Ten times! The new graphene greatly increases the capacity of sodium batteries, which may be comparable to lithium batteries in the future.

Whether it's making a special Bubble as a thermal switch or mixing it with ceramics to form a super-strong electrolyte, graphene is shaping the future of battery technology in some interesting ways. Now, scientists from Sweden have applied the magic material to sustainable sodium batteries, increasing their capacity by more than ten times that of traditional sodium batteries.

On the way to improve and create battery design, scientists are attracted by the rich sodium in the earth and regard sodium as an excellent substitute for lithium-ion batteries. These sodium-ion batteries function much like today's lithium-ion batteries, generating electricity by shuttling ions between a pair of electrodes in a liquid electrolyte, but for now, their performance is not satisfactory.

Part of the reason is that sodium ions are larger than lithium ions, so they do not blend well with graphite electrodes composed of graphene stacks. In general, when the battery is cycled in a process called intercalated (intercalationintercalation), the ions will move freely in and out of the graphite electrode, but the larger sodium ions cannot be effectively stored in the structure. This seriously affects the performance of sodium-ion battery, so that its capacity is about 35 mAh/g, which is the same as that of lithium-ion battery.

To find a solution to this problem, scientists at (Chalmers University of Technology) at the Chalmers Institute of Technology in Sweden turned to a new type of graphene with special properties. The team's Janus graphene is named after a Roman god known for his two faces, characterized by a molecule with only one side that is both a spacer and an active interaction point for sodium ions.

In fact, before that, scientists had applied two-sided thinking to so-called Janus particles, such as allowing spheres to both attract and repel water. In this case, molecules found on only one side of the graphene material promoted Static interactions between stacks and created more space between them, which the team found resulted in a huge increase in capacity.

Jinhua Sun, a member of the team, explained: "We added a molecular gap on one side of the graphene layer. When these layers are stacked together, the molecules create more space between the graphene sheets and provide an interaction point, which leads to a significant increase in capacity. "

It is reported that by using the new Janus graphene instead of graphite, scientists have achieved a capacity of 332 mAh/g in experimental sodium batteries, about 10 times higher than the traditional design, close to the capacity of lithium batteries using graphite. The research was recently published in the journal Scientific Progress.

Professor Aleksandar, author of the study, said: "it's really exciting when we observe that sodium ions are inserted at such a high capacity. The study is still in its early stages, but the results are promising. This shows that it is possible to design a graphene layer suitable for the ordered structure of sodium ions to make it comparable to graphite. "