Chi604e electrochemical workstation

In the experiment, the phase was identified using a BRUKER D8 ADVANCE diffraction analyzer of Bruker company in Germany. The microstructure was analyzed using an SU8020 scanning electron microscope of Hitachi company in Japan. The FT-IR analysis was performed on an IS10 FT-IR spectrometer produced by Nicolet company in the United States, and the XPS data was collected on a Thermo Escalab 250Xi electron spectrometer produced by Mercury Technology in the United States. The specific surface area, pore volume and pore size were measured using a Mike ASAP 2460 physical adsorption instrument. Electrochemical tests of CV and EIS were performed using a CHI604E electrochemical workstation produced by Shanghai Chenhua Instrument Co., Ltd, and constant current charge and discharge were tested using a CT-4008Tn-5V 20mA-164 produced by Guangdong Xinweier Electronics Co., Ltd.

The as-prepared active materials, acetylene black and carboxymethyl cellulose (CMC) binder with a weight ratio of 7:2:1 in deionized water were intensely stirred overnight to form a homogeneous slurry. The working electrodes were formed by coating the slurry on a copper foil and drying it at 80 °C in a vacuum overnight. The loading mass of active material Si/AC was controlled to be 1.05 mg and the loading density is 0.93 mg cm⁻². The active material loading mass of Si@Fe₃O₄/AC/CNR was 1.19 mg and the loading density is 1.05 mg cm⁻². The counter electrode and reference electrode were lithium metal foil with a thickness of 1.2 mm. The coin cells (2025-type) were assembled in an Ar-filled glove box, using Celgard 2400 as the separator and 1 M LiPF₆ dissolved in a solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) (1:1, vol%) as the electrolyte, respectively. Cyclic voltammetry (CV) evaluations and electrochemical impedance spectroscopy (EIS) were operated on the Chenhua CHI604E electrochemical workstation at room temperature. The galvanostatic discharge-charge test was conducted on a Neware battery test system.

The surface and composition of electrodes were characterized by SEM (Zeiss Sigma HD, Germany) and XRD (Bruker D8 Advance, Germany) with Cu (Kα) radiation at 40 kV/40 mA.
The electrochemical performance of as-prepared electrode was evaluated in a three-electrode system at room temperature on CHI604E electrochemical workstation (Shanghai, Chenhua Instrument Co. Ltd., China) with saturated calomel electrode (SCE) as the reference electrode, platinum sheet as the counter electrode. The potentials appearing in the text were referred to SCE. Electrochemical double-layer capacitance was measured using CV in 0.5 M KOH solution, and the potential scanning range was from 0.5 V to 0.6 V. The CV was also used to test the electrochemical active area of the electrode in 0.1 M KCl and 1 mM K₃Fe(CN)₆ solution by sweeping from −0.1 V to 0.5 V. The LSV curves were tested in 0.5 M H₂SO₄ solution with a sweep rate of 50 mV s⁻¹. The EIS was carried out in the AC frequency range of 100 000–0.1 Hz with the amplitude of 5 mV under the applied potential of 2 V and the results were fitted using Zsimpwin software.