The significant performance decay in conventional graphite anodes under low‐temperature conditions is attributed to the slow diffusion of alkali metal ions, requiring new strategies to enhance the charge storage kinetics at low temperatures. Here, nitrogen (N)‐doped defective crumpled graphene (NCG) is employed as a promising anode to enable stable low‐temperature operation of alkali metal‐ion storage by exploiting the surface‐controlled charge storage mechanisms. At a low temperature of −40 °C, the NCG anodes maintain high capacities of ≈172 mAh g−1for lithium (Li)‐ion, ≈107 mAh g−1for sodium (Na)‐ion, and ≈118 mAh g−1for potassium (K)‐ion at 0.01 A g−1with outstanding rate‐capability and cycling stability. A combination of density functional theory (DFT) and electrochemical analysis further reveals the role of the N‐functional groups and defect sites in improving the utilization of the surface‐controlled charge storage mechanisms. In addition, the full cell with the NCG anode and a LiFePO4cathode shows a high capacity of ≈73 mAh g−1at 0.5 °C even at −40 °C. The results highlight the importance of utilizing the surface‐controlled charge storage mechanisms with controlled defect structures and functional groups on the carbon surface to improve the charge storage performance of alkali metal‐ion under low‐temperature conditions.
Nitrogen‐doped carbon nanofibers (CNFs) were synthesized using a facile electrospinning technique with the addition of urea as a nitrogen‐doping agent. The amount of urea was selectively adjusted to control the degree and effectiveness of N‐doping. The morphology of N‐doped CNFs was investigated by scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction, whereas their electrochemical performance was studied using cyclic voltammetry and galvanostatic charge–discharge experiments. The nitrogen content of N‐doped CNFs increased significantly from 11.31 % to 19.06 % when the doping amount of urea increased from 0 % to 30 %. N‐doping also played an important role in improving the electrochemical performance of the CNFs by introducing more defects in the carbon structure. Results showed that N‐doped CNFs with the highest nitrogen content (19.06 %) exhibited the largest reversible capacity of 354 mAh g−1under a current density of 50 mA g−1; and when the current density was increased to 1 A g−1, a capacity of 193 mAh g−1was still maintained. It is, therefore, demonstrated that N‐doped CNFs have great potential as suitable sodium‐ion battery anode material.
more » « less- NSF-PAR ID:
- 10238532
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Energy Technology
- Volume:
- 4
- Issue:
- 11
- ISSN:
- 2194-4288
- Page Range / eLocation ID:
- p. 1440-1449
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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