Analogous Chelation to Boost Utilization of Sb in Sb Nanoparticles and N-doped Carbon Composites for Enhancing Potassium Storage.

ABSTRACT

Antimony (Sb) is an attractive anode material for potassium-ion batteries (PIBs), but it suffers from aggregation during the charging-discharging process, thus causing embedded active sites and collapsed structure. The analogous chelation refers to the reaction in which the central nanoparticle is linked to the matrix through multiple coordination bonds to form a stable composite. This strategy can inhibit aggregation and maintain the nanosized structure of Sb, thus activating the utilization of Sb active sites and structural stability. Given the special position of nitrogen (N) in the periodic table of elements and the strong bond energy of Sb-N, the N element can serve as an intermediate to connect Sb nanoparticles and an intrinsic N-doped carbon network via strong Sb-N-C/Sb-N═C covalent bonds using analogous chelation. Herein, a hybrid material of Sb@CTF-NC is fabricated via analogous chelation. The Sb atoms exposed on the surface of Sb nanoparticles are used to chelate with the N-doped carbon for high-performance PIBs. The mechanism underwent ex situ characterizations. The calculation of density functional theory reveals that the increase of adsorption energy and reduction of the K+ diffusion barrier accelerate the electrochemical reaction kinetics.