Eco-friendly mass production of multi-walled carbon nanotubes

In a paper published in the journal Nano Letters, it was shown that iron-based carbon nanomaterials can be derived from cotton for use in batteries using an inexpensive procedure for mass production.

Renewable Energy – A Need

Since the turn of the century, there has been a worldwide increase in the desire to produce renewable energy.

As awareness of climate change increases, industries are increasingly aware of their environmental impact and are trying to reduce their carbon footprint. This has been accompanied by regulations aimed at reducing carbon dioxide emissions.

However, utilities have had to adapt to the influx of intermittent renewables. Storage capacity for intermittent electricity has also become more important, as renewable energy sources such as solar and wind power can suddenly shift generation without warning.

The problem with charging storage batteries

Most batteries use lithium or cobalt as raw materials. They are operated by mining companies that use around 400,000 gallons of water to extract a ton of lithium.

Other more environmentally friendly mining processes exist, but they are not currently cost competitive.

Lithium mining also has adverse consequences around the world. For example, in China, this inevitably led to polluted rivers.

American researchers have also discovered traces of lithium in fish collected more than 200 km downstream from lithium production plants.

Lithium-Sulfur Batteries – A Superior Combination to Li-ion

Lithium-sulfur (LiS) batteries are gaining popularity because they offer higher energy density and theoretical capacity than Li-ion batteries.

However, LiS batteries face two challenges in their approach to widespread use: sulfur volume changes and the shuttling effect.

To jointly address these challenges, carbon materials, such as graphene, and carbon nanotubes (CNTs) are used.

Due to toxic chemicals, toxic chemicals, and excess carbon emissions, the total manufacturing cost and environmental footprint when manufacturing these nanostructures have skyrocketed.

An alternative, greener approach to producing environmentally friendly and low-cost CNTs is urgently needed.

Biomass material – a potential solution

Biomass energy, or energy derived from living things, has been used by humans since early Neanderthals used open flames for cooking, shelter and heating.

Plants, wood and waste are the most frequently used biomass sources for energy.

Fortunately, widely abundant, accessible, and renewable biomass resources hold great promise for creating nanocarbon compounds in a more environmentally friendly and cost-effective way.

Low cost fabrication of carbon nanotubes

Cotton, a biomass material composed of more than 85% cellulose fibers, is the oldest and most frequently used natural cellulosic material.

In this paper, cotton textiles were converted into activated carbon textiles (ACT) and used as both a carbon source and a substrate to synthesize iron=carbon-filled multi-walled nanotubes.

The researchers presented a low-cost method to mass-produce multi-walled carbon nanotubes using a combination of solid-liquid-solid (SLS) and vapor-liquid-solid (VLS) processes, in which cotton was broken down into particles containing carbon. and amorphous carbons.

These were then solubilized in Fe nanotubes, resulting in iron-carbon encapsulated multi-walled carbon nanotubes.

Improved performance parameters in batteries

The iron-carbon-sulfur nanocomposite (cathode) and iron-carbon (interlayer) lithium-sulfur (LiS) battery demonstrated exceptional cycling stability, remarkable specific capacity, and extraordinarily low capacity decay factor.

During cycling, the iron-carbon-sulfur combination improved electrode stability and reduced polysulfide dissolution.

During the cycle, multi-walled carbon nanotubes encapsulated in iron and carbon were found to be effective in damping the sulfur volume change.

The remarkable mechanical and chemical characteristics of Fe/Fe₃CMWCNTs, which reduced host carbon deformation and inhibited polysulfide dissolution, were primarily responsible for the superior electrochemical performance.

Cotton-derived iron-carbon nanotubes have significant potential for energy storage systems because they are green, durable, and inexpensive.

What to expect ?

By commercializing such processes that encourage the economical use of abundant materials, we can expect to have cheaper energy alternatives.

These green energy alternatives will be beneficial for civil, industrial, scientific and military applications.

Continue reading: Recent developments in the green synthesis of nanoparticles.

Reference

Chen, R., Zhou, Y. & Li, X. (2022). Fe/Fe3C encapsulated carbon nanotubes derived from cotton for high performance lithium-sulfur batteries. Nano-letters. Available at: https://pubs.acs.org/doi/10.1021/acs.nanolett.1c04380

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