A carbon-coated shuttle-like Fe 2 O 3 /Fe 1- x S heterostructure derived from metal-organic frameworks with high pseudocapacitance for ultrafast lithium storage.

Pursuing active, low-cost, and stable electrode materials with superior rate capability and long-life cycling performances for lithium-ion batteries remains a big challenge. In this study, a carbon-coated shuttle-like Fe 2 O 3 /Fe 1- x S heterostructure is synthesized by simply annealing Fe-based metal-organic frameworks (MIL-88(Fe)) as precursors and sublimed sulfur. Carbon-coated Fe 2 O 3 /Fe 1- x S displays a unique structure with ultrafine Fe 2 O 3 /Fe 1- x S nanoparticles distributed in the hollow and porous carbon matrix, which offers a large specific surface area and fast charge transfer ability, and alleviates the volume change upon cycling. When evaluated as an anode material for lithium-ion batteries, it exhibits an ultra-high specific capacity of 1200 mA h g -1 at 0.1 A g -1 , and superior high rate capability with a capacity of 345 mA h g -1 at a very high current density of 5.0 A g -1 owing to its high electrical conductivity and enhanced pseudocapacitive contribution from surface effects. The current strategy is promising to synthesize the carbon-coated porous structure from metal-organic frameworks for next-generation energy-storage applications.