A fascinating analysis of why sodium-ion batteries are only now coming into widespread use. Dr Ben Miles discusses the chemistries of lithium- and sodium-ion and how they developed, and why hybrid batteries with lithium-ion and sodium-ion cells might make sense.
Also, note this: CATL (who developed the new sodium-ion batteries) has just received a 60 GWh order for new sodium-ion batteries, equal to 50% of its lithium-ion battery sales last year. Remember that LFP (lithium-iron-phosphate) batteries cost $55-$70/kWh, while sodium-ion are heading for $19/kWh. And that's not the end of the likely price decline: CATL thinks they can over time cut the cost to $10/kWh. Sodium-ion batteries also support 10,000 cycles. In other words, even if you fully charged and discharged it every day, it would still last 27 years.
And all this has happened in one year, going from laboratory to mass production!
Implication: as solar prices continue to decline, gas and oil is (again) proved to be volatile and unreliable, and storage costs fall precipitously, wind, solar and storage will be so much cheaper than fossil fuels that they will rapidly replace them. Only the US won't join in this bounty of dirt-cheap energy. The rest of the world will receive a huge boost to economic growth as electricity costs plunge.
A joint team of researchers from Nankai University in Tianjin and the Shanghai Institute of Space Power Sources (SISP) has developed a hydrofluorocarbon-based electrolyte that significantly enhances the performance of lithium batteries. As reported by the South China Morning Post, the new electrolyte more than doubles the energy density of existing batteries at room temperature, meaning batteries of the same size can last twice as long.
The researchers also claim that the new electrolyte remains stable in extreme cold, allowing batteries to function seamlessly in temperatures as low as -94 ºF (-70 ºC), well over 2.5 times the temperature of your refrigerator.
Chemical batteries, such as lithium batteries, utilize electrolytes – a chemical medium that allows ions to flow between the positive and negative electrodes, converting stored chemical energy into electrical current. In lithium batteries, the electrolytes are usually nitrogen- and oxygen-based compounds, mainly because of their effectiveness at dissolving lithium salts.
However, these electrolytes are sensitive to operating temperatures. Cold temperatures increase viscosity and slow down ion mobility, reducing charge transfer efficiency. When this happens, the battery delivers less power, takes longer to charge, and loses usable capacity, providing less runtime than its stored energy would suggest. This is why lithium batteries appear to die quickly in extreme cold. In certain conditions, such as charging the battery when the temperature is below 32 °F (0 ºC), permanent damage may occur.
In the study published in Nature, the researchers outlined how their solution, synthesized hydrofluorocarbon-based (hydrogen, fluorine, and carbon) electrolytes, eliminates this problem in lithium batteries. The cold-resistant electrolyte offers improved stability and lower viscosity at low temperatures, enabling batteries to continue operating efficiently below -94 °F.
Another outstanding feature of the electrolyte is its energy density – the amount of charge it can store per weight. In the study, the team created lithium metal pouch cells that achieved an energy density of 317 watt-hours per pound (Wh/lb) at room temperature. The cells still maintained a density of 181 Wh/lb at -50 °F (-46 ºC).
In comparison, conventional lithium batteries, such as those found in Tesla EVs, have an energy density of 73-136 Wh/lb at room temperature. This figure more than halves when temperatures fall to just -4 °F (-20 ºC).Technically speaking, the researcher’s electrolyte could triple the range of some EVs with the same battery size!
“For the same mass of lithium battery, the room temperature energy storage capacity is increased by two to three times,” said study author Li Yong, a researcher at SISP.
Beyond the automotive industry, this development could have far-reaching implications across many sectors and everyday life. We are talking drones, robots, smartphones, and consumer electronics that last twice as long while still being able to operate efficiently in extreme cold.
Research robots operating in Antarctica could function reliably, while subsea exploration vehicles could significantly extend their operational range. Similarly, satellites and spacecraft, which endure extreme temperature swings in orbit, could benefit from more stable and predictable power systems. The list goes on and on.
Before we get carried away, it's important to note that the electrolytes are not exactly “all weather” ... yet. The team noted that the electrolyte’s high-temperature stability still needs improvement. Should they succeed in raising the boiling point of the electrolyte, we could have a true all-climate solution.
This is obviously still at the laboratory stage, and as such, may never enter commercial production. However, you may depend upon it: engineers at Chinese and other countries' battery manufacturers will have read the article in Nature, and will be keenly examining the results to see if there is any way they can increase the range and reduce the cost of their own batteries. There is a ferment in battery technology and manufacture, and the likely outcome is more of the same: plunging costs, higher energy density, and greater range. Sodium-ion batteries, for example, which also allow low-temperature use, are just one of the ways battery makers have slashed costs. This new electrolyte keeps lithium-ion in the game.
CATL's new sodium-ion batteries have 5 advantages over lithium-ion:
Sodium-ion batteries used to have a much lower energy density than lithium-ion: 140 Watt-hours per kilogram vs lithium's +-200 Wh/kg. CATL's new sodium-ion batteries have an energy density of 175 Wh/kg. That's a higher energy density than BYD's lithium-ion blade battery, which has an energy density of 160 Wh/kg. But, here's the point: sodium is about 4.5 times cheaper than lithium, even after lithium's big decline in price over the last two years.
Sodium-ion batteries work much better in freezing temperatures, for example, at -20 to -40 degrees C, where lithium-ion batteries lose much of their performance, and even stop working at -40 C and below.
They can be very rapidly charged, even at low temperatures.
They should last for 10,000 recharge cycles, or about 4.8 million kilometres (3 million miles), vs the very best lithium-ion batteries, with maybe 3.5 million km.
Safety: sodium-ion batteries are much less inflammable than lithium-ion, and don't catch alight even if sawed or drilled into.
So, sodium-ion batteries are likely to rapidly replace lithium-ion batteries, with battery costs (my estimate) at least halving, a combined effect of longer life and cheaper materials.
This has huge implications for EV prices. Remember, outside the USA, EVs have already reached or are close to price parity. For example, in Australia, the cheapest BYD Dolphin has price parity with the cheapest all-petrol Toyota Corolla. CATL's new sodium-ion battery means that EVs will now achieve price parity with even the smallest and cheapest petrol cars, and better than that with all mid-size cars. Expect EV prices to continue to decline, even as range is increased.
It also has equally big implications for the grid. Battery storage costs will fall so much that 8 hours of storage will be almost as cheap as 4 hours is today. And, of course, this is not the end of the decline in battery prices. The pace of technological and manufacturing advance is breathtaking. This in turn means that every electricity grid within the sunbelt -- between 40 degrees N and S of the equator -- will find solar irresistibly cheap. And even grids which are only partially within the sunbelt will be heavily dependent on solar. Europe, for example, will combine North Sea wind with solar from Spain, Morocco, Italy and Turkey. This is the end of coal and baseload gas. High latitude locations will probably continue to need peaking gas, but these new super cheap batteries will outcompete gas peakers everywhere else.
The energy transition will accelerate. EVs will reach 100% of sales everywhere (except the USA) by 2030 or before. Oil demand will plunge. Coal power stations will stop being profitable, and will be closed. Emissions will start to fall. Air pollution will decline. Blood-soaked petro-states will lose their influence.
China is reaching new heights in diversifying the battery chemistries used in electric vehicles. The country is already leading in subcategories of lithium-based chemistries, like nickel-manganese-cobalt (NMC), nickel-aluminum-cobalt (NCA) and lithium-iron-phosphate (LFP). Earlier this year, state-run utility company China Southern Power Grid even deployed sodium-ion batteries for stationary energy storage. Now CATL, the world's largest battery maker, claims to have unlocked new levels of extreme weather performance with sodium-ion batteries.
The role of sodium ions is similar to lithium ions, where charge-carrying ions travel between the positive and negative electrodes during the charge and discharge cycles. Studies suggest that sodium-ion batteries could eliminate the pesky traits of lithium-ions: There’s less risk of thermal runaway, they can operate at varied temperatures and crucially, the cost of sodium hydroxide, a key raw material, is far lower than lithium-hydroxide. (Although battery companies have reached better economies of scale with lithium-ions.)
Sodium-ion batteries have already entered production in China. Cars that use them include the Yiwei EV produced by Volkswagen-backed JAC and the JMEV EV3. Speaking at the World Young Scientists Summit, CATL chief scientist Wu Kai said that its second-generation sodium-ion cells can discharge normally even at -40 degrees Celsius, as per several local Chinese media reports. That means EVs with such batteries won't lose range under frigid temperatures, which could help address some of the lingering concerns regarding the extreme weather performance of batteries.
They will launch in 2025 in China, with mass production expected to begin in 2027.
Tesla's 4680 NCM cells present in some newer Model Ys have an estimated energy density of up to 296 watt-hours per kilogram, as per some early teardowns. Sodium-ion batteries are less energy dense. While CATL has not disclosed the energy density of the new cells, it reportedly aims to reach a figure of 200 Wh/kg—a tough goal given that even LFP batteries have only recently hit that mark. That would only be appropriate for low-range EVs or entry-level trims. Some reports also claim that sodium-ion batteries are expected to replace 20-30% of LFP batteries in select applications.
A study published in the U.S. government’s National Library of Medicine calls sodium-ion batteries a “rising star.” Battery giants like CATL, BYD, and Sweden’s Northvolt are already investing in and developing these next-generation cells. So either way, one thing is clear: the future of battery chemistry isn’t headed in a single direction but will likely embrace a mix of chemistries tailored to specific use cases.
In principle, sodium-ion batteries should be cheaper than lithium-ion, because sodium is far more common and far cheaper than lithium (salt is sodium chloride, and the sea is full of it). But production is still limited, so they are not cheaper yet. As volumes expand, though, they will fall in cost just as fast as lithium-ion batteries have fallen, cutting battery cell costs to below $35/kWh, and battery pack costs to ~$65/kWh. At that price, the average EV battery pack will cost between $2600 and $4000, making EVs cheaper to buy as well as to run than petrol cars. For reference, in 2010, lithium-ion batteries cost $1392/kWh. Expect EVs to rapidly move to 100% of all sales, as costs continue to plunge--except of course in the US, where tariffs will stop this happening. They already make up more than 50% of sales in China, the world's largest car market.
Because of lower energy density, initially battery-packs will combine sodium-ion and lithium-ion cells. But cheaper cars, with shorter ranges, will be the first to get 100% sodium-ion batteries.
Rising raw material and battery component prices and soaring inflation have led to the first ever increase in lithium-ion battery pack prices since BloombergNEF (BNEF) began tracking the market in 2010. After more than a decade of declines, volume-weighted average prices for lithium-ion battery packs across all sectors have increased to $151/kWh in 2022, a 7% rise from last year in real terms. The upward cost pressure on batteries outpaced the higher adoption of lower cost chemistries like lithium iron phosphate (LFP). BloombergNEF expects prices to stay at similar levels next year, further defying historical trends.
The above figures represent an average across multiple battery end-uses, including different types of electric vehicles, buses and stationary storage projects. For battery electric vehicle (BEV) packs in particular, prices were $138/kWh on a volume-weighted average basis in 2022. At the cell level, average BEV prices were just $115/kWh. This indicates that on average, cells account for 83% of the total pack price. Over the last three years, the cell-to-pack cost ratio has diverged from the traditional 70:30 split. This is partially due to changes to pack design, such as the introduction of cell-to-pack approaches, which have helped reduce costs.
On a regional basis, battery pack prices were cheapest in China, at $127/kWh. Packs in the US and Europe were 24% and 33% higher, respectively. Higher prices reflect the relative immaturity of these markets, the higher production costs, the diverse range of applications and battery imports. For the higher end of the range, low volume and bespoke orders push prices up.
Prices could have risen further in 2022 had it not been for the higher adoption of the low-cost cathode chemistry known as LFP, and the continued reduction of expensive cobalt in nickel-base cathodes. On average, LFP cells were 20% cheaper than lithium nickel manganese cobalt oxide (NMC) cells in 2022. However, even low-cost chemistries like LFP, which is particularly exposed to lithium carbonate prices, have felt the bite of rising costs throughout the supply chain. LFP battery pack prices rose 27% in 2022, compared to 2021.[The lithium carbonate price rose 5-fold in 2022, but has since halved again]
Evelina Stoikou, an energy storage associate at BNEF and lead author of the report, said: “Raw material and component price increases have been the biggest contributors to the higher cell prices observed in 2022. Amidst these price increases for battery metals, large battery manufacturers and automakers have turned to more aggressive strategies to hedge against volatility, including direct investments in mining and refining projects.”
While prices for key battery metals like lithium, nickel and cobalt have moderated slightly in recent months, BNEF expects average battery pack prices to remain elevated in 2023 at $152/kWh (in real 2022 dollars).
BNEF expects battery price to start dropping again in 2024, when lithium prices are expected to ease as more extraction and refining capacity comes online. Based on the updated observed learning rate, BNEF’s 2022 Battery Price Survey predicts that average pack prices should fall below $100/kWh by 2026. This is two years later than previously expected and will negatively impact the ability for automakers to produce and sell mass-market EVs in areas without subsidies or other forms of support. Higher battery prices could also hurt the economics of energy storage projects.
Yayoi Sekine, head of energy storage at BNEF, said: “Despite a setback on price declines, battery demand is still reaching new records each year. Demand will reach 603GWh in 2022, which is almost double that in 2021. Scaling up supply at that rate of growth is a real challenge for the industry, but investment in the sector is also rising rapidly and technology innovation is not slowing down.”
Kwasi Ampofo, head of metals and mining at BloombergNEF, added: “Lithium prices remain high due to persistent supply chain constraints and the slow ramp up in new production capacity. Additional lithium supply could ease the pressure on prices in 2024, while geo-politics and trade tension remain the biggest uncertainties for other key battery metal prices in the short-term. Resolving these tensions could help calm prices in 2023 and beyond.”
Continued investment in R&D, manufacturing process improvements, and capacity expansion across the supply chain will help to improve battery technology and reduce costs over the next decade. BloombergNEF expects next-generation technologies, such as silicon and lithium metal anodes, solid-state electrolytes and new cathode material and cell manufacturing processes, to play an important role in enabling further price reductions.
The new sodium-ion batteries that BYD is putting in its cheaper cars (at 160 Wh per kilo, they have a lower energy density than li-ion's 180 Wh/kg) cost US$77/ kWh, or half the cost of li-ion, and are expected to drop to $40/kWh as mass production starts. Even if li-ion battery pack prices only fall slowly from now on, that won't slow down the EV boom. Cars will just have sodium-ion or perhaps a mixture of li-ion and sodium-ion batteries. This means that average battery pack prices will fall below $100/kWh this year. And that is the point at which EVs have the same sticker price as petrol/diesel cars. They are already cheaper to run, because they're much more efficient and require far less servicing than ICEVs. Now they'll be cheaper to buy, too.
