Chain Rigidity Modulating Closed Pore and Inter-Graphitic Domain Channels in Resin-Derived Hard Carbon for Fast...

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 Zn²⁺ 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.