For the first time, prototypes have been developed sodium ion battery with performances that make them competitive with traditional lithium batteries, and are also capable of short charging times. It was created by a team of researchers from the Department of Materials Science and Engineering at KAIST (Korea Advanced Institute of Science and Technology) led by Young Ku Kangwho achieved this result by using a particular combination of materials for the two electrodes of the battery. This is a significant step forward in the relatively recent field of sodium batteries, which are increasingly taking shape as more sustainable, economical and safe alternatives to traditional lithium batteries, which is considered a critical raw material, especially in key sectors such as electric vehicles whose batteries currently rely mainly on lithium.
How the Korean sodium battery is made and how it can recharge in a few seconds
Like normal batteries, sodium batteries work via oxidation-reduction reactions which produce ions which are exchanged from the positive electrode to the negative one (anode And cathode respectively) thus generating a potential difference that can feed an electric current in a circuit. As you might guess, lithium batteries produce lithium ions (There+) while sodium batteries produce sodium ions (No+).
As we will see later, the main limitations of sodium batteries at present are the low power density (i.e. how much power can 1 kg of reagents deliver) and long charging times. The “loophole” that KAIST took to solve this problem is very simple, but at the same time effective. At the moment there are two main applications of sodium technology: sodium batteries hey sodium capacitorsThe latter, like all capacitors, deliver a lot of power and can therefore recharge very quickly, but they have a energy density (how much energy can 1 kg of reagents deliver) very low compared to a battery, and therefore a low autonomy. The idea is therefore to create a “hybrid” with one battery electrode and one capacitor electrode, so you have the best of both worlds.
Attempts made in the past years had a major problem: the two electrodes accumulate energy at very different rates. Following the principle of “go slowest first”, the electrode with the slowest kinetics acts as a bottleneck. As you can imagine, this imbalance is a serious limitation that prevents direct competition with commercial lithium batteries. To overcome this problem, researchers at KAIST have tested a anode with “battery” materials, but with improved reactivity thanks to active materials embedded in a porous carbon structure: this avoids the “bottleneck” effect between the two electrodes thus drastically reducing charging times. cathode Instead, it uses materials typical of supercapacitors, ensuring a high power density.
Result: KAIST’s sodium battery prototypes achieved a maximum energy density of 247Wh/kg (comparable to that of a commercial lithium battery) with a power density of 34.75 W/kg (higher than other sodium batteries) and a 100% stability (i.e. no loss of capacity) after 5000 charge and discharge cycles. For the versions with higher power densities, the minimum charging time was around 5 seconds (but the versions with higher energy density, i.e. greater autonomy, have longer charging times, on the order of an hour). The graph below shows that overall the prototype represents a significant step forward compared to other “hybrid” sodium batteries. If this path continues, in the future it could also be applied to electric vehiclesalthough in these cases the conditional is always obligatory.
Sodium vs. Lithium Batteries: The Pros and Cons
To understand the differences between the two types of batteries we can take a look at the periodic table of elements. Here we see that lithium and sodium are chemically related: they both belong to the first group (i.e. the first column of the periodic table), in the second and third row respectively. This means that they have the same external electronic configuration: in particular, they have only one electron in theorbital s outermost. In fact, the chemical properties of lithium and sodium are very similar: they tend to lose that one electron very easily.
However, there are some differences that have important practical implications from the point of view of technological development. Compared to lithium, sodium is at least 500 times more abundant in nature, less expensive And more recyclable. This is why it was chosen as an alternative to lithium: it has a similar electrochemical behavior but allows the production of batteries cheaper, more eco-friendly and also saferbecause they are more stable and therefore less at risk of developing fires.
However, sodium batteries also have some disadvantages disadvantages compared to sodium batteries. Again from the periodic table we note that sodium is heavier than lithium, whose ion however carries the same net electric charge. This means that sodium batteries have a lower energy densitythat is, they transport less energy for the same mass, and this translates into a less autonomy. To give an idea, a typical energy density for a sodium battery can be 160Wh/kgwhile that of a commercial lithium battery is around 250Wh/kWh. Additionally, the electrodes tend to be less reactive and this means longer charging times.
Why KAIST’s Sodium Battery Is Big News
For these reasons sodium batteries are used in situations where high performance and rapid charging are not required, such as pedal-assisted bicyclesbut they struggle to find application in key sectors such as electric mobilitywhere lithium for now remains essential despite the heavy environmental and geopolitical consequences. From this point of view, the goal is to advance sodium technology enough to make it competitive, in order to have an advantageous alternative and reduce the “lithium dependence” of Western and developing countries. However, a battery with high capacity, high energy density, high power density and rapid kinematics is needed, and from this point of view the prototype created by KAIST is very promisingfrom an environmental, economic and even geopolitical point of view.
