A Serious Contender To Lithium-Ion Batteries
Sodium batteries are among the more advanced challengers to lithium ion dominance but, like other alternatives to Li-ion batteries, they have been plagued by persistent problems with their performance. Now, a team of South Korean scientists have reported an improvement that could bring sodium batteries into the spotlight.
The team reports in a study published in Advanced Science that they had made an electrode for their sodium battery of copper sulfide and that the compound had displayed superior properties in terms of durability. Based on the findings, the researchers say a sodium battery with copper sulfide electrodes could last for as long as five years if charged once daily.
This is obviously early days. Five years is not so long, and the once-a-day charging condition is quite limiting. Yet there is clearly an international drive to advance sodium batteries as an alternative to lithium ion ones.
The allure of sodium—cheap, abundant, and the right chemistry for batteries—has been growing, and there are already functioning projects.
Last year, scientists from the Australian University of Wollongong announced that they had solved one problem with sodium batteries that had made them too expensive to produce: namely the materials. Some of these materials were sensitive to air, which made it challenging to produce the batteries cheaply enough to make them commercially viable and guarantee a certain level of performance.
This year, researchers from the Nagoya Institute of Technology in Japan said they’d found a way around the main obstacle for swapping lithium with sodium: the larger size of the ions in sodium and its different chemistry. They did this by finding a sodium compound that displayed a crystal structure that was compatible with battery use, along with a favorable electric structure and electrochemical properties. The compound yielded shorter charging times than lithium-ion batteries and a potentially longer battery life.
Meanwhile, other areas of research are yielding results that could be used across battery types. One such area is electrode coating, where German scientists in June announced a promising breakthrough. They developed a new coating process that coats electrodes with dry film rather than a liquid. Seemingly insignificant, the process is much less energy-intensive than the liquid coating one, and it does not involve toxic solvents. Ultimately, it’s better than the standard coating process, and it’s cheaper.
Cost is the number-one problem with batteries. They are the most expensive component of an electric vehicle and as such, the biggest obstacle to mass adoption of EVs. Getting the cost down is tricky: drivers want longer ranges and longer productive lives from their car batteries, and that goes counter to most standard cost-cutting tactics.
So, battery researchers are looking for new ways to reduce battery costs, whether by replacing one key element with another, as in the case of swapping sodium for lithium and copper sulphide for other chemicals, or improving other parts of the battery manufacturing process such as electrode coating.
It’s worth noting, however, that most battery-related breakthroughs in the news are reported from the lab, and despite assurances that the technology is potentially scalable, few have been actually tested. According to the Korean scientists that revealed the superior properties of copper sulphide as electrode material, their discovery would bring sodium batteries a step closer to scalability: the ultimate test for success.
By Irina Slav for Oilprice.com
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