Soft carbon with a high reversible capacity has been proposed as an anode material for high-power lithium ion batteries. In this work, we investigate the effect of phosphoric acid (H3PO4) addition during preparation on the microstructure and electrochemical performance of soft carbon. H3PO4 facilitates the formation of nanopores by terminating C-C bonding and forming C-Ox-P (0<x≤4) chemical bonds. The newly integrated nanopores are mainly responsible for increasing the reversible capacity of soft carbon and maintaining excellent cycle performance and rate capability. In addition, the proposed synthetic route is simple and cost-effective, which will be helpful for successfully employing soft carbon on a commercial scale.