Sustainable and high-energy pre-sodiation cathode using Na₂C₂O₄ and dry-processing method for sodium-ion batteries

Sacrificial sodium-rich salts are promising pre-sodiation method to compensate the irreversible capacity of SIBs for energy density enhancement. To increase the capacity utilization ratio and decrease the decomposition potential, the particle size of sacrificial salts is generally reduced to lower than 10 um. However, large amounts of solvent are required to disperse the salts in slurry-coating electrodes, which increases the electrode production cost and limits the mass loading of electrode. This work utilizes dry-processing method to achieve sustainable and high-energy pre-sodiation cathode using Na₂C₂O₄, which is free of using solvent and able to produce ultra-thick electrodes. The feasibility of Na₂C₂O₄ as additive in ultra-thick dry-processing electrode has been demonstrated by electrochemical performance evaluation and electrode structure characterization. The full cells with pre-sodiation achieve large reversible capacity of 101.52 mAh g^-1 at high areal capacity of 5.4 mAh cm^-2 under 0.1 C as well as superior energy density of 309.3 Wh kg^-1 and stable cycling. The novel electrode production strategy is promising for large-scale manufacturing of high-energy-density and low-cost SIBs.