In today’s podcast, we’re going to look at boron-based polymers for EV storage. Boron-based polymers such as BNNTs or boron nitride, nanotubes are two-dimensional nanomaterials with excellent properties for improving electric vehicle energy storage, given their high surface areas, large aspect ratios, and good thermal conductivity.
Boron-based Polymers for EV Storage
Today we examine the potential for use of BNNTs in electrical vehicle transmissions and batteries. Electric vehicle sales have been on an upward trend for years and projections show that this will continue into the future. In 2020, the global market for electric vehicles was valued at 246.7 billion US dollars. COVID 19 of course has had a massive and unprecedented worldwide impact but electric car sales are still seeing a steady increase in demand in all regions.
According to a study, the global market growth was down by 9.7% in 2020 compared to average year-on-year growth from 2017 to 19 but during the future period, 21 to 28, the market is expected to bounce back at a CAGR of 24.3% from 287.36 billion in 2021. This large increase in compound annual growth rate is due to the growth and demand expected as a result of a return to pre-pandemic levels once the coronavirus crisis is over.
Let’s have a closer look at BNNTs. Well, the question is how will boron nitride nanotubes support electric power and vehicles. One answer may be through introducing BNNTs into a polymer, nanocomposites to improve electrical conduction.
Polymer nano-composites incorporating BNNTs show enhanced dielectric properties due to synergistic effects of the nanoparticles and the host matrix. However, the electrical conductivity of these composites is still currently too low to meet the requirements of practical applications.
In an attempt to overcome this, researchers from Penn state university in Pennsylvania propose a novel approach based on the use of BNNTs, having a wider band gap than those of common semiconductors or insulators. By introducing these BNNTs into the polymers the electrical conduction of the composites can be effectively suppressed while maintaining the high dielectric property of the BNNTs. This strategy may open up a new avenue for designing advanced dielectric materials for energy storage. It’s also thought that breakdown, strength, and mechanical moduli I can be further improved by reducing the thickness of hydrogen boron, nitride powders to boron nitride nanosheets with a monolayer or at least a small number of layers.
In the BNNT fabrication process. epitaxial growth of boron nitride nanosheets by chemical vapor disposition or CVI is still a challenge because the precursors must be separated into two parts. The precursor should be kept away from the substrate during the whole process and of course, a proper substrate is necessary.
For recently reported polymer dialectics, the utilized BNNTs were mostly prepared via what’s called top-down methods, which is a kind of mechanical exfoliation or chemical exfoliation. These exfoliation methods ensure that highly ordered crystalline phases of the products are there but the lateral sizes are usually limited to a few hundred nanometers. It’s been known for many years, that strong lip-lip interactions exist between boron nitrate layers, which makes it difficult to achieve complete exfoliation.
But the current focus is now on developing high-yield mechanical or chemical exfoliation approaches for the scalable production of BNNTs. To date, exfoliation approaches yield not only small lateral sizes but few layered crystallized structures which limits the ability to produce large quantities of mono-layered BNNTs. However, a recent study has shown that a mild milling process could produce a number of few layered crystallites with slightly reduced lateral dimensions.
This new approach may be useful for varying large quantities of monolayer BNNTs. A planetary mill is used for crushing. h-BN into powder form. Further, exfoliated BN sheets are produced using various methods, such as ball milling, vortex fluid exfoliation, and hydrothermal exfoliation.
These exfoliated sheets are then incorporated into polymer matrices. And as a result, these composites show improved dielectric and thermal performance.
Well, despite this progress, there are still current limitations on the use of BNNTs in electric vehicle storage. Besides the many desirable characteristics, such as the wide band gap, the high breakdown field, the high dielectric constants, and the excellent mechanical properties, there are challenges which need to be solved.
Barriers include the liquid exfoliation technique costs, which are still very high and the actual production rate is still low. Moreover, the process is, unfortunately, toxic and harmful to humans.
For more information on boron-based polymers for EV storage, please refer to the Borates Today website. And that’s all for today. Thanks for listening.