MXene as a tolerable anode material accommodating large ions in dual-ion batteries

Dual-ion batteries (DIBs) suffer potential matching problem of anode and cathode, which originates from the contrasting size difference between the corresponding small metal cations and large polyatomic anions from metallic salt solution electrolyte. With wide voltage window and high stability, ionic liquid (IL) can provide larger cations occupying similar radius with anions, which can be a facile solution for unbalanced match of both electrodes. Thus, searching for electrode materials with large interlayer space for IL is in a great demand. MXene, a 2D transition metal nitride or carbide with high conductivity, provides large layer distance to accommodate large ions of ILs. The electrochemical intercalation behavior of EMIm(+) cations and MXene has been investigated and a delicate design of an IL-based DIB is proposed. On the basis of size match on both anode and cathode, the DIB also shows promising energy-power characteristic and excellent cycling stability.