Activating an MXene as a host for EMIm+ by electrochemistry-driven Fe-ion pre-intercalation

Abstract

EMIm⁺, as a substitute for Li⁺, can solve the initial problems that accompany lithiation/delithiation processes on an anode. However, the larger size of EMIm⁺ limits the options when it comes to electrode materials. Herein, a multilayered Ti₃C₂T_x MXene was electrochemically pre-intercalated with Fe ions to achieve EMIm⁺ hosting abilities. As a result, a pre-intercalated MXene electrode exhibited enhanced EMIm⁺ transport and storage capabilities. When integrated with an EMIm⁺[PF6]⁻ ionic liquid electrolyte, the assembled DIB provides an energy density of 76 W h kg⁻¹ at a power density of 360 W kg⁻¹, and 94.3% of the energy density is retained after 50 cycles. Compared with a pristine example, the Fe pre-intercalated Ti₃C₂T_x MXene showed a significant increase in electrochemical performance. Employing this approach to optimize layered materials may open up a new route for accurately tuning intercalated materials.