Heterochelation boosts sodium storage in π-d conjugated coordination polymers

Abstract

The emerging π-d conjugated coordination polymers (CCPs) have attracted increasing attention in the past several years for various applications. However, to date, almost all the reported CCPs are based on a single type of chelating atom (e.g. N, S, O and Se) and only a few works have focused on the co-existence of heterochelating atoms in the ligands of CCPs. Herein, two Ni-based CCPs with N and S as co-chelating atoms were proposed for application in sodium-ion batteries (SIBs). The co-existence of N and S as chelating atoms resulted in high electrical conductivity and high stability, leading to a high capacity, excellent cyclability and high rate capability for the CCPs. Their electrochemical performances are superior to that of all the previously reported CCPs with only N or S as the chelating atom for SIBs. These results enrich the CCPs, deepen our understanding on the chemical states of CCPs and would stimulate further investigations of CCPs with heterochelating atoms for various applications.