Frabrication And Electrochemical Performances Of Sb₂O₃/rGO Anodes For Lithium/Sodium Ion Batteries

Owing to the high natural abundance and high specific capacity,Sb₂O₃ has been investigated as a promising anode material for Li-ion batteries（LIBs）.However,most of the previous studies put emphasis on the synthesis and structure design of Sb₂O₃,rather than focusing on the ion storage mechanisms of Sb₂O₃.At the same time,based on the research of anode materials for LIBs,many efforts have been devoted to exploring high-performance anode materials for Na-ion batteries（NIBs）.In this manuscript,Sb₂O₃/reduced graphene oxide（rGO）nanocomposites were synthesized through a facile solvothermal process and displayed superior performances as anode materials for both LIBs and NIBs.The ion storage mechanisms of Sb₂O₃/rGO in LIBs have been investigated and compared to that in NIBs for the first time.In this paper,Sb₂O₃ and Sb₂O₃/rGO nanocomposites are synthesized through a facile solvothermal process,using SbCl₃、NaBH₄、ethylene glycol、graphite oxide suspension as raw material.The irregular polygon particles of Sb₂O₃ are uniformly dispersed in the rGO nanosheet network,manifesting a composite structure with lots of voids and interfaces.Owing to the the unique structure,which facilitates electronic/ionic diffusion and conversion-alloying reaction,the Sb₂O₃/rGO electrodes show the outstanding electrochemical performances.The Sb₂O₃/rGO nanocomposite electrode vs.lithium delivers a capacity retention of approximately 63.69%for over 100 cycles(at 100 mA·g^-1),and superb discharge specific capacity of 663.30 mAh·g^-1 for Li at 1000 mA·g^-1 and491 mAh·g^-1 for Li at 4000 mA·g^-1.While,the Sb₂O₃/rGO nanocomposite electrode vs.sodium delivers a capacity retention of approximately 91.30%for over 100 cycles(at 100mA·g^-1),and superb discharge specific capacity of 332.40 mAh·g^-1 for Na at 1000 mA·g^-1 and 296.80 mAh·g^-1 for Na at 4000 mA·g^-1.The CV,in-situ XRD,quasi in-situ XPS,SEM and GITT study reveals the ion storage mechanisms of Sb₂O₃/rGO nanocomposites in LIBs.It shows that the crystalline Sb₂O₃ nanoparticles are converted into Li₃Sb and Li₂O phase via two steps of conversion-alloying reactions in LIBs and the Li-ion cannot transport to the center of the Sb₂O₃nanoparticles,which makes an incomplete conversion-alloying reaction in LIBs.At the same time,the product Li₂O is unstable during the electrochemical cycle.Meanwhile,based on the research of Sb₂O₃/rGO in LIBs,through in-situ XRD,quasi in-situ XPS,SEM amd GITT,the ion storage mechanisms in NIBs were also systematically investigated.It reveals that the Sb₂O₃/rGO are directly and completely converted into amorphous Na_x-O_y-Sb compounds and Na₂O phase by one step reaction in NIBs.At the same time,the reaction product amorphous Na₂O is stable during electrochemical cycle.