Constructing N, O, S-tri doped carbon @ hard carbon architectures as advanced anodes materials for sodium-ion batteries

Abstract

Biomass-derived hard carbon from biological resources shows considerable potential as an anode material for sodium-ion batteries (SIBs). However, poor electrochemical performance and stability restrict their practical application. Herein, by growing polyaniline on the surface of poplar fibers and employing high-temperature calcination to form a N, O, S-tri doped carbon @ hard carbon bilayer structure (NOSC@HC), which enhances the platform capacity of the anode material. The resulting bilayer carbon has a reversible specific capacity of 317.42 mAh g^-1 (current density:0.2 A g^-1)(93.28 % of capacity remaining after 200 cycles) in a half-cell. The capacity in the plateau region (< 0.1 V) accounted for 58.9 % of the total capacity. When composed of the full cell, an energy density of 151 Wh kg^-1 (0.2 A g^-1) was achieved. Theoretical calculations indicate that multi-element doping within the carbon layer enhances the adsorption of sodium-ion from the original defects, improves electrochemical kinetics, and increases charge transfer through electron density rearrangement, leading to a strong sodium storage capacity for the NOSC@HC anode. Our results provide new research ideas and insights into the development and practical application of biomass-derived hard carbons.