Lithium batteries lie down in extremely low temperatures? Scientists come up with new solutions

In order to explore more promising lithium batteries, scientists have all turned their attention to metal anode solutions based on pure lithium, rather than the currently widely used hybrid materials. At the same time, in order to overcome the shortcomings of its poor performance at low temperatures, scientists in this field have also been 'struggling their brains' and have made some breakthroughs. According to reports, the research team at the University of California, San Diego (UCSD) is trying to develop a battery that can be charged and discharged at extremely low temperatures, which usually requires an additional heating system, but this time they focused on the electrolyte. , Relying on the weak bonding in the electrolyte, the lithium metal battery releases unprecedented performance under cold conditions. It is understood that compared with the currently used graphite/copper hybrid anode, the pure lithium metal anode has an excellent energy density, so it is considered a very promising technology. In the face of such a big difference, some battery researchers even describe lithium metal as a 'dream material' and regard it as the key to breaking the energy density bottleneck. As a solution that carries lithium ions back and forth between the two poles of the battery during the cycle, the importance of the electrolyte in a battery is self-evident. The goal of the UCSD research team this time is to develop an electrolyte that does not freeze, allowing lithium ions to move in cold environments. Specifically, the researchers used two types of electrolytes for experiments, one of which can be firmly bound to ions, and the other is much weaker, to verify which situation is more suitable for low-temperature conditions. It was found that in an environment of -60°C (-76°F), this group of experimental batteries using a firmly bonded electrolyte could only last for two cycles, and then stopped working. In contrast, batteries using weakly bound electrolytes can still run smoothly after 50 cycles and maintain a capacity of 76%. If the operating temperature is changed to -40°C (-40°F), this solution can even maintain 84% of the capacity. John Holoubek, the first author of the study, said, 'We found that the combination between lithium ions and the electrolyte, and the structure occupied by the ions in the electrolyte, have a great correlation with their performance at low temperatures.' It is worth mentioning that, Further research on such proof-of-concept batteries also shows that weakly bound electrolytes can allow ions to be deposited more uniformly on the battery anode, while strong bound electrolytes can lead to massive and needle-like deposition (dendrites). This is another focus of attention of scientists studying lithium metal batteries, because they can quickly cause serious failures such as battery short-circuits and failures. The researchers stated that “by understanding the interaction between lithium ions and electrolytes at the atomic level, not only can the low-temperature performance of lithium batteries be improved, but it can also help prevent the formation of dendrites.” Based on these findings, the research team established a Prototype of lithium metal battery with sulfur-based cathode and weakly bound electrolyte. It is said that this equipment will be expected to play an important role in areas such as outer space exploration and deep sea exploration. 'The significance of this work is actually twofold,' the researchers said. From a scientific point of view, it puts forward insights that are contrary to traditional views. Technically speaking, this is the first lithium metal battery that can be charged at ultra-low temperatures. It can also provide considerable energy density when fully operated at -60 degrees Celsius. Both of these aspects provide a complete solution for ultra-low temperature batteries.