Hello Everyone!
This week's story is another excerpt from my manuscript. This would nominally be chapter 2, so it would take place right after Alex arrives in Halifax. If you want to read this as it will appear in the book, then this story would be immediately followed by the first part of So Help Me God (up until the first **********). Also, there's quite a bit of battery jargon in this story. I've added footnotes at the end, so hopefully that helps. If I recall correctly, I was reading Infinite Jest when I wrote this, which explains a lot. That's all. Enjoy! -RCD * * * * * * * * * * The Doane Group (Part 1) Jim Doane was a legend. In addition to being the author of more than 500 papers, he also had his name on the patents of over 80% of the cathode materials currently used in commercial lithium-ion batteries. He was a down-to-earth, no bullshit, straight-talker. When reviewing drafts of papers, he had a binary comment system; in between the margins, in red felt-tipped pen, he would write either the worst thing I’ve ever read in my life or this is genius!! I joined his research group in the summer of 2012. The Brendan Fraser University Physics building looked like an old high school and Jim’s lab space was spread out over the top two floors. He also had a machine shop with a dedicated machinist located in the basement. I arrived in mid-June, so I was ahead of schedule of the incoming class that year. I walked down the third-floor hallway and stopped in front of the double-doors leading into his main lab space. This is it I thought. I’m here. I’m at the Doane Group. I took a deep breath, closed my eyes, and exhaled through my nose, before pushing the door open and walking in. Upon entering the lab, I heard the familiar droning and beeping and clicking of test equipment humming away in the background. In front of me was a floor-to-ceiling wall of carefully arranged high-precision voltmeters and current sources with blinking digital displays and temperature-controlled test chambers that blocked off the back half of the lab from view. This, no doubt, was the High Resolution Cycler (HRC); the crown jewel of the Doane group. I’d read about this before coming up here, but to see it here in person, in all of its wire-tangled, obtrusive glory, made the hairs on my arm stand up and gave me a slight tingly feeling just behind the corner of my jaw. Allow me to explain: The battery pack of an electric vehicle (EV) makes up about a third of the cost of the car; by far, the most expensive single component. Additionally, even with the current state-of-the-art in energy storage technology, one could only really expect the battery pack to last a little over 3 years. As you can imagine, having to spend over 30% of the cost of your car on a new battery pack every 3 years is a strong deterrent for potential customers. Ideally, we would like for our batteries to last 10-30 years - to even outlast the car itself and be transferred into a new car. So, of course, all of these battery research groups all around the world are devoting their time and energy researching chemistries that will extend the lifetime of commercial lithium-ion batteries. The problem is; how do you know that a battery will last for 10 years unless you spend 10 years testing it? Well, you could assume two full charge/discharge cycles a day, everyday, for 10 years - that’s 2x365x10 = 1,460 cycles. So, if you wanted to test out a new chemistry without waiting 10 years for the results, you could up your current and, instead of doing 2 cycles per day, you could do 2 cycles per hour (4C[1]), and it would take you just over a month to get enough cycles to give you the answer. So, in theory that is an excellent way to test your batteries and, in fact, that is the way that several prominent research labs assess the performance of new battery chemistries. That does not, however, keep it from being completely wrong. As several battery researchers were starting to discover, notably among them being Colclasure, et al[2], the number of cycles that a battery was subjected to had very little to do with its degradation in performance. Actually, the term cycle-life was kind of a nothing metric. Rather, the vast majority of the capacity loss in a battery was due to time-dependent parasitic reactions that were occurring in the background during normal cycling. These reactions were continually consuming electroactive species by doing things like forming a solid electrolyte interphase (SEI) on the anode, thus reducing the number of lithium-ions available for charging and discharging which, in turn, gradually reduced the performance of the battery over time. The rate at which these reactions happened was independent of how fast or slow you cycled your battery. That being said, whatever new battery chemistry you were testing, the only valid way to prove that it could last 10 years would be to cycle it for 10 years. As you can imagine, this would slow down battery research to a grinding halt. Enter the HRC; the Doane group's brilliant solution to this very problem. Instead of waiting ten years to know whether or not your battery was