Most of the rechargeable batteries used in today’s technology, from electric cars to the phones in our pockets, are lithium-ion (Li-ion) batteries. Since its inception in the early 1990s, Li-ion battery technology has been widely adopted for its high energy density, lightweight construction, and ability to provide high voltage on demand for both gadgets and vehicles.
But researchers are working on a new contender that threatens to relegate Li-ion to the past — at least in specific applications. Sodium-ion (Na-ion) batteries (sometimes called NIBs as an abbreviation for Na-ion battery) are a new battery technology that stores charged sodium ions in the battery’s electrodes, instead of lithium ions as in Li-ion batteries.
Na-ion batteries also come with inherent safety benefits that could make them more palatable for large-scale, static battery setups, say researchers working on the technology.
Na-ion batteries vs Li-ion batteries: What are the advantages?
The main advantage of Na-ion batteries is that they are cheaper, easier and more sustainable to produce due to the wide availability of sodium.
“In particular, sodium is cheaper, more abundant and less geographically concentrated than lithium,” explained Dustin Baueran associate at the intellectual property firm Reddie & Grose with PhD experience studying the synthesis, composition and use of Na-ion batteries and Li-ion batteries.
Due to the operating voltage of the batteries, Li-ion requires the use of copper for the negative current collector, but copper is more expensive and weighs more than aluminum
Carmen M. López, Principal Scientist in the Electrochemistry Group at the National Physical Laboratory (NPL).
With the last decade having made the potential pitfalls of the global supply chain visible, as well as climate targets requiring a mass switch to electrified grids and transport where possible, there is a clear advantage to adopting batteries that do not rely on critical minerals that are difficult to obtain to function.
“For reference, sodium is the sixth most common element on Earth, with a natural abundance of 2,360 mg/L, while lithium, at number 32 on the list, has a natural abundance of 20 mg/L,” said Carmen M. Lópezprincipal researcher in the electrochemistry group at the National Physical Laboratory (NPL).
Once Na-ion battery supply chains are operational at scale, they can help drive costs well below Li-ion batteries, flooding the world market with cheaper energy storage options. For example CATL, the the world’s largest battery manufacturerrecently started commercial production of Na-ion batteries for heavy vehicles.
Beyond the silicon used for the cathode in the battery, the chemistry of Na-ion batteries also bypasses the need for other expensive components.
“Because of the operating voltage of the batteries, Li-ion requires the use of copper for the negative current collector, but copper is more expensive and weighs more than aluminum,” López said.
She added that Na-ion batteries have the potential to replace organic electrolytes – used as the conducting medium for ions in Li-ion batteries – with aqueous electrolytes. This will make battery production more sustainable and still cheaper.
Battery chemistry is also at the heart of the safety requirements surrounding Na-ion batteries. Thermal runaway – an exothermic chain reaction that can occur inside battery cells and cause them to catch fire – is less likely to occur in a Na-ion battery than a Li-ion battery.
This is because sodium ions are larger than lithium ions and therefore have greater “friction” – the result is that in the event of damage that could lead to thermal runaway, they flow to the point of impact at a rate unlikely to cause a rapid temperature rise. Lithium ions, on the other hand, can flow rapidly, causing overheating, release of oxygen and ignition.
Finally, Na-ion batteries offer improved temperature resistance compared to Li-ion batteries, due to their low volatility and the reduced viscosity of the electrolyte. Briefly, this refers to the degradation of performance at low temperatures associated with the lower charge density of sodium ions compared to lithium ions, meaning that the ions continue to move freely even at low temperatures.
In a recent study published on December 12 in the journal Chinese chemical charactersresearchers at Hunan First Normal University and Central South University found that Li-ion batteries could retain only 20% of their energy capacity at room temperature when tested at -4 degrees Fahrenheit (-20 degrees Celsius). Na-ion batteries, the researchers noted, may offer better performance, subject to further testing.
Can Na-ion batteries be good for electric cars?
The lower cost and increased safety of Na-ion batteries make them a suitable candidate for EV batteries. First and foremost, as the world increases its EV adoption – with 39 countries having passed 10% EV sales share by 2025, according to energy think tank Ember — More sustainable and scalable supply chains for vehicle batteries will be required.
Once achieved on a large scale, Na-ion production can be highly regionalised, with factories in most regions of the world capable of capturing or synthesizing the hard carbon that forms the backbone of the devices.
