Realizing uniform dispersion of MnO2 with the post-synthetic modification of metal–organic frameworks (MOFs) for advanced lithium ion battery anodes

Abstract

MnO₂ nanoparticles were uniformly loaded on the surface of zeolitic imidazolate frameworks (ZIF-67 and ZIF-8) with ligand modification via a facile method with no other impurities introduced, with an average diameter of less than 10 nm. The MnO₂/ZIF-COOH composites with stable structures can effectively alleviate expansion tension and provide a fast ion transport channel during electrochemical performance tests. The introduction of carboxyl (–COOH) increases the specific capacity due to Li insertion, enhances the conductivity with ionization, and improves stability through the formation of H-bonds. When used as an anode for lithium ion batteries, the MnO₂/ZIF-67-COOH composite exhibits an excellent rate performance (1208 mA h g⁻¹ at 50 mA g⁻¹, 931 mA h g⁻¹ at 100 mA g⁻¹, 828 mA h g⁻¹ at 200 mA g⁻¹, 684 mA h g⁻¹ at 500 mA g⁻¹, 566 mA h g⁻¹ at 1000 mA g⁻¹, 431 mA h g⁻¹ at 2000 mA g⁻¹, and 242 mA h g⁻¹ at 5000 mA g⁻¹) and high cycle stability even at high rates (a high capacity of 664 mA h g⁻¹ is achieved at 1000 mA g⁻¹ and is maintained at approximately 100% after 100 cycles).