Inorganic-organic competitive coating strategy derived uniform hollow gradient-structured ferroferric oxide-carbon nanospheres for ultra-fast and long-term lithium-ion battery

The gradient-structure is ideal nanostructure for conversion-type anodes with drastic volume change. Here, we demonstrate an inorganic-organic competitive coating strategy for constructing gradient-structured ferroferric oxide-carbon nanospheres, in which the deposition of ferroferric oxide nanoparticles and polymerization of carbonaceous species are competitive and well controlled by the reaction thermodynamics. The synthesized gradient-structure with a uniform size of similar to 420nm consists of the ferroferric oxide nanoparticles (4-8nm) in carbon matrix, which are aggregated into the inner layer (similar to 15nm) with high-to-low component distribution from inside to out, and an amorphous carbon layer (similar to 20nm). As an anode material, the volume change of the gradient-structured ferroferric oxide-carbon nanospheres can be limited to similar to 22% with similar to 7% radial expansion, thus resulting in stable reversible specific capacities of similar to 750 mAh g(-1) after ultra-long cycling of 10,000 cycles under ultra-fast rate of 10Ag(-1). This unique inorganic-organic competitive coating strategy bring inspiration for nanostructure design of functional materials in energy storage.