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No, man, we haven’t even figured out sodium-ion batteries yet, and potassium-ion batteries are already here?

Recently, a 18650 potassium-ion battery from Group 1 has emerged, claiming to be able to use a lower price than lithium-ion batteries.Energy density reaches 160-180Wh/kg . What is the concept?BYDThe lithium iron phosphate blade battery is only 140 Wh/kg.

The sodium-ion batteries promoted before can also achieve an energy density of 160 Wh/kg, and even CATL’s second-generation 200 Wh/kg sodium-ion batteries are already under development.

Damn, are lithium-ion batteries going to be abandoned soon?

Eh~it’s not that simple.

First we need to correct this ratio. “Energy density” actually has “Battery Pack Energy Density”and “Battery cell energy density”In both cases, the battery pack has more shells than the battery cell, so the value is naturally much lower.

The sodium and potassium ion batteries mentioned above refer to The term "battery cell energy density" refers to BYD's blade battery, while BYD's blade battery generally refers to the "battery pack energy density", so they cannot be compared in this way.

According to the current technical level,The energy density of sodium and potassium ions can only be similar to that of lithium iron phosphate.

Because the "performance" of sodium and potassium ions is not as good as that of lithium ions.VoltageandSpecific capacityBoth are lower (the product of the two is the energy density).

Let's first look at the voltage.

You should know that the power batteries generally installed in cars are called "rocking chair batteries" because the ions will swing between the positive and negative poles like a rocking chair. . .

Uh... If this statement is too abstract, then we can also regard the process of battery charging and discharging as going to and from get off work.The positive electrode is the rental house, the negative electrode is the office building, and the worker is the metal ion., for the sake of electronics, it travels between these two points all day long.

Hey, stop talking, stop talking, I see myself...

The reason why lithium, sodium and potassium were chosen as the chosen workers is, of course, because they have extraordinary talents and unique structures.

Many people say that it is because these three are related by blood, and all of them are from the alkali metal family, which is located in the first column of the chemical element table. So the next generation of batteries can be guessed with eyes closed, it must be rubidium ions. . .

But that’s not really the case.

Essentially, we are still looking at the activity of chemical properties.For example, lithium, potassium, calcium, sodium, magnesium, and aluminum have lower standard electrode potentials, which means they are more likely to lose electrons.If you use them as batteries, the voltage will be even higher.

So we can see that among these elements, lithium, sodium and potassium are the best among the best, but the question is, why is it only lithium that is admitted to university in the end?

This needs to be seen againSpecific capacity, specific capacity refers to the amount of electricity (the amount of charge) per unit mass.In other words, the more lithium, sodium, and potassium particles are packed into a piece of positive electrode material, the higher the specific capacity.

You should know that among this pile of metal elements, lithium is the thinnest, ranking third in the chemical element table, while sodium is 11 and potassium is 19. The higher the number, the fatter it is.

So in the same room, you can squeeze in more lithium ions than sodium and potassium.Specific capacityandEnergy DensityNaturally, it is much higher.

So sodium and potassium ions are completely out of the question.

In fact, everything can be a "wheelchair" Battery performance is not only determined by metal ions, but also by the entire cathode material. As we all know, the cathode materials of lithium-ion batteries are divided into lithium iron phosphate and ternary lithium. Although both are lithium, ternary lithium has better performance than lithium iron phosphate.

Therefore, sodium and potassium ions can also change the positive electrode material to improve performance. Generally speaking, there are three types:Transition metal oxides, polyanionic compoundsandPrussian blue analogue.

The ternary lithium mentioned above is the first type, lithium iron phosphate is the second type, and from the current technical solution, sodium and potassium ions will use the third type.Prussian blue analogs。

Although the name sounds strange, Prussian blue analogs, like the previous two brothers, represent a compound, that is,Ferric ferrocyanideIf it carries two metal ions, it will show Prussian blue, so it is called Prussian blue. If it carries one metal ion, it is called Prussian white.

Yes, that's right. Ningde's sodium-ion batteries used Prussian white, and potassium-ion batteries used Prussian blue, because experiments showed that this solution had the best overall performance.

In short, in combination with Prussian blue analogues, the current sodium and potassium ion batteries can achieve an energy density similar to that of lithium iron phosphate.

But even so,Sodium and potassium ion batteries are also difficult to replace lithium iron phosphate at present.

You know, the reason why people develop them is mainly because they have lower manufacturing costs, because these two items are everywhere. For example, sodium can be found in a lot in my kitchen, and potassium can be found in the commonly used fertilizer "wood ash" in rural areas.

The problem now is that the price advantage of sodium and potassium batteries is not obvious, because the price of lithium has already fallen sharply.

A few days ago, there was news saying that the price of lithium carbonate fell below 80,000 yuan/ton. Although it is not as cheap as copper and iron, it is already one-sixth cheaper than 500,000 yuan/ton in the previous two years.

For potassium-ion batteries that use Prussian blue analogs, although the positive electrode material is cheap, the cost of materials such as the diaphragm and negative electrode is more expensive than lithium iron phosphate, so the price advantage is not obvious, and it may even be higher than lithium. . .

To be honest, I was a little overwhelmed by this.

The bigger problem is the craftsmanship.The current production consistency of sodium and potassium ion batteries is still relatively poor.Whether it can achieve the performance of the laboratory is still a question.

Take the sodium-ion batteries that are now in mass production. In theory, they are safer than lithium batteries and less likely to spontaneously combust. However, there are also UP hosts on BiliB, who found through homemade needle puncture experiments that they still have safety risks (this guy is really awesome).

So at least for now, sodium and potassium ion batteries may be more suitable for energy storage rather than the power batteries of our electric vehicles. Even if there is sufficient technology and process to support them one day in the future, they will not be able to replace the more powerful ternary lithium batteries because the upper limit of the material is so much.

Actually, to put it bluntly,People are developing various types of batteries, not because lithium-ion is not good, but because there is too little lithium.

Because lithium is a rare metal, its reserves on Earth are very small and concentrated in South America. Moreover, after being made into batteries, lithium is difficult to recycle and will be used up sooner or later.

Therefore, even if the performance is a little worse, we still have to develop a battery that is cheap and available in large quantities to cope with the possible shortage of lithium in the future. At worst, we can just build more battery swap stations.

The emergence of potassium-ion batteries is mainly to make up for the debuff of sodium-ion batteries that cannot use graphite negative electrodes.So the first thing it replaces is not lithium, but sodium.

In short, no matter what, from the current technology point of view, sodium and potassium are only the lower-level substitutes for lithium. Whether they can make breakthroughs in the future depends on whether the brothers in battery research and development can give more efforts.

If a substitute for lithium iron phosphate is really developed, we will have to change cars again, right?