In the previous post about Lithium-ion polymer battery, we realized and this rechargeable battery is composed of solid polymer electrolyte which does not conduct electricity but allows ion exchange. We also discussed the design, analyses and modification of polymers in the post Nanotechnology and Polymer Technology in Thin-Film Batteries. Polymers have many applications and scientists keep on discovering them. The block copolymer (BCP), a copolymer formed when the two monomers cluster together and form ‘blocks’ of repeating units, is the latest in their studies.
Block Copolymer Microstructure
Image Source: Royal Society of Chemistry Website
New Findings: Nano-channels in Block Copolymers
New research suggests that the shape of nano-channels through which ions can travel can be controlled in plastics known as block copolymers (BCPs). According to the research, controlling the movement of ions in the nano-channels in BCPs can optimize the electricity that a battery can generate. The research being conducted by McCormick School of Northwestern Engineering aims to solve the known disadvantages of lithium-based batteries such as high flammability.
Nanoscale Section of Block Copolymer
Image Source: IEEE Website
Research Background
In June 2014, researchers from Northwestern University published a paper entitled “Electrostatic control of block copolymer technology”. This paper centers on investigating the characteristics of BCPs, a leading material used as ion conductors. BCPs can self-assemble into nanostructures which enable ion charge transport and maintain structural integrity. The main objective of the research is to find safer batteries that can be a better replacement to lithium, the most popular element used in batteries since the 1970s. Polymers have been the right choice yet the lack of understanding of how the material will change when an ion is introduced has been a major hindrance to many researchers for decades.
Scientific Basis
There are two theories that serve as the basis to understanding the behavior of block copolymers. These are the Self Consistent Field Theory which describes how molecules behave and the Liquid State Theory which describes how charges operate on atomic levels. Researchers combined these two theories and the findings were phenomenal. They discovered that the electrical charge known as ion is associated with an oppositely charged molecule known as counter-ion and both were present in the nano-channels of BCPs. The interaction between these two opposite charges has two effects. First, it forms a salt which then clusters into miniature crystals. Second, the crystals exert force on the nano-channels, thereby deforming the channel-structure. By observing the deformation pattern, the scientists can predict the dynamics of the nano-channel systems in BCPs, and design a “highway system” through which ions are transported. Moreover, according to one of the researchers, “If you can optimize the ability of the charge to move through the system, then you can optimize the power that actually comes out of the battery”.
Implication for Battery Technology
Scientists are still conducting experiments to better understand the systems behind BCPs. The success of this on-going research will pave the way for many applications, one of which is a new class of polymer batteries.
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