The rate performance of LiFePO₄ batteries is improved by inserting a carbon interlayer, which is synthesized by a simple and cheap pyrolysis of the filter paper commonly used in the laboratories. The specific capacity of the LiFePO₄ batteries at low current density is only slightly improved after the introduction of the carbon interlayer, while the specific capacity at high current density is greatly enhanced with a specific capacity of 90 mA h g⁻¹ and 76 mA h g⁻¹ at 10 C and 20 C, respectively, compared to a specific capacity of 17 mA h g⁻¹ and 8 mA h g⁻¹ of LiFePO₄ batteries without a carbon interlayer. The improved electrochemical performance is attributed to the porous architecture of the carbon interlayer, serving as a conductive skeleton, largely reducing the charge transfer resistance.