Rational design of hard carbon anodes for sodium-ion batteries: Precursor engineering, structural modulation and industrial scalability

Abstract

Sodium-ion batteries (SIBs) have abundant resource, higher safety, and superior low-temperature performance, holding great potential for large-scale energy storage systems. Hard carbon (HC) with numerous sodium storage sites and high specific capacity is the mainstream anode materials for SIBs. The precursors of hard carbon are widely sourced, including biomass, synthetic polymers, coal and pitch. However, different molecular structure of precursors leads to uneven electrochemical performance of various HC. Pretreatment and post-treatment steps can effectively adjust structural parameters and surface state of hard carbon, influencing the performance of SIBs directly. This article summarizes different precursor sources, synthesis methods, structural parameters (morphology, defects, microcrystals, nanopores), and electrolyte interfaces to achieve better performance. Furthermore, Ah-level full batteries based on hard carbon anodes are also analyzed to provide new assistance for industrial production.