In this work, a novel dual‐graphite battery (DGB) based on a pure 1‐ethyl‐3‐methylimidazolium trifluoromethanesulfonate (EMImTfO) ionic liquid electrolyte is constructed. Within a charge/discharge voltage range of 1.0–3.9 V and at a current of 400 mA g−1, batteries with dual‐natural‐graphite electrodes exhibit a high discharge plateau above 3.0 V with an initial discharge capacity of 46.2 mAh g−1, delivering a capacity retention of 71.0 % after 100 cycles. Comparative studies between the natural graphite and the synthetic graphite (KS6) electrodes are also conducted. Charge‐discharge tests reveal that the dual natural‐graphite battery presents a higher discharge voltage plateau and better retention than the dual KS6‐graphite battery. To confirm the principle of the dual‐graphite systems, a cyclic voltammetry test is conducted. The results demonstrate that the EMIm+ cation exhibits an even more stable intercalation/de‐intercalation behavior than the TfO− anion. Further tests, including ex situ X‐ray diffraction and ex situ Raman spectroscopy, are performed to reveal the mechanism of TfO− and EMIm+ intercalation into graphite, both demonstrating a reversible process.

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Herein, a new type of composite anode with a Cu foil current collector modified with polyaniline (PANI) was prepared (PANI/Cu). SEM manifests that the PANI layer is 1.8 μm thick and composed of PANI particles with a diameter of 50 nm nanometers, which provides a large contact surface area to enhance the strength of adhesion to the electrode material. FTIR and UV/Vis analysis confirmed that the PANI layer existed in the emeraldine (conductive) form. Half‐cells were assembled by using PANI/Cu and bare/Cu (both coated with Li4Ti5O12 electrode material) as the working electrode, and Li wafers as the counter electrode. Cycling performance tests demonstrated that, after cycling for 500 cycles at 1 C, the discharge capacity was 155.0 mAh g−1 and 137.6 mAh g−1 for PANI/Cu battery and bare/Cu battery, respectively. Electrochemical impedance revealed the impedance of the PANI/Cu battery is decreased effectively by the PANI layer.

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