[en] Highlights: • MoS₂-reduced graphene oxide aerogels have been firstly printed with a three-dimensional freeze printing method. • The hybrid structure consists of small MoS₂ patches attached on larger two-dimensional rGO flakes in a macroporous framework. • The hybrid aerogels are utilized for sodium ion battery anodes. -- Abstract: This study reports a 3D freeze-printing method that integrates inkjet printing and freeze casting to control both the microstructure and macroporosity via formation of ice microcrystals during printing. A viscous aqueous ink consisting of a molecular MoS₂ precursor (ammonium thiomolybdate) mixed with graphene oxide (GO) nanosheets is used in the printing process. Post-treatments by freeze-drying and reductive thermal annealing convert the printed intermediate mixture into a hybrid structure consisting of MoS₂ nanoparticles anchored on the surface of 2D rGO nanosheets in a macroporous framework, which is fully characterized with FESEM, TEM, XRD, Raman spectroscopy and TGA. The resulting hybrid MoS₂-rGO aerogels are studied as anodes for sodium ion batteries. They present a high initial specific capacity over 429 mAh/g at C/3.3 rate in the potential range of 2.5–0.10 V (vs Na⁺/Na). The process involves both reversible 2 Na⁺ insertion and slow irreversible conversion of MoS₂ to metallic Mo. At higher rates, the conversion reaction is suppressed and the electrode is dominated by fast Na⁺ intercalation with good stability. This demonstrates that the 3D printing technology can be used as a processing technique to control the materials properties for energy storage.

[en] Highlights: • An electrospun self-supported CNF membrane used as a conductive framework. • Pulse electrodeposition forms a uniform V₂O₅ shell on the continuous CNF framework. • Proper thermal annealing yields an amorphous CNFV₂O₅ core-shell structure. • Near theoretical capacity with high stability for both 2 and 3 Li⁺/V₂O₅ insertion. • High degree of stability and capacity retentions at high rates up to 1500 mA g⁻¹. This study reports an approach to achieving stable 2 and 3 Li⁺ insertion, respectively, into vanadium pentoxide (V₂O₅) as lithium-ion battery (LIB) cathode materials using a core-shell structure based on a self-standing carbon nanofiber (CNF) membrane fabricated by an electrospinning process. Uniform coaxial V₂O₅ shells are coated onto continuous CNF cores via a pulsed electrodeposition. The materials analyses confirm that the V₂O₅ shell after 4 h of thermal annealing at 300 °C forms a partially hydrated amorphous structure. SEM and TEM images indicate that the uniform 30–50 nm thick V₂O₅ shell forms an intimate interface with the CNF core. Lithium insertion capacities up to 291 and 429 mAh g⁻¹ are achieved in the voltage ranges of 4.0–2.0 V and 4.0–1.5 V, respectively, which are in good agreement with the theoretical values of 294 mAh g⁻¹ for 2 Li⁺/V₂O₅ insertion and 441 mAh g⁻¹ for 3 Li⁺/V₂O₅ insertion into crystalline V₂O₅ materials. Moreover, after 100 cycles, remarkable retention rates of 97% and 70% are obtained for 2 Li⁺/V₂O₅ and 3 Li⁺/V₂O₅ insertion, respectively. These results reveal that it is potentially feasible to fabricate the core-shell structure with electrospinning and electrodeposition processes to break the intrinsic limits of V₂O₅ and enabling this high-capacity cathode materials for future LIBs.