Sodium ion battery trims renewable energy storage costs
The researchers have developed what they claim is the first battery using sodium ions in the ‘18650’ format, an industry standard. The main advantage of the prototype is that it relies on sodium, an element far more abundant and less costly than lithium. The batteries have displayed performance levels comparable to their lithium counterparts. The battery could be used to store renewable energies in the future.
The idea for using sodium in batteries dates back to the 1980s. At the time, lithium was preferred to sodium as the material of choice and it has been widely used ever since for portable electronic devices such as tablets, laptops and electric vehicles. However, lithium has a drawback in that it is relatively rare. Teams from the RS2E (with the CNRS as the leading partner) have turned towards sodium, which is a thousand times more abundant than lithium. The researchers have developed sodium-ion battery prototypes where sodium ions move from one electrode to another in a liquid during the charge and discharge cycles.
The first step was to find the ideal ‘recipe’ for the positive electrode (cathode) of the battery. Six partner laboratories of the RS2E were involved in the project with the goal to find the right composition for the sodium electrode. The development of a future prototype was then entrusted to CEA, a member of the RS2E network. In only six months, CEA was able to develop the first sodium-ion prototype in the ‘18650’ format, that of the batteries found on the market, i.e. a cylinder 1.8 cm in diameter and 6.5 cm in height which should facilitate technology transfer to existing production units.
The second stage made it possible to move from the laboratory scale (synthesis of several grams of cathode material) to the ‘pre-industrial’ scale (synthesis of 1kg batches) which enabled the production of batteries with unmatched power performance levels. The technology, which is already showing promising results, has an energy density of 90 Wh/kg, a figure already comparable with the first lithium-ion batteries. The battery’s lifespan – the maximum number of charge/discharge cycles that a battery can withstand without any significant loss of performance – exceeds 2,000 cycles. Most of all, the cells are capable of charging and delivering their energy rapidly. The main advantage of the technology is that it does away with lithium, a rare element only found in specific locations, contrary to sodium. The other advantage is financial, as using sodium could make it possible to manufacture less expensive batteries.
The next stage of the project is to optimize and increase the reliability of processes with a view to future commercialization.
The partners involved in the project include:
- Six RS2E laboratories
- The Institut de chimie de la matière condensée de Bordeaux (CNRS)
- The Laboratoire réactivité et chimie des solides (CNRS/Université de Picardie Jules Verne)
- The Centre interuniversitaire de recherche et d’ingénierie des matériaux (CNRS/Université de Toulouse III – Paul Sabatier/INP Toulouse)
- The Laboratoire ‘Chimie du solide et de l’énergie’ (CNRS/UPMC/Collège de France)
- The Institut Charles Gerhardt Montpellier (CNRS/Université de Montpellier/ENSC Montpellier)
- The Institut de sciences des matériaux de Mulhouse (CNRS/Université de Haute Alsace)
- Rosa Palacin, a researcher at the ICMAB (Institut des sciences des matériaux de Barcelone) contributed, alonsgside these six laboratoires, to the development of the liquid medium (électrolyte) of the battery.
- Liten, a CEA Tech institute.
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