摘要
Development of high-energy-density anode is crucial for practical application of Na-ion battery as a post Li-ion battery.Hard carbon(HC),though a promising anode candidate,still has bottlenecks of insufficient capacity and unclear microscopic picture.Usage of the micropore has been recently discussed,however,the underlying sodiation mechanism is still controversial.Herein we examined the origin for the high-capacity sodiation of HC,based on density functional theory calculations.We demonstrated that nanometersize Na cluster with 3–6 layers is energetically stable between two sheets of graphene,a model micropore,in addition to the adsorption and intercalation mechanisms.The finding well explains the extended capacity over typical 300 mAhg^(−1),up to 478 mAhg^(−1) recently found in the MgO-templated HC.We also clarified that the MgO-template can produce suitable nanometersize micropores with slightly defective graphitic domains in HC.The present study considerably promotes the atomistic theory of sodiation mechanism and complicated HC science.
基金
This work was supported in part by MEXT as Elements Strategy Initiative,Grant Number JPMXP0112101003
Program for Promoting Researches on the Supercomputer Fugaku(Fugaku Battery&Fuel Cell Project)
Grant Number JPMXP1020200301
by JSPS KAKENHI,Grant Number JP19H05815
The calculations were carried out on the supercomputers in NIMS and The University of Tokyo as well as Kyushu University.This research also used computational resources of the HPCI system through the HPCI System Research Project(Project IDs:hp190126,hp200131).
