Fe₂Mo₃O₈/MoO₂@C composites with pseudocapacitive properties and fast diffusion kinetics for the anode of Lithium-Ion batteries

Pseudocapacitance, which is a rapid faradaic surface redox reaction and charges storage to offer high power density for electrochemical applications. Herein, adjusting the molar ratio of Fe: Mo, a series of Fe₂Mo₃O₈ composites were designed and synthesized through wet assisted-high temperature calcination process for lithium storage and used as a target to illustrate pseudocapacitance behavior. The Fe₂Mo₃O₈/MoO₂@C (Fe: Mo = 1:1.5, named as FM_1.5) has polyvalent Fe₂Mo₃O₈, highly conductive MoO₂, and coated by microporous-mesoporous carbon skeleton, which can strengthen electric conductivity and manifest typical pseudocapacitance behavior. Furthermore, the unique oxygen vacancy and two-phase heterointerface in FM_1.5 significantly enhance Li⁺ ion diffusion kinetics and improve pseudocapacitance contribution (contributes 95.7% of total capacity at 2 mV s⁻¹). The high extent of pseudocapacitive storage in FM_1.5 obtains high energy/power density with excellent rate performance (695.2 mA h g⁻¹ at 10 A g⁻¹) and large-current long-cycle stability (460.6 mA h g⁻¹ remained at 5 A g^-1after 1000 cycles).