Nanocarbon in Sodium-ion Batteries – A Review. Part 1: Zero-dimensional Carbon Dots

In the recent past, sodium-ion batteries (SIBs) have assumed to be an alternative to lithium-ion batteries (LIBs) as sodium is abundantly available in nature. It is low cost with its storage mechanism almost similar to LIBs. The ionic radius of Na is three-fold larger than that of Li and offers a low standard electrochemical potential than Li. The built-in SIBs are better than LIBs. However, in terms of energy density, specific capacity, and rate capability, there is a lack of suitable anode materials for SIBs. Interestingly, carbon-based quantum dots are a new class of zero-dimensional (0D) material with ultra-small size having unique physicochemical properties. The utility of carbon quantum dots (CQDs), graphene quantum dots (GQDs) and graphitic carbon nitride quantum dots (g-C₃N₄ QDs) has drawn attention to the scientists and industrialists for the development of SIBs due to their quantum size and structural diversities, physicochemical properties, amenability for doping with heteroatoms and good electrical conductivity. This article reviews the role of various carbon quantum dots commonly used as anodes in SIBs.