CATL sodium-ion batteries are changing the odds

Until now, sodium-ion batteries had seemed unlikely to displace the far more widespread lithium-ion alternatives. CATL has, however, just changed the equation.

The Chinese giant recently unveiled the second generation of its sodium-ion battery, marking a turning point - and a revolution. Its energy density of 175 Wh/kg even exceeds that of LFP lithium-ion batteries, while its cost is 7.5 times lower. Compared with Tesla’s 4680 cylindrical batteries, which use NMC chemistry, it is 10 times cheaper.

CATL has already started mass production, making this an ideal moment to invite Dr Helena Braga, a researcher at the Faculty of Engineering of the University of Porto, back to discuss sodium batteries. She took to the Auto Talks stage - Razão Automóvel’s new editorial format, launched at the ECAR Show - to help explain the technology and its potential:

Dr Helena Braga is an internationally recognised figure in battery development, particularly for her work on solid electrolytes, a technology also expected to transform the batteries of the future.

Her research drew the attention of John Goodenough (1922-2023), the Nobel Prize in Chemistry winner and one of the inventors of the lithium-ion battery. The pair subsequently worked together on research into solid-state batteries.

More recently, she introduced an innovative sodium-ion, or salt-based, battery capable of recharging itself. That development was the subject of a live Auto Rádio broadcast.

Sodium: a cheaper, more abundant alternative

Unlike conventional lithium-ion batteries, sodium batteries use an element that is 1,000 times more plentiful: salt. “There is far more salt than lithium on Earth,” said Helena Braga, who also noted that both elements coexist in the same saltworks, yet lithium accounts for only 4% of what is extracted.

That abundance partly explains the quoted price: just US$10 per kWh. This is substantially below the roughly US$75/kWh of LFP batteries - the technology favoured by China’s automotive industry - and the approximately US$100/kWh of Tesla’s NMC 4680 cylindrical batteries (Source: BloombergNEF).

During Auto Talks, Dr Helena Braga gave another reason why CATL’s sodium batteries are so inexpensive: they are anodeless, meaning they do not have a conventional anode, or negative electrode, fitted.

The anode forms during the first charging cycle. This creates major benefits on the production line, as controlled-environment rooms are no longer needed to install the anode, unlike with lithium-ion batteries. There are further reasons behind such a low price, which can be seen or heard in the video above.

CATL sodium batteries: stronger performance and greater safety

Price is not the only advantage of CATL’s new-generation sodium batteries. They offer the same energy density as LFP batteries, at around 175 Wh/kg, and are expected to achieve the same lifespan: 10,000 charging cycles.

They are also more tolerant of sub-zero temperatures, down to -40°C, and could be considerably safer because they do not contain an anode. This is due to the unusual architecture of CATL’s batteries, which the Portuguese researcher suspects may be solid-state batteries, given their defining characteristics.

This Auto Talks episode also gave Dr Helena Braga the chance to address the international landscape for innovation and battery production, an area in which China is ahead of everyone else - including Europe. Why? Perhaps it can be summed up in a few words:

“We are far too tied up in bureaucracy. Europe wants to accelerate on paper, but hesitates in practice. China shows how it is done: it invests, produces and takes risks.”

Dr Helena Braga, FEUP researcher

See you at the next Auto Talks

There is therefore no shortage of reasons to watch or listen to the latest Auto Talks, Razão Automóvel’s new editorial format, on the usual platforms: YouTube, Apple Podcasts and Spotify.