Chain Rigidity Modulating Closed Pore and Inter‐Graphitic Domain Channels in Resin‐Derived Hard Carbon for Fast Plateau Sodium Storage

Abstract

ABSTRACT Hard carbon (HC) stands as the most commercially promising anode material for sodium‐ion batteries; however, its limited closed‐pore content and inherently sluggish ion diffusion severely restrict its plateau capacity and rate performance. Herein, we propose a chain rigidity engineering strategy to promote the formation of closed pores and inter‐graphitic domain channels in resin‐derived HC, enabling synergistic optimization plateau capacity and rate capability. The chain rigidity of 3‐aminophenol‐formaldehyde resin was enhanced by utilizing the weak coordination between Zn 2+ and the amino group of 3‐aminophenol to suppress the amino‐site‐mediated flexible bridging pathway during polymerization. Improved chain rigidity introduces rich inter‐chain voids in the resin, promoting the formation of closed pores in HC; meanwhile, it effectively suppresses carbon layer rearrangement to construct abundant ion diffusion channels between short and thin graphitic domains together with enlarged interlayer spacing, thereby significantly enhancing bulk diffusion kinetics. As a result, the optimized HC delivers an ultrahigh reversible capacity of 437.9 mAh g −1 with a plateau capacity of 309.9 mAh g −1 and excellent rate performance (293.4 mAh g −1 at 2 A g −1 ). This work provides insights into the role of polymer chain rigidity in promoting the formation of closed pores and ion diffusion channels in HC.