How Long Will Tomorrow's Automotive Lithium Batteries Last?
Automotive lithium battery pack by A123 Systems.Image credit:FuelEfficientVehicles.org
Regardless of electric vehicle maker's claims and warranties for lithium battery longevity, consumer doubts will linger, shaped by the many preceding year's worth of computer and cell phone battery disappointments. (Example: ever notice that the cell phone battery replacement always costs more than a new phone, and is needed just about the time a new phone design comes out?)
I've been looking for third party tests of the newest commercial automotive batteries, or next-gen prototypes. Carnegie Mellon researchers are reporting the first such results I've seen. Here's a one-sentence quote from a draft research paper abstract: "The cells tested showed promising capacity fade performance: more than 95% of the original cell capacity remains after thousands of driving days worth of use." Full Abstract below.The draft research paper title is: Lithium-Ion Battery Cell Degradation Resulting from Realistic Vehicle and Vehicle-to-Grid UtilizationBy: Scott Peterson, Jay Apt, and Jay Whitacre
The Pre-Publication Abstract is as follows.
The effects of combined driving and vehicle-to-grid (V2G) usage on the lifetime performance of relevant commercial Li-ion cells were studied. We derived a nominal realistic driving schedule based on aggregating driving survey data and the Urban Dynamometer Driving Schedule, and used a vehicle physics model to create a daily battery duty cycle. Different degrees of continuous discharge were imposed on the cells to mimic afternoon V2G use to displace grid electricity. The loss of battery capacity was quantified as a function of driving days as well as a function of integrated capacity and energy processed by the cells. The cells tested showed promising capacity fade performance: more than 95% of the original cell capacity remains after thousands of driving days worth of use. Statistical analyses indicate that rapid vehicle motive cycling degraded the cells more than slower, V2G galvanostatic cycling. These data are intended to inform an economic model.I'll post on the final findings once the paper reaches publication stage.
After 'fade performance', the next big threshold test for battery "greenness" will be recycling.
Not only should biