this the solvent is toxic,
蒸发出的溶液是有毒性的
so removing it from the process would benefit the environment.
若是移除这一步骤对环境是有好处的
Maxwell instead uses a binding agent and conductive agent,
Maxwell并没有用粘合剂和导电剂
which I assume will work similarly to electrostatic painting.
我估计他们应该是用了和静电涂层类似的技术
Where a metal being painted will be given a negative charge,
在被喷涂的金属上加上负电荷
while the paint will be given a positive charge
喷射的涂料加上正电荷
as it is sprayed attracting it to the metal where it will cling to it.
这样涂料就会被吸附从而附着在金属上
This painting process also eliminates the solvents needed in paint.
这个喷涂步骤也会减少喷涂所需的溶液量
In this paper, published by Maxwell technologies,
在这份Maxwell技术部发表的论文中
they detail how their dry coating manufacturing techniques
他们详述了干式涂层技术
could result in a high energy storage capacity of the electrodes,
是如何使得电极有更大的能量存储能力的
due to a denser and thicker coating.
得益于这一层又密又厚的涂层
Resulting a potential increase in battery capacity to 300 Watt hours per kilogram,
电池的容量因此增大至300瓦时每千克
20% up from our best estimates of Tesla’s current specs.
我们预估特斯拉电池的电流也增加了百分之二十
Only time will tell if this claim can be realised at an industrial scale.
这项技术应用到工业生产中会有怎样的改变 时间自会证明
Perhaps, more importantly to Tesla, they now own this manufacturing technique.
对特斯拉来说 拥有这项技术才是最重要的
Currently Panasonic owns the manufacturing process for Tesla,
现在 松下掌管着特斯拉的生产线
there is a literally a line of demarcation
在超级工厂内有一条明确的界限
in the gigafactory separating Panasonic and Tesla,
将松下和特斯拉划分开
denoting the point at
它表示了
which the ownership of batteries transfers hands.
电池的所有权的转移
Having to buy their batteries from Panasonic adds cost,
从松下那购买电池无疑也是一笔费用
that Tesla will want to avoid in future
这笔费用是特斯拉期望在未来能避免的
and this step could allow for full vertical integration of their battery manufacturing.
这将会有助于他们电池生产的垂直统一管理
Thereby making electronic vehicles more affordable to the everyday consumer.
也会使电动汽车走进寻常百姓家
All of this technology is powered
所有的这些技术都得归功于
by incredibly smart engineers working to solve really interesting problems,
致力于解决这些有趣问题的杰出的工程师们
and with so much focuson battery technology across the entire tech industry
也得感谢整个科技产业在电池技术上给予了很多的关注
there’s a high demand for qualified engineers.
对于合格的工程师的需求量是很大的
For anyone looking to build or advance their engineering career
对于任何有志于工程师职业或是试图在这个领域再进一步的人
I’d highly recommend Brilliant.
我都强烈推荐Brilliant 网
Brilliant recently introduced a new feature, called “Daily Problems”,
Brilliant 网最近增加了一个新功能 名叫“每日问题”
which will present with you with interesting scientific
“每日问题”会给你推送有趣的科学问题
and mathematical problems to test your brain.
和数学问题来测试你的脑力
Like this one, that teaches you about rolling resistance.
就像这个 告诉你什么是滚动阻力
One of the ways vehicles lose energy.
这是汽车能量损耗的一种方式
It takes you through a short explanation
它会给你一段简短的关于滚动阻力的介绍
of rolling resistance, giving you the framework
并且会给你一个框架
you need to rationalise a question they pose to you.
你需要合理地说明他们提出的问题
Here the answer is pretty simple.
这里的问题都很简单
Rolling resistance occurs from the loss of energy to the ground and wheels,
滚动阻力是车轮和地面之间的能量损失
so by driving from gravel to concrete
所以从碎石路行驶到水泥路之后
we lose less energy to the ground.
滚动阻力消耗的能量会变少
If you answer a question wrong though,
如果问题回答错了
you can get help by discussing the solution with thousands of other users.
你可以参与其他用户的讨论并从中获得帮助
Allowing you to learn from your mistakes.
如此便可以在错误中学习到东西
Brilliant even have an app
Brilliant 网还有一个手机应用
that you can download to play these brain teasers
你可以在早上通勤的时候
on your morning commute.
用这个APP来玩这些智力难题
If you like the problem and want to learn more,
若你喜欢它 并想学习更多的知识
there’s a course quiz that explores
它还会提供课堂测验
the same concept in greater detail.
对同一个概念进行深度解析
“Daily problems” are thought provoking challenges
“每日问题”通过每天一次的挑战
that will lead you from curiosity to mastery one day at a time.
将会使你从好奇逐渐达到精通的程度
So what are you waiting for?
还在等什么呢?
Go to brilliant.org/realengineering/ and finish your day a little smarter.
登录 brilliant.org/realengineering/ 让你每天都聪明一点点
And the first 500 of you to do so
前五百名通过链接进入的使用者
will get 20% off the annual subscription to view
将会获得全年订阅费用百分之二十的减免
all problems in the archives.
订阅者可以查阅题库中的所有题目
As always thanks for watching and thank you to all my patreon supporters.
一如既往地感谢观众的收看和我的支持者们
If you would like to see more from me, the link is to my Instagram
如果你想看更多我的视频 这是我的Ins链接

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视频概述

特斯拉收购了Maxwell,获得了两项关于电池的关键性技术。这可能会让它在电池方面取得重大突破。

听录译者

收集自网络

翻译译者

momo

审核员

审核员_DY

视频来源

https://www.youtube.com/watch?v=DE_PZQ13YTY

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