Metastable FeCN2@nitrogen-doped carbon with high pseudocapacitance as an anode material for sodium ion batteries

Hui Qi; Chenxu Zhao; Jianfeng Huang; Chaozheng He; Lin Tang; Wen Deng

doi:10.1039/d1nr06705b

Metastable FeCN₂@nitrogen-doped carbon with high pseudocapacitance as an anode material for sodium ion batteries

Nanoscale. 2022 Jan 20;14(3):780-789. doi: 10.1039/d1nr06705b.

Authors

Hui Qi¹, Chenxu Zhao¹, Jianfeng Huang², Chaozheng He¹, Lin Tang¹, Wen Deng¹

Affiliations

¹ School of Mechatronic Engineering, Xi'an Technological University, Xi'an, 710021, China. hecz2019@xatu.edu.cn.
² Shaanxi University of Science & Technology, Xi'an, 710021, China. huangjf@sust.edu.cn.

PMID: 34951433
DOI: 10.1039/d1nr06705b

Abstract

Pseudocapacitive materials are good candidates for fast charging anodes of sodium ion batteries (SIB). However, pseudocapacitive materials with a high surface area face the severe problem of low initial coulombic efficiency. In this work, micro-sized nitrogen-doped carbon (NC) coated and supported polyhedron FeCN₂ networks are designed and synthesized by a facile in situ gel-swelling technique. Impressively, FeCN₂@NC as an SIB anode exhibits excellent rate performance with highly reversible rate capacities of 466 and 303 mA h g^-1 at 0.2 and 10.0 A g^-1, respectively. Furthermore, the FeCN₂@NC anode shows a high initial coulombic efficiency (ICE) of 86% due to a low surface area. Electrochemical tests and density functional theory (DFT) calculation indicate that the metastable character enables the low intercalation/conversion reaction energy for FeCN₂ and further greatly promotes the fast pseudocapacitive storage mechanism for FeCN₂@NC. This work provides evidence that FeCN₂ is a new type of metastability induced pseudocapacitive material with high initial coulombic efficiency.