Solution-combustion Synthesis Of Iron Titanium Oxide As The Anode Materials Of Lithium And Sodium Ion Batteries

Lithium ion batteries?LIBs?have been favored by the industries for their advantages,such as high energy densities,long cycle lives and no memory effect.Meanwhile,since sodium as an alkali metal adjacent to lithium has similar physical and chemical properties with lithium,which is abundant,cheap and easy to get,sodium ion batteries?SIBs?research has attracted much concern.The properties of the electrode materials determine the overall performances of the batteries.As anode materials,Titanium-based materials have attracted the attention of researchers due to their structural stability,performance safety,small volume expansion and other advantages.However,the shortcomings of low capacities and high costs can not be ignored.In this paper,Fe₂TiO₅ and NaFeTi₃O₈ materials with three-dimensional porous network structure framed by nano-sized primary particles were synthesizied by a simple and rapid solution combustion method for the application of LIBs and SIBs,respectively:?1?As the anode material of LIBs,Fe₂TiO₅ combined the structural stability of Ti02 and the high capacity of Fe₂O₃.The electrochemical performance of Fe₂TiO₅show that the discharge capacity can be maintained as 371.4 mA h g^-1 after 100 cycles.Even at a large current densiny(3.2 A g^-1),it still hold a high capacity of 76.6 mA h g^-1.Based on the Raman,XPS and EIS test results,the possible electrochemical reactions of Fe₂TiO₅ are discussed in detail.The results show that the crystal transformation of Fe₂TiO₅ might be ascribed for the irreversible capacity.Due to the coupling effect of Fe₂O₃ and TiO₂,Fe₂TiO₅ behaved the excellent cycling stability.?2?The solution combustion method is applied to the synthesis of Na-Ti-O series material for the first time.NaFeTi₃O₈ with three-dimensional porous net-like sheet morphology was prepared by the solution combustion method.Encouragingly,when being assessed as an anode electrode for SIBs,the NaFeTi₃O₈ net-like sheet composite exhibits superior electrochemical properties.We also studied the effect of the combustion agent glycine.The results indicate that the NaFeTi₃O₈ composite tended to be porous with glycine as the combustion agent,while the NaFeTi₃O₈ composite without glycine as the combustion agent showed a massive appearance.Characted by electronchemical measurement,the porous NaFeTi₃O₈ composite achives more excellent long cyclic stability(discharge capacity of 91 mA h g^-1 after 1000 cycles at the current density of 0.5 A g^-1)and superior rate performance(84.4 mA h g^-1 even at 1.6 A g^-1)than that of NaFeTi₃O₈ without glycine as the combustion agent.The stability and reversibility of the structure are confirmed by XRD and EIS.The theoretical calculations analyzes the little volume expansion of NaFeTi₃O₈ during the charge and discharge processes.Higher discharge capacity,excellent rate performance and little volume expansion make NaFeTi₃O₈ possible to be applied as the anode material for the large-rate and long-cycle SIBs.With the advantages of uniform mixing of liquid phade,simple operation,rapid reaction and the unique porous net-like morphology of the products,the solution combustion method can be widely applied for synthisis of materials with enhanced electrochemical properties,since high specific surface areas are favorable for the infiltration of the electrolyte.In addition,the nano-scale particles can effectively shorten the ion diffusion path.