In this work, a freestanding and binder-free NiS₂/FeS holey film is developed using a facile and scalable electrochemical route. Both experimental study and computational investigation were performed to have an insightful understanding of the charge storage mechanism of this advanced energy material for LSBs. Such freestanding NiS₂/FeS holey film provides unique merits for LSBs: i) Porous structure of holey film enables a large surface area for an enhanced ion/mass diffusion and reduced volume expansion; ii) The binder-free electrode combines the current collector (residual NiFe alloy) and active materials (sulfides) together, improving electron transport; iii) Sulfides are more stable as active materials than sulfur, showing only a small capacity decay while retaining high cyclability performance. A high volumetric capacity of 580 mAh cm^-3 and a long-term stability over 1000 discharge-charge cycles were, therefore, achieved due to these merits.