Unveiling the Crosslinking Architecture Governed Carbon Yield in Phenolic Resin‐Derived Porous Carbons for Cost‐Effective Energy Storage

ABSTRACT Porous carbons are indispensable for supercapacitors and as hosts for silicon anodes in next‐generation lithium‐ion batteries, yet their commercialization is crippled by the low carbon yield of phenolic resin precursors. What fundamentally controls the yield and how to improve it have long puzzled both academia and industry. Here, we address the root cause by systematically tuning the formaldehyde‐to‐phenol (F/P) molar ratio. We discover that the methylene bridge density in the cured resin is the key determinant of carbon yield. At the optimal F/P ratio of 2.0, the resin achieves the most complete crosslinked network, boosting the porous carbon yield from below 36% (PC‐1.0) to 47.15% (PC‐2.0), without compromising pore development. PC‐2.0 retains a high specific surface area of 2580.6 m 2 ·g −1 and delivers an outstanding specific capacitance of 371.8 F·g −1 at 0.5 A·g −1 . Moreover, it exhibits a high capacitance retention of 95.76% after 10 000 cycles at a current density of 10 A·g −1 , demonstrating competitive advantages over various electrode materials reported in recent years. Quantitative analysis confirms a strong positive correlation between methylene content and yield, solving the long‐standing puzzle. This work provides a simple, scalable strategy to break the yield‐performance trade‐off, reducing raw material cost by 16.47% compared with commercial resin.