In this Letter, we numerically simulate the generation of a 1–15 μm mid-infrared supercontinuum (SC) from a highly nonlinear ${\mathrm{Ge}}_{11.5}{\mathrm{As}}_{24}{\mathrm{Se}}_{64.5}$-based photonic crystal fiber (PCF). This ultra-broadband SC is achieved in a 100 mm long PCF pumped using 85 fs laser pulses operated at 3.1 μm and a peak pulse power of 3 kW. The proposed design offers a flat dispersion profile with two zero dispersion wavelengths. This broad and flat dispersion profile of the ${\mathrm{Ge}}_{11.5}{\mathrm{As}}_{24}{\mathrm{Se}}_{64.5}$ PCF, combined with the high nonlinearity ($2474{\mathrm{W}}^1{\mathrm{km}}^1$), generates an ultra-broadband SC.