Spent Carbon Cathode Used as a Cathode Material for High-Performance Dual-Ion Batteries: High-Value Utilization

Aluminum electrolysis spent cathode carbon (SCC) is one of the high-risk solid waste products in the aluminum electrolysis industry. Generally, harmless storage treatment is used, which fails to achieve high-value utilization. In this study, HCl was used to purify SCC. The purified material showed a rich-edge structure, expanded layer spacing, and good graphitization. Using SCC as a DIB cathode material and LiTFSI/EC+DMC as an electrolyte, the best electrolyte concentration (6 M) was determined by comparing the electro-chemical performance of different-concentration electrolyte systems. Under the 6 M LiTFSI electrolyte system and the voltage window of 3.0-5.1 V, the battery has a high reversible specific capacity of 66.4 mAh g(-1) at a current intensity of 400 mA g(-1) and has excellent long cycle stability. After 350 cycles, the capacity retention of the battery is 104.52%, and the discharge medium voltage can be stable at 4.3 V. The high discharge medium voltage enables the battery to meet the needs of high-voltage equipment. Meanwhile, the rich-edge structure and the large layer of SCC spacing can explain the good rate performance of the battery. In addition, the cathode of SCC under different charge and discharge voltages was characterized by X-ray diffraction, which explained in depth the reversible intercalation/deintercalation process of TFSI-. Finally, the full battery composed of the SCC cathode and the metal aluminum anode also showed good energy density (145.9 Wh kg(-1)) and power density (1980 W kg(-1)). The good electrochemical performance shows the feasibility of SCC as a DIB cathode material and realizes the purpose of harmless and high-value utilization of SCC.