Unlocking Plateau Capacity with Versatile Precursor Crosslinking for Carbon Anodes in Na-Ion Batteries

Abstract

While the precursor material inherently determines the fundamental structure of hard carbons, a direct intervention at the molecular structure of precursors holds promise for more versatile design of hard carbon's architecture, which plays a pivotal role in dictating the final microstructural properties and, consequently, the overall sodium storage performance. In this study, we present a novel generalized strategy that employs P and O double cross-linking to convert pitch into a thermosetting precursor, instigating the formation of copious micropores within pitch-based carbon. These micropores serve as essential pathways and active binding sites for sodium ion transport and storage. The resultant pitch-derived hard carbon exhibits a remarkable specific capacity of 416.1 mAh/g and an impressive initial coulombic efficiency (ICE) of 89.7%. An exhaustive study was conducted to unravel the critical influence of cross-linking on enhancing the plateau capacity, revealing a robust positive correlation between this enhanced capacity and the closed pore volume. This correlation serves as compelling evidence supporting the microporous filling mechanism in sodium storage. Our research underscores the groundbreaking significance of cross-linking treatments on precursor materials, paving the way for the design and synthesis of next-generation, high-capacity hard carbon anodes for Na-ion batteries.

Keywords: precursor crosslink, pitch, high capacity, Hard carbon, Sodium-ion batteries