2.3. Cell Fabrication and Electrochemical Characterizations

To test the electrochemical performance of obtained cathodes, the as-prepared binder-free Cu_xS/Cu foams were cut into 16 mm disks. Coin-type cells of CR2032 were assembled in an argon-filled glove box using Li foil as a reference electrode and 1 M lithium bis(trifluoromethane sulfonamide) (LiTFSI) in 1,3-dioxolane (DOL) and dimethoxyethane (DME) with a volume ratio of 1:1 as an electrolyte. The mass loading of CuS active material varied between 8.7 and 10.4 mg·cm^–2. Celgard 2400 microporous polypropylene was used as the separator membrane. The cells were tested in the voltage range between 1.0 and 3.0 V with a multichannel battery test system Arbin, which had a constant current in the form of a 0.1 C rate (1 C = 7–7.3 mAh). Electrochemical impedance spectroscopy (EIS) measurements were performed on a CHI660C electrochemical workstation under open-circuit conditions over a frequency range of 0.01 Hz to 100 kHz by applying an AC signal of 5 mV in amplitude throughout the tests.