电池技术革新依然遥遥无期

    今后我们可能会使用空气

    IBM研究院(IBM Research)科技部主任钱德拉塞卡尔•纳拉延是电池500项目(Battery 500 Project)的成员。该项目的目标是，开发能够提供行驶500英里路程所需电量的电池。IBM公司自身并不会生产电池，而是与消费类产品制造商开展合作，将这一技术带到现实中。

    经过多年的努力之后，纳拉延看到了锂-空气技术的前景，即用汽车自身补给的氧气取代石墨和其他的金属。这类电池可以变得更轻，更安全，而且供电时间也更长。但是研发新的混合物，将它们制成新材料，并检测其在数千辆汽车上的安全性，需要花费非常漫长的时间。

    纳拉延说：“目前没有一个指导性原则显示，我们能够年复一年地获得进步，也没有捷径可以走。要得到这种范式，唯有创建一种全新的化学反应，而这一点并非创新所能企及的。”

    当前，锂-空气电池必须克服堵塞、内部腐蚀和稳定性问题。即便空气电池能够顺利地演变为一种可行产品，纳拉延认为，在今后，电池技术将不再是“通用型”。“例如，对于电网存储来说，它或许不是什么好技术。尤其是有尺寸要求的行业，我们或许很快将看到多种多样的电池类型。”

    当前我们能做些什么：降低价格

    凯特林大学（Kettering University）的凯文•白和周轩（音译）在实验室中从事电池行业研究，但他们的谈吐更像是买车人而不是实验室的书呆子。周轩表示，现今的混合动力车存在多方面的优缺点。

    周轩说：“目前，混合动力的售价是每千瓦时500-600美元，但合理的价格应该是200美元。而且冷却系统的价格跟电池的价格是差不多的。如果汽车需要6,000美元的电池，那么就需要6,000美元的冷却系统。”此外，凯文•白指出，这类电池的体积蚕食了本应属于后备箱或乘坐的空间。两位科学家也认为，电动汽车不应给人们带来沉重的财务负担。

    但是谁也不知道，哪些现有材料才能构造出最安全、发热量最低和重量最轻的电池混合材料，而且其价格要比现有的产品便宜。

    现今在助听领域使用的锌-空气电池重新激起了人们的兴趣，而且尤为重要的一点在于，锌很容易获取。钠-空气电池也是一样，成本更低，而且组装起来更容易，只是潜在功率赶不上锂-空气电池。人们还尝试过用硅来取代石墨和固体碳，但是硅并不便宜。或者，我们可以只专注于改善实验室和摩托车使用的锂-铁电池的成本和性能。

    凯文•白表示，建造更大规模的电池厂、开发更好的电池管理工具以及更加智能的充电电网在很多方面要比等待一两项新化合物获得成功更为实在。

    凯文•白说：“我们实际上离使用全新电池的交通工具还很远很远。只有在新材料经过10年的测试之后，汽车行业才能放心使用新材料。”他表示，人们至少要等到2020年才能看见使用锌-空气电池的四轮车辆，然后，人们需要更长的时间才能看到这一电池技术的成熟。

    What we might use next: air

    Chandrasekhar “Spike” Narayan, director of science and technology at IBM Research, is part of the Battery 500 Project. The goal is to get batteries to power a car of average cost on a 500-mile trip. IBM won’t build the batteries itself, but will partner with manufacturing and consumer companies to get them into the wild.

    After years of work, Narayan sees a future for lithium-air technology, which replaces graphite and other metals with oxygen, refreshed by the car itself. Such batteries could be lighter, safer, and last far longer. But working with new mixtures, pushing them into new materials, and seeing how safe they are over thousands of charge cycles takes a very, very long time.

    “There is no guiding principle that suggests you get improvement from year to year,” Narayan says. “There is no magic knob you can turn. The only way we can get to that kind of paradigm is a completely new kind of chemistry, and innovation doesn’t work like that.”

    Currently, lithium-air batteries have to overcome problems with blockages, internal rust, and stability. Even if air batteries are smoothed into a viable product, Narayan sees a future where battery technology is no longer one-size-fits all. “It may not be a great technology for power grid storage, for example. Especially when there is a size requirement, we may see differentiation among battery types soon.”

    What we can do in the meantime: get cheaper

    Kevin Bai and Xuan “Joe” Zhou at Kettering University work in labs and in battery industry research, but they talk like car shoppers than laboratory wonks. With the hybrid vehicles of today, Zhou notes, there are lots of trade-offs, in several ways.

    “Right now [hybrid] batteries are selling for $500 to $600 per kilowatt hour, but they should be $200,” Zhou says. “And every dollar you spend in the battery is another dollar in cooling. If the car needs a $6,000 battery, it’s a $6,000 cooling system.” What’s more, Bai notes, the size of such a battery eats up trunk or seating space. The scientists agree that an electric vehicle should feel like less of a financial albatross.

    But it’s anybody’s guess as to which current materials may work out to have the safest, coolest, and most lightweight mix, while still selling for less than today’s offerings.

    Zinc-air batteries, used in hearing aids today, are seeing renewed interest, especially given zinc’s easy availability. The same goes for sodium-air, which are cheaper and easier to assemble, if not as potentially powerful as lithium-air. There are also attempts to replace the graphite and carbon solids in batteries with silicon, though silicon isn’t cheap. Or we might just improve the cost and performance of the lithium-iron batteries in our drills and motorcycles in the meantime.

    In many ways, Bai says, building larger battery plants, better battery management tools, and a smarter power grid for charging is going to bear greater fruit than waiting on one or another chemical combo to pay off.

    “We are actually very far away from a brand-new battery for vehicles,” Bai says. “The automotive industry, they must feel they can stand behind 10 years of testing before they are comfortable trying a new material.” It will be at least 2020, he says, before you see zinc-air batteries in the first four-wheeled vehicles–and then a long while more before that battery technology matures.