Ultrafast synthesis of amorphous VOx embedded into 3D strutted amorphous carbon frameworks–short-range order in dual-amorphous composites boosts lithium storage

Abstract

Crystalline vanadium oxides have some unique advantages, including abundant material sources, high energy density, and a typical layered structure, making them promising anode candidates for lithium-ion batteries. However, the intrinsic low electrical conductivity and volume expansion side effects severely limit their capacity and cyclability at high charge/discharge rates. Herein, unique dual-amorphous composites with 3D strutted amorphous carbon sheet framework encapsulated amorphous vanadium oxide particles have been prepared by an ultrafast (within one minute), ultralow temperature (172 °C), one-step and large-scale combustion synthesis method. We demonstrate that the dual-amorphous VO_x/C composites provide a large number of accessible active sites and defects for lithium ion intercalation/deintercalation and are self-accommodative to tolerate volume expansion. Another noteworthy point is the short-range ordered atomic arrangement observed in amorphous VO_x that exhibits a larger interlayer spacing (d₍₀₀₁₎ = 4.80 Å) than other crystalline vanadium oxides. This particular structure has the potential to accommodate more lithium ions and tolerate the volume expansion. Meanwhile the 3D hierarchical porous sheet-like structure facilitates the transfer of electrons and lithium ions. The electrochemical measurements show excellent lithium storage performance with high capacity, good rate capability and long-term cycling stability of the composites.