Marc Juzkow, Vice President of R&D and Engineering Leyden Energy, talks to AZoM about advances in Li-ion battery technology. Interview conducted by Gary Thomas.
GT: Could you please provide a brief introduction to the industries that Leyden Energy works within and outline the key drivers?
MJ: Leyden Energy is an innovator in lithium-ion (Li-ion) batteries, which power a wide range of consumer, automotive and industrial applications. The global appetite for Li-ion batteries is insatiable; given that there’s one in virtually every cell phone (all six billion of them!), it’s not surprising that more than two billion Li-ion batteries are manufactured every year. The explosive growth of consumer mobility (e.g., smartphones, tablets, ultrabooks) is the main driver of this market.
Electric transportation doesn’t account for anywhere near the volume of mobility batteries, but there’s lively interest in Li-ion for everything from electric bicycles to full electric vehicles (EVs) such as the Tesla Roadster. A good bet for growth here is start-stop vehicles (SSVs). These are cars whose internal-combustion engine starts and stops during travel to save gas and reduce greenhouse gas emissions. According to Kevin See, Senior Analyst at Lux Research, “We forecast that the micro-hybrid market will benefit most from the global trend towards increased fuel economy and lower carbon emissions, reaching 39 million vehicles in 2017, creating a $6.9 billion opportunity for energy storage technologies.”
Our new Li-imide™ chemistry platform offers advantages important for both mobility and transportation applications.
GT: Could you briefly explain how a lithium-ion battery works and how they are different to conventional cells?
MJ: First off, let me note the difference between a battery and a cell. The cell is the fundamental unit of a battery, which may comprise one or more cells. For instance, very thin smartphones are likely to use a single cell battery: a soft Li-ion pouch cell, which is what I’ll use as an example here when talking about batteries.
The fundamental difference to other battery chemistries is the higher voltage of Li-ion cells (currently 3.6 V nominal) compared to nickel-cadmium (NiCd) or nickel-metal hydride (NiMH) at 1.2V, which makes a higher energy density possible. This is the amount of energy delivered by a given size (volumetric) or weight (gravimetric) of cell, and is important for both consumer mobility and transportation applications. Li-ion batteries have twice the energy density, by weight, of nickel-based active materials, and four times that of the lead-acid batteries used in automobiles today. In fact, Li-ion cells can deliver so much energy that protective circuitry is a necessary component to assure safety, in case of short circuits or other conditions.
As in virtually all types of cells, a Li-ion cell comprises a set of anodes and cathodes (the active materials) held apart by separators and electrically connected to the cell terminals by current collectors. In a Li-ion pouch cell, the whole interior of the polymer bag that encases the cell is permeated by a liquid electrolyte, which is not only a source of lithium ions, but the medium through which these ions are exchanged between anode and cathode. This is the basis of the charge-discharge cycle. (The combination of specific active materials and electrolyte is called the “chemistry” of the cell.) During discharge, the anode gives up electrons and lithium ions, while the cathode takes up electrons and lithium ions, a process called intercalation; the result is a current flow between the terminals of the battery in the same direction as the movement of lithium ions inside the battery.
The tendency of an active material to give up or take up electrons is measured by its electromotive force (EMF) in volts; the difference in EMF between the anode and the cathode is the voltage across the terminals, with no load on the cell. This drops when the cell is actually powering something, depending on the current demanded. Putting a higher voltage across the terminals from an outside source in the opposite direction drives the reaction in reverse to charge the cell: the anode takes up electrons (and lithium ions) and the cathode gives up the electrons (and lithium ions). Cells can be put in series to increase the voltage, or in parallel, to increase current capacity.
GT: What are the benefits of using Li-ion cells?
MJ: Their greater energy densities allow for sleeker, smaller mobile device designs, and help to keep vehicle weight down, compared to lead-acid, NiMH, or NiCd. They are also more environmentally friendly, especially in manufacturing; cadmium in particular has a very high environmental cost. Lead’s environmental impact is somewhat mitigated by an extensive recycling industry.
