Freezing‐Induced Phase Separation and Conformational Inheritance of Macromolecules in Polyacrylonitrile Solution toward Advanced Porous Electrode Materials

Abstract Micropore size matching and pore connectivity of carbon electrode materials are the core bottlenecks restricting their electrochemical energy storage performance, because poor pore structure leads to a significant mismatch between specific capacitance and specific surface area in supercapacitors. Disordered‐structured precursors can enable the preparation of high‐performance electrode materials through regulation, but during their molding and solidification process, the forming local microcrystals will cause the failure of pore structure regulation in derived carbons, thereby limiting the further improvement of energy storage capacity. In this study, a freeze‐induced phase separation strategy is proposed, which realizes the “fixation‐inheritance” of highly disordered random coil conformations in polyacrylonitrile solution by virtue of the crystallization characteristics of solvent and water. The derived carbon electrode materials prepared by this strategy exhibits a high specific capacitance of 528 F g −1 (at a current density of 0.5 A g −1 ) under a normal specific surface area of 726.9 m 2 g −1 , demonstrating efficient pore structure utilization efficiency. When this strategy is extended to hard carbon anodes for sodium‐ion batteries, the prepared materials also show excellent sodium storage performance: at a current density of 0.2 A g −1 , the initial capacity reaches 399.0 mAh g −1 , and the initial Coulombic efficiency is 92.7%.