Na-metal batteries are considered as the promising alternative candidate for Li-ion battery beneficial from the wide availability and low cost of sodium, high theoretical specific capacity, and high energy density based on the plating/stripping processes and lowest electrochemical potential. For Na-metal batteries, the crucial problem on metallic Na is one of the biggest challenges. Mossy or dendritic growth of Na occurs in the repetitive Na stripping/plating process with an unstable solid electrolyte interphase layer of nonuniform ionic flux, which can not only lead to the low Coulombic efficiency, but also can create short circuit risks, resulting in possible burning or explosion. In this communication, the atomic layer deposition of Al O coating is first demonstrated for the protection of metallic Na anode for Na-metal batteries. By protecting Na foil with ultrathin Al O layer, the dendrites and mossy Na formation have been effectively suppressed and lifetime has been significantly improved. Furthermore, the thickness of protective layer has been further optimized with 25 cycles of Al O layer presenting the best performance over 500 cycles. The novel design of atomic layer deposition protected metal Na anode may bring in new opportunities to the realization of the next-generation high energy-density Na metal batteries.

CO 2 electroreduction to chemical feedstocks has suffered from CO 2 reactant loss and a severe energy consumption/production penalty associated with carbonate formation. We divided the process into two cascading steps-CO 2 reduction to CO in a solid-oxide electrolysis cell (SOEC) and CO reduction to multi-carbon products in a membrane electrode assembly (MEA) electrolyser. In the full SOEC-MEA cascade approach, we achieve CO 2 -to-C 2 H 4 with no loss of CO 2 to carbonate and a ~48% reduction in energy intensity compared with the direct route.

Alkali metal-oxygen (Li-O2 , Na-O2 ) batteries have attracted a great deal of attention recently due to their high theoretical energy densities, comparable to gasoline, making them attractive candidates for application in electrical vehicles. However, the limited cycling life and low energy efficiency (high charging overpotential) of these cells hinder their commercialization. The Li-O2 battery system has been extensively studied in this regard during the past decade. Compared to the numerous reports of Li-O2 batteries, the research on Na-O2 batteries is still in its infancy. Although, Na-O2 batteries show a number of attractive properties such as low charging overpotential and high round-trip energy efficiency, their cycling life is currently limited to a few tens of cycles. Therefore, understanding the chemistry behind Na-O2 cells is critical towards enhancing their performance and advancing their development. Chemical and electrochemical reactions of Na-O2 batteries are reviewed and compared with those of Li-O2 batteries in the present review, as well as recent works on the chemical composition and morphology of the discharge products in these batteries. Furthermore, the determining kinetics factors for controlling the chemical composition of the discharge products in Na-O2 cells are discussed and the potential research directions toward improving Na-O2 cells are proposed.

Chemical composition of the discharge products as well as charging overpotential of the Na–air cell is correlated with the kinetic parameters.