Carbon coated tetrakaidecahedron tin ferrite (SnFe2O4) with high pseudocapacitance as anode material for lithium-ion batteries

• Synthesized a series of SnFe 2 O 4 @carbon polyhedrons by changing surfactant amount. • Tetrakaidecahedral SnFe 2 O 4 @carbon was obtained assisting by CTAB at the second CMC. • A solid carbon layer directly derived from ferrocene without additional carbon source. • Tetrakaidecahedral SnFe 2 O 4 @carbon shows stable capacities and super rate capability. • Tetrakaidecahedral SnFe 2 O 4 @carbon shows higher pseudocapacitance behavior. A series of carbon coated SnFe 2 O 4 (SFO) with octahedron, decahedron and tetrakaidecahedron morphologies have been synthesized by a simple hydrothermal process using ferrocene as common source of iron and carbon, applying a cationic surfactant CTAB to modify the morphology. Compared with the octahedral SFO (no CTAB) and decahedral SFO-0.1 (with CTAB at the first critical micelle concentration (CMC)), the tetrakaidecahedral SFO-0.7 (with CTAB at the second CMC) as an anode of LIB shows a high charge/discharge capacity of 481.0/482.7 mAh g −1 after 1000 cycles at 2 A g −1 , and 281.0/281.6 mAh g −1 after 2000 cycles at 6 A g −1 . The investigations on Li-ions inter-/de-intercalation kinetics show that the main rate-controlled step of SFO-0.7 is pseudocapacitive behavior, with higher contribution of 95.88% at a scan rate of 2.0 mV s −1 . The results suggest that the carbon layer obtained directly from ferrocene can effectively inhibit the volume expansion and structure damage of SnFe 2 O 4 . At the same time, more oxygen-vacancies increase the conductivity, the enhanced strength of the dominant (1 1 1) plane can adsorb Li-ions more easily, and the smaller SnFe 2 O 4 can reduce the diffusion distance of Li-ions, all of which lead to a high and stable Li-ions storage capacity and rate capability.