Preparation And Characterization Of Titanium Niobate As Energy Storage Materials

In order to meet the demand of large scale application,it is necessary to develop durable anode materials for lithium ion batteries with high power and energy density.Here,we report the preparation and modification of TiNb₂O₇ and TiNb₂₄O₆₂.These two materials are characterized by a series of electrochemical tests,and the lithium ion storage mechanisms of these two materials are investigated.Firstly,we report the synthesis of one-dimensional TiNb₂O₇ hollow nanofibers.The TiNb₂O₇hollow nanofibers exhibit high platform,low charge-transfer resistance,and fast kinetics.The results obtained from a series of electrochemical tests show that the reversible capacity of one-dimensional TiNb₂O₇ hollow nanofibers can keep 210.1 mAh g^-1 after 150 cycles at 0.4 C,and even at 10 C,TiNb₂O₇ hollow nanofibers deliver a high charge capacity of 158.4 mAh g^-1.Such results can be attributed to hollow nanostructure.Meanwhile,the lithiation mechanism of one-dimensional TiNb2O7 hollow nanofibers is also studied.The discharge process of one-dimensional TiNb₂O₇ hollow nanofibers can be divided into three parts,two solid-solution processes and one two-phase coexistence.It is found that one-dimensional TiNb2O7 hollow nanofibers show the high structural stability and electrochemical reversibility.Therefore,one-dimensional TiNb2O7 hollow nanofibers can be a candidate of anode material for lithium ion batteries.Secondly,we also report the preparation of one-dimensional nitrogen doped carbon coated TiNb24O62 nanowires.The electrochemical results show that the reversible capacity of nitrogen doped carbon coated TiNb₂₄O₆₂ nanowires can keep 218 mAh g^-1 at 0.5 C,and even at 10 C,nitrogen doped carbon coated TiNb₂₄O₆₂ nanowires deliver a high charge capacity of 148.9 mAh g^-1.Such results can be ascribed to nitrogen doped carbon coating and nanostructure.In addition,the lithiation mechanism of nitrogen doped carbon coated TiNb₂₄O₆₂ nanowires is also investigated by an in situ XRD technique.the phases transformation of nitrogen doped carbon coated TiNb₂₄O₆₂nanowires are caused by the expansion of TiNb₂₄O₆₂ unit cell along with b aixs.It is found that nitrogen doped carbon coated TiNb24O62 nanowires show the high structural stability and the outstanding electrochemical reversibility.Therefore,nitrogen doped carbon coated TiNb₂₄O₆₂nanowires can also be a candidate of anode material for lithium ion batteries.