Preparation of Nitrogen-Doped ZnFe2O4-Modified Carbon Composite and Its Collaborative Energy Storage Mechanism

The pyrolytic carbon of polymer adsorbent resin (SAP) is used as a waste carbon source, which can be used as a porous carbon network via pyrolysis to remove surface sodium carbonate and other substances. In this paper, a ZnFe2O4/nitrogen-doped porous carbon composite was prepared using the template method. Through the high-temperature carbonization of a polymer and crystallization of inorganic elements, the morphology of the composite showed uniform load characteristics. This well-defined structure and morphology facilitate the transport of Li+, enhance the effective contact area with the electrolyte, and provide a wealth of active sites. For the SAP-Fe/Zn anode, at a high current density of 0.1 A g−1, the reversible capacity of the anode reached 753 mAh g−1 after 200 cycles, showing excellent magnification performance. The final modified SAP-Fe/Zn&NC electrode had a reversible capacity of 205.6 mAh g−1 after 1000 cycles at the high current density of 2 A g−1, and the cycle retention rate was as high as 80.7%. The enhanced electrochemical performance can be attributed to the abundant active sites and shortened diffusion pathway of the composite. This ensures adequate conversion reactions during the Li-litization process between Zn, Fe, and Li+, alleviates volume expansion, and prevents comminution/aggregation during long cycles at high current densities.