Electrochemistry of Catalytically Graphitized Ball Milled Carbon in Li Batteries

Abstract

High carbon Fe-C composites with starting concentrations of 10, 20, 30, and 40 wt% Fe (2.3 -12.5 atomic % Fe) were prepared by ball milling followed by annealing. Increasing the Fe concentration and annealing temperature resulted in catalytic graphitization of the carbon. Mössbauer spectroscopy analysis indicated that Fe concentration and annealing temperature had significant effects on the Fe magnetic hyperfine field, quadrupole splitting, and the formation of γ-Fe. When used as electrodes in Li cells, the electrochemistry of ball milled Fe-C powders annealed at low temperatures resembled that of amorphous carbon. Fe-C with 40 wt% Fe annealed at 2000 • C had electrochemical characteristics of a pristine graphite electrode with good cycling performance. These results demonstrate that lithium battery negative electrodes with good cycling performance can be produced from catalytically prepared graphite.

Catalytic Graphitization of Biocarbon for Lithium‐Ion Anodes: A Minireview

“…Graphite crystallite size increased with temperature for each loading rate with the largest L c sizes of 56.9 nm and 57.3 nm for the samples with 10 wt % and 40 wt % catalyst loading treated at 2000 °C, respectively. Electrochemical performance of the 40 wt % iron loading treated at 2000 °C resembled that of commercial graphite with a reversible capacity of 360 mAh g −1 at 0.2 C, initial coulombic efficiency of 85 %, and low capacity loss after the first cycle [30] . This process produced anode material at lower temperatures than typically required for synthetic graphite production (3000 °C), which may lead to potentially lower production costs [30] .…”

“…Metal‐catalyzed graphite grows in the vertical c‐axis to a greater extent than mineral graphite, which typically favors the lateral $${\alpha }$$ ‐axis [26,27,38] . Thus, the morphologies of metal catalyzed graphite typically consist of crystallites with high dimension ratios of vertical stacking (L c ) to horizontal expansion (L a ) (Figure 5), making them suitable for lithium‐ion intercalation and de‐intercalation [30] . Unlike most high‐value graphite applications, lithium‐ion anodes do not require large flake graphite morphologies with extensive L a dimensions, hence why synthetic graphite performs well [13] .…”

Are lignin-derived carbon fibers graphitic enough?

“…Multiple studies that successfully graphitized lignin used intensive milling or other techniques to reduce particle size to the micron level prior to thermal treatment, indicating that initial particle size may play a major role in the degree of graphitization. 38,40,49 Yoon et al (2018) carbonized acid hydrolysis lignin at 900 and 1300°C for use as anode material in a Na-ion battery. 43 As shown in Fig.…”

Voronoi‐Tessellated Graphite Produced by Low‐Temperature Catalytic Graphitization from Renewable Resources

“…It is well known that catalysts such as elements, oxides, and salts, can significantly lower the graphitization temperature of soft carbons and enable the graphitization of hard carbons . Two mechanisms have been proposed to explain the process of graphitization using metal catalysts: one is the dissolution–precipitation mechanism, in which the carbon precursor dissolves into the catalyst, followed by its precipitation as a graphitic carbon; the other one is the formation–decomposition of carbide intermediates, in which the carbon precursor forms carbides with the catalyst, which subsequently decomposes, leaving behind a graphitic carbon .…”

“…Two mechanisms have been proposed to explain the process of graphitization using metal catalysts: one is the dissolution–precipitation mechanism, in which the carbon precursor dissolves into the catalyst, followed by its precipitation as a graphitic carbon; the other one is the formation–decomposition of carbide intermediates, in which the carbon precursor forms carbides with the catalyst, which subsequently decomposes, leaving behind a graphitic carbon . Catalytic graphitization at low temperature (900–1300 °C) with transition metals and their corresponding salts and oxides as catalysts has been widely studied . However, transition metal catalysts are difficult to remove after graphitization, reducing the practicality of this method, especially in applications where high‐purity graphite is desired.…”