Pre‐Oxidation Strategy Transforming Waste Foam to Hard Carbon Anodes for Boosting Sodium Storage Performance

Abstract Large reserves, high capacity, and low cost are the core competitiveness of disordered carbon materials as excellent anode materials for sodium‐ion batteries (SIBs). And the existence and improper treatment of a large number of organic solid wastes will aggravate the burden on the environment, therefore, it is significant to transform wastes into carbon‐based materials for sustainable energy utilization. Herein, a kind of hard carbon materials are reported with waste biomass‐foam as the precursor, which can improve the sodium storage performance through pre‐oxidation strategy. The introduction of oxygen‐containing groups can promote structural cross‐linking, and inhibit the melting and rearrangement of carbon structure during high‐temperature carbonization that produces a disordered structure with a suitable degree of graphitization. Moreover, the micropore structure are also regulated during the high‐temperature carbonization process, which is conducive to the storage of sodium ions in the low‐voltage plateau region. The optimized sample as an electrode material exhibits excellent reversible specific capacity (308.0 mAh g −1 ) and initial Coulombic efficiency (ICE, 90.1%). In addition, a full cell with the waste foam‐derived hard carbon anode and a Na 3 V 2 (PO 4 ) 3 cathode is constructed with high ICE and energy density. This work provides an effective strategy to conversion the waste to high‐value hard carbon anode for sodium‐ion batteries.