Ternary metal sulfides are emerging as a new class of electrochemical energy storage materials outperforming their oxide counterparts. We report here a facile and scalable solvothermal synthetic approach for growth of carbon doped MnCo2S4 microcubes (edge length, 10μm) directly on Ni foam. The simple approach of binder-free design, in-situ carbon doping and the use of 3D current collector resulted in an extraordinarily high specific capacity of 1892Cg−1 (525.7mAhg−1) at 5Ag−1 and outstanding rate performance of 516Cg−1 (143.3mAhg−1) at a very high current density of 100Ag−1 when tested as a faradaic electrode in aqueous KOH electrolyte. X-ray photoelectron spectroscopy (XPS) results indicate concurrent intercalation of both H+ and OH− ions from the electrolyte during the electrochemical processes. In two-electrode symmetric MnCo2S4//KOH//MnCo2S4 cells, mimicking the physical configuration of practical cells, specific capacity of 215Cg−1 (59.7mAhg−1) could be achieved at 1Ag−1. Further, the symmetric cell delivers energy densities of 106.5 and 15.2Whkg−1 at power densities of 0.85 and 18kWkg−1 demonstrating great application prospects.