you'll know that batteries are complicated.

多様な形と大きさ 容量があり あらゆる物に内蔵されている

They come in all shapes, sizes, charge capabilities,

標準を定めたバッテリー技術といえば―

and we use them in everything.

リチウムイオン電池

And if there's one battery technology that sets the gold standard,

エネルギー貯蔵に優れた 唯一無二の電池で―

it's the lithium-ion battery.

小さくて軽いデザイン

These batteries are one of the only types

[番組ホスト　マレン･ハンスバーガー]

to pack powerful energy storage

未来のバッテリー技術には―

in a small and lightweight design.

この電池の利点を上回る設計が必要よ

So, when designing battery technologies for the future,

リチウムイオン電池は 世界市場を支配してるけど―

the challenge is to improve upon the advantages

改良の余地は大いにあるの

that the lithium-ion battery already has.

例えば出力や容量

Because even though lithium-ion batteries

コストや寿命 そして安全性

currently dominate the global battery market,

技術を向上させるうえで 最も期待できる設計は―

there are quite a few things about them that could be improved,

リチウムシリコン電池

like power output, energy capacity,

リチウム硫黄電池

cost, lifespan, and safety.

全固体リチウムイオン電池

Now some of the most promising designs

そして それらの組み合わせ

for giving lithium-ion battery technology a boost

アノードとカソード 電解質に使う物質の変更は―

are the lithium-silicon battery,

まさに科学者が行ってきた

the lithium-sulfur battery,

では これらが未来の電池になるために 必要なものとは？

solid-state lithium-ion batteries

電池の設計の少しの違いが―

and one that's a common nation of approaches.

[デレク･ミューラー]

And changing out the materials used

電圧と容量に大きな影響を及ぼす

to make anodes, cathodes and electrolytes

14個のセルを持つ 手作りのバッテリーを用意した

is exactly what scientists have been doing.

材料は製氷皿と鋼のネジ

But what is it gonna take for one of these

銅線と１対の導線　そして電圧計だ

to become the new battery of the future?

原理としては 個々の部屋が セルになっている

It's important to note that a simple change

銅がカソードの役割で電子を受け取り―

in a battery's design can significantly affect

鋼がアノードとして電子を失う

its voltage and storage capacity.

そして塩水が電解質として電荷の流れを作る

Here I've made a really simple homemade battery

じゃあ電圧計につないで値を読み上げるよ

with 14 cells using an ice cube tray,

約200ミリボルトだ

steel screws, copper wire, a couple electrical leads,

では 電解液を変えると どうなるだろう

and this voltmeter.

お酢では？

And the way this works is that each little ice cube tray

レモン汁では？

is its own battery cell.

どれもバッテリーの電圧と容量に

So you've got the copper acting like the cathode.

重大な影響を与え得るんだ

It's gaining electrons.

まずはシリコンアノード電池

The steel is acting as the anode.

アノードはセル内の負の電極よ

It's losing electrons.

前回 話したように―

And the salt water is acting as my electrolyte,

リチウムイオンのアノードの素材は 黒鉛が一般的

allowing that flow of charges.

黒鉛の構造はリチウムイオンを 効率的に蓄えられる

Now, when I hook it up to the voltmeter,

でもアノードに蓄えられる量には 上限があって―

you can see I am reading a voltage of around 200 millivolts.

それが電池の容量を決める

Now, what I'm interested in is what would happen

リチウムイオンの吸収と保持の点で シリコンは黒鉛より優秀よ

if we changed out the electrolyte solution

そのため 電池は小型化し エネルギー効率が上がり―

to the, say, vinegar.

安価になる

Lemon juice.

もちろん問題もある

So all these sorts of things can make a significant impact

シリコンは充電中にリチウムに触れると 急激に膨張しやすく―

on the voltage and the storage capacity of the battery.

電池が放電する時に収縮する

MAREN: First up, silicon anode batteries.

膨張と収縮を繰り返せば 電池の寿命は縮み―

Remember that anodes are the negative electrode within a call?

