Electrochemical properties of nitrogen-doped carbons prepared by the thermal reduction of furfurylamine-intercalated graphite oxide

Abstract

Nitrogen-doped carbons were prepared by the thermal reduction of furfurylamine-intercalated graphite oxide. The nitrogen atom content in the resulting samples was around 6 wt% and was almost constant, independent of the thermal reduction temperature. The nitrogen atoms were introduced in the forms of pyridinic, pyrrolic and graphitic, and the amount of graphitic nitrogen greatly increased for the sample prepared at 800 °C. The discharge capacity above 1.0 V greatly decreased for nitrogen-doped carbon samples when used as anodes of a lithium ion battery. It reached a maximum value of 334 mA h/g for the sample prepared at 500 °C. X-ray diffraction measurements during a charge-discharge cycle indicated that lithium ions were stored between and extracted from the layers in the material and the increase in the interlayer spacing after lithium storage was similar to that observed for graphite. This result has been well reproduced by theoretical calculations and nitrogen atoms stayed at almost the same position even after the intercalation of lithium ions. This would prevent the intercalation of a large amount of lithium and accordingly lower the capacity.

Electrochemical Intercalation Behaviors of Lithium Ions into Graphene-Like Graphite

“…For the last issue, the structural changes of GLG during intercalation of lithium ions would be important. We have reported that lithium ions are intercalated into it at a higher cell voltage of 0.48 V and the interlayer spacing reached a very large value of 0.48 nm at 0 V. We have also found that all of the lithium species stored in fully charged GLG are in the ionic state, based on the 7 Li NMR measurement. 5 However, the intercalation behavior of lithium ions into GLG especially at the early stages of it has not yet been studied, which would be strongly related to the formation of SEI.…”

“…[5][6][7] They are denoted as GLGT (T; heat-treatment temperature). Air treated GLG800 obtained in our previous study 5 was also used and was denoted as A-GLG800.…”

“…The lithium storage capacity of GLG is strongly related to the oxygen content and the large expansion of interlayer spacing during the intercalation of lithium ions was ascribed to the high capacity, reaching 673 mAh/g of discharge capacity. 6,7 The coulombic efficiency of GLG was higher than those reported for graphene-based carbons, however, was still not enough high (50-56% with a cutoff voltage of 2 V). In the case of a graphite anode operated in an ethylene carbonate based electrolyte solution, solvated lithium ions are first intercalated into it and then the solvent molecules are reduced to form a lithium ion conducting passivation layer so called solid electrolyte interphase (SEI) at higher potential regions of around 0.8 V vs Li/Li + .…”

Insight into the Origin of the Rapid Charging Ability of Graphene-Like Graphite as a Lithium-Ion Battery Anode Material Using Electrochemical Impedance Spectroscopy

“…In this regard, our group has proposed a new carbon-based anode material named graphene-like graphite (GLG). − GLG is synthesized via the thermal treatment of graphite oxide (GO) under a vacuum. In this process, the expanded interlayer distance of GO decreased, and the resulting GLG shows almost the same interlayer distance as that of graphite.…”

Effects of Pre-Lithiation on the Electrochemical Properties of Graphene-Like Graphite

“…In this regard, we have recently introduced graphene-like graphite (GLG) as a new candidate for an anode material of LIBs, which can overcome these intrinsic difficulties of the carbon-based materials. [7][8][9][10] The capacity of GLG reaches 608 mAh g ¹1 with a cutoff voltage of 2 V, and it shows good cycle performance. In addition, the rate capability of GLG is superior to that of graphite; the capacity of GLG at 6 C remains 79% of the capacity at 0.1 C. GLG is synthesized via thermal reduction of graphite oxide (GO) under vacuum with quite small increasing-rate of temperature to avoid exfoliation of graphene sheets.…”