However, current Li-ion chemistries have a common weakness: the instability of the electrolyte used in virtually all Li-ion cells: a solution of lithium hexafluorophosphate (LiPF6) in an organic carbonate-based solvent system. That is the opportunity Leyden Energy’s Li-imide chemistry platform addresses.
GT: What are the limitations of LiPF6 as an electrolyte?
MJ: The manufacturing process inevitably leaves traces of H2O in Li-ion cells. Unfortunately, LiPF6 is unstable in the presence of water and reacts with it to create hydrofluoric acid (HF), one of the most corrosive chemicals known. HF will leach metal ions out of the cathode (e.g., manganese, iron, cobalt), and these metals will react with and poison the anode, thus reducing its ability to intercalate lithium ions and diminishing the cell’s energy. It can also corrode other components, and these reactions generate a gas that causes the cell to slowly swell over its lifetime, or, in the worst case, swell rapidly enough to destroy the device.
Of course, all this accelerates with temperature, like any chemical reaction. Both consumer mobility situations (e.g., smartphone in a parked car in the sun, a pocket or even just operation while plugged in) and certainly automotive applications, tend to be hotter than LiPF6-based cells can tolerate. The result is ever lower energy and shorter battery life (e.g., less runtime on a tablet). For smartphones, with their average 22-month turnover, this is not as much of a problem. For applications with longer amortization periods, like tablets and certainly SSVs, it’s huge.
GT: How does Leyden Energy's patented Li-imide technology combat these limitations?
MJ: Leyden Energy’s Li-imide electrolyte does not react with residual water, nor does it generate hydrofluoric acid—making it far more stable, especially at higher temperatures.
GT: How are Leyden Energy batteries unique?
MJ: Leyden Energy’s Li-imide chemistry platform combines this advanced electrolyte salt with a process for coating the aluminum cathode collectors to prevent corrosion. The result is greater volumetric energy density (higher run time per charge), longer cycle and calendar life and reduced swelling—all due to greater thermal resilience, while using the same manufacturing lines as standard Li-ion batteries. Thus, the cost of this technology is on par with that of traditional Li-ion technology, despite its superior performance and battery life.
Perhaps more important is the fact that the Li-imide electrolyte salt is compatible with a very wide range of the active materials under consideration by various companies and research groups for higher energy density and other desirable qualities. This makes Li-imide and its thermal stability applicable to many different potential Li-ion cell chemistries, putting it at the forefront of battery research.
GT: Leyden was recently selected by AlwaysOn as a GoingGreen Silicon Valley Global 200 Winner – could you tell us a little more about this and what it means to the company?
MJ: The AlwaysOn editorial team partnered with top global venture capitalists and industry leaders to find the top 200 private cleantech companies based on innovation, market potential, commercialization, stakeholder value and media buzz. We’re very happy to have made the cut and regard this honor as further validation of our vision for Li-ion technology.
GT: What are the primary applications of Leyden Energy’s batteries?
MJ: Mobile consumer electronics and, in time, start-stop automotive applications.
Leyden Energy is putting a lot of effort into the mobile consumer electronics industry—particularly tablets, ultrabooks, smartphones and mobile battery-powered accessories (e.g., mobile juice packs, mobile routers, mobile storage devices—basically any device whose mobility would benefit from untethering). That’s where the widening energy gap that Moore’s Law creates between batteries and semiconductors (which evolve a thousand times faster) gives our Li-imide battery chemistry technology maximum leverage.
The problem is that ever more powerful processors and the applications they make possible evoke customer behavior and stress legacy Li-ion chemistries beyond their design specs, especially because of the heat generated and the current spikes and rapid charging demanded. The best-known result is mobile computing as an eternal search for the next power outlet: smartphones that don’t last the day, and tablets that barely do. “Based on analysis of Strategy Analytics’ SpecTRAX database, the average tablet battery provides just 7.5 hours of run time (web browsing or video playback) on a full charge, with no significant increase evident in the last 12 months,” says Stuart Robinson, director of the Handset Component Technologies (HCT) Program in the analyst firm’s Strategic Technologies Practice.
