Metal–Organic Framework Derived CoS2 Wrapped with Nitrogen-Doped Carbon for Enhanced Lithium/Sodium Storage Performance

Abstract

Transition metal sulfides are attractive electrode materials for both lithium-ion (LIBs) and sodium-ion batteries (SIBs). Starting from micron-sized Co(IPC)·H2O (IPC: 4-(imidazole-1-yl) phthalic acid) and polydopamine as the metal-organic framework (MOF) precursor and carbon source, respectively, we produced a CoS2/C/C composite constituting CoS2 nanoparticles decorated with N-doped carbon layers and subjected to sulfurization. N-doped carbon layers provided a robust network for the CoS2 nanoparticles, enhancing the structural integrity and electronic conductivity of the resulting CoS2/C/C composite, which exhibited electrochemical performance superior to most existing CoS2 composites, and was one of the best among all MOF derived CoS2 anodes for LIBs and SIBs. The use of nanosized CoS2 particles reduced the diffusion length for the transfer of Li+/Na+ ions, resulting in a high specific capacity at a higher current rate. N-doped carbon layers derived from the MOF precursor and polydopamine provided an electrically conductive network between the CoS2 nanoparticles, thus preventing their aggregation and inhibiting adverse side reactions between the electrolyte and the surface of the electrode, and the high pseudocapacitive contribution resulted in the enhanced rate performance of the CoS2/C/C electrodes.