Behavior of Nitrogen‐Substituted Carbon  (  N  z  C 1 − z  )  in Li / Li (  N  z  C 1 − z  ) 6 Cells

Abstract

Nitrogen-containing carbons N~C~_z have been made from different precursors at temperatures between 850 and I050~ Their composition and structure have been studied by chemical analysis, powder x-ray diffraction, x-ray absorption spectroscopy, and Auger electron spectroscopy. These techniques show that some nitrogen has been incorporated substitutionally for carbon. Nitrogen affects the behavior of Li/Li(NzC~ ~)8 electrochemical cells in two ways. First, the irreversible capacity observed during the first electrochemical reaction of Li with NzC~_~ (during the first discharge) increases with the nitrogen content of the samples. Second, the incorporated nitrogen causes a shift of the cell capacity to lower voltages compared to pure carbon electrodes. The first effect can be understood qualitatively using a model where Li reacts irreversibly with nitrogen-containing species (we call these nitrogen atoms chemical nitrogen) to form lithium-nitrogen-organic compounds. The second effect is caused by the nitrogen which has been substituted for carbon in the lattice (so-called lattice nitrogen). Such nitrogen-containing carbons are not considered useful as anodes for Li-ion cells.

Carbon Nanomaterials for Advanced Energy Conversion and Storage

“…In addition to the formation of composite materials with metal oxide, the modification of carbon nanomaterials (e.g., graphene) with chemical dopants such as boron,394 phosphorous,395 and nitrogen,396 has been investigated to improve the specific capacity of carbon materials. Recently, Leela et al390 reported that the N‐doped graphene made by CVD method showed almost the double reversible discharge capacitance compared with that of pristine graphene.…”

Lithium storage in nitrogen-rich mesoporous carbon materials

“…Chemically doped carbon materials often show substantially increased specific capacities in comparison with non-doped carbon materials. In recent years, phosphorus, 1 sulfur, 2 boron, 3,4 nitrogen [5][6][7][8][9][10][11][12][13][14][15][16] and boron-nitrogen 17 have been used as dopants to improve the electrochemical performance of carbon materials. Of these, nitrogen is attractive because its electronegativity (3.5) is higher than that of carbon (3.0) and because its atomic diameter is smaller.…”

Nitrogen‐Enriched Carbons from Alkali Salts with High Coulombic Efficiency for Energy Storage Applications

“…As an alternative to graphite, amorphous carbons have been studied as candidates for anode materials in LIBs because of their good chemical and thermal stabilities as well as high Li‐storage capacity 4–13. In addition, various heteroatoms such as phosphorus, sulfur, boron, and nitrogen have been used as dopants to modify the carbon structures in an effort to increase their lithium storage capacity 14–19. Among these heteroatoms, nitrogen is a very promising candidate because of its high electronegativity, small atomic diameter, and additional free electrons contributing to the conduction band of carbons.…”