Preparation And Electrochemical Performance Of Stimony-based Anode Materials In Sodium Ion Batteries

Though Sb2O3 and Sb-2S3 have high theoretical capacity by alloy-conversion reaction,its have problems of low capacity and poor stability during repeated charge and discharge processes.In this paper,the antimony materials and antimony-carbon compounds are designed via antimony-containing organic salt and natural stibnite ore as raw materials.To explore the internal relationship between materials and electrochemical reaction,the physical chemical characterization are conducted to analyze the morphology and structure of materials as well as the electrochemical detection methods are used to study the sodium storage properties of materials.The study expect that provides a reference for the development of anode materials and the application of natural ore directly as an active substance in sodium ion batteries.(1)An octahedral Sb2O3 was prepared through hyperthermia-crystallization method using antimony-containing organic salt in strong alkali solution.SEM results show that the Sb2O3 have uniform size of 3μm and more complete morphological characteristics than commercial Sb2O3.XRD refinement analysis show that the octahedral Sb2O3 unit cell volume(1407.220)is larger than the commercial Sb2O3 unit cell(1401.068),which is favorable for sodium ion diffusion.(2)In the SIBs,the charge/discharge capacity of the octahedral Sb2O3 is 395.6/742.5 mAh·g-1(1st)and 435.6 mAh·g-1(112%/127%of the charge and discharge capacity of the commercial Sb2O3 material),CE is 97.97%,indicating that the octahedral Sb2O3 materials have a higher specific capacity than the commercial Sb2O3;the reversible capacity of the octahedral Sb2O3 is 582.1,524.9,455.3,413,364 and 374.4 mAh·g-1 at different current densities of 0.05,0.1,0.2,0.3,0.4 and 0.5 A·g-1,while commercial Sb2O3 has reversible low capacities of 478.4,423.6,387.5,286.6,211.9 and 208.6 mAh · g-1,indicating that the octahedral Sb2O3 rate performance is superior to commercial Sb2O3.The octahedral Sb2O3 Rct(1301 Ω)is smaller than the commercial Sb2O3 Rct(1544 2),indicating that the octahedral structure is more conducive to the diffusion of sodium ions.(3)The surface of graphite are activated via reflux condensation in mixed acid(HNO3:H2SO4=3:1)under 80 ℃ for 8 h.Subsequently,the graphite/stibnite(G/Sb2S3)with high reversible capacity,long cycle life and high rate performanceare are prepared through stibnite ore and activated graphite in high temperature and high pressure.The activated graphite ID/IG was 0.15,which was close to the D/G peak ratio of the untreated graphite,indicating that the structure of graphite was not greatly damaged during the acid treatment.The peaks at 286.1 eV in the XPS high-resolution spectrum of C is O-C=C characteristic peaks,indicating that partial oxidation occurs on the graphite surface to produce some oxygen-containing functional groups which are favorable for SEI film formation.(4)In the SIBs,the G/Sb2S3 material has a reversible capacity of 400.1 mAh·g-1(80th)and a capacity retention rate of 75.2%under the condition of current density of 0.1 A·g-1.However,the reversible capacity of the stibnite has a reversible capacity of 190.1mAh·g-1 and a capacity retention rate of 30.7%.At 1 A·g-1 current density,the reversible capacity of the G/Sb2S3 composites are still 317.3 mAh·g-1(100th),which is much higher than the reversible capacity of the stibnite(157.9 mAh·g-1).At current densities of 0.1,0.3,0.5 and 1 A·g-1,the reversible capacities of G/Sb2S3 composites are 642.3,507.6,392.1 and 264.9 mAh·g-1,respectively.When the current density returns to 0.1 A·g-1,the reversible capacity of G/Sb2S3 composites still return to 598.4 mAh·g-1.To study the stability of G/Sb2S3 after rate test,the capacity of G/Sb2S3 is 412 mAh·g-1(75th)and capacity retention rate of 82.9%,but capacity of stibnite is 80 mAh·g-1.(5)Two-dimensional sulfur-doped carbon nanosheets(SCS)were obtained through calcining sulfur-containing surfactants and carbon quantum dots with rich oxygen-containing functional groups which are prepared by acetaldehyde as carbon source in alkaline solution.The results of characterization indicate that the carbon nanosheets contained more oxygen-containing functional groups and were structurally complete with a highly graphitized structure(ID/IG = 0.621).The peak of 169.3 eV in the XPS high-resolution map of C is C-SOx-C bond.,indicating that the sulfur atom is successfully incorporated into the carbon nanosheet.Subsequently,a Sb2S3/SCS composite anode material with electrochemical properties superior to that of natural stibnite ore is prepared by using sulfur-doped carbon nanosheets as the substrate and natural stibnite ore as the main active materials.(6)In the SIBs,the reversible capacity of stibnite/sulfur-doped carbon nanosheets(Sb2S3/SCS)material is 455.8 mAh·g-1(100th)at 0.1 A·g-1.At the current densities of 0.1,0.3,0.5 and 1 A·g-1,the reversible capacities of the Sb2S3/SCS materials are 636,497,392 and 263 mAh·g-1,respectively.When the current density returns to 0.1 A·g-1,the reversible capacity of Sb2S3/SCS composites can still be maintained to 595 mAh·g-1.To study the stability of G/Sb2S3 after rate test,the capacity of Sb2S3/SCS is 422 mAh·g-1,(75th)and capacity retention rate of 82.9%,but capacity of stibnite is 80 mAh·g-1.