Reversible Intercalation of 1‐Ethyl‐3‐methylimidazolium Cations into MoS2 from a Pure Ionic Liquid Electrolyte for Dual‐Ion Cells

Herein, we present a novel dual‐ion cell with a molybdenum disulfide (MoS2) anode, a graphite cathode, and a pure 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (EMImTFSI) electrolyte. During charging, the EMIm+ cations intercalate into the anode‘s MoS2 interlayers and the TFSI− anions synchronously penetrate into the cathode‘s graphite lattice. During discharging, both the cations and anions deintercalate from the electrodes. The reversible intercalation of EMIm+ into MoS2 is systematically evaluated by cyclic voltammetry, galvanostatic cycling, XRD, Raman, and SEM tests. The results reveal that within 0.5–3.6 V and at 0.5 C, the batteries present a high medium discharge plateau of ∼2.5 V, a decent discharge capacity of 77.0 mAh g−1, and a good energy density of 175.6 Wh kg−1; at 4 C, the cells exhibit a superior cyclability with 84.3 % capacity retention for 300 cycles and a high Coulombic efficiency of 96.1 %. Electrode characterizations indicate that both the MoS2 anode and the graphite cathode display a high stability over a long‐term cycling process. This novel cell configuration opens a new avenue to further develop promising rechargeable dual‐ion energy storage systems. A dual‐ion cell with an MoS2 anode, a graphite cathode, and a pure 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (EMImTFSI) electrolyte is presented. The cell exhibits a working voltage of ∼2.5 V, a discharge capacity of 77.0 mAh g−1, and an energy density of 175.6 Wh kg−1. Upon charging, the EMIm+ cations intercalate the MoS2 interlayers while the TFSI− ions penetrate the graphite cathode. Upon discharging, both the cations and anions deintercalate from the electrodes. It is shown that flake MoS2 displays a high stability for hosting EMIm+ over a long‐term cycling process.