Mesoporous Weaved Turbostratic Nanodomains Enable Stable Na<sup>+</sup> Ion Storage and Micropore Filling is Revealed to be More Unsafe than Adsorption and Deintercalation
Manikandan Palanisamy, Ramakrishnan Perumal, Vilas G. Pol
Abstract
Advanced wave-shape non-graphitizable carbon sheets are derived, comprising mesoporous weaved turbostratic micropore enabled stable Na+ ion storage. The non-graphitizable amorphous characteristics are determined from the obtained two broad diffraction peaks at 22.7° and 43.8°. The observed D-band at 1325 cm–1 and G-band at 1586 cm–1 confirm the disordered graphitic structure, attributed to the measured specific surface area of 54 m2 g–1. Mesoporous weaved wave-shape carbon sheet architecture is confirmed by surface morphological studies, showing lattice fringes of disordered graphitic structures and dispersed ring patterns for the non-crystalline characteristics. The predominant stable redox peak at 0.014 V/0.185 V and the broader rectangular shape between 0.9 and 0.15 V depict the adsorption–micropore filling mechanism. The mesoporous hard carbon sheet delivers discharge–charge capacities of 450/311 mAh g–1 (1st cycle) and 263/267 mAh g–1 (250th cycle) at 25 mA g–1, exhibiting a superior anode for sodium-ion batteries. Besides, in situ multimode calorimetry results disclose that the micropore filling Na+ ion storage shows a higher released total heat energy of 721 J g–1 than the adsorption (471 J g–1). Ultimately, differential scanning calorimetry analysis of micropore filling Na+ ion storage (discharged state at 0.01 V) has revealed a predominant exothermic peak at 156 °C with the highest released total heat energy of 2183 J g–1 compared to adsorption (553 J g–1) and deintercalation (85 J g–1), indicating that micropore filling status is more unsafe than the adsorption and deintercalation for SIBs.