In addition, the reduced chance of thermal runaway occurring in Na-ion batteries could increase the safety of EV batteries, which currently burn at rates similar to gasoline and diesel, according to National car loading data.
However, no technology is perfect and we are unlikely to see Na-ion batteries replacing all Li-ion batteries anytime soon. This is because the disadvantages of Na-ion make it a more situational alternative to the lithium-based batteries we know so well.
First and foremost, Na-ion batteries have a lower energy density than Li-ion batteries. This is for the same reason they have a lower viscosity – sodium ions are simply larger than lithium ions, which reduces the total movement that can occur in the Na-ion battery’s electrolyte and translate into current.
The mass of sodium is also three times that of lithium, per American Physical Societywhich means you get less charge per gram of Na-ion battery.
In practice, this means that Na-ion batteries cannot compete with Li-ion for the large amount of energy held. The same data from the American Physical Society stated the average energy density of Li-ion batteries to be in the range of 100-300 watt hours per kilogram. CATL’s first generation Na-ion batteries, on the other hand, achieved a figure of only 160 Wh/kg.
The inherently lower energy density of Na-ion batteries compared to Li-ion is a major stumbling block to using them for electric vehicles, despite the potential safety benefits of doing so. Bauer described the issue of energy density as the “main and possibly decisive” drawback for Na-ion batteries, and it is clear that researchers are working hard to overcome this challenge.
“There’s a lot of debate in the battery community about this,” López told LiveScience. “Because of the limitations in power and energy density, to power your typical electric vehicle, the size and weight of Na-ion batteries that would be required would make them unsuitable for onboard deployment. The best chance in transport would (be) in slow-charging infrastructure, and/or ultra-compact, short-range vehicles.”
López added that the disadvantages of Na-ion’s lower energy density cannot be fully offset by its lower cost and weight due to its simpler, copper-light design. So at the moment the economics of some Na-ion batteries don’t add up.
All this means that Na-ion batteries are currently more suitable for static systems – and are therefore not the first choice for EV batteries. But this is far from a niche market.
Online storage beckons
In fact, one of the most promising use cases for Na-ion batteries, supported by the experts LiveScience spoke with, is grid-scale energy storage such as battery energy storage systems (BESS).
These huge arrays of batteries are becoming increasingly important for the stability of national and regional grids, especially for storing intermittent energy production from renewable energy sources such as solar power and wind farms for later use.
For example, the British Parliament have investigated the risk of thermal run for grid-scale BESS, citing examples of fires at BESS sites linked to the process in both Liverpool and Essex.
But even with the lower upfront costs of Na-ion taken into account, energy density is still a disadvantage for the technology in terms of energy storage. For example, EV and battery giant BYD’s MC Cube-SIB ESS, its Na-ion BESS product, delivers an energy storage capacity of just 2.3 MWh in its 20-foot size, as reported by News about energy storage. This compared with around 6.4 MWh for BYD’s Li-ion offer in the same lineup.
Bauer pointed out Baochi storage station in Yunnan as an example of both Li-ion and Na-ion being used to store renewable energy on a large scale. Some of the key reported benefits of the approach include faster discharge of batteries — six times faster than current battery models, according to Global Times — and better resilience in weather conditions from (-4 to 113 degrees F (-20 to 45 degrees C).
When will Na-ion batteries be commercially available?
While Na-ion research is ongoing and new breakthroughs are helping to improve the energy density of Na-ion batteries, this is a mature research field with great commercial potential. In fact, we are already seeing manufacturers deliver products powered by Na-ion batteries.
“Commercial production is already underway, with early mass production capacity coming online,” Bauer said.
“CATL, which is the world’s largest manufacturer of Li-ion batteries, unveiled in 2025 a Naxtra passenger EV NIB with an energy density of 175 Wh/kg, and Freevoy, a mixed-ion battery (mixed NIB and LFP Li-ion). More recently, CATL revealed the Tianxing II, a “mass-produced utility vehicle.”
Despite this, López cautions that more real-world safety tests for Na-ion batteries still need to be completed: “For example, would it be more desirable and feasible to deploy these batteries in urban vs remote environments? How do we adapt them to existing electricity infrastructure? Among other things, that needs to be considered,” she said.
