Onium Salts-Derived Heteroatom Doped Carbon As Anode Material For High-Performance Sodium-Ion Batteries

Based on the advantages of low cost,environmental benignity,diverse structure and chemical stability,carbon material is the most potential anode materials for Na-ion batteries(SIBs).In the case that it is difficult for traditional graphite to effectively store Na+,heteroatom doped carbon materials become a research hotspot due to their dilated interlayer distance and large number of Na+ storage sites.In this paper,a series of mono-atom and dual-atoms doped carbon materials were prepared with onium salt containing heteroatoms as raw materials,so as to explore the effect of heteroatom doping on the structure of carbon and the mechanism of Na+ storage by combining physical characterization and electrochemical performance analysis.The specific research results are divided into three parts:(1)With the C24H20BNa as the precursor,B doped carbon(BC)were prepared by one-step pyrolysis approach.The results indicate that Na+ storage capacity of BC is closely related to the dopant amount and defect content.The dopant of B atom distorts the structure of carbon matrix and creates massive defects for adsorbing Na+.Meanwhile,the interlayer distance was widened for Na+embedding and transmission.The B doped carbon materials treated by 700?(BC-700)deliver the reversible capacity of 253 mAh g-1 at the current density of 50 mA g-1,and retains the Na+ storage capacity of 211 mAh g-1 after 200 cycles.(2)With the onium salts containing B and P as the precursors,B/P dual-doped carbon microspheres(BPC)have been successfully prepared by a facile one-step pyrolysis approach.According to X-ray photoelectron spectroscopy(XPS)and Raman spectrum analysis,the B/P co-doping synergistic effect enhances the distortion of carbon matrix and provides more defect sites for Na+ impregnation.In addition,the Na+ storage model of B/P dual-doping was analyzed by combing XPS analysis and electrochemical test,especially cyclic voltammetry(CV).The B/P dual-doped carbon microspheres treated by 1000?(BPC-1000)demonstrate a high reversible capacity of 221.9 mAh g-1 at 50 mA g-1 and excellent cycling stability.In this work,we firstly attempt to prepare B/P dual-doped carbon for SIBs,providing a new doping method for their anode carbon materials.(3)With the onium salts containing B and S as the precursors,B/S dual-doped broken shell-like carbon microspheres(BSC)were prepared by one-step pyrolysis approach.According to XPS analysis,co-doping with S(B)can synergistically promote the content of counterpart B(S).The Na+ storage mode of B/S and B/P dual-doping effect was analyzed by electrochemical impedance spectroscopy(EIS)and CV curves comparison.Benefiting from the content of 3.96%B and 3.04%S,The B/S dual-doped carbon microspheres treated by 800?(BSC-800)exhibite excellent Na+ storage capacity and stable cycling performance.At the current density of 50 mA g-1,the Na+ storage capacity of 268.6 mAh g-1 is delivered.After 200 cycles,its reversible capacity remains around 234.4 mAh g-1.At the high current density of 1A g-1,the BSC-800 can still maintain a capacity of 100.3 mAh g-1 after 4000 cycles.In this work,we firstly attempt to prepare B/S dual-doped carbon materials for the anode materials of SIBs.