Abstract
Na-CO(2) batteries have attracted significant attentions due to their high energy density and effective utilization of greenhouse gas CO(2). However, all reported Na-CO(2) batteries employ excessive preloaded metal Na, which will lead to safety issues such as dendrite formation and short circuit. In addition, the charging mechanism of reported Na-CO(2) batteries is not very clear. Here we report the Na-CO(2) batteries, starting from the cathode of cheap Na(2)CO(3) and multiwalled carbon nanotubes (CNTs). Due to the effective electron transfer and high reactivity, the decomposition of Na(2)CO(3) and CNTs could take place under 3.8 V. The charging mechanism of 2Na(2)CO(3) + C → 4Na + 3CO(2) without any side reactions is revealed by in/ex situ techniques such as Raman, gas chromatograph, and optical microscope. Dendrite-free Na can quantitatively deposit on the Super P/Al anode because of large specific surface area and low nucleation barrier of the anode for Na plating. The batteries could deliver an energy density of 183 Wh kg(-1) (based on the whole mass of the pouch-type batteries, 4 g) with stable cycling performance. This work reveals that safe rechargeable Na-CO(2) batteries could be constructed by cheap Na(2)CO(3) and multiwalled carbon nanotubes.