有用性も減る

Well, like we talked about in the last episode,

エノビクスの研究者は この課題に取り組んでいる

the current most popular anode material

[エノビクスCEO　ハロルド･ラスト]

in lithium-ion cells is graphite.

膨張と収縮を制御します

This is because graphite's structure helps keep

我々の特許の３次元構造で とても薄いステンレスを電池に組み込めば―

those lithium ions efficiently stored in the anode.

シリコン膨張を抑制する均一な力を 電池にかけられます

But there is a maximum amount of lithium-ions

充電と放電どちらの際にもです

that can be stored in the anode,

アノードが注目される一方で―

and that determines the cell's capacity.

カソードに目を向け 開発されたのが リチウム硫黄電池

And as it turns out,

リチウムは単体だと不安定な物質で

silicon does a much better job than graphite

[オクシス･エナジーCEO ヒュー･ハンプソン･ジョーンズ]

at absorbing and holding lithium-ions.

空気や水にも反応します

And this means batteries can be made smaller,

オクシスの科学者が取り組むのは―

more energy-efficient, and cheaper.

硫黄という電気を通さない とても安価な物質です

But, of course, this does all come with a catch.

硫黄をリチウムの周りで 難燃剤として使用しました

Silicon anodes have a tendency to dramatically expand

もし空気や水がリチウムに影響しても―

when encountering lithium during charging.

熱暴走や発火 爆発が 起きないようにするためです

And those anodes also then shrink

シリコンアノードと同様 硫黄カソードは―

when the battery discharges.

通常のコバルトのカソードより リチウムイオンを吸収する

And this repeated expansion and contraction

低コストなうえ エネルギー密度が高く―

shortens the lifespan of the battery,

リチウムイオンと比べて安全

and ultimately, its usefulness.

リチウム硫黄電池の決め手の１つは―

But researchers like those at Enovix,

リチウムイオン電池より 50～60％軽量なことです

are aiming to fix this problem.

巨大な電池で走るバスを例とします

We don't eliminate anode expansion and contraction,

リチウム硫黄の技術に 取り替えられれば―

but we do control them.

重量を減らすことができて 走行距離が長くなります

Propendent 3D cell architecture

再生可能な交通システムの 大きな転換点となるでしょう

enables us to integrate

リチウム硫黄電池は まだ完璧でなく―

a very thin stainless steel constraint

多硫化リチウムの生成という課題がある

into our battery design.

シャトル効果として知られてる

This applies a uniform force around the battery

硫黄の電極も 膨張と収縮のサイクルを持ち―

to constrain the silicon expansion within the cell.

バッテリー効率や出力密度 エネルギー密度に影響する

during the charging cycles and during discharge.

解決策がアノードでもカソードでもなく―

MAREN: While some researchers have set their sights on the anode,

電解質なら？

others are experimenting with the cathode

ここで全固体電池の登場よ

with one innovation being lithium sulfur cells.

固体の電解質には歴史があり―

Lithium on its own is a very volatile substance.

安全性の向上が約束されていて 未来の電池候補として人気がある

It reacts to air, it reacts to water.

高分子固体は極限状態にも耐えるの

So what the OXIS scientists have done

熱せられれば液体のようになり 炎の中でも安全に機能する

is taken sulfur as a non-conductive, very cheap material.

研究者の中には 全固体電池で 電気自動車の航続距離が―

and used the sulfur to act as a fire retardant

805キロ以上になると言う人も

around lithium metal,

自由に想像してみよう

so that if air or water impacts lithium metal,

ワールドソーラーチャレンジの出場車に 全固体電池を搭載すれば―

thermal runaway, fire, explosion, doesn't take place.

航続距離が伸びるかも

Sulfur cathodes, like their silicon anode counterparts,

では全固体電池の弱点は何か？

can absorb more lithium ions

液体の電解質と違って 電極の隅々までは接触できないため―

than the typical cobalt-based cathodes.

