兼具液态/固态电池优点 科学家发明室温工作的全液态金属电池

液态电池和固态电池各有优缺点，不过来自德克萨斯大学奥斯汀分校的研究团队声称找到了同时兼顾这两种电池优点的全新电池。科研团队称这是首款可以在室温环境下正常工作的全液态金属电池，而且各项性能明显优于传统锂离子电池。

常见液态金属电池的电极由液态金属制成，相比较固态电池的好处是不会形成枝晶(dendrites)，从而破坏电池组件。而且这种电池非常容易扩大规模，只需要在更大的罐子中添加更多液体就可以了。

但液态金属电池有个缺点，就是温度。为了使金属保持液态，这些电池大多需要加热到至少240°C（464°F）。而做到这一点，会让电池变得笨重和耗能。

在最新的研究中，该科研团队发现了在室温状态下能够保持液态的合金。他们确定了两种工作良好的合金，使用钠钾合金作为阳极，而使用镓铟合金作为阴极。这些电池能够在20°C（68°F）的温度下保持液态，该团队称这是所有全液态金属电池的最低工作温度。

两个液态金属电极被中间的有机电解液隔开，电解液也是液态的。该团队表示，新电池的充放电速度可以比锂离子电池快几倍，并且具有很高的能量和功率密度。该团队表示，随着温度障碍的消除，新的液态金属电池有可能开始用于为各种规模的电子产品供电，从小型可穿戴设备到电网规模的储能系统。

该研究的主要作者 Yu Ding 表示“这种电池可以提供固态和液态的所有优点--包括更多的能量、更高的稳定性和灵活性--而没有各自的缺点，同时还能节省能源。”

尽管如此，仍有很大的改进空间。镓的价格有点贵，所以团队计划研究其他更常见的材料制成的合金。其中一些其他材料也有可能让电池在更低的温度下工作。更具导电性的电解质也可以帮助提高功率输出。

原文如下：

AUSTIN, Texas — Researchers in the Cockrell School of Engineering at The University of Texas at Austin have built a new type of battery that combines the many benefits of existing options while eliminating their key shortcomings and saving energy.

Most batteries are composed of either solid-state electrodes, such as lithium-ion batteries for portable electronics, or liquid-state electrodes, includingflow batteriesfor smart grids. The UT researchers have d what they call a “room-temperature all-liquid-metal battery,” which includes the best of both worlds of liquid- and solid-state batteries.

Solid-state batteries feature significant capacity for energy storage, but they typically ener numerous problems that cause them to degrade over time and become less efficient. Liquid-state batteries can deliver energy more efficiently, without the long-term decay of sold-state devices, but they either fall short on high energy demands or require significant resources to constantly heat the electrodes and keep them molten.

The metallic electrodes in the team’s battery can remain liquefied at a temperature of 20 degrees Celsius (68 degrees Fahrenheit), the lowest operating temperature ever recorded for a liquid-metal battery, according to the researchers. This represents a major change, because current liquid-metal batteries must be kept at temperatures above 240 degrees Celsius.

“This battery can provide all the benefits of both solid- and liquid-state — including more energy, increased stability and flexibility — without the respective drawbacks, while also saving energy,” said Yu Ding, a postdoctoral researcher in associate professor Guihua Yu’s research group in the Walker Department of Mechanical Engineering. Ding is the lead author of a paper on the room-temperature battery the team published recently inAdvanced Materials.

The battery includes a sodium-potassium alloy as the anode and a gallium-based alloy as the cathode. In the paper, the researchers note that it may be possible to  a battery with even lower melting points using different materials.

The room-temperature battery promises more power than today’s lithium-ion batteries, which are the backbone of most personal electronics. It can ge and deliver energy several times faster, the researchers said.

Because of the liquid components, the battery can be scaled up or down easily, depending on the power needed. The bigger the battery, the more power it can deliver. That flexibility allows these batteries to potentially power everything from smartphones and watches to the infrastructure underpinning the movement toward renewable energy.

“We are excited to see that liquid metal could provide a promising alternative to replace conventional electrodes,” Professor Yu said. “Given the high energy and power density demonstrated, this innovative cell could be potentially implemented for both smart grid and wearable electronics.”

The researchers have spent more than three years on this project, but the job isn’t done yet. Many of the elements that constitute the backbone of this new battery are more abundant than some of the key materials in traditional batteries, making them potentially easier and less expensive to produce on a large scale. However, gallium remains an expensive material. Finding alternative materials that can deliver the same performance while reducing the cost of production remains a key challenge.

The next step to increasing the power of the room-temperature battery comes in improving the electrolytes — the components that allow the electrical ge to flow through the battery.

“Although our battery cannot compete with high-temperature, liquid-metal batteries at the current stage, better power capability is expected if advanced electrolytes are designed with high conductivity,” Ding said.