Ideally realized sodium-ion capacitor via irreversible oxidation of sodium azide to pre-metalate the anodic host
[ 1 ] Instytut Chemii i Elektrochemii Technicznej, Wydział Technologii Chemicznej, Politechnika Poznańska | [ SzD ] doctoral school student | [ P ] employee
2024
scientific article
english
- Sodium-ion capacitor
- Activated carbon EDL electrode
- Sodium azide sacrificial material
- Irreversible oxidation
- Hard carbon pre-sodiation
- Nitrogen gas by-product
EN Herein, sodium azide (NaN3) is used as sacrificial cathodic material to address the metal deficiency issues in the anodic host of sodium-ion capacitors (NICs). Electrochemical online mass spectroscopy at C/40 (C theoretical capacity of NaN3) on a NaN3–C65 electrode percolated by carbon black (C65 conductive additive) demonstrates a complete irreversibility of the oxidation process, with the evolution of N2 (1.5 mol for 1 mol of NaN3) as sole by-product. Gas adsorption analysis at 77 K on pristine and oxidized NaN3-AC (AC = activated carbon) electrodes reveals a noteworthy regeneration of the porous texture of activated carbon after oxidation. Laminated NaN3-AC//HCM cells (HCM: hard carbon) were prepared, and sodium was transferred to the HCM negative electrode by electrochemical oxidation of NaN3, giving rise to AC//NaxHCM sodium-ion capacitors. Over a voltage range from 2.0 V to 3.8 V, the NICs demonstrated impressive capacitance retention of 90%, and energy efficiency of 95% after 15,000 galvanostatic cycles. In terms of energy and power performance, the NICs exhibited output energy of 38 Wh kg−1 up to 4 kW kg−1. These results demonstrate that sodium azide is an ideal “zero dead mass” sacrificial material holding the potential for the one-step realization of cost-effective NICs presenting attractive electrochemical characteristics.
11.05.2024
234637-1 - 234637-12
Article Number: 234637
140
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