If we plan to replace fossil fuels with renewable energy, we’ll need batteries… as in… a lot of batteries, and in the world of battery storage, lithium-ion batteries reign supreme. However, there’s a big problem.
We may not have enough lithium and other raw materials to make all the necessary batteries.
But what if I told you that we might have already found a possible solution in the form of a new battery that isn’t constrained by the limited supply of a couple of scarce materials? Enter the sodium-ion battery, and it’s sort of a big deal. I’m Ricky, and this is Two Bit da Vinci.
Our efforts to replace fossil fuels with clean and renewable energy have been seriously paying off in the past decade. As of making this video, there are 16.5 million electric cars on the streets, with 2 million sold during this year’s first quarter alone [source]. That’s a growth of 75% compared to the same period last year.
In the US, a little over 600,000 EVs were sold in 2021, but that number is expected to hit over 4.7 million by 2030 and could go into the billions by 2040! LINK LINK That means the demand for batteries for transportation will continue to grow exponentially in the coming years.
Considering that lithium-ion batteries make up between 95 and 99% of the electric car battery market LINK this means that the demand for lithium and other scarce metals like nickel and cobalt for the electric vehicle industry will also continue to rise.
But it’s not just vehicles.
To replace fossil fuels with intermittent renewables like solar and wind, we need to store an equivalent of at least 5% of our renewable energy production to balance out that intermittency [source].
Pumped hydro is a reliable long-term energy storage solution. Still, even though 94% of our current grid energy storage capacity comes from pumped hydro, we can’t usually build those where we need them, near PV power plants and wind farms, forcing us to use batteries instead. Right now, more than 90% of the batteries used for grid storage are also Lithium-Ion. LINK
With wind and solar energy increasing by 5 and 6% annually in the coming decade, LINK and EVs growing faster, we need to face a vital truth. Lithium and the other components of the Li-ion battery are hardly inexhaustible resources. LINK
While we’re still not running out of lithium, several red flags are already in the air. So much demand for this alkali metal has sent its price through the roof, increasing more than seven-fold in the past couple of years. LINK
But, of course, lithium isn’t the only problem. These batteries require other rare elements like manganese and cobalt, which are in much lower supply and are available in only a few countries, some of which, like the Democratic Republic of the Congo, are weighed down by environmental and humanitarian concerns. LINK
When there are not enough resources to go around, suppliers are forced to decide where to allocate their products, affecting lithium battery production. With lithium batteries being so ubiquitous, this has the potential to affect ALL OF US.
Can you imagine what would happen if suppliers all of a sudden decided to prioritize the EV or grid storage industries and we ran out of batteries for our electronic devices? However unlikely, it’s a scary thought we need to consider.
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Needless to say, when it comes to a clean, green future for our planet, we cannot put all our eggs in one lithium ion basket.
So, we need to find an alternative energy storage solution, one that is at least as energy and power-dense as lithium-ion (so we can also use it to power electronics and EVs) but that is also made of abundant materials that are environmentally friendly and easy to extract.
This is where the sodium-ion battery comes in.
For chemists, an obvious solution to the lithium problem would be to replace it with its close cousin, sodium. Like lithium, sodium is an alkali metal and shares many of the same chemical properties but with some key differences.
As the sixth most abundant element on the planet, sodium is more than 100x more abundant than lithium in the Earth’s crust. We can find it virtually everywhere, starting with salt water, where it’s found as sodium chloride. LINK LINK LINK
This makes sodium much cheaper than lithium and an almost inexhaustible resource. For a quick comparison, mining lithium can cost anywhere between $15,000 and $32,000 per metric ton, depending on the source.
And, as I mentioned before, prices have ballooned ridiculously in the last two or so years—with lithium hydroxide increasing roughly 250% and lithium carbonate increasing approximately 413% since the beginning of 2021, according to S&P global. LINK LINK
On the other hand, sodium is not only 100 times more abundant but also 100 times cheaper than lithium, as mining sodium ranges between $150 and $380 per metric ton! LINK
This makes sodium an ideal alternative for battery manufacturing… if we can get it to work like lithium, that is.
So, to see if we can, let’s start with how these batteries actually work.
As you may imagine, sodium batteries work very similarly to lithium-ion cells. Just like other chemical batteries, they have a cathode, an anode, and an electrolyte.
The cathode contains a sodium salt or oxide that provides the sodium ions, similarly to how in the lithium battery, the cathode contains different types of lithium compounds that provide lithium ions.
When we charge the battery, electrons are pushed by an electrical potential difference toward the anode, where the accumulating negative charge attracts the sodium ions. These move from the cathode to the anode through the electrolyte.
In the anode, they fit nicely in the little interstitial spaces between the layers of the anode material.
To draw power out of the battery, we let the electrons flow back to the cathode from the anode through an external circuit or load (our phone, for example), and at the same time, the sodium ions push back to the cathode through the electrolyte. LINK LINK
This is pretty much where similarities between sodium and lithium-ion batteries end. As it turns out, you can’t simply swap one element for another and expect everything to work the same way.
For instance, instead of a graphite anode, sodium-ion batteries use “hard carbon” materials, but more on that in just a bit. LINK
For the cathode’s active material, lithium-ion batteries use one of several oxides with transition metals like cobalt, manganese, and nickel that help increase battery life and improve energy density LINK.
In the case of sodium-ion batteries, there are three distinct variations in the cathode material, leading to three types of batteries, namely:
- Polyanion batteries,
- Prussian Blue Analogues or PBAs, and
- Layered Oxide batteries
Polyanion types use metal oxide clusters with discrete molecular structures and negative charges. Their robust 3D framework significantly decreases the structural stress when sodium ions go in and out of the structure.
This helps improve cycle stability and safety but also lowers electric conductivity and capacity, which restricts their application. LINK
The second type is known as “Prussian Blue Analogues.” Prussian Blue is a dark blue pigment produced by the oxidation of salts containing iron and cyanide. It’s known for being relatively low cost, with a highly stable, open, three-dimensional crystal structure which makes it ideal for batteries since it lets ions in and out easily. LINK LINK
The benefit of these two battery chemistries is that they largely eliminate the need for many of the transition metals, like nickel and cobalt, that are prevalent in lithium-ion.
This doesn’t only make them cheaper, but it also means there’s less chance of a supply chain bottleneck when we scale to global production, something we absolutely need to do if we want to get rid of fossil fuels.
But there’s a trade-off because these materials have low atomic packing densities, so they have fewer sodium ions per unit volume, meaning lower energy density.
Finally, there are the Layered Oxide batteries. These are much more similar in structure to standard li-ion batteries and are the most studied type of sodium-ion batteries.
The key difference, though, is that, instead of nickel, cobalt, and manganese oxides, which are in shorter supply than even lithium, these sodium batteries use iron and magnesium oxides which are far more abundant.
As a consequence, the sodium cathode, which makes up about 44% of the total battery cost, is much cheaper to produce and is much more widely
available than the lithium cathode LINK.
Faradion, the company that seemingly gave birth to the sodium-ion battery, claims their current in-development layered-oxide battery will be 25-30% cheaper than lithium iron phosphate batteries at scale LINK.
But, if they’re cheap and work like lithium-ion, why don’t we see sodium-ion batteries everywhere? What’s the holdup?
There’s plenty to unpack here. You see, costs and supply chain aren’t the only things we need to look at. The first thing to consider is performance. Thisis where the sodium battery starts losing ground to lithium.
The biggest problem is that capacity depends on how many sodium ions you can pack in the cathode’s and anode’s crystal structures.
But sodium ions are much bulkier than lithium ions, so they’ll take up more space. This implies that, in most crystal structures, there’ll be fewer sodium ions per unit volume than in similar lithium compounds. Therefore, sodium batteries tend to have lower energy densities or energy per unit volume.
Furthermore, sodium ions are over three times heavier than lithium ions, so sodium batteries also tend to have lower specific energy densities than lithium-ion batteries.
