Precision tailoring the nanopore architecture of lignin-derived hierarchical porous carbon for high-performance zinc ion storage

Abstract

Precisely tailoring the pore structures in carbon materials and exploring the relationship between pore characteristics and the Zn²⁺ ion storage capability is crucial for enhancing the power/energy densities of ZIHCs. In this work, we propose a coupled chemical activation and hard-template strategy to prepare lignin-derived hierarchical porous carbon (LHPC) with tunable mesopore structures successfully. The microporous and mesoporous structures of LHPC are finely tuned via the synergistic effects of nano ZnO templates and potassium acetate chemical activators. The optimized LHPC-2-800 exhibits a high specific surface area and a substantial mesopore volume. The unique mesopore with size of 10 nm provides a rapid ion diffusion channel, shortening the diffusion distance of Zn²⁺ ions while accelerating the transport kinetics of Zn²⁺ and enhancing the utilization rate of the active site. As a result, LHPC-2-800 delivers an ultrahigh specific capacitance of 440 F g⁻¹ at 0.1 A g⁻¹, maintaining a capacitance retention ratio of 44.7 % within the current density range of 0.1–50 A g⁻¹. This work proposes a novel method to precisely tune the mesopore structure of lignin-derived hierarchical porous carbons and emphasizes the pivotal role of large mesoporous structures in enhancing the electrochemical performances of ZIHCs.