Tesla’s road to a cheaper electric car has always appeared to lead straight to Reno, where the electric automaker is building a $5 billion gigafactory designed with enough capacity to reduce the per-kilowatt-hour cost of its lithium-ion battery packs by over 30% by the end of 2017.

    Many companies are already planning concepts around the promise of cheaper, higher-capacity batteries. But, it turns out that TeslaTSLA 0.40% has more than one path toward its ultimate goal of an electric car that’s 50% cheaper than its luxury Model S.

    The newest direction Tesla is headed toward is silicon—not the Valley, but the material that is changing the way batteries are made. Tesla’s new 90 kilowatt-hour battery pack—an upgrade announced Friday that increases pack energy by 5% and adds about 15 miles of range to its vehicles—might look the same. But the inclusion of silicon is an advance for lithium-ion technology.

    During a call with reporters last week, CEO Elon Musk said the company had improved the battery by shifting the cell chemistry for the pack to partially use silicon in the anode.

    “This is just sort of a baby step in the direction of using silicon in the anode,” Musk said during the call. “We’re still primarily using synthetic graphite, but over time we’ll be increasing silicon in the anode.”

    For the unfamiliar, this might sound like minor tinkering. It’s actually an important and challenging step for Tesla (and other battery manufacturers) that could lead to a better, cheaper battery.

    “It’s a race among the battery makers to get more and more silicon in,” said Jeff Dahn, a leading lithium-ion battery researcher and professor at Dalhousie University in Nova Scotia who recently signed a 5-year exclusive partnership with Tesla. “The number of researchers around the world working on silicon for lithium-ion cells is mindboggling. A large number of academics and industrial folks are working really hard on this problem.”

    Batteries 101

    A battery contains two electrodes: an anode (negative) on one side and a cathode (positive) on the other. An electrolyte, essentially the courier that moves ions between the electrodes when charging and discharging, sits in the middle.

    Graphite is commonly used as the anode in commercial lithium-ion batteries. However, a silicon anode can store about 10 times more (per unit volume) lithium ions. In theory, if you replaced a lot of graphite in the cell with silicon, the thickness of the graphite negative electrode could be reduced. There would be more space to add more active material and you could, in turn, increase the energy density—or the amount of energy that can be stored in a battery per its volume—of the cell.

    In other words, you could pack more energy in the same space. Plus, the silicon used in the battery space doesn’t need to be the same quality as what’s used in solar cells and integrated circuits, which means it’s cheaper. The more silicon you put in the battery, the easier it is to drive costs down.

    That’s the goal of battery makers everywhere: to improve their product while reducing costs.

    Sounds easy enough, right? Hardly, says Dahn, who is currently working on a project funded by 3M and the Natural Sciences and Engineering Research Council of Canada to develop longer lasting, lower cost lithium-ion battery cells. Their exclusive partnership with Tesla will begin in June 2016, once Dahn has completed the 3M research project.

    The trick is that when you add lithium to the silicon you end up with almost five times the original number of atoms you started with. And that causes all kinds of problems.

    特斯拉生产平价电动汽车的计划似乎总是指向内华达州的里诺市，该公司正在这里兴建价值50亿美元的超级电池厂，它的目标是在2017年底前获得足够的产能，以便将锂离子电池组的每千瓦时成本削减30%以上。

    许多公司都表示要降低电池价格并提高容量，并且正在确立相应的概念。特斯拉的最终目标是推出比Model S豪华电动汽车便宜一半的产品。实际情况表明，该公司有好几条路可走。

    特斯拉的最新方向是硅。不是硅谷，而是硅这种材料，它正在改变电池的生产方式。上周五，特斯拉展示了新的90千瓦时电池组，这种升级产品的容量提高了5%，可以让特斯拉的电动汽车多行驶15英里（约24公里）左右。虽然外观可能没有变化，但它使用了硅，这是锂离子电池技术的一个进步。

    上周，特斯拉首席执行官埃隆·穆斯克在电话里告诉记者，该公司对电池进行了改进，具体方法是在阳极中使用了一些硅材料，进而改变了电池的化学反应过程。

    穆斯克说：“我们的方向是用硅来做阳极，以上做法只是迈出一小步。我们用的主要材料仍是人造石墨，但我们会慢慢地在阳极中加入越来越多的硅。”

    对外行来说，这听起来也许跟镜面加工很像。而实际上，这样做有可能让电池变得更好、更廉价；对特斯拉（和其他电池制造商）来说，它既重要又难度极大。

    加拿大新斯科舍省戴尔豪西大学锂离子电池首席研究员杰夫·达恩教授最近和特斯拉签订了为期五年的独家合作协议。他说：“电池厂商正在争相提高电池中的硅含量。在全球锂离子电池领域，正在进行硅课题攻关的研究人员不计其数。许多学术界和实业界人士也在非常努力地钻研这个问题。”

