N-doped catalytic graphitized hard carbon for high-performance lithium/sodium-ion batteries

Abstract

Hard carbon attracts wide attentions as the anode for high-energy rechargeable batteries due to its low cost and high theoretical capacities. However, the intrinsically disordered microstructure gives it poor electrical conductivity and unsatisfactory rate performance. Here we report a facile synthesis of N-doped graphitized hard carbon via a simple carbonization and activation of a urea-soaked self-crosslinked Co-alginate for the high-performance anode of lithium/sodium-ion batteries. Owing to the catalytic graphitization of Co and the introduction of nitrogen-functional groups, the hard carbon shows structural merits of ordered expanded graphitic layers, hierarchical porous channels, and large surface area. Applying in the anode of lithium/sodium-ion batteries, the large surface area and the existence of nitrogen functional groups can improve the specific capacity by surface adsorption and faradic reaction, while the hierarchical porous channels and expanded graphitic layers can provide facilitate pathways for electrolyte and improve the rate performance. In this way, our hard carbon provides its feasibility to serve as an advanced anode material for high-energy rechargeable lithium/sodium-ion batteries.

Three‐Dimensional Graphene‐based N‐doped Carbon Composites as High‐Performance Anode Materials for Sodium‐ion Batteries

“…[20] The specific surfacea rea of the NCL@GF wasr ecorded up to 277 m 2 g À1 by Brunauer-Emmett-Teller (BET) method, which markedly contrasted thato fG F(% 179 m 2 g À1 )a nd NCF-GF (57 m 2 g À1 )( FigureS2b). [23] The charge-discharge profiles of the 1st, 2nd, 100th, 150th and 200th cycles of the NCL@GF electrode at acurrent density of 0.1 Ag À1 were shown in Figure 4b,w hich were similart ot hose previously reported for N-doped carbon materials. 2) The more defects were introduced to the graphene surface after the PI polymer layers converted to the carbonw ith pyrolysis.…”

“…[6,21] In contrast, only the broad peak at ca. [23] It was furtherdemonstrated by Raman spectra of the NC@GF-T with visible Da nd Gb ands at about 1330 and 1600cm À1 ,r espectively ( Figure S2 a). [6,22] These results indicated that the PI had been successfully converted to amorphous after carbona nnealing process 23 .T his finding was further elucidated by the Fouriert ransform infrared (FTIR) spectra of the composites before anda fter carbonization treatment ( Figure 3b).…”

“…There were two diffraction peaks centered at ca. [6,22] These results indicated that the PI had been successfully converted to amorphous after carbona nnealing process 23 .T his finding was further elucidated by the Fouriert ransform infrared (FTIR) spectra of the composites before anda fter carbonization treatment ( Figure 3b). [6,21] In contrast, only the broad peak at ca.…”

“…[6,22] These results indicated that the PI had been successfully converted to amorphous after carbona nnealing process 23 .T his finding was further elucidated by the Fouriert ransform infrared (FTIR) spectra of the composites before anda fter carbonization treatment ( Figure 3b). [23] Applied to the anode of SIBs, both the large surfacea rea and the existence of considerable number of N-containing specieso f NCL@GF create more actives ites for sodium storagebysurface absorption and faradicreaction. [17] For the NCL@GFa nd NCF-GF samples, the disappearance of the peak at 1650 cm À1 ,f urtheri ndicated that PI had been carbonized.…”

“…2) The more defects were introduced to the graphene surface after the PI polymer layers converted to the carbonw ith pyrolysis. [23] The first discharge and charge capacities of NCL@GF were 663.8 and 412 mAh g À1 ,r espectively.T he initial Coulombic Efficiency (CE) was calculated to be 62 %. The x-ray photoelectron spectroscopy (XPS) was furtherp resented to investigate the chemical nature of the NCL@GF and NCF-GF (Figure3c and d).…”