Batteries are always in the news, in an alternation of euphoria and gloom. Euphoria due to the all-solid state battery, a subject I covered in last year's lecture. Gloom due to the recent difficulties encountered by European gigafactories as a result of the slowdown in the electric vehicle market. Added to this are the difficulties encountered in meeting orders and competition from China. As highlighted last year, the rise of LiFePo4 and LiFe1-xMnxPO4chemistries, of which China has a virtual monopoly, is intensifying, threatening European sovereignty. Less publicized, but just as crucial, is Na-ion technology, positioned as a more environmentally-friendly alternative to Li-ion due to the abundance of the element Na (sodium) in nature.
This technology is now on the roadmap of a number of companies, with many already marketing it (TIAMAT in France, CATL and HiNa in China, Natron in the USA). Na-ion, which competes with Li-ion in terms of power, has a shorter battery life. It is currently coveted for power applications, as a buffer for renewable energy, but also for the new generation of urban vehicles, for which fast charging is preferred to long autonomy. But what's really behind this technology in terms of materials and electrolytes ? What about its cost and safety aspects ? What about its scope for progress ? Is an all-solid-state Na-ion version realistic ? This lecture will attempt to answer all these questions.
First of all, Na-ion technology will be placed in the current battery context. We will then describe the different sodium-ion chemistries based on positive electrodes, either polyanionic compounds, lamellar oxides or Prussian blues. Although carbon is the negative electrode of choice for Na-ion technology, we will look at the possibilities offered by sodium alloys or conversion electrodes. In a third time, we will deal with the electrolyte, which can be liquid (organic or aqueous) or solid, leading us to non-aqueous, aqueous and all-solid Na-ion technologies. In this race towards more environmentally-friendly batteries, the state of research into K-ion technology will also be reviewed, as will the return to Fe-air technology, which is attracting renewed interest.
The lectures will be followed by seminars dedicated to the contribution of AI to battery assembly (Alejandro Franco), the electrochemistry of Zn-MnO2 (Véronique Balland) and Ca/Mg-ion batteries (Rosa Palacin), the study of interfaces using laboratory techniques (Ozlem Sel) or large-scale instruments (Sandrine Lyonnard), and recycling issues (Cyril Aymonier). An industry representative, Hervé Beuffe, CEO of TIAMAT, will close this series of lectures.