Single-Source-Derived Nitrogen-Doped Soft Carbons for Application as Anode for Sodium-Ion Storage

Abstract

Recently sodium-ion batteries have gained considerable attention over lithium-ion batteries because of their high earth abundance and low cost of sodium metal. Soft carbons with higher crystallinity and fewer defects compared to hard carbon are the preferred electrode material for tuning the reversible capacity of Na+ ion storage. In this work, we have successfully prepared N-doped soft carbons from formamide via a simple solvothermal process followed by pyrolysis at high temperatures. The presence of disorders and graphitic character was controlled via variation of the annealing temperature from 800 to 1400 °C. The prepared electrode material as an anode for Na+ storage shows a specific capacity of nearly 201 mA h g–1 under a current density of 20 mA g–1. The designed electrode also shows an excellent cyclic stability of 87% at 100 mA g–1 for 500 cycles. The enhanced performance of the optimized soft carbon may be ascribed to the synergistic interaction of graphitic and disordered domains and the doping of N into the soft carbon structure.

Rational Design of Sulfur-Doped Carbon with Expanded Inter-layer Spacing toward Anode Material of Sodium-Ion Batteries

“…The Raman spectra of all three samples in the range of 700–2000 cm –1 are shown in Figure b. The D-band at 1335 cm –1 and the G-band at 1584 cm –1 in CSs reflect disordered and crystalline graphite, respectively . The D-band correlates to the hexagonal carbon structure’s disordered A 1g vibration mode; the G-band relates to the six-membered aromatic ring and corresponds to the sp2-hybridized C atoms’ E 2g vibration mode .…”

“…The D-band at 1335 cm −1 and the G-band at 1584 cm −1 in CSs reflect disordered and crystalline graphite, respectively. 30 The D-band correlates to the hexagonal carbon structure's disordered A 1g vibration mode; the G-band relates to the six-membered aromatic ring and corresponds to the sp2-hybridized C atoms' E 2g vibration mode. 31 The comparative intensity ratio of the D-band and Gband (I D /I G ) aids in determining the crystalline phase contribution in the sample.…”

“…This demonstrates how, after cycling the electrode material, the charge transfer resistance increased and the electrochemical performance decreased. R CT ’s value may have increased as a result of material degradation and volume expansion over repeated cycling. , …”

“…R CT 's value may have increased as a result of material degradation and volume expansion over repeated cycling. 30,41…”

Multilayered Architecture Assembled from Sn(HPO4)2 Nanosheets and Reduced Graphene Oxide As Superior Cyclability Anodes for Sodium-Ion Batteries

“…For three-dimensional lattice-embedded sodium anode materials, electrochemical properties of sodium storage are highly dependent on the structure and chemistry of their surface and near surface. Therefore, decreasing the size/dimension of metal oxides/carbide/phosphide, − metallic sulfide/selenides, − and alloy-based − anode materials to expose more active sites for sodium storage to the surface and regulating the pore structure , and doping , of carbon-based anode materials to shorten the diffusion distance of sodium ions inside the electrode and enhance the surface charge accumulation ability can all greatly enhance the rate capability. However, the volume change of the electrode structure still hinders the stability of long-term charge/discharge cycles.…”