Nitrogen doped porous carbon fibres as anode materials for sodium ion batteries with excellent rate performance

Abstract

Nitrogen-doped activated porous carbon fibres (ACFs) were prepared as anode materials for Na-ion batteries. They exhibit excellent electrochemical performance, especially rate performance. The excellent rate performance is ascribed to the fibre-like morphology and the facilitated charge transfer. The influence of nitrogen functionalities on charge transfer and electrochemical performance of N-doped carbon anodes for Na ion batteries is discussed.

Is single layer graphene a promising anode for sodium-ion batteries?

“…All these experiments were performed using 1M NaPF 6 (EC:DEC, 1:1, w:w) as the electrolyte solution. In general terms, the intense cathodic and anodic peaks due to the insertion and de-insertion processes of Na + ions in carbon materials [5,7,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] do not appear in the CVs of SLG/Cu electrodes. More specifically, the CV of cycle 1 displays a significant cathodic current that has been previously observed in the study of the interaction of Li + ions with SLG [34] and attributed to the formation of a solid electrolyte interphase (SEI) layer as a consequence of the electrolyte irreversible reduction.…”

“…3, the cells start to show good electrochemical performance in terms of cycling stability as well as coulombic efficiency (≥ 90 %, ≥ 85 % for NaClO 4 in PC electrolyte) after 20 discharge-charge cycles. However, during the initial cycles (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20), these electrochemical parameters, particularly the capacity retention, were much lower.…”

“…Moreover, the sodium graphite intercalation compounds (NaC x with x = 36, 16,12,8,6) are unstable [9]. In fact, they do not exist under moderate conditions, which was reported to be a consequence of the clash between the graphite structure (graphite is stressed when some Na + ions intercalate into it) and the size of the Na + ion (its ionic radius is approximately 0.3 Å larger than that of Li + ion, this difference leading to changes in thermodynamic and kinetic properties) [9,10].…”

“…Therefore, efforts have been focused on the identification of other host carbon materials to achieve a successful reversible intercalation/insertion of the larger Na + anions. Thus, a variety of carbons having a certain degree of porosity, a low-ordered structure consisting of few-layers graphite nanocrystallites (graphite domains) and different morphologies, including hard and soft carbons [5,7,[11][12][13][14][15], carbon fibers and nanofibers [16][17][18][19][20], spherical carbons [21], hollow carbon nanowires [22] and nanospheres [23], reduced graphene oxide, [24] pyrolytic carbons from graphite oxide [25], as well as highly disordered carbon composites [26,27] have been investigated as anodes for SIBs. Good results as regards capacity and cycling stability were achieved with some of these carbons, the rate capability and particularly, the low coulombic efficiency during the first charge/discharge cycle due to the relatively large surface area (as compared with graphitic carbons) being the main drawbacks to overcome.…”

Solvothermal‐Derived S‐Doped Graphene as an Anode Material for Sodium‐Ion Batteries

“…The peak observed at 1.0 V was attributed to the irreversible reaction of the functional groups with sodium ions. Another cathodic peak at 0.4 V is related to formation of solid electrolyte interphase (SEI) layer 12. Contrary to CVs of the pristine SG, two additional redox couples were observed at 1.6/2.2 and 1.1/1.8 V in CVs of S‐SG.…”