The world of conductive plastics/polymers, introduced several decades ago, features breakthrough technologies and novel usage of conductive polymers. These materials conduct electricity and are used in countless applications in many industries because they are easy to extrude or injection mold into desired shapes and sizes.
“Conductive polymers are already used in fuel cells, computer displays and microsurgical tools, and are now finding applications in the field of biomaterials,” reports the journal Acta Biomaterialia.1 “These versatile polymers can be synthesized alone, as hydrogels, combined into composites or electrospun into microfibers. They can be created to be biocompatible and biodegradable.”
For example, The University of Auckland’s Polymer Electronics Research Centre was “established in 2003 to promote, facilitate, and advance research in the field of polymer electronics.”2 Their research projects include biomedical applications of conducting polymers and nanomaterials and composite plastics for “smart” packaging and organic electronic devices. They are even developing DNA sensor technologies based on conducting polymers, photoluminescent polymers, and quantum dots for gene detection.
To date, conductive polymers have had few large-scale applications aside from ESD (electrostatic dissipation). However, advances in the technological development of conductive polymers are leading to their incorporation in batteries, super capacitors, biomaterials, solar cells, flexible transparent displays, electromagnetic shielding, stealth aircraft coatings, and more.
Current Needs, New Materials
Today the trend of “lightweighting” holds heavyweight importance. Analysts predict that automotive lightweighting, the process of reducing weight for improving performance and improving fuel efficiencies, will become a $300 billion annual market as global trends point to CO2 reduction and resource efficiencies as being vital to meeting regulatory and industry mandates in the transportation sector. New materials development, including conductive plastics, is a major driver in this trend.
The federal government’s new Corporate Average Fuel Economy (CAFE) standards require automakers to raise the average fuel efficiency of new cars and trucks to 54.5 miles per gallon by 2025. Electrically assisted vehicles can certainly meet or exceed CAFE requirements, but these vehicles carry their own weight issues, as batteries and electrical systems add hundreds of pounds to the vehicle.
The added electronics add another problem that needs to be addressed: electromagnetic compatibility (or interference, EMI). Conductive resins will play an ever increasing role in the lightweighting industry. At my company, we’re doing our part in the fight against vehicle obesity by utilizing our conductive hybrid plastics as EMI shielding solutions.
Our patented material—ElectriPlast pellets (Figure 1), which utilize Long Fiber Technology—allow for superior shielding of today’s high voltage components. Our process is compatible with nearly any resin. We typically utilize carbon fiber or stainless steel fiber, but essentially any metal fiber can be used.
Our material is manufactured specifically for the customer’s end-use application by using Flexible Content Technology™. Depending on the application specifications, ElectriPlast varies the composition of the pellet accordingly, ensuring that the final result is the most cost efficient.
We have developed numerous applications for connectors, covers, and enclosures, and are currently jointly developing shielded cable with Delphi Automotive. We’re able to provide the same shield effectiveness as the aluminum or cast aluminum parts, while providing on average a 60% weight savings.
Bipolar Battery Plates
A bipolar battery concept was published in the early 1920s, and there are multiple patents awarded for the design of bipolar batteries and bipolar plates. However, there are no commercially viable, high-volume-capable design solutions for a true bipolar battery and bipolar plate due to the non-existence of a practical, fully defined, and high-volume manufacturable design of the bipolar plate using conventional high-volume production processes.
The evolution from monopolar to bipolar technology reduces battery weight and overall size. However, commercialization has been hampered by challenges ranging from corrosion to current leakage. The bipolar capabilities remain attractive because of the energy and power capabilities that could be packaged into a relatively low-cost offering.
The development of an operationally reliable and manufacturable bipolar battery will further extend lead acid capabilities and prove disruptive to the energy storage industry. By utilizing Long Fiber Technology, my company has been addressing hurdles to scalability by redefining the bipolar plate design based on a plate core made of conductive loaded resins with metal-covered surfaces. In several lead acid battery technologies, including bipolar and lead/carbon, the ElectriPlast material can be used as the electrode plate (Figure 2).
“The molding process for our bipolar battery allows us to produce a nearly unlimited number of 3-D shapes and sizes which allow the bipolar plate and integral structures to be executed in any desired embodiment,” says Slobodan “Bob” Pavlovic, vice president, engineering, of ElectriPlast Corp. “And the inherent conductivity of ElectriPlast eliminates the need for conductive vias or other means to connect electrically two sides of the plate—a common solution for quasi-bipolar plates.”
The plates are lightweight and easy to assemble into the bipolar battery package; they can also be made as a drop-in replacement for some existing quasi-bipolar plates. Bipolar technology eliminates the use of a top lead to connect the plates, thereby reducing weight by over 50%. These unique characteristics allow the technology to be applied in other sectors such as motorcycles, golf carts, and forklifts.
However, the applications for bipolar plates are not limited to transportation, as the bipolar technology can be used in stationary applications, including flow batteries that are being developed to improve grid efficiency and for fuel cells for baseload power.
The fast growth in portable smart devices, as well as electric automobiles, has led to increasing demands for battery power. However, R&D and innovation of battery technology has not kept pace with strides on the consumer electronics and “green” automotive side, or with the burgeoning demand for power storage.
Conductive plastic will continue to innovate in the battery technology sector to meet growing demand in the transportation and dynamic energy storage marketplaces. Advantages include high conductivity, corrosion resistance, flexibility, moldability, and cost effectiveness.
About the Author: Doug Bathauer is CEO of Integral Technologies, whose wholly owned subsidiary, ElectriPlast Corp. (www.electriplast.com), engages in the discovery, development, commercialization, and licensing of electrically conductive hybrid plastics products used primarily as raw materials in the production of industrial, commercial, and consumer products and services worldwide.