going to fail, what if, instead, you could know, to a very high precision, the rate at which your battery was failing? If your resolution was high enough, you could determine the fade within the first 10 cycles and extrapolate to determine how long your battery will last. This is exactly what the HRC did. Through a few simple, back-of-the-envelope calculations, Jim had determined that, in order to be able to predict the lifetime of a particular battery in any reasonable amount of time, you would need to be able to measure the coulombic efficiency [3] (CE) of said battery to within an accuracy of ±0.01%. The current state-of-the-art in battery cyclers could, at best, get down to an accuracy of ±0.1%. They had to be ten times better than anything else out there. Achieving a CE accuracy of ±0.01% was no easy task. One had to find a voltmeter that was capable of resolving voltages below 100μV, a current source that could deliver currents to within 0.01% of the specified value, and, on top of all of that, one had to monitor and control the temperature of the cell to within ±1°C. To monitor the voltage, they went with the Keithley Instruments model 2750/2000 scanning voltmeter. For the high precision currents, they chose another Keithley instrument, the model 6220/220 programmable current source. Being the pragmatic, resourceful researcher that he his, Jim was able to obtain all of these instruments off of eBay for considerably reduced prices. For the temperature control requirement, all cells were cycled in home-built thermostats that were coupled with Omega CNi3233/4201A-PC2 temperature controllers with a precision of ±0.1°C. Once all of the pieces were in place, he coupled them together with in-house software written on LabView and, voila, the High Resolution Cycler was born. I knew all of this because I had meticulously read all of the HRC papers that I could get my hands on before I came up here. To my right, as I walked in, was a hodgepodge collection of desks and computers, three rows deep, that were all unattended with the exception of a single Indian guy with big eyes sitting at one of the computers in the middle row. His shoulders were hunched up and he was staring intently at this monitor; the classic position of someone sifting through cycling data. He looked up at me briefly with an indifferent expression before reverting his attention back to the screen in front of him. ‘Helloo,’ I said. ‘Hi,’ he replied, as he looked back up at me over his monitor. A warm smile crept up on his face and his shoulders relaxed down to regular height. I hadn’t noticed how poorly lit the room was until I saw how the glow from the screen made the top half of his face, from the nose up, look especially dark by contrast. ‘I’m looking for Jim,’ I said. I’d been cautioned against calling him Dr. Doane or Professor Doane. Everyone who knew him knew him only as Jim. ‘Ooh..’ he said with a slight frown as he shook his head, ‘no, he’s not here. He won’t be back until Thursday, I think.’ ‘Oh,’ I said, as I looked down to the left and released a shallow breath through my lips. ‘Okay. Alright. I’ll, uh, try back then. Thanks.’ I gave him a quick, karate-chop hand-wave. ‘Thanks,’ I said again, as I let myself out. He watched me with an expression of mild bewilderment as I exited. As I got to the stairwell down the hallway, I heard the door to the lab complete its slow, pneumatically-controlled closing motion and click shut behind me. I headed down to the administrative office on the second floor to get my new-student paperwork taken care of. I’d been in correspondence with the graduate coordinator for the school of physics, Tammy, during my application process and I knew I owed her some documents. ‘Helloo…,’ I said, as I knocked on the metal door frame. ‘Hi there,’ replied a heavy-set lady with bedroom eyes peeking up from behind the chest-high reception desk opposite the entrance. ‘What can I do you for?’ ‘Hi. I, ah, was wondering if Tammy was in.’ She looked over to her left toward a middle-aged lady with possibly-died black hair sitting at a desk in a recessed section of the office space. ‘Hi, I’m Tammy,’ she said. There was a slight raspiness to her voice that told me that she might have been a smoker at one time. She also had a motherly tone to her words that seemed fresh, and out of place for her age. Like a woman whose maternal nature hadn’t been dried up by having kids of her own. ‘Hello,’ I said, as I held up a still-handed wave. -- to be continued... [1] C-rate is a measure of a current delivered to a battery relative to its nominal capacity. For example, 1C equates to a full charge or discharge in an hour, 2C would take 30 minutes, and C/2 would take 2 hours, etc. [2] A. Colclasure, K. Smith, and R. Kee, Electrochimica Acta, 58, 33 (2011). [3] Coulombic efficiency is the measure of the capacity of your discharge cycle over the capacity of the subsequent charge cycle and is a good indicator of the loss of electroactive species due to parasitic reactions. duh.
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December 2017
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