A study in Cell Reports Physical Science found that a commercial sodium-ion battery from China has reached manufacturing quality and power performance comparable to leading lithium-ion cells used in Tesla vehicles. The analysis gives researchers a rare look inside a battery chemistry that could reshape parts of the electric vehicle and grid-storage market.
The cell, made by Hina Battery, replaces lithium with sodium, a far more abundant element. Researchers at RWTH Aachen University tested the battery under demanding conditions, then opened it to inspect its materials and design. Their results show a technology that is already mature in several important ways, even as cold-weather charging and energy density remain central targets for improvement.
The finding matters because battery supply chains are under pressure. Lithium-ion cells dominate electric vehicles and large storage projects, but their raw materials can be expensive and unevenly distributed around the world. A commercially proven sodium-ion battery could give manufacturers another route for shorter-range vehicles, fleet use and stationary storage.
A commercial sodium-ion cell put to the test
The research team examined a battery that has moved beyond the laboratory. Hina’s commercial sodium-ion cells are already being used in China in vehicles and large-scale energy storage systems, which made them a valuable test case for judging how close the technology has come to lithium-ion performance.
To check production quality, the researchers analyzed 120 battery cells using electrochemical impedance spectroscopy. This method sends a small electrical signal through each cell and measures how the battery responds. In practical terms, it reveals whether cells from the same product line behave consistently.
That consistency was one of the clearest surprises. The study reported only 5.3% impedance variation across the tested cells, a level that points to tight manufacturing control. “We were positively surprised by how uniform the cells are,” said Moritz Schütte, a battery researcher at RWTH Aachen University.
Uniformity matters in real battery packs. When cells behave similarly, engineers can manage charging, discharging, heat and aging more predictably. That helps battery packs operate safely and efficiently over time, especially when hundreds or thousands of cells are connected together.
How researchers compared it with Tesla batteries
The team benchmarked the sodium-ion cells against advanced lithium-ion batteries associated with Tesla’s current battery architecture. The comparison focused on measurable qualities such as manufacturing consistency, power capability, temperature behavior and internal design.
Researchers tested each cell under realistic operating conditions. They measured energy and power performance across different charging rates and temperatures ranging from −20 °C to 45 °C. This range is important because batteries often face heat, freezing weather and heavy demand outside ideal laboratory conditions.
The cell delivered strong performance at high current. According to the study, capacity remained above 100% at 4C and 25°C. A 4C rate means the cell is charged or discharged at a speed that would complete the process in about 15 minutes under simplified conditions. In real use, such high-rate behavior points to strong power delivery.
“The high-power performance was better than one might expect from an early commercial sodium-ion product,” Schütte said. That finding is especially relevant for applications that need bursts of power, such as regenerative braking, grid services and commercial vehicles that operate on fixed routes.
After performance testing, the researchers used X-ray imaging to view the cells’ internal structures. They then disassembled the batteries to study electrode dimensions, material composition and microscopic features. This combination of outside-in and inside-out analysis helped connect performance to physical design.
A tabless design inside the cell
Inside the Hina cell, the researchers found a sophisticated layout. The battery uses a tabless design with a double-aluminum current collector. This architecture helps reduce electrical resistance and supports more even temperature distribution through the cell.
In many cylindrical batteries, small metal tabs serve as current pathways between the internal electrode roll and the external terminals. A tabless architecture creates a broader current path. That can lower resistance, reduce hotspots and help the cell handle higher power.
The design resembles architecture used in current Tesla batteries. That resemblance is notable because it shows sodium-ion technology adopting advanced engineering approaches that have already improved lithium-ion cells. Better architecture can help offset some of the chemistry’s natural limits.
The team also identified a distinctive cathode composition, described in the study as NaCu1/9Ni2/9Fe1/3Mn1/3O2. In simpler terms, the cathode contains sodium along with copper, nickel, iron and manganese. The researchers observed an unusual spatial separation of copper from the other transition metals within individual particles.
That copper pattern raises questions for future work. The team suggested that its role in performance and aging deserves further study. Understanding how each element behaves over many cycles will be important if sodium-ion cells are expected to serve in demanding, long-lived battery packs.
Strong cold discharge, weaker cold charging
Cold weather often exposes battery weaknesses. Chemical reactions slow down as temperatures fall, which can reduce available energy and make charging more difficult. The Hina cell showed a mixed cold-weather profile, with impressive discharge behavior and more limited charging performance.
At −20 °C, the cell retained more than 80% usable discharge energy. That means it could still deliver much of its energy in freezing conditions. For stationary storage, cold-climate fleet vehicles and equipment that must operate outdoors, that is an encouraging result.
Charging in the cold was more difficult. The study reported that usable energy in the charging direction dropped to 56% at −20°C. Low-temperature charging can stress batteries because ions move more slowly through internal materials. Engineers may need thermal management systems or operating strategies that warm the pack before rapid charging.
Schütte emphasized that point in discussing likely applications. For uses that require frequent charging at low ambient temperatures, the battery will need careful control. That could include preheating, slower charging profiles, or pack designs that keep cells within a safer temperature window.
This split behavior helps define the near-term role of sodium-ion batteries. Strong cold discharge supports reliability in harsh environments. Better cold charging would make the chemistry more attractive for vehicles that need fast turnaround in winter.
Why sodium could lower battery costs
Sodium’s biggest advantage begins with supply. It is abundant and widely distributed, which could ease dependence on lithium resources. That matters for automakers, utilities and countries trying to scale battery production without bottlenecks in raw materials.
In battery manufacturing, material availability can influence cost, resilience and long-term planning. A cell chemistry based on abundant sodium could reduce pressure on lithium supply chains. It could also give battery makers more flexibility when market prices move sharply.
The study points to the strongest near-term uses for sodium-ion cells. Stationary energy storage is one promising area because large grid batteries can tolerate lower energy density more easily than long-range electric cars. Size and weight matter less when a battery sits beside a solar farm or substation.
Shorter-range vehicles are another plausible fit. Delivery vans, city cars, buses and commercial fleets often run predictable routes. For those vehicles, lower cost and strong power may matter more than maximum driving range.
The chemistry still has room to grow. Today’s commercial sodium-ion cells generally have lower energy density than the best lithium-ion cells. That means a sodium-ion pack usually needs more mass or volume to store the same energy. Improvements in materials and cell design could narrow that gap over time.
What researchers want to improve next
The next stage of research will focus on charging below freezing. The RWTH Aachen team wants to understand how the cell behaves at temperatures below 0°C, then improve safety and efficiency under those conditions. This is a practical target because cold-weather charging affects real vehicles and outdoor storage systems.
Materials development is another major path forward. “Advances in hard-carbon anodes and electrolyte formulations may be especially promising,” Schütte said. In a sodium-ion cell, the hard-carbon anode stores sodium ions during charging. The electrolyte carries those ions between electrodes.
Small changes in those materials can make a large difference. A better electrolyte can help ions move more smoothly at low temperatures. A refined anode can improve storage capacity, charging speed and long-term stability.
The cathode will also draw attention. The study’s detection of copper in the cathode, along with its uneven distribution, gives researchers a specific chemistry question to pursue. Future sodium-ion technologies may aim for cathodes with fewer costly or supply-sensitive metals while keeping competitive performance.
For now, the teardown shows that commercial sodium-ion batteries have entered a more serious phase. The Hina cell matched important lithium-ion benchmarks in quality and power and it revealed clear engineering targets. That combination makes sodium-ion technology a real contender for storage systems and vehicles where cost, supply security and reliable power carry the most weight.
