Vanadium disulfide was synthesized via a simple hydrothermal method, using a small fraction of ethylene glycol as a co-solvent. A dimethyl sulfoxide (DMSO)-based ink was subsequently formulated from the hydrothermal VS2, and employed to fabricate 3D printed cathodes, as illustrated in Scheme 1. The presence of ethylene glycol in the reaction system, with lower dielectric constant and higher viscosity than water, hinders the crystal growth and leads to the formation of small VS2 microflowers ~ 5 µm in diameter (Figure ). Additionally, ethylene glycol can act as a reducing agent, helping to prevent the re-oxidation of V +4 to V +5 during the synthesis. In contrast, large VS2 crystals and by-products are formed if ethylene glycol is not added (Figure ). The microflower morphology is well suited for the extrusion-based 3D Printing process, since microflowers can be easily ejected throughout small nozzles (< 500 µm) without causing obstructions resulting in flow instabilities. The phase purity of hydrothermal VS2 was demonstrated by EDS, XRD and Raman spectroscopy (Figure and Figure ). All the XRD reflections can be assigned to the 1T phase of VS2 (space group P3 ̅ m1); similarly, the Raman modes are comparable with previous reports of hydrothermally grown VS2. Bright field TEM imaging shows the atomically thin nature of the microflower petals (Figure -e), while HRTEM and SAED patterns (Figure ) confirm that individual petals are made of highly crystalline areas, with the SAED pattern agreeing well with the (101) plane of 1T VS2. This is consistent with previous studies on hydrothermal VS2 displaying an unusually intense (101) reflection at 35.8º in the XRD pattern (Figure ). The two doublets in the high-resolution XPS spectrum of V 2p (Figure ) indicate the coexistence of two different oxidation states for vanadium on the surface of the microflowers, The doublet at higher binding energies (516.8 eV and 524.2 eV) agrees well with the values reported for the 2p3/2 and 2p1/2 core level electrons of V 4+ . The doublet at 513.7 eV and 521.4 eV corresponds to lower oxidation states, probably V 3+ , originating from the reduction of the V 5+ precursor during the synthesis or the possible presence of intercalated V atoms. The S 2p spectrum (Figure ) also present two doublets, indicating the presence of polysulfides (Sn 2-), which probably originate from the excess free sulfides in the reaction system. The VS2 inks were formulated starting from a suspension of carbon black in DMSO. Carbon black particles are known to form loosely-interacting aggregates in suspension, that turn into a space-filling network of connected particles above a critical concentration. Concentrated suspensions behave as elastic solids at rest, while being able to flow under the action of a sufficiently high stress (yield stress), which disrupts the connectivity of carbon black particles. The existence of a finite yield stress is a key property for extrusionbased printing, since each ink layer must retain its initial shape and support the weight of successive layers. The critical concentration for carbon black suspensions in DMSO falls between 2.7 wt% and 5.3 wt%, as evidenced by oscillatory rheology (Figure ). All the suspensions with concentration higher than 5.3 wt% present constant viscoelastic moduli in the range of frequency investigated (0.1 to 100 Hz), with a storage modulus significantly higher than the loss modulus, indicating a gel-like behaviour and a predominantly elastic response. On the contrary, the 2.7 wt% suspension exhibit a crossover point for the viscoelastic moduli at ~ 2 Hz, indicating a liquid (viscous) response in the limit of small frequencies (Figure ). The values of storage modulus and yield stress progressively increase with concentration, reaching ~30 kPa and ~235 Pa at 10 wt%, respectively. At higher concentrations the suspension becomes inhomogeneous and unsuitable for extrusion.