CATL sodium batteries: a revolution that is 10 times cheaper than Tesla’s 4680 batteries

Until now, sodium-ion batteries had shown only limited potential as replacements for the more widespread lithium-ion alternatives. CATL, however, has just changed the odds.

The Chinese giant recently unveiled the second generation of its sodium-ion battery, marking a turning point - a genuine revolution. Its energy density (175 Wh/kg) even exceeds that of LFP lithium-ion batteries, while costing 7.5 times less. Against Tesla’s cylindrical 4680 batteries (NMC chemistry), it is 10 times cheaper.

CATL has already begun 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. Taking to the stage at Auto Talks - Razão Automóvel’s new editorial format, launched at the ECAR Show - she helped us understand the technology and its potential:

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

Her research caught the attention of John Goodenough (1922-2023) - Nobel Prize in Chemistry laureate and one of the inventors of the lithium-ion battery - and she later worked with him on solid-state battery research.

More recently, she introduced an innovative sodium-ion (salt-based) battery that can recharge itself. This was the subject that prompted a live Auto Rádio session.

Sodium: a cheaper and more abundant alternative

Unlike conventional lithium-ion batteries, sodium batteries use an element that is a thousand times more abundant: salt. “There is far more salt than lithium on Earth,” Helena Braga stated, noting that both elements coexist in the same salt flats, although lithium accounts for only 4% of what is extracted.

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

During Auto Talks, Dr Helena Braga gave another reason why these CATL sodium batteries can be so inexpensive: they are anodeless, meaning that they do not have a conventional fitted anode (negative electrode).

The anode is created during the first charging cycle. This brings major production-line benefits, as controlled-environment rooms are no longer required to install the anode, as they are for lithium-ion batteries. There are further reasons behind such a low price, which can be watched or heard in the video above.

Better performance and greater safety

Price is not the sole 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 deliver identical longevity: 10,000 charging cycles.

They also tolerate sub-zero temperatures more effectively (down to -40°C) and, because they contain no anode, have the potential to be considerably safer. The explanation lies in the unusual architecture of these CATL batteries, which the Portuguese researcher suspects may be solid-state, given their defining characteristics.

This Auto Talks episode also gave Dr Helena Braga the opportunity to discuss the international landscape for innovation and battery production, where China leads 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 speed things up on paper, but hesitates in practice. China shows how it is done: it invests, produces and takes risks.”

• Dr Helena Braga, FEUP researcher

The next Auto Talks is already in the diary

There are therefore plenty 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.