COPNA resin-derived hard carbon: enhanced low-voltage plateau behavior from three-dimensional structured precursors

Abstract

Petroleum products can be utilized as precursors for the synthesis of hard carbon (HC) anode materials for sodium-ion batteries (SIBs), enabling the value-added utilization of these low-value resources. However, the inherent compositional complexity of petroleum products fundamentally hinders precise control over the HC structures. In this study, the spatial architecture of condensed polynuclear aromatic hydrocarbon (COPNA) resin, derived from petroleum products, is systematically engineered to produce HCs with an enhanced low-voltage plateau. By enabling the molecular chains to undergo three-dimensional (3D) cross-linking, the subsequent graphitization during high-temperature treatment is effectively inhibited. Consequently, the as-synthesized HCs deliver an extended low-voltage sodium storage plateau, with the plateau capacity increasing from 19.5 to 114.9 mAh g⁻¹ at 0.05 A g⁻¹. Furthermore, the electrode exhibits excellent cycling stability, retaining 85.1% of its initial capacity after 800 cycles at a current density of 0.1 A g⁻¹. A PHC//NFM333 pouch cell assembled with COPNA-derived HC exhibited an energy density of 223 Wh kg⁻¹, comparable to existing high-performance reported pouch cells. These findings establish a novel precursor design strategy for transforming petroleum products into HCs.