Exploration of the lithium ions storage performance and mechanism of ZrN@reduced graphene oxide composite

The lithium ions storage behavior of zirconium nitride (ZrN) has been rarely explored. This work proposes a facile covalent self-assemble strategy to prepare the ZrN@reduced graphene oxide (ZrN@rGO) composite for enhanced lithium-ion battery (LIB). The X-ray photo spectra realizes that the strong Zr-C covalent bond is formed between ZrN and rGO. The Bader charge analysis features that the electron transferred from ZrN to rGO promotes the charge density at the ZrN@rGO heterointerface. Remarkably, the volume change decreases from 34% to 18% after the lithiation, corresponding to ZrN and ZrN@rGO, which highlights that the volume change of ZrN can be effectively alleviated by coupling with rGO. Further, the density functional calculation proves that the Li atom prefers to adsorb on Zr-N bridge site, and the adsorption energy of Li atom on ZrN@rGO (−2.01 eV) is higher than that on ZrN (−1.59 eV). Beyond that, the density of states of ZrN@rGO is significantly increased at the Fermi level, implying the high conductivity and fast charge transfer kinetics of ZrN@rGO. As a result, the specific capacity of ZrN@rGO remains at 199.5 mAh·g −1 at 1.0 A·g −1 after 1000 cycles.