BEYOND Li-ION BATTERIES: THE Na AND Mg OPTIONS

The success in development and commercialization of Li ion batteries (the greatest achievement of modern electrochemistry) stimulates development of battery systems based on other active metals which are much more abundant than lithium. Na-ion batteries is an emerging field. A plethora of cathode materials, which insert Na ions reversibly at relatively high specific capacity, were discovered and explored in recent years. A good surprise is the relatively fast kinetics of Na ion intercalation in sodiated transition metal oxides, which outperform in several cases their Li counterparts. The negative electrodes for Na batteries are still a challenge. A completed study of Na ions batteries: optimized anodes, cathodes, electrolyte solutions, binders and pretreatments, will be described herein. It appears that the operation of Na ion batteries depends also on passivation phenomena of the SEI (solid electrolyte interphase) type, as is relevant for all kinds of Li batteries.

In contrast, elaboration of rechargeable Mg batteries requires development of surface films free electrodes, because rigid solid surface films cannot allow Mg ion transport through them. Over the years, several families of electrolyte solutions for secondary Mg batteries were developed, in which Mg anodes remain bare and function fully reversibly. The electrochemical windows of these solutions is wider than 3 V. The main challenge related to these system, is the development of high capacity/high voltage cathodes that can be compatible with electrolyte solutions in which Mg anodes behave fully reversibly.

References

1.D. Aurbach et Al. Development of advanced rechargeable batteries: - Review, J. Electrochem. Soc., 162 ,A2424 (2015)