????參加聚會的電極顆粒

????達恩解釋說，大家可以把電池電極想象成一個房間，電極中的大量顆粒就像在房間里聚會的人。如果這些人都突然變得很胖，房間里就裝不下那么多人了。

????他說：“如果大家都擠了進去，然后他們都變得有400磅重，那就會帶來大麻煩。”

????用硅制作所有電極顆粒就會出現這樣的情景。但如果房間里只有一些人變胖，問題就不那么大，大家可以挪動一下，給胖人留下足夠的空間。

????達恩指出：“最初只添加少量硅的原因就在這里。”

????但使用硅材料的問題還不止于此。我們還用上面的比喻來解釋，大家可以想象一下，這些胖人（或者說較大的電極顆粒）在充電時變瘦，放電時再次變胖。其體積的大幅變化會引發另一個問題。所有硅電極顆粒都浸泡在電解液中，當它們變大時，就會不斷拉伸包裹著它們的保護膜；當它們縮小時，保護膜則有可能脫落，這可能影響到電池的使用壽命。

????達恩說，這種情況意味著用的硅越多，電池的壽命就越難保證。

????這就是目前電池廠商和研究人員的處境。

????達恩說：“眼下只能加一點點硅，就像灑魔粉那樣，這樣的量還可以接受。幾年后，硅會用得越來越多。這是件好事，因為它意味著這些產品會越變越好。”

????達恩的研究團隊打算既提高鋰離子電池的能源密度，又延長它的使用壽命。這或許有助于降低電動汽車和電網能源存儲的成本。但正在這么做的不光是他們。達恩指出：“世界上有好些公司都在往陰極里添加硅。不僅僅是為特斯拉提供電池的松下，三星和其他一些公司也在這樣做。”

????薩姆·杰斐曾在清潔能源研究和分析機構Navigant Research長期從事分析工作，現在他是初創公司Cygnus Energy Storage的首席執行官。他認為，目前大多數電池中的硅含量都非常低，包括消費電子產品使用的電池。

????問題在于特斯拉用了多少硅。杰斐說，業界標準是硅占電池原材料的1-3%。他認為特斯拉已經找到了提高硅含量的辦法。

????他指出：“特斯拉已經顯著改變了電池的能源密度，而且公開宣稱是硅讓他們做到了這一點，這讓我覺得他們在提高電池硅含量方面已經取得了進展。當然，現在這只是猜測。”

????Model X和作為供應商的特斯拉

????車輛估值及汽車市場研究機構Kelley Blue Book高級分析師卡爾?布勞爾對《財富》雜志表示：“所有業內人士都有很大的動力來不斷改進電池技術。這當然是特斯拉的命根子。”

????他說，特斯拉的Model X SUV備受期待，為此該公司必須提高電池容量。這是因為Model X較重，不提高電池容量的話，行駛里程就會縮短。

????布勞爾認為，特斯拉把精力集中在電池技術上不光是為了做出更好的汽車，它還想轉型為供應商。

????許多公司都預計價格更低、性能更好的鋰離子電池將投入使用，并且爭相把這項技術用于民用和商用電網中。上述舉措有可能讓特斯拉成為這個新興革命性能源行業中的領跑者。（財富中文網）

????譯者: Charlie

????校對：詹妮

????An Electrode Particle Walks Into a Party

????Think of the battery electrode as a room and a lot of electrode particles—or people— are packed in there for a party, Dahn explains. Now imagine that everybody in that room suddenly becomes obese; the people aren’t going to fit anymore.

????“If everyone is already packed in there and they all become 400 pounds, you’re in big trouble,” says Dahn.

????This is what happens when all the particles in the electrode are silicon. But if only a few people in the room become obese, it’s not so bad because they can shuffle around and make enough space for these obese folks.

????“This is why only a small amount of silicon is being initially added,” Dahn says.

????That’s not the only issue with using silicon. To take the crowded room analogy a step further, imagine these obese people (or electrode particles) shrink when the battery is charged and then blow up again when it’s discharged. That enormous volume change causes another issue. The surface of every silicon particle is in contact with the electrolyte, and the protective film on the silicon is continually being stretched as the size of those particles change. When it shrinks it can flake off, which can impact the lifespan of the battery.

????This means that the more silicon you put in, the more challenging it is to maintain cycle life, Dahn says.

????Which brings us to where battery makers and researchers are today.

????“Right now, you put in a touch—a little pixie dust—and it’s tolerable,” says Dahn. “Over the years, more and more will go in and that’s a good thing because it means these products are going to improve and get better.”

????Dahn’s research team aims to increase both the energy density and the lifespan of lithium-ion cells, which could, in turn, help drive down costs in automotive and grid energy storage applications. They aren’t the only ones. “There are quite a few companies around the world that are starting to put silicon in the negative electrode,” explains Dahn. “And it’s not just Panasonic, Tesla’s supplier. Samsung and other companies around the world are doing this too.”

????Most batteries today, even those in consumer electronics, have tiny amounts of silicon, says Sam Jaffe, a longtime analyst, formerly of Navigant Research, and now CEO of startup Cygnus Energy Storage.

????The question is what percentage of silicon is Tesla using. The industry standard is between 1 to 3% silicon in battery recipes, Jaffe says. He believes Tesla has figured out how to use more.

????“For them to have made a significant change in the energy density of the battery and then to publicly say it’s the silicon increase makes me think—and this is speculation now—that they’ve made progress getting higher percentages of silicon into the cell,” Jaffe says.

????Model X and Tesla as a Supplier

????“There’s a lot of incentive to continue to improve this battery technology for everyone in the industry,” Karl Brauer, a senior analyst at Kelley Blue Book, told Fortune. “It’s certainly the lifeblood for Tesla.”

????Tesla had to increase the battery capacity for the highly anticipated Model X SUV because it’s heavier and without it, the vehicle would have lost range, Brauer says.

????Brauer also believes the focus on battery tech isn’t just to improve the cars, but to set the company up as a supplier.

????With many companies already anticipating the use of cheaper, more powerful lithium-ion batteries and competing to apply that technology to residential and commercial power grid applications, Tesla’s move could put them at the forefront of a newly revolutionized energy industry.