Liquid Exfoliation And Charge/discharge Characteristics In Libs Of Two-dimensional Ti₃C₂ Nanosheets

Ti3C2, as a new type of two-dimensional materials, has unique and excellent properties of mechanic, electronic and magnetic. So Ti3C2 has important application values. But the current preparation of high quality Ti3C2 still exist a lot of key problems to be solved, such as the layer number of control is not high,poor uniformity and crystal size is not big. This work prepares of Ti3 Al C2 and Sn solid solution Ti3(Al,Sn)C2 materials,then makes the synthesis of Ti3C2Tx(Tx=OH,F,O). This work focused on the influence of process parameters in crystal structure, grain size, and charge/discharge characteristics in LIBs.The results demonstrated that the best preparation of Ti3 Al C2 powder is Ti:Al:C=3:1.1:2, sintering temperature 1400℃, the heating rate of 5℃/min, the heat preservation time of 4h. The sintering process is also applicable to Sn solid solution of Ti3(Al,Sn)C2 materials.For intercalating Ti3 Al C2 phase, The best preparation of Ti3C2 Tx is 30 wt.%HF acid soaking Ti3 Al C2 powder for 4h.But Ti3(Al,Sn)C2 phase can not be intercalated.Reaction of HF acid and Ti3 Al C2 mainly divides into two steps.The first step, HF acid and Ti3 Al C2 reaction, generate Ti3C2.The second step, Ti3C2 continue to react with HF acid or water, forming Ti3C2 with functional groups(OH)x Fy structure.After sonication of the supernatant, The resulting film was comprised of delaminated flakes, The thickness is only a few nanometers.By rapid heating Ti3C2 Tx, it can effectively improve the separation, but also damage the integrity of the lamella.After sonication, it is difficult to observe lager film of Ti3C2 Tx.Increasing layer spacing can effectively improve the performance of lithium ion batteries, especially under high current density.Ti3C2Tx after rapid heating, charging capacity for the first time, the initial discharge capacity and coulomb efficiency is improved.In addition, reversible battery capacity ascends greatly.Reversible capacity in the current density of 30 m A·g-1and 100 m A·g-1increased by 25% and 50% respectively.