One Step Forward in post Li-ion Batteries

To reduce the consumption of primary energy sources, which are mostly based on fossil fuels and nuclear energy, cleaner alternatives need to be developed. Storage of renewable energy, e.g. solar and wind, and the development of clean mobility are of utmost importance. Li-ion batteries are, to date, the most reliable and efficient commercial products that can store electric energy for different applications (e.g. medical devices, electric vehicles, and portable electronics). Over the last 25 years, most research has been dedicated to the development of novel electrode materials and their engineering, which has led to an increase in the energy density by a factor of three, from 85 Wh/kg in 1991 to 240 Wh/kg for the battery commercialized nowadays. Unfortunately, Li-ion technology is reaching its own limitation due mostly to several factors among them, safety, cost and energy density. Alternative chemistry and/or electrolyte are currently under intense investigation to tackle the pre-cited issues. From safety point of view, the electrolyte, which was quite often neglected in the literature, is regaining interest with intensive research in inorganic solid electrolyte (oxide and sulfide based) or polymer solid electrolyte (PEO based and other chemistry, copolymers, Single-ion…). In this area, there is a regain of interest in the field of water-based batteries. Indeed, so far, aqueous batteries were only sporadically studied due to their very small electrochemical stability windows. The outcome of the water-in-salt approach removed this bottleneck allowing larger electrochemical stability windows.

Alternative and multivalent cations (such as Na, K, Ca, Mg, Al) give the promise of low cost and high energy density battery but still some fundamental questions remains about the electrolyte, passivation layer and electrode materials. Finally, organic based batteries give hope to develop bio-sourced, low cost and tunable electroactive material that can be highly suitable also in the aqueous based electrolyte.

In this Research Topic we wish to demonstrate that there is a bright future beyond conventional Li-ion batteries and that several systems listed below can be key player in near future.

• All solid state batteries (Li, Na, Mg, etc.)
• Polymer-based batteries
• Organic-based batteries
• Aqueous-based batteries
• Alternative (Na, K) and multivalent (Mg, Ca, Al) chemistries

We welcome submissions in the form of perspectives, mini-reviews, reviews and exemplary original research covering all aspect of post-Li ion technology.