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2018-4-22 19:30| 发布者: dymodel| 查看: 592| 评论: 0|原作者: green

摘要: 廉价的可再生能源,可以储存更环保,更安全的液体电池。在哈佛大学开发的一个新的流体电池,取村非常丰富,便易而且安全环保。


Greener, safer flow battery could store renewable energy on the cheap

A new flow battery developed at Harvard University uses only Earth-abundant materials, making it cheaper, safer and greener than previous designs 

Improving on their previous design, scientists at Harvard University have developed a cheap and highly adaptable flow battery that could prove ideal for storing renewable energy throughout the day. The battery is made using Earth-abundant materials, is much safer than previous designs, and could reach the market in as little as three years.

Lithium-ion batteries are great for smartphones and electric SUVs, but they may not be the best solution to handle the stresses that solar and wind power put on the electric grid. To get the most out of renewables, we need something more flexible, scalable, and most importantly, cheaper than a solid-state battery (Elon Musk would have you use lithium-ion cells for home storage too, but his entry-level Powerwall goes for US$3,000).

So-called flow batteries could be the perfect solution. Such devices store energy in liquid form, in external tanks, and collect or release power by having those liquids exchange ions through a special membrane. This makes flow batteries extremely flexible: their capacity can be tweaked by modifying the size of the tanks, and their power output can be changed by adjusting the area of the membrane. Flow batteries can also remain idle for long periods of time without losing charge and are not affected by temperature extremes.

Prof. Michael Aziz and team have now built on previous work to design a safer and greener flow battery. Their device relies on cheap and abundant elements like carbon, iron and potassium to form compounds that are nontoxic, fire-resistant and generally safer. As such, the battery might find a place in our homes to store the intermittent energy produced by solar panels (or portable wind turbine, if you've got one).

Flow batteries are a relatively new technology and, to put it mildly, their first generation didn't feature the best choice of materials. Such batteries have commonly used vanadium and bromine dissolved in acid as their electrolytes (energy-carrying liquids). Though effective, this combination is expensive, dangerous and even toxic.

In last year's development Aziz and his team designed a flow battery that dropped the vanadium for the more environmentally friendly quinones – naturally occurring chemicals involved in photosynthesis. Their latest battery improves on this by replacing bromine with ferrocyanide, which is commonly added to kitchen salt as an anticaking agent.

The new battery also works in an alkaline, not acidic, solution. The higher pH is less corrosive, allowing the tanks to be built out of plastic instead of heavier and more expensive metals. An alkaline environment creates more electrical resistance in the membrane, but this was compensated by increasing the battery's voltage.

According to the team, the cell's current efficiency exceeded 99 percent, while round-trip efficiency was measured at 84 percent. The data also suggests that the battery will have a lifetime of at least 1,900 cycles, which is much longer than a lithium-ion battery.

The Achilles' heel of the technology appears to be its low energy density, or amount of energy that can be stored inside the battery per unit volume. The researchers achieved 19 Wh per liter in their published study, and slightly higher figures using methods they've developed since.

This falls well short of lithium-ion batteries, which are closer to the 300 Wh/L mark. That could make a home-use flow battery out of the question for some (you'll most likely need a roomy basement). But for large-scale applications at the grid level, where space isn't such a concern and cost is the primary issue, these cheap, highly adaptable cells could prove to be the perfect solution.

The scientists are now working on improvements to increase cycle life and reduce the cost of the membrane. They tell us the battery could become commercially available in about three years' time.

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锂离子电池是伟大的智能手机和电动SUV,但他们可能无法处理,太阳能和风力发电在电网中的应力的最佳解决方案。为了获得最大的可再生能源,我们需要更灵活的,可扩展的,最重要的是,比一个固态电池便宜(Elon Musk要你使用锂离子电池为家庭存储太多,但是他的入门级的Powerwall都是3000美元)。
Michael Aziz教授和团队现在已经建立在以前的工作,设计一个更安全,更环保的电池。他们的设备依靠廉价和丰富的元素,如碳、铁和钾的形式,是无毒的化合物,和一般的安全防火。因此,电池可能会在我们的家中找到一个地方储存太阳能电池板(或便携式风力涡轮机,如果你有一个)产生的间歇性能量。
这远低于锂离子电池,这是接近300瓦时/ L的标志。这可以使一个家庭使用的液流电池出问题了(你可能需要一个宽敞的地下室)。但在网格级的大规模应用,其中的空间是不是这样的关注和成本是首要问题,这些廉价的,高度适应能力的细胞可以被证明是完美的解决方案。






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