Here, we bring to the readers the outcome of Group 1 discussion: Future after lithium. The group has covered battery chemistries that are often being considered as "post-Li" battery technologies. After extensive deliberations, the group concluded that the current vibe about the need of future technologies after the lithium era and, thus, the quest for which new technologies can replace lithium-based battery technology, are somewhat inappropriate and misleading (partially incorrect), respectively. The discussion group reached the conclusion that it would be wise to approach and refer at these technologies as "side-byside" to Li-based batteries. As such, we elaborate here in details on these "side-by-side" promising technologies.Evaluation of the battery concepts depends on several aspects, among which performance is one of the key parameters. Hence, the performance comparison of different cell chemistry is everything, but immediate. As a matter of the fact, the European Commission, e.g., funded the ETIP Batteries Europe (https:// batterieseurope.eu/) as the "one-stop shop" for the batteryrelated R&I ecosystem and aims to accelerate the establishment of a competitive, sustainable and efficient value chain and globally competitive European battery industry through Research and Innovation. Within this ETIP, several working groups have been established, including the one dealing with new and emerging cell technologies. This group, led by Prof. Edström, Dr. Steven and one of the co-authors of this manuscript (SP), is expected to identify the key performance indicators (KPIs) enabling a fair comparison of commercial, new and emerging cell technologies with respect to their applications. However, these KPIs have not been identified yet. Hence, the current study aims to provide insights into "side-by-side" new emerging technologies and also to report a comparative analysis to Li-ion batteries by using a simple approach (i.e., mainly considering cost, energy density, and cycle life). Nonetheless, due to the fact that most of the "side-by-side" technologies are at the early stage of development, a comparison among them is not trivial. Thus, we point out in this progress report only the possibly suitable applications of the new technologies without a comparison.
Sodium-Ion Batteries (Na-Ion)
IntroductionTo relieve the environmental issues, solving the problem caused by intermittent availability of renewable energy resource, e.g., solar energy, wind energy and geothermal energy, is mandatory. Thus, energy storage systems, especially electrochemical energy storage (EES) systems including batteries, supercapacitors, etc., are in the focus of intensive research and development efforts. [1][2][3] In 1991, the Japanese Sony Corp. developed the first commercial lithium-ion batteries with LiCoO 2 and graphite as electrode materials. [4,5] With the blooming of portable electronic Yasin Emre Durmus is currently a PostDoc researcher at the Forschungszentrum Jülich (Germany) within the Institute of Fundamental Electrochemistry (IEK-9). ...
