Phenolic resin-derived hard carbon for sodium-ion batteries: insights and prospects

Phenolic resin (PF) has garnered considerable interest as a precursor for anode materials in sodium-ion batteries (SIBs) owing to its high carbonization yield, tunable molecular structure, and well-established synthetic technology. Despite their promise, these materials still face challenges such as low initial Coulombic efficiency, limited rate capability, and inadequate long-term cycling stability. The rational design of high-performance PF-derived carbon anodes necessitates a fundamental understanding of the relationship between their microstructure and sodium storage behavior. In this review, we start from the polymerization and carbonization reaction of PF and discuss the key issues of PF-based hard carbon, along with the sodium storage mechanism. The recent advances in optimizing PF-derived hard carbon are summarized, encompassing the selection of phenolic resin monomers and modification of PF-based hard carbons and their composites. In addition, we offer some perspectives for the design of better PF-based hard carbons for SIBs.