Low-Temperature Fluorination of Soft-Templated Mesoporous Carbons for a High-Power Lithium/Carbon Fluoride Battery

Abstract

Soft-templated mesoporous carbons and activated mesoporous carbons were fluorinated using elemental fluorine between room temperature and 235 °C. The mesoporous carbons were prepared via self-assembly synthesis of phloroglucinol–formaldehyde as a carbon precursor in the presence of triblock ethylene oxide–propylene oxide–ethylene oxide copolymer BASF Pluronic F127 as the template. The F/C ratios ranged from ∼0.15 to 0.75 according to gravimetric, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy analysis. Materials have mesopore diameters up to 11 nm and specific surface areas as high as 850 m2 g–1 after fluorination as calculated from nitrogen adsorption isotherms at −196 °C. Furthermore, the materials exhibit higher discharge potentials and energy and power densities as well as faster reaction kinetics under high current densities than commercial carbon fluorides with similar fluorine contents when tested as cathodes for Li/CF x batteries.

Insights on the reactivity of ordered porous carbons exposed to different fluorinating agents and conditions

“…Nevertheless, in the case of carbonaceous lattices, which are highly reactive because of their size (carbonaceous nanomaterials such as SWCNTs [27], graphene [60], or fullerenes [29] or their high surface area (highly porous materials [20], the reaction with fluorine gas may result in decomposition as volatile species (CF 4 and C 2 F 6 ) in addition to fluorination (grafting of fluorine atoms). Because of the loss of carbon atoms, the fluorine content is underestimated using weight uptake.…”

“…Recently, Fluvio et al [20] reported the modification of ordered carbonaceous materials by fluorine gas, which exhibited higher energy and power densities and faster reaction kinetics at high current density in primary lithium batteries compared to commercial carbon fluorides. It is worth mentioning that studies concerning the fluorination of porous carbonaceous materials are rather limited, most of the works being devoted to graphite fluorides, which are already recognized as performing materials in industrial applications as electrodes for primary batteries and solid lubricants [21][22][23].…”

“…Activated carbon or carbon nanofibers were fluorinated and subsequently used for energy and CH 4 storage [32,33]. Various amounts of fluorine were introduced into ordered mesoporous carbonaceous materials by tuning the fluorination temperature (25-300°C) [20,34] in order to improve the performance of primary Li + ion batteries. We have also studied [35] the fluorination of an activated carbon and in particular the influence of its surface chemistry on the obtained fluorinated carbonaceous materials as well as their interaction with water during water intrusion and adsorption/desorption measurements.…”

Lithium and lithium ion batteries for applications in microelectronic devices: A review

“…The CeF bonds of CF x materials prepared by the roomtemperature catalytic approach have more ionic character than compounds using the high-temperature approach, leading to cells with higher voltage and better kinetics [97,99,103]. The less invasive low-temperature process also helps preserve the pore structures of various carbon materials [107]. However, residual catalysts may be present causing aging issues and need to be removed by thermal treatment [103,108].…”

Adsorption analysis of carbon dioxide, hydrocarbons and moisture on carbon

“…For example, increase in adsorption capacity [177], as well as an increase in conductivity and performance in super-capacitors [178] and batteries [179] have been reported based on targeted modification of surface chemistry. Oxygen [180], fluorine [181][182][183], nitrogen [184,185], and sulphur [186,187] [ 189] and Im et al [190] report fluorination of phenolic activated carbon and polyacrylonitrile-based activated carbon nanofibers to enhance electrochemical capacitance and CH 4 storage respectively. Leroux and Dubois [191] demonstrate improved performance of primary Li + ion batteries using ordered mesoporous carbonaceous materials having various amounts of fluorine, with tuning the fluorination temperature.…”