Coordination Preassembly-Driven Ellagic Acid with Synergistic Zinc Volatilization Enables Manganese-Based Cathode...

This paper proposes a "coordination pre-assembly-zinc volatilization-induced pore formation" synergistic strategy, using ellagic acid, which is rich in phenolic hydroxyl and carboxyl groups, as the carbon source and organic ligand, and conducting coordination pre-assembly with Mn2+ and Zn2+ in an aqueous solution. This successfully resulted in the preparation of a multilevel- pore MnO/oxo-carbon composite cathode material. In this strategy, Zn2+ uniformly occupies specific sites in the precursor during the coordination stage. During high-temperature carbonization, the Zn species volatilize and escape, and within the MnO/carbon composite matrix, the original site-bridging micropore-mesopore channels are constructed in situ. Ellagic acid is transformed into an oxygen-containing carbon coating layer with a moderate degree of graphitization, providing a continuous electron transmission network and acting as a physical barrier to inhibit Mn dissolution. This sample has a uniform porous agglomerate morphology, a high specific surface area, and abundant micropore/mesopore structures. Electrochemical tests show that 5% Zn-EAMn-850 has a specific capacity close to 500 mAh g-1 at 0.1 A g-1, and after 2000 cycles at a current density of 1.0 A g-1, the capacity retention rate is excellent. DRT analysis further reveals that this material has lower charge transfer impedance and faster Zn2+ diffusion kinetics throughout the charge-discharge process. This study demonstrates that the multilevel structural design of "porous channels-defect sites-carbon coating layer" can effectively solve the key challenges of insufficient conductivity, slow ion diffusion, and unstable structure in manganese-based cathode materials.