For example, at the time of making this video, Faradion claims to have developed a layered oxide Sodium Ion battery cell that can achieve energy densities of about 160-170 Wh/kg. While this falls in Lithium Ion’s range of 100-265 Wh/kg, it’s still at the lower end of the spectrum LINK LINK.
On the other hand, the company also says that it’s in the process of developing a battery that can reach up to 200 Wh/kg! To reach those higher numbers, though, the battery chemistry would need to be at least 50% nickel.
This reintroduces one of those materials prone to a supply bottleneck, so it sort of undermines the whole point of Sodium Ion batteries in the first place. LINK LINK LINK
Then there’s the issue of scaling.
Sodium-ion hasn’t been around for as long as lithium-ion and has received far less R&D.
However, Faradion was recently bought by a major Indian solar company called Reliance Industries which has said they plan to scale up Sodium Ion battery production over the next two years, hopefully producing between 10 and 20 GWh by 2024. This is a major win for Faradion and its battery tech.
But the biggest promise for sodium is that the largest battery manufacturer in the world, the Chinese behemoth Contemporary Amperex Technology Ltd. or CATL got in on the game in 2021 when they announced the launch of a 160 Wh/kg sodium-ion battery.
They also claim to have a second-generation battery in the works that can reach upwards of 200 Wh/kg.
Contrary to Faradion’s solution, which is a layered oxide battery, CATL is building a PBA battery from Prussian White — an inexpensive, easy-to-produce material that can maintain 95 percent capacity after 10,000 cycles! LINK This is an order-of-magnitude improvement in battery life over lithium!
The best part is that this battery will only rely on Earth-abundant materials — meaning it could scale for decades without ever hitting a bottleneck. LINK LINK LINK
Now, if you remember, earlier in the video, I mentioned how sodium ion batteries use hard carbon anodes. Hard carbons are forms of carbon that can’t be turned into graphite. They can be made from dozens of materials, but currently, there isn’t a robust supply chain for manufacturing hard carbon anodes.
Fortunately, CATL is a big company, and it developed its own material, which enables abundant storage giving the batteries performance and life cycles similar to graphite LINK.
Because of these features, CATL says that their battery will be 40-50% cheaper than lithium-ion, aiming at a long-term cost of around $40/KWh, less, even, than lithium-iron-phosphate batteries that currently cost $80 to $100 per kWh. LINK
As far as scaling, CATL says they will use the same equipment already used to build their lithium-ion batteries. Still, the company doesn’t expect to have its supply chain in place until at least 2023, meaning it could still be another five years before they reach large-scale commercial operations.
So, to summarize, sodium-ion batteries are cheaper to produce and use fewer hard-to-find materials, depending on the particular chemistry.
But, their energy densities are on the lower end of lithium-ion. Plus, it will take at least 5-7 years for the industry to begin catching up to Lithium-ion, so it’s safe to say that we won’t see them storing solar energy or powering our EVs anytime soon.
But even if their performance can’t compete with the best li-ion batteries, that doesn’t mean they’re not valuable.
Considering the amount of energy storage needed to replace fossil fuels, we’ll need every energy storage technology we can get our hands on, not just sodium-ion batteries.
Perhaps in the future, lithium-ion batteries will be reserved for those applications where only the highest possible energy density can be used, and I’m not even talking about electric cars; I’m talking about electric airplanes and helicopters.
On the other hand, Sodium-ion will likely benefit applications that don’t require lower mass or smaller size, like in stationary grid storage applications for renewable energy, which is precisely what we’ll need most of our energy storage capacity to begin with.
We need to start developing competitive battery technologies now to begin taking some of the strain off of our current battery materials. How great would it be to have not just one battery technology eating up 90% of the market but a robust, competitive battery marketplace with dozens of technologies filling up the landscape?
Sound like a win-win to me!
But what do you think? Do the sodium-ion battery’s cost and material benefits outweigh their lower energy density? Would you be willing to buy the same Tesla for 20% less in exchange for a slightly lower range but longer battery life? Sound off in the comments below!
