Electrochemical Performance and Conductivity of N-Doped Carbon Nanotubes Annealed under Various Temperatures as Cathode for Lithium-Ion Batteries

Abstract

Nitrogen-doped carbon nanotubes (NCNTs) are obtained using a post-treatment method under different sintering temperatures. The catalysts can be removed from the Carbon Nanotubes (CNTs) within an acid treatment process. Then, the purified CNTs can be employed as a nitrogen doping basis. This research adds melamine as a nitrogen source during the sintering procedure under different temperatures to achieve NCNTs, which are applied to the cathodes. LiMn2O4 (LMO) cathode slurries are prepared using pristine CNTs and NCNTs samples as conductive additives. Coin cell lithium-ion batteries (LIBs) are fabricated using slurry samples. X-ray photoelectron spectroscopical analysis shows the nitrogen doping degree is up to 5 atom%, and graphitic-N nitrogen groups are the dominating species present on the NCNT’s surface while being treated at 800 °C. Graphitic-N nitrogen groups improve the conductivity and surface area of the NCNTs, which increases the rate capacity (106.8 mA h g−1 at 5 C) and cyclic retention (92.45% of initial capacity after 200 cycles at 5 C) of the lithium-ion batteries. The morphology of the NCNTs, the concentration of NCNTs elements, and the electrochemical performances of coin cell batteries are extensively discussed.

Constructing Reversible Li Deposition Interfaces by Tailoring Lithiophilic Functionalities of a Heteroatom-Doped Graphene Interlayer for Highly Stable Li Metal Anodes

“…In both NG7 and NG9, the concentration of pyrrolic and pyridinic N is high, while that of graphitic N rather increases for NG9 with a decrease in pyridinic N due to the thermal stability . Graphitic N has a high electrical conductivity due to the n-type carrier but unfortunately shows a poor lithiophilicity compared to pyrrolic N and pyridinic N as well as pristine graphene, which means that NG7 has a higher lithiophilicity than that of NG9, possibly affecting the migration and deposition of Li ions in the cell. , For B-doped graphene, B is more electropositive than C, thereby transferring electrons to adjacent C. Such electronegative C sites have a Li ion adsorption ability higher than those over pristine graphene. Therefore, all B-doping functional groups contribute to an enhanced lithiophilicity than pristine graphene .…”

“…The electrical conductivity of the heteroatom-doped graphene-coated separators was obtained by four-point probe measurements. N-doped graphene-coated separators have a relatively higher electrical conductivity than B-doped counterparts due to their lower oxygen content with a higher doping concentration, which can be translated into the recovery of sp 2 carbon network and a high carrier concentration required for electron conduction (Figure d). − Both NG9- and BG9-coated separators exhibit a higher electrical conductivity than NG7- and BG7-counterparts, attributed to the increase in graphite-like functional groups, such as graphitic N and BC 3 , as well as the lower oxygen content resulting from thermal reduction …”

“…47−49 Both NG9-and BG9-coated separators exhibit a higher electrical conductivity than NG7and BG7-counterparts, attributed to the increase in graphitelike functional groups, such as graphitic N and BC 3 , as well as the lower oxygen content resulting from thermal reduction. 35 The charge transfer kinetics of each separator was analyzed by electrochemical impedance spectroscopy (EIS) in Li|Li symmetric cells, as shown in Figure 2e. The charge transfer resistance (R ct ) can be estimated from the diameter of the semicircle in the high-frequency region of the Nyquist plot, which measures the interface resistance between the electrolyte and Li electrode.…”

Microwave-Mediated Stabilization and Carbonization of Polyacrylonitrile/Super-P Composite: Carbon Anodes with High Nitrogen Content for Lithium Ion Batteries

“…The larger capacities in the sloping region were due to the higher N atomic content and increased surface area (Figures b,S6). − ,, More pyridinic-N and graphitic-N in M1000W resulted in the exposure of more active sites for Li ions and enhanced electronic conductivity. − Therefore, facile redox reactions could be achieved, particularly at high current densities. The capacity increase in the plateau region is influenced by the larger crystallite size, which improves electronic and ionic transport. , The M1000W demonstrated an initial Coulombic efficiency (ICE) of 48.6%, whereas the T1000°C displayed an ICE of 52.4%.…”

“…Carbon materials produced via microwave heating exhibited remarkable advantages over those produced via thermal convection, in terms of their reversible capacities and rate performance. The superior performance of microwave-heated carbon can be attributed to its high nitrogen content, which provides additional active sites for Li ion adsorption and enhanced electron transport. − Overall, it can be concluded that microwave carbonization represents a promising strategy for the production of carbon materials with enhanced electrochemical properties for LIBs and other next-generation batteries.…”