Altering Thermal Transformation Pathway to Create Closed Pores in Coal‐Derived Hard Carbon and Boosting of Na⁺ Plateau Storage for High‐Performance Sodium‐Ion Battery and Sodium‐Ion Capacitor

Abstract

Coal features low‐cost and high carbon yield and is considered as a promising precursor for carbon anode of sodium‐ion batteries (SIBs) and sodium‐ion capacitors (SICs). Regulation of microcrystalline state and pore configuration of coal structure during thermal transformation is key to boost Na+ storage behavior. Herein, a facile strategy is reported to create abundant closed pores in anthracite‐derived carbon that greatly improves Na+ plateau storage. An altered thermal transformation pathway of chemical activation followed by high‐temperature carbonization is adopted to achieve the conversion of open nanopores and ordered carbon crystallite into closed pores surrounded by short‐range carbon structures. The optimized sample delivers a large reversible capacity of 308 mAh g–1 that is dominantly contributed by the low‐voltage plateau process. Experimental results reveal the enhanced pore‐filling mechanism in the developed closed pores. Benefitting from the improved plateau behavior, the constructed SIB delivers a high‐energy density of 231.2 Wh kg–1 with an average voltage of 3.22 V; the assembled full‐carbon SIC shows high energy and power densities (101.8 Wh kg–1 and 2.9 kW kg–1). This work provides a universal thermal transformation approach for designing high‐performance carbon anode with closed porosity from low‐cost and highly aromatic precursors.

Low-content SnO2 nanodots on N-doped graphene: lattice-confinement preparation and high-performance lithium/sodium storage

“…36 As a result, the integral area ratio of the D band and G band for SnO 2 @N-rGO is 4.14, reflecting the disordered amorphous carbonaceous part in the composite. 37,38 Moreover, the exact content of each component in SnO 2 @N-rGO was measured using TG analysis in air (Fig. 2b).…”

“…36 As a result, the integral area ratio of the D band and G band for SnO 2 @N-rGO is 4.14, reflecting the disordered amorphous carbonaceous part in the composite. 37,38…”

Directional Regulation of Surface Chemistry of Graphene Using Carbon Dots for Sodium-Ion Battery Anodes

“…The decrease of L c and L a indicates that CDs/rGO is more disordered. 33 In addition, Raman was used to further study the disorder degree of the samples. As shown in Figure 2b, the characteristic G band (1590 cm −1 ) and D band (1350 cm −1 ) 18 The C−C sp 3 hybridization corresponds to the disorder degree of carbon materials, while C−C sp 2 hybridization corresponds to a high degree of ordered structure.…”

“…According to the peak positions and FWHM of (002) and (100) peaks, as listed in Table , the thickness ( L c ) and average width ( L a ) of graphite crystallites were calculated. The decrease of L c and L a indicates that CDs/rGO is more disordered . In addition, Raman was used to further study the disorder degree of the samples.…”

The structural changes and sodium storage in the carbon phase of cobalt sulfide/carbon composites

“…Additionally, the lateral size of the carbon microcrystal (L a ) was obtained according to the Scherrer formula. 34,35 The Co 4 S 3 -HC composite had the smallest L a value of 6.24 nm compared with those of N/S-HC (6.52 nm) and HC (7.44 nm). The L a values showed a decreasing trend after Co 4 S 3 introduction, indicating the destruction of the regular carbon structure and high defect concentration along the graphite crystallite, facilitating Na + adsorption.…”