Mo2CTx MXene pillared by transition metal complexes [Fe(III), Co(III), or Ni(II)] with ultra−high lithium storage performance

In this work, two−dimensional Mo 2 CT x MXene pillared with transition metal complexes [Fe(III), Co(III), or Ni(II)] was prepared, which shows ultra−high performance as the anode of lithium−ion batteries (LIBs). Firstly, Mo 2 CT x was pretreated with hexadecyl trimethyl ammonium bromide (CTAB) as a surfactant and then mixed with hydrated chloride (FeCl 3 ·6H 2 O, CoCl 2 ·6H 2 O, or NiCl 2 ·6H 2 O) at room temperature. The molar ratio of MXene to hydrated chloride was 1:1. In this process, metal ions (Fe 3+ , Co 2+ , or Ni 2+ ) were successfully loaded on the nanosheets of Mo 2 CT x . The ions were combined with the surface terminated oxygen of MXene to form transition metal complexes by liquid phase agitation method. Moreover, transition metal complexes contribute a portion of their capacity and help Mo 2 CT x enhance its own capacity to a large extent. However, the electrochemical effects on Mo 2 CT x vary depending on the type of transition metal ions. As anodes of LIBs, the final discharge specific capacities after 100th cycles at 2 A g −1 were 511.68 mAh g −1 , 229.22 mAh g −1 and 78.19 mAh g −1 for Fe(III)@Mo 2 CT x , Co(III)@Mo 2 CT x , and Ni(II)@Mo 2 CT x , respectively, while the capacity of pure Mo 2 CT x after delamination was only 31.17 mAh g −1 . At 6 A g −1 , the final discharge capacity of Fe(III)@Mo 2 CT x was 227.4 mAh g −1 after 500th cycles. Therefore, Mo 2 CT x MXene pillared by the complexes, especially Fe(III) complexes, is a promising anode material with high−performance for lithium−ion batteries.