Regulating the multi-metal-sulfur bonds in the layered double hydroxide crystalline structure for rechargeable aqueous zinc batteries and supercapacitors

Layered double hydroxide (LDH) electrodes usually suffer from the limitations like unsatisfactory conductivity and electrochemical reversibility. Therefore, a novel and feasible method of introducing multi-metal-sulfur bonds in the main LDH crystalline structure, especially the Cu-S bonds, has been proposed and designed in this work. According to the experimental and theoretical analysis, the multi-metal-sulfur bonds could remarkably improve the electrochemical reversibility, activity and electrical conductivity of the LDH-based electrode. In addition, the designed material synthesis method could greatly enhance the specific surface area of the electrode, and via the subtle modulation of the copper and sulfur adulteration, the crystalline degree and the metal composition could be effectively adjusted. The prepared C/N-NiCoMnCu-LDH/S hollow structures (C/N-NCMC/S) possess a high specific capacitance of 1742 F g⁻¹ at 1 A g⁻¹ and could retain 68.6% of the capacitance at 20 A g⁻¹. As for the assembled zinc battery, a specific capacity of 203.6 mAh g⁻¹ could be achieved at 1 A g⁻¹ and 74% of the capacity could be retained after 1500 cycles. Additionally, the hybrid supercapacitor delivers a super-long cycling stability of 98.1% capacitance retention after 40,000 cycles. Moreover, the battery and the supercapacitor present high energy densities of 127.2 and 41.4 Wh kg⁻¹, respectively.