電極間のイオンの移動と 必要な電流の生成が難しくなる

offering a reduced battery cost

でも これまでの革新技術を組み合わせれば？

with increased energy density and improved safety

我々は液体の電解質から 固体のリチウム硫黄へ―

compared to lithium-ion batteries.

転換できたのです

HUW: Because one of the key factors

削減の議論があるのは―

of lithium sulfur

ディーゼルエンジンのトラックやバス

is that it is 50 to 60% lighter than lithium-ion.

そして航空機が消費する加鉛ガソリン

Now, if you take a bus with a very large battery,

どれも人間が出す最大の汚染物質です

if you can replace that technology with lithium-sulfur

全固体電池は その達成を より現実的なものにしてくれます

and you reduce the weight and still

オクシスはソーラーカー市場に 参入してないけど―

extend the distance covered,

代わりに 航空機や船舶 電気自動車に注力している

then you have a major breakthrough

500ワット時毎キログラムという エネルギー密度が達成間近で―

in the renewable transportation systems.

600ワット時毎キログラムを次の目標に掲げてる

But lithium-sulfur cells are still not quite perfect

本質としては 将来 こうした電池で―

because they face the challenge

電気自動車が充電１回で 1,000キロ走る可能性があるということ

of lithium-polysulfide formation,

商業的に最も進出している テスラの パナソニック製リチウムイオン電池は―

or what's known as the polysulfide shuttle.

航続距離531キロなので約半分

The sulfur electrode also expands and contracts

どの電池の革新技術も印象的だった

as it cycles, which results in a loss of battery efficiency

でもソーラーカーの普及には―

and power and energy density.

高いエネルギー密度とバッテリー効率の 強力な蓄電システム

But what if the answer isn't in the anode or the cathode?

そして雨でも長距離を走れる性能が必要

What about the electrolyte?

これを達成できるものは市場になく 開発もされてない

Well, that's where solid state batteries come in.

だから ワールドソーラーチャレンジのような 大会が必要よ

Solid state electrolytes have been around for a while

こうした乗り物を作る時 人は限界まで技術を押し上げる

and have recently caught on

as a contender for future batteries

because of their promise of improved safety.

But solid state polymers can better withstand extreme conditions.

So when heated, they behave like liquids,

but they can operate without the danger of bursting into flames.

Some researchers believe that solid state batteries

could even give electric vehicles

over 500 miles of range.

And if we really let our imaginations run wild,

using solid state batteries in solar powered vehicles

like the ones that compete in the World Solar Challenge

could potentially lead to even longer ranges.

Now, what's the downside to these solid state batteries?

Well, unlike liquid electrolytes,

they can't stay in contact

with every bit of the electrodes all the time.

And this makes it harder for the ions

to move between electrodes

and create that flow of electricity that we need.

But what if we were able to combine

a few of these innovations that we've already talked about?

We could now make a transition

from liquid electrolyte to solid state lithium sulfur.

And I'm talking about removing the diesel trucks, diesel buses,

the lead based fuel that our aircraft consume.

These are the biggest pollutants that we've got on the planet,

and solid state is certainly the phenomenon

that will render those achievements more realistic.

MAREN: So OXIS Energy is currently not in the solar car market,

but is instead focusing on aerospace,

marine vessels, and electric vehicles.

They're close to achieving an energy density

of 500 watt-hours per kilogram

with their battery,

and have already set a new target

of 600 watt-hours per kilogram.

Essentially, that means a battery like this in the future

could be capable of powering an electric car

for 1,000 kilometers on a single charge.

By comparison, Tesla's Panasonic lithium-ion battery cells,

which are currently the most commercially advanced,

are about half as energy dense.

So all of the battery innovations we've covered

are definitely impressive.

But if we want more solar vehicles on the roads,

we're gonna need a powerful battery storage system

with high energy density, high efficiency,

and the ability to last long on the road, rain or shine,

because currently, none of the options on the market

or even in development totally do the job.

That's why it's important to have events like the World Solar Challenge,

'cause when creating a vehicle like this,

you're pushing technology to its limit.