Investigation Of Sodium Storage Performance Based Heteroatom Modified Ordered Mesoporous Carbon

Sodium ion batteries?SIBs?are deemed as the promising candidate to alternate Lithium ion batteries in the large scale energy storage fields due to the abundant reserves,low cost,and the similar physicochemical characterizations to lithium.Exploiting the suitable anode materials with good sodium storage capacity are the key factors for the development of SIBs.Ordered mesoporous carbon?OMC?has a high surface specific area and characteristic interconnected mesoporous channel for Na⁺adsorption and diffusion,showing great potential for the SIBs anodes.But OMC faces the problems of low electronic conductivity and scanty surface active sites.To address these problems,this paper aims to modify the OMC through heteroatom doping and oxygen functionalization to synthesis high-performance SIBs anodes.The electrochemical properties and structure information are also investigated.The main research contents and achievements are as follows:?1?A nitrogen and sulfur co-doped OMC was synthesized via a facile one-step method,and we studied the effects of dopant usage on the structure such as d-spacings,defects,pore structures and chemical bonds and electrochemical performances.Furthermore,theoretical calculation was applied to investigate the adsorption capability and electron conductivity of the OMC after heteroatom doping.?2?It reveals that N/S doping could effectively enhance the electronic conductivity and increase the defects,which are favorable for the rapid charge transfer and Na⁺surface adsorption process,leading to the enhanced sodium storage performance.The obtained N/S-OMC-5 with moderate doping ratio delivers a high rate capability of 220 mA h g^-1 at 5 A g^-11 after 3000 cycles.?3?OMC was oxygen functionalized using different concentrations of H₂O₂to systematically investigate the effects of oxygen functional groups on the sodium storage behavior,without any other change of d-spacing,defects and chemical compositions.Both the experimental data and theoretical calculation reflect that the introduced oxygen functional groups,especially groups such as carboxylic anhydrides and quinones with double C=O bonds and strong Na⁺adsorption capability,greatly contributing to the sodium storage capacity.Comparably,carboxylic acids has only one active sites?C=O?,and weak Na⁺adsorption capability,exhibiting lower priority during the sodiation process.?4?Introducing OFGs with volumetric ratio of 75%H₂O₂ could boost the surface redox reaction kinetics,and thus promote the enhancement of sodium adsorption capacity.The obtained oxygen functionalized OMC delivers a high rate capability of 218 mA h g^-1 at 2 A g^-1 even after 4000 cycles,and a 64.7%capacity increase than that of OMC.