Electrochemically induced crystallization of amorphous materials in molten MgCl₂: boron nitride and hard carbon

Abstract

A novel and versatile strategy toward the amorphous-to-crystalline transformation of boron nitride was developed through an electrochemical pathway using molten MgCl2 at low temperature (750 °C) and can be extended for transformation of amorphous carbon to graphite.

Low-Cost Transformation of Biomass-Derived Carbon to High-Performing Nano-graphite via Low-Temperature Electrochemical Graphitization

“…Activated coconut charcoal (ACC) from coconut waste (Fisher Scientific, 50–200 mesh) and anhydrous CaCl 2 (Sigma-Aldrich, 97%) were used as received. The salts were predried to remove the moisture following the protocol described in the literature …”

“…Several approaches (oxidizing the surface, increasing the interlayer distance, creating pores, coating the surface to counteract the volume expansion) have been tried to modify the graphite structure to enhance the fast-charging performance. ,− However, these approaches either do not meet the required criteria or are economically not viable to apply on already costly graphite. Our group has developed the low-temperature electrochemical transformation of amorphous carbon precursors to graphite ,, with high crystallinity, porosity with a highly tunable nanoflake architecture, and interlayer spacing that can facilitate faster lithium diffusion and relieve the stress created by ion intercalation.…”

“…2,26−31 However, these approaches either do not meet the required criteria or are economically not viable to apply on already costly graphite. Our group has developed the lowtemperature electrochemical transformation of amorphous carbon precursors to graphite 1,32,33 with high crystallinity, porosity with a highly tunable nanoflake architecture, and interlayer spacing that can facilitate faster lithium diffusion and relieve the stress created by ion intercalation.…”

“…The salts were predried to remove the moisture following the protocol described in the literature. 33 Electrochemical Graphitization. Approximately 250 g of anhydrous salt (CaCl 2 ) was heated in a magnesia crucible (inner diameter: 6.4 cm and height 15 cm) in a sealed molybdenum reactor using an electric furnace (The Mellen Company) under an argon atmosphere (moisture and oxygen content < 1.0 ppm).…”

A Review of Cobalt-Containing Nanomaterials, Carbon Nanomaterials and Their Composites in Preparation Methods and Application

“…When it is used as the anode material of a lithium-ion battery, it can provide a reversible capacity of about 280 mA h g −1 at the charge and discharge rate of 5 C (1.86 A g −1 ). Zhang put forward the corresponding concept of "electrochemical graphitization" in research that found that cathodic polarization in molten chloride can graphitize amorphous carbon at about 820 • C, and this method has been proved to be suitable for all amorphous carbon, providing a basis for preparing sustainable graphite as a high-performance anode [132][133][134][135][136][137][138]. To sum up, carbon nanotubes, graphene and carbon microspheres have great application potential in lithium-ion batteries, but they also have certain advantages and disadvantages.…”