There are many other shortcomings, as well. Li-imide gives mobile designers a lot more flexibility and choice in how they balance run-time per charge, affordability, thinness, battery life, charging rate and application support to offer consumer value at the appropriate price point.
The other industry on which Leyden Energy focuses is automotive: particularly start-stop vehicles, which offer a five to 15 percent advantage in gas mileage at a relatively low additional cost. Ordinary internal combustion engines call upon batteries for start, lighting and ignition (SLI) functions. The batteries are kept at 100 percent charge, but are only expected to start the car a few hundreds or thousands of times, before being replaced. An SSV battery may need to start the car a hundred times in one journey, especially in heavy traffic, and must support frequent shallow discharges and rapid recharges (even more so in SSVs with regenerative braking, sometimes also referred to as micro-hybrids).
This isn’t a good operational profile for lead-acid batteries, even advanced Absorbed Glass Mat (AGM) designs, but it is ideal for Li-imide, especially given its heat resistance, cold crank capability and higher energy density, which means a lighter vehicle and an even better mileage delta. The compatibility of the Li-imide electrolyte chemistry system with a wide range of active materials also offers promising avenues of research for bringing down the higher cost of Li-ion batteries with innovative, low-cost materials.
GT: Where does Leyden Energy currently supply to? Are there plans to expand operations in the near future?
MJ: We’ve announced relationships with NVIDIA and Dr. Battery and have established technology partnerships with companies like Powermat, but unfortunately we are unable to elaborate further at this time, due to very specific non-disclosure agreements we have in place with our partners.
GT: How do you see the demand for Li-ion batteries changing over the next decade?
MJ: Demand for Li-ion batteries, and with it, for Li-imide batteries, will only grow due to several trends, most notably increasing mobility and the rapid adoption of start-stop vehicle technology in response to the rising cost of oil and to greenhouse gas reduction initiatives. Untethered computing is practically going asymptotic, and eventually everything that can be untethered, will be. All these mobiles devices will rely on cloud-based services, which can deliver data, but unfortunately can’t deliver the power those often-background services consume. That will be the job of Li-ion batteries.
Electric vehicles of all types, from bikes to mopeds to buses, trucks, SSVs, electric and hybrid vehicles, are also a growth industry with a rising demand for Li-ion batteries. A third driver of change may well be the use of Li-ion batteries for smart grid, solar and wind applications, which is slowly accelerating, although energy density is less a concern here than thermal stability and long cycle life (how many charge-discharge cycles can be delivered) and calendar life (how long the battery lasts independent of the number of cycles).
About Marc Juzkow
Renowned battery scientist, developer and technology industry veteran, Marc is an industry leader with a unique skill set from lithium ion battery, ultracapacitor research and development, application engineering, sales, marketing and executive management. Marc has designed and built a variety of world class products.
In the field of lithium batteries and ultracapacitors, Marc has worked for EaglePicher, PolyStor, Cooper Bussmann (PowerStor), Qynergy and OMG (cobalt supplier), and founded three companies: Volt Source (consulting), UNCAP (ultra-capacitors) and Mobile Power Solutions (independent battery testing).
Marc began his battery career at Moli Energy in Vancouver, Canada in rechargeable lithium battery research. In the early 1990's, he managed the Product Development and Evaluation teams during the development of the first lithium-ion cell in North America and later assembled their Sales and Marketing Group to commercialize Moli's lithium-ion technology. Marc has over 35 publications and formal presentations, including keynote, plenary and many invited presentations internationally. He holds an Executive MBA and an MS in Chemistry from Simon Fraser University in Vancouver, BC.