Iron encased organic networks with enhanced lithium storage properties

Abstract

Developing promising electrode materials for next‐generation high‐performance lithium ion batteries (LIBs) becomes critically important. So far, a great number of transition metal (M)‐based composites (e.g., oxides, sulfides, selenides, and M‐carbon) as promising anodes have been intensively reported. Despite the huge progress achieved on the development of M‐nitrogen‐doped carbon (M‐N‐C) as catalysts in the field of electrocatalysis, the study of M‐N coordination sites, and how they might affect the anode properties of M‐N‐C for LIBs, is still rare. Here, we designed and fabricated a series of Fe‐N‐C hybrids as anodes for LIBs, including iron (Fe) nanoparticles cores encapsulated in well‐defined nitrogenated holey graphitic structures (Fe@C2N) and Fe encapsulated in a three‐dimensional (3D) cage‐like organic network (Fe@CON). Such hybrids display promising lithium ion storage properties. In particular, benefitting from its 3D‐interconnected microporous structure and rich Fe‐N‐C species, one Fe@CON (e.g., HCF@3DP) exhibits a superb reversible capacity of 747.3 mAh g−1 at 0.1 C, excellent rate capability (e.g., 320.8 mAh g−1 at 10 C) and long cycling stability (over 400 cycles).