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Sodium-ion and Potassium-ion Batteries

Litium ion batteries are causing a revolution around the world. The energy density of batteries of this type is still increasing, and prices are rising as production capacity of new batteries is not keeping up with demand. But to anyone with a basic science education its pretty strange to see this intense focus on Lithium, while there are plenty of other metals to choose from that are more abundant and cheap. Two of them are Sodium (called Natrium in Europ) and Potassium (called Kalium in Europe). Sodium or Na is part of what we know as common table salt which is NaCl. Potassium is in all life because it actually stores energy in plants and animals.

We may be looking at an economic effect in the sense that the battery that generates the most cashflow is invested in more, because banks rather loan for projects that generate a lot of cashflow. Sodium and Potassium batteries as you can see below have mega potential and the fact we aren’t using them widely yet is hard to explain.

Sodium-ion batteries or NIB

Sodium batteries are about as easy to make as lithium ion batteries, but they require a different kind of electrode, because sodium does not ‘dissolve’ in grafite as lithium does. Sodium-ion Batteries Market is expected to exceed more than US$ 1.77 Billion by 2024 which is tiny compared to what it could be if we started way earlier. These batteries are amongst other uses expected to be replacements for lead-acid but with better characteristics. There are different ways to build a sodium battery, so with either a liquid electrolyte or a non-aqueous one, with sodium as cathode or only in the electrolyte. More information can be found here. We will list some companies that are working on Sodium-ion batteries.

Source

AMG batteries is a cooperative with Renault working to create sodium-ion batteries for use in cars. The energy density can be as high as Lithium also because there is no need for copper electrodes. A lot of patents on sodium batteries are held by Faradion. Above you see a graph that shows the different electrolytes being tested and how they perform (the dots not the formulas).

A Sodium sulfur battery

Chinese NIB producers are HiNa Battery Technology, Wuhuhaili (Sodium-sulfur), Qintang New Energy, Liaoning Hongcheng (Liaoning Xingkong), NGK, Zhejiang Lvming Energy (Durathon), Sodium-sulfur batteries have been applied for large scale energy storage, but they are high-temperature (300-350 Celsius), now room temperature variants are being developed which is promissing.

Other projects around Sodium batteries are the Naiades EU project. Interestingly there is a spinoff towards desalination because sodium is one of the main ions in seawater, and sodium batteries separat the sodium towards or away from the electrodes. Once you have a positively charged membrane that repulses sodium you can use it to filter water. This electrochemical approach to desalination is usually less energy intensive than the market dominating (and aggresively monopolizing) reverse osmosis filtering method.

Natron Energy makes Sodium-ion Batteries for utility scale power for now

Australia will have a 30 kWh sodium ion battery pack in a trial led by the University of Wollongong’s Institute for Superconducting and Electronic Materials (ISEM). It seems this project could be copied quickly and widely.

About the 30 kWh Sodium battery in Australia

Many universities research Sodium Ion batteries, but seem to give them less priority. We hope to see more examples and wider attention soon.

Potassium-Ion or KIB (also PIB)

Potassium-Ion batteries seem to be even easier than Sodium yet get even less attention. The battery potential of KIB batteries will be closer to that of Lithium-Ion batteries, making them an easier replacement than NIBs. The challenge seems to be smaller which makes it puzzling why we don’t see them offered much more yet.

“Potassium batteries can accept a wide range of cathode materials which can offer rechargeability lower cost. One noticeable advantage is the availability of potassium graphite, which is used as an anode material in some lithium-ion batteries. Its stable structure guarantees a reversible intercalation/de-intercalation of potassium ions under charge/discharge.”

Comparative challenges of KIB batteries (source)

A common mistake that is being made is to strive for high energy density right away, high performance of KIB batteries is not needed as long as the cost/performance is attractive in the market. The article that the above image comes from was more negative than one would expect. It may be that lower cachflow alternatives to Lithium-Ion are not that welcome, so then people say “more research is needed”. This is the “go look for a solution” strategy when the solution is not desired by the banks that control the market.

Fast Potassium-Ion batteries with organic cathodes

It is certainly great to read this in the press “Skoltech researchers led by Professor Pavel Troshin have made significant advances in the development of sodium and potassium batteries based on organic cathode materials” and ” sodium and potassium batteries that charge in 30 to 60 seconds while retaining their energy storage capacity after thousands of charge-discharge cycles”. So apparently these scientists tested things for all three metals Sodium, Lithium and Potassium (and alloys!). They tried different polymers and found that a dihydrophenazine-based one had great characteristics.

The world is not an island, so it seems we are about to see a rapid growth of Sodium and Potassium batteries to replace and augment the current Lithium capacity. As these metals will never run out (and are actually an undesired by product of desalination for example), the development of batteries will certainly be exiting in the next decade!