<p>With the increasing demand for efficient and cost-effective energy storage systems, there is a need for advanced materials that can improve the performance of batteries. This study presents the synthesis of nitrogen-doped porous biomass graphene flower bud (N-PBGFB) materials, developed through a multi-step process involving carbonization of phoenix tree leaves, activation with potassium hydroxide (KOH), and nitrogen doping via a hydrothermal technique. The resulting materials exhibit significant interlayer spacing, abundant oxygen-containing functional groups, and a high degree of structural disorder. Electrochemical evaluation as cathode materials in open-system chloride-ion (Cl) batteries reveals that the optimized N-PBGFB material achieves a remarkable discharge capacity of 108.77 mAh g⁻¹ (0.3046 mAh cm⁻²) at a constant current of 0.5 A g⁻¹, significantly outperforming conventional carbon materials such as bare carbon (0.1852 mAh cm⁻²), commercial graphite powder (47.19 mAh g⁻¹, 0.1652 mAh cm⁻²), carbon black (99.64 mAh g⁻¹ (0.2790 mAh cm⁻²), and synthesized carbonization carbon (93.15 mAh g⁻¹, 0.2608 mAh cm⁻²). Notably, the N-PBGFB material also demonstrates superior discharge capacity efficiency compared to these reference materials. This work highlights the potential of N-PBGFB materials derived from low-cost phoenix tree leaves, providing a sustainable approach for reducing battery production costs while offering enhanced performance. The detailed characterization and electrochemical evaluation offer valuable insights into the structure–property relationships, paving the way for the further development and application of these materials in next-generation energy storage systems.</p>