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经济学人下载:让乌龟和兔子交配(2)

2020-11-13来源:Economist

Capacitors, by contrast—whether basic or "super"—consist of a pair of electrically conductive plates placed either side of a separator material. When a voltage is applied to these plates, a positive charge builds up on the surface of one and a corresponding negative charge on the other. Connect the plates through an external circuit and, as with a battery, a current will then flow. 

相比之下,无论是碱性电容器还是超级电容器,都是由一对导电板组成,它们分别位于隔膜材料的两侧。当导电板被施加电压时,其中一块导电板的表面产生正电荷,另一块导电板的表面则产生相应的负电荷。之后通过外部电路将两块导电板进行连接,就像电池一样,电流就会开始流动。

Making the leap from a basic capacitor to the super variety involves two things. One is to coat the plates with a porous material such as activated carbon, to increase the surface area available for energy storage. The other is to soak them in an electrolyte. This creates yet more storage area in the form of the electrolyte's boundary with the plates. But adding an electrolyte to the mix also brings the possibility of adding a bit of battery-like electrochemistry at the same time. And Skeleton Technologies, an Estonian supercapacitor firm, plans to do just that. 

从基础电容器到超级电容器的飞跃涉及两点。一点是要在导电板上涂上如活性炭等的多孔材料以增加存储能量的可用表面积,另一点是要将它们浸泡在电解质中,这样就能在电解质与极板的边界处形成更多的存储区域。不过,在混合物中加入电解质的同时可能也会加入一些类似电池的电化学元素。爱沙尼亚的一家超级电容器公司“骨架技术”正计划这样做。

Plate tectonics 

导电板构造

Skeleton has already developed plates composed of what it calls "curved" graphene, for a new range of straightforward supercapacitors. Ordinary graphene is a single layer of carbon atoms arranged in a hexagonal grid. It is highly conductive. Skeleton's curved variety consists of crumpled sheets of the stuff. The consequent increase in surface area will, the firm hopes, push the energy density of its new products to 10-15wh/kg—a good fraction of the theoretical maximum for a supercapacitor of 20-30wh/kg. 

骨架公司已经开发出一种由所谓的“弯曲”石墨烯组成的导电板,用于一系列新的简单的超级电容器。普通石墨烯是一层排列成六边形网格的碳原子,导电性很强,而骨架公司的“弯曲”石墨烯则是由褶皱的材料组成的。该公司希望由此增加的表面积能将其新产品的能量密度提高到10-15wh/kg——即一个20-30wh/kg的超级电容器理论上能够达到的最大值的一个不错的节点。

That, though, is just the start of Skeleton's plan. The firm's engineers are now working with the Karlsruhe Institute of Technology, in Germany, to use curved graphene in what it calls its "SuperBattery". Though this remains basically a supercapacitor, storing most of its charge electrostatically, the electrolyte will, says Sebastian Pohlmann, Skeleton's head of innovation, also provide some chemicalenergy storage. The company is keeping mum about the electrolyte it uses and the chemistry involved. "It is not comparable to the classic lithium-ion chemistry," is all that Dr Pohlmann will say. But the overall consequence, he claims, will be something that is rechargeable within 15 seconds and has the ability to store 60wh/kg. Skeleton aims to start producing this commercially by 2023. 

而这只是骨架公司计划的开胃小菜。该公司的工程师正在和德国卡尔斯鲁厄理工学院合作,将弯曲石墨烯用于所谓的“超级电池”当中。骨架的创新负责人塞巴斯蒂安·波尔曼说,虽然它本质上还是一个超级电容器,以静电方式储存大部分电荷,但电解质也能提供一些化学能量储存。然而,该公司对其使用的电解质和所涉及的化学成分闭口不提。波尔曼博士只是说:“传统的锂离子化学无法和它相提并论。”他声称,最后的成果就是,该电池可以在15秒内充满电并储存60wh/kg的能量。骨架公司计划于2023年前对该超级电池进行商业化生产。

Other groups, too, are working on ways to add chemical-energy storage to a supercapacitor. Researchers at Graz University of Technology in Austria, for example, have developed a version that has its electrical contacts coated with carbon which is pierced by tiny pores. One contact operates like a capacitor plate, the other like a battery electrode. Unlike Skeleton, the Graz group are open about their approach to electrolyte chemistry. They are using aqueous sodium iodide (ie, a solution of sodium ions and iodine ions). At the electrode, the iodide turn into elemental iodine, which crystallises within the pores during discharge. This process then reverses itself when the device is charging. The pores in the plate serve to accommodate sodium ions similarly. 

其他研究小组也在研究如何为超级电容器增加化学能量存储。例如,奥地利格拉茨科技大学的研究人员已经开发出了一种电触点上涂着能被小孔穿透的碳的电池。其中一个电触点相当于一个电容板,另一个电触点相当于电池的电极。和骨架公司不同的是,格拉茨小组对电解液化学的研究方法持开放态度。他们使用的是碘化钠水溶液(即钠离子和碘离子的溶液)。碘离子在电极上转化为碘元素,在放电过程中在小孔中结晶。当设备进行充电时,这一过程会反过来进行。电容板上的孔也同样用于容纳钠离子。