Black phosphorus (black P), which is a promising candidate as an anode material for lithium-ion batteries, was synthesized by a high-pressure and high-temperature (HPHT) method from white and red phosphorus. The study revealed the electrochemical activity of pure black P under different pressures and temperatures systematically. The sample shows higher crystallinity and purity by the HPHT method. Lithium-ion batteries containing black phosphorus as anode materials exhibited a high specific capacity and excellent cycling performance. Black phosphorus obtained from white phosphorus exhibited the highest first discharge and charge capacities of 2505 and 1354 mAh·g–1 at 4 GPa and 400 °C and that obtained from red phosphorus exhibited the highest first discharge and charge capacities of 2649 and 1425 mAh·g–1 at 4.5 GPa and 800 °C. Black P was characterized by X-ray diffraction, Raman microscopy, scanning electron microscopy, and high-resolution transmission electron microscopy.