Vitreum Etching‐Assisted Fabrication of Porous Hollow Carbon Architectures for Enhanced Capacitive Sodium and Potassium‐Ion Storage

Abstract

Carbonaceous materials exhibit promising application in electrochemical energy storage especially for hollow or porous structure due to the fascinating and outstanding properties. Although there has been achieved good progress, controllable synthesis of hollow or porous carbons with uniform morphology by a green and easy way is still a challenge. Herein, a new artful and green approach is designed to controllably prepare hollow porous carbon materials with the assistance of boron oxide vitreum under a relatively low temperature of 500 °C. The vitreous B2O3 provides a flowing carbonization environment and acts as etching agent accompanying with boron doping. By this general strategy, hollow and porous carbon architectures with various morphology of spheres and hollow polyhedrons are successfully fabricated by metal organic framework (MOF) precursors. Furthermore, such hollow carbon materials exhibit considerably excellent Na+/K+ storage properties through enhanced capacitive behavior due to due to the highly porous structure and large surface area. It is notable that hollow carbon spheres display nearly 90% initial Coulombic efficiency, outstanding rate capability with 130 mAh g‐1 at 30 A g‐1 and long cycling life for sodium ion storage.

Free-Standing, Self-Doped Porous Hard Carbon: Na-Ion Storage with Enhanced Initial Coulombic Efficiency

“…This ample self-doped nitrogen was ascribed to the presence of a high amount of PAN in the PHC/PAN blend . Increasing nitrogen/oxygen functional groups and porous fiber structure (HC@PCNF) helps provide more active sites, enhanced electrical conductivity, and surface polarity, all favoring excellent Na + ion reversibility. ,− Additionally, the presence of heteroatoms’ content in HC@PCNF improved its surface functionality, − which in combination with its surface roughness resulted in excellent hydrophilicity, as shown in Figure S7a,b (Supporting Information).…”

Guiding Fabrication of Continuous Carbon-Confined Sb2Se3 Nanoparticle Structure for Durable Potassium-Storage Performance

“…The carbon in the C–C/SS composite showed a similar charge–discharge curve as that of the previously reported carbon anode, suggesting an absorption/intercalation K + -reaction mechanism (Figure S13b). − Because of the limitation of the absorption/intercalation K + -reaction mechanism, the carbon with a low theoretical capacity usually provided a negligible contribution to metal/carbon composites. ,, The K + -storage behavior of the C–C/SS electrode is illustrated in the following conversion reactions: These results support the two-step conversion–multistep alloy K + -storage behavior of the C–C/SS electrode, suggesting a huge volume change of Sb 2 Se 3 during the potassiation and depotassiation process. Because of the large volume change, inhibiting pulverization to promote K + -transfer reversibility is a great challenge for achieving durable performance in the Sb 2 Se 3 anode.…”

Double‐Walled NiTeSe–NiSe2 Nanotubes Anode for Stable and High‐Rate Sodium‐Ion Batteries

“…[ 26 ] The b ‐value represents the slope of log( i ) versus log( v ) for NiTeSe–NiSe 2 in Figure 4b. [ 27 ] If the b value is close to 0.5, the storage behavior is mainly dominated by ion diffusion‐controlled behaviors, and if it is ≈1.0, the capacitive‐controlled process belongs to a capacity‐contribution behavior. The b ‐value of the NiTeSe–NiSe 2 anode for five peaks during anodic/cathodic processes are ≈0.80, 0.83, 1.06, 1.00, and 0.74, respectively, manifesting it is a capacitive‐controlled Na + storage mechanism.…”