Sodium-based batteries aren’t new to the energy storage market, but the technology began attracting industry attention in the early 2020s as the industry sought alternatives to lithium. Sodium-ion batteries are built and function much like typical lithium designs and are therefore easier to implement than other advanced technologies, such as flow batteries. But just as there are multiple lithium chemistries, different sodium batteries are more effective for particular applications. Here’s an explanation of the new technology.
What is a Sodium Battery?
Abundant sodium produces harmless electricity in sodium-based batteries. They are non-flammable and non-explosive (unless additional materials are introduced to the chemistry) and can work over a broad temperature range. You can also discharge sodium battery cells to 0 charge without damaging the system.
Sodium ions flow from cathode to anode during charging and from anode to cathode during discharge. They are made the same way as lithium batteries. The cathode and anode are covered with a slurry, the cell pouch is filled with electrolytes, and then the module is sealed. Sodium cell producers are following similar form factors as lithium batteries to enable simple adoption. Sodium batteries employ aluminum in their current collector designs, whereas lithium uses aluminum and copper. The price of sodium batteries should theoretically be lower by using only aluminum.
Sodium batteries are less risky than lithium BESS because they are not a fire danger and have a broad operating temperature range; therefore, they do not need the heating, cooling, and fire-suppression gear visible in lithium BESS. That means a large-scale sodium energy storage device has a substantially smaller physical footprint than lithium.
What are the different sodium battery types?
There are numerous varieties of sodium batteries, but the three most prevalent are NFM, NCO, and NFPP.
Sodium nickel iron manganese (NFM) is often compared with lithium nickel manganese cobalt (NMC) and is used in light e-mobility applications like scooters and e-bikes. NFM batteries, like the NMC batteries used in electric cars, may be harmful and can catch fire. They are not suitable for large-scale applications
Sodium chromium oxide (NCO) is often used as a substitute for lithium cobalt oxide (LCO). NCO has high energy density, extended cycle and calendar life. These layered metal oxide batteries have a reduced risk of thermal runaway, but their cost is still greater than NFM today.
Commonly, sodium iron-phosphate pyrophosphate (NFPP) is compared to lithium-iron phosphate (LFP). They offer longer cycle lives, higher heat tolerance, and almost no fire risk. To further reduce fire risk, US-based producer Alsym has added a non-flammable electrolyte to its NFPP+ design. NFPP designs offer lower energy density than LFP, but need less HVAC and other BESS add-ons.
Where are Sodium Batteries Being Made and Deployed?
Today, like with other battery products, China dominates manufacturing. Sodium battery manufacturing can be simply integrated into an LFP line, and several established Chinese lithium companies have already switched idle or surplus lines in their factories to build sodium designs. There are a few sodium-ion R&D activities going on in the United States, and the battery’s plentiful chemical basis, together with its lack of essential ingredients, implies the United States could soon onshore the manufacture of sodium-ion energy storage devices.
Boston-based Alsym has been developing NFPP cell designs, and large-scale energy storage company ESS recently announced it will use Alsym innovation in its planned sodium-ion battery launch.
“We’re going to begin with an NFPP because that’s a good technology. It falls in the same characteristics that ESS has followed since its birth — no risk of fires, and it’s safe,”
said Randy Selesky, ESS chief commercial officer.
UC San Diego spin-off Unigrid is working on NCO cells and has partnered with manufacturer Syntropic Power to produce sodium-ion batteries in the United States. Unigrid co-founder and CEO Darren Tan said the two businesses are targeting the home sector since it’s ripe for some lithium alternatives.
“We already have water storage at home; we have food storage. I think it’s very conceivable that in the next two decades (energy storage) will be at home for everyone, if the energy storage is as affordable, as safe and as reliable as a refrigerator,”
he added.
“This is sodium-ion’s opportunity.”
Peak Energy said it would establish a 4-GWh-per-year production plant in Sacramento in 2027 to produce 3.1-MWh NFPP systems. Peak is utilizing imported cells for now, but executives are actively working to secure additional components, said Peak head scientist Brandon Kelly.
“You can make hard carbon, the anode, out of pretty much anything. Now we utilize coconuts. We’re going to do some peach pits and some other strange things. It makes for funny supply chain conversations,”
he said.
“But you can make it out of coal, and you can make it out of petroleum byproducts, and those are things we’re good at here in the States. But it’s not something that is scaled today, but it’s something that will be quite easy for us to do [in the United States] relative to lithium.”
The U.S. corporations wouldn’t be building that manufacturing infrastructure if there wasn’t demand for the new battery technology. The installed capacity may be limited today, but every business spokesperson Solar Power World spoke to said the sector is at the dawn of something big.
“Last year we produced more than 3 GWh of sodium,”
Kelly remarked.
“A lot of people think of it as a lab technology, but the reality is that these are commercial-quality cells that have already demonstrated their performance in that large format at the gigawatt-hour scale. “It’s ready for the big time.”
