Until now, the scope for sodium-ion batteries to replace the far more common lithium-ion packs looked fairly limited. CATL has just changed that equation.
The Chinese heavyweight has unveiled the second generation of its sodium-ion battery, and it marks a genuine turning point. With an energy density of 175 Wh/kg, it even outperforms LFP lithium-ion batteries, while costing 7.5 times less. Against Tesla’s cylindrical 4680 cells (NMC chemistry), it works out 10 times cheaper.
With CATL already moving into mass production, it was the perfect moment to invite Dr Helena Braga, a researcher at the Faculty of Engineering of the University of Porto, to talk us through sodium batteries. She joined us on stage at Auto Talks - Razao Automovel’s new editorial format, launched at the ECAR Show - and helped clarify the technology and what it could mean.
Dr Helena Braga is widely regarded as an international reference in battery development, particularly for her work on solid electrolytes - a route that also promises to transform the batteries of the future.
Her research drew the attention of John Goodenough (1922–2023) - Nobel laureate in Chemistry and one of the inventors of the lithium-ion battery - and the two later collaborated on solid-state battery research.
More recently, she presented an innovative battery that can recharge itself using sodium ions (salt). That was the topic that prompted a live episode of Auto Radio.
Sodium: a cheaper, more abundant alternative
Unlike conventional lithium-ion batteries, sodium batteries use an element that is around a thousand times more abundant: salt. “There’s far more salt than lithium on Earth,” said Helena Braga, also noting that both materials occur in the same salt pans, yet only 4% of what is extracted is lithium.
That abundance helps explain the price being discussed: just $10 per kWh. This is dramatically lower than the roughly US$75/kWh for LFP batteries - the technology favoured by China’s automotive industry - or the approximately US$100/kWh for Tesla’s NMC 4680 cylindrical cells (Source: Bloomberg NEF).
At Auto Talks, Dr Helena Braga added another reason CATL’s sodium batteries can be so inexpensive: they are anodeless, meaning there is no conventional anode (negative electrode) fitted.
Instead, the anode forms during the first charging cycle. This brings major advantages on the production line, because there is no longer a need for controlled-environment rooms to install the anode, as is the case with lithium-ion batteries. There are further factors behind the low cost, which you can see/hear in the video above.
Better performance and improved safety
Price is not the only advantage of CATL’s new generation of sodium batteries. They offer the same energy density as LFP batteries (around 175 Wh/kg) and are expected to reach the same lifespan: 10 thousand charging cycles.
They are also more tolerant of sub-zero temperatures (down to -40°C) and, because they do not include an anode, potentially far safer. The explanation lies in CATL’s unusual battery architecture, which the Portuguese researcher suspects may be solid-state, given the defining characteristics it appears to show.
During this Auto Talks session, Dr Helena Braga also addressed the international landscape for innovation and battery production, where China is ahead of everyone - including Europe. Why? In her view, it can be summed up succinctly:
“We’re very tied up in bureaucracy. Europe wants to accelerate on paper, but in practice hesitates. China shows how it’s done: it invests, manufactures and takes risks.”
Dr Helena Braga, researcher at the Faculty of Engineering of the University of Porto
See you at the next Auto Talks
There is, therefore, no shortage of reasons to watch/listen to the latest Auto Talks, Razao Automovel’s new editorial format, on the usual platforms: YouTube, Apple Podcasts and Spotify.
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