    锂离子电池小科普

    电池有两端，一端是阳极，另一端是阴极，二者之间是电解液。在充电和放电过程中，离子通过电解液在两极之间移动。

    商用锂离子电池的阳极一般由石墨制成。如果用硅制作阳极，其单位体积锂离子容量可达到前者的10倍左右。理论上，如果用硅大量取代石墨，石墨阴极就可能变细，从而扩大容纳活性材料的空间。这样就可以提高电池的能量密度，也就是单位体积能量存储能力。

    换句话说就是，尺寸不变，能量增多。同时，在锂离子电池中，硅的质量不需要像太阳能电池或集成电路中那么高，这就意味着价格较低。电池中的硅越多，就越容易降低成本。

    这就是所有电池厂商的目标——提高产品质量，降低成本。

    听起来很容易吧？但达恩说，难得很。达恩正在3M或者加拿大自然科学与工程研究理事会资助的一个项目中，这个项目就是要开发持续时间更长、成本更低的锂离子电池。完成了3M的研究项目后，达恩将从2016年6月开始和特斯拉进行独家合作。

    把锂和硅放在一起的难点在于，最终出现的原子数量几乎是初期的五倍，而这会带来各种各样的问题。

    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.

    参加聚会的电极颗粒

    达恩解释说，大家可以把电池电极想象成一个房间，电极中的大量颗粒就像在房间里聚会的人。如果这些人都突然变得很胖，房间里就装不下那么多人了。

    他说：“如果大家都挤了进去，然后他们都变得有400磅重，那就会带来大麻烦。”

    用硅制作所有电极颗粒就会出现这样的情景。但如果房间里只有一些人变胖，问题就不那么大，大家可以挪动一下，给胖人留下足够的空间。

    达恩指出：“最初只添加少量硅的原因就在这里。”

    但使用硅材料的问题还不止于此。我们还用上面的比喻来解释，大家可以想象一下，这些胖人（或者说较大的电极颗粒）在充电时变瘦，放电时再次变胖。其体积的大幅变化会引发另一个问题。所有硅电极颗粒都浸泡在电解液中，当它们变大时，就会不断拉伸包裹着它们的保护膜；当它们缩小时，保护膜则有可能脱落，这可能影响到电池的使用寿命。

    达恩说，这种情况意味着用的硅越多，电池的寿命就越难保证。

    这就是目前电池厂商和研究人员的处境。

    达恩说：“眼下只能加一点点硅，就像洒魔粉那样，这样的量还可以接受。几年后，硅会用得越来越多。这是件好事，因为它意味着这些产品会越变越好。”

    达恩的研究团队打算既提高锂离子电池的能源密度，又延长它的使用寿命。这或许有助于降低电动汽车和电网能源存储的成本。但正在这么做的不光是他们。达恩指出：“世界上有好些公司都在往阴极里添加硅。不仅仅是为特斯拉提供电池的松下，三星和其他一些公司也在这样做。”

    萨姆·杰斐曾在清洁能源研究和分析机构Navigant Research长期从事分析工作，现在他是初创公司Cygnus Energy Storage的首席执行官。他认为，目前大多数电池中的硅含量都非常低，包括消费电子产品使用的电池。

    问题在于特斯拉用了多少硅。杰斐说，业界标准是硅占电池原材料的1-3%。他认为特斯拉已经找到了提高硅含量的办法。

    他指出：“特斯拉已经显著改变了电池的能源密度，而且公开宣称是硅让他们做到了这一点，这让我觉得他们在提高电池硅含量方面已经取得了进展。当然，现在这只是猜测。”

    Model X和作为供应商的特斯拉

    车辆估值及汽车市场研究机构Kelley Blue Book高级分析师卡尔•布劳尔对《财富》杂志表示：“所有业内人士都有很大的动力来不断改进电池技术。这当然是特斯拉的命根子。”

    他说，特斯拉的Model X SUV备受期待，为此该公司必须提高电池容量。这是因为Model X较重，不提高电池容量的话，行驶里程就会缩短。

    布劳尔认为，特斯拉把精力集中在电池技术上不光是为了做出更好的汽车，它还想转型为供应商。

    许多公司都预计价格更低、性能更好的锂离子电池将投入使用，并且争相把这项技术用于民用和商用电网中。上述举措有可能让特斯拉成为这个新兴革命性能源行业中的领跑者。（财富中文网）

    译者: Charlie

    校对：詹妮