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We report the design and nanoengineering of carbon-film-coated iron sulfide nanorods (C@Fe7S8) as an advanced conversion-type lithium-ion storage material. The structural advantages of the iron-based metal–organic framework (MIL-88-Fe) as both a sacrificed template and a precursor are explored to prepare carbon-encapsulated ploy iron sulfide through solid-state chemical sulfurizing. The resulting core–shell nanorods consisting of approximately 13% carbon and 87% Fe7S8 have a hierarchically porous structure and a very high specific surface area of 277 m2 g–1. When tested for use in fabrication of a redox conversion-type lithium-ion battery, this composite material has demonstrated high lithium-ion storage capacity at 1148 mA h g–1 under the current rate of 500 mA g–1 for 170 cycles and an impressive rate-retention capability at 657 mA h g–1 with a current density of 2000 mA g–1. On the basis of systematic structural analysis and microscopic mapping, we discuss the charge–discharge mechanisms and the crucial factors associated with the stability and structural changes upon charge–discharge cycling.

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Poly(styrene-b-isobutylene-b-styrene) (PSt−PIB−PSt) triblock copolymers have been prepared for the first time via coupling of living PSt-PIB diblock copolymers in a one-pot procedure. The PSt−PIB diblock copolymer was synthesized by living sequential cationic polymerization in methylcyclohexane (MeChx)/methyl chloride (MeCl) or hexane (Hex)/MeCl solvent mixtures at −80 °C using TiCl4 as co-initiator. It was found that, due to decomposition of the living PSt ends, the crossover efficiency (C eff) from living PSt to IB decreases precipitously with time at close to 100% St conversion. To obtain high C eff, IB must therefore be added at ≤95% St conversion. It was also found that in the presence of unreacted St the rate of IB block copolymerization decreases with time; this was attributed to the formation of relatively unreactive −St−IB−Cl ends. Due to the relatively high concentration of these ends, coupling of living PSt−PIB was slow and incomplete. The obtained PSt−PIB−PSt triblock copolymers exhibited reasonable but significantly lower tensile strength (16−20 MPa) than that (23−25 MPa) reported for model PSt−PIB−PSt triblock copolymers of similar composition.

Recent progress on two-dimensional layered nanomaterials supported wearable biomedical sensors and power devices is comprehensively reviewed.

Three-dimensional (3D) carbon-wrapped iron sulfide interlocked graphene (Fe7S8@C-G) composites for high-performance sodium-ion storage are designed and produced through electrostatic interactions and subsequent sulfurization. The iron-based metal-organic frameworks (MOFs, MIL-88-Fe) interact with graphene oxide sheets to form 3D networks, and carbon-wrapped iron sulfide (Fe7S8@C) nanoparticles with high individual-particle conductivity are prepared following a sulfurization process, surrounded by interlocked graphene sheets to enhance the interparticle conductivity. The prepared Fe7S8@C-G composites exhibit not only improved individual-particle and interparticle conductivity to shorten electron/ion diffusion pathways, but also enhanced structural stability to prevent the aggregation of active materials and buffer large volume changes during sodiation/desodiation. As a sodium-ion storage material, the Fe7S8@C-G composites exhibit a reversible capacity of 449 mA h g-1 at 500 mA g-1 after 150 cycles and a retention capacity of 306 mA h g-1 under a current density of 2000 mA g-1. The crucial factors related to the structural changes and stability during cycles have been further investigated. These results demonstrate that the high-performance sodium-ion storage properties are mainly attributed to the uniquely designed three-dimensional configuration.

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