Advanced materials for Sodium-ion batteries

Energy conversion and storage have become key issues concerning our welfare in daily life. Electrochemical systems, such as batteries and super capacitors, that can efficiently store and deliver energy on demand are playing a crucial role in this field. Presently, lithium-ion batteries (LIBs) are the most widespread rechargeable batteries in the consumer electronic and portable device markets because of their unique properties. Due to their high energy density, LIBs are already considered in the transportation field and used to power hybrid and full electric vehicles.[1] However, the increased demand of lithium and the comparably limited geographic location of resources is reflecting in a rapid rise of its price. As a consequence, the identification of energy storage systems alternative to lithium is now seen as a valid step to lead to the development of economically sustainable secondary batteries. Among these, sodium-based batteries appear as very promising candidates due to the low cost and high abundance of sodium.[2] Here we will present an overview about Na-ion battery materials, with the aim of providing a wide view of the systems studied in our group. We will focus on poly-anionic networks and layered compounds as cathode materials and alloying nanostructured compounds at the anode side for conventional sodium-ion batteries based on the intercalation chemistry process. [3] Furthermore recent studies on ‘‘low temperature’’ Na–S batteries, analogous to Li–S batteries which offer great promise as low-cost, high-capacity energy storage systems will be presented.