Sodium?ion batteries are gradually becoming a powerful alternative to lithium?ion batteries in the low?speed two?wheeled electric vehicle market and large?scale energy storage applications due to their excellent low?temperature performance, significant cost?effectiveness,and high safety features.The potential of hard carbon with improved performance to substitute graphite in the sodium ion battery anode has attracted widespread attention.However,the high energy consumption and expensive cost still need to be overcome for commercialization of hard carbon anode.The key to developing anode materials for sodium?ion batteries that combine low cost,high sodium ion storage capacity,and excellent cycling stability will help to extend the application of hard carbon anodes in sodium?ion batteries.Biomass has become an attractive raw material for the preparation of hard carbon due to its renewable,low?cost,and environmentally friendly characteristics.It has been shown that the sodium storage properties of biomass?derived hard carbon are affected by multiple factors such as carbonization temperature,precursor variety,and microstructure.Hence,this review summarizes the relevant models proposed for the sodium storage mechanism in terms of the sodium storage behavior of hard carbon.The preparation of hard carbon anode materials,including the effect of electrochemical optimization procedures such as pyrolysis,activation, and doping is discussed.A further analysis of the sodium storage mechanism offers guidance for addressing the current issues such as the selection of precursors,the low initial Coulombic efficiency,and the limited means of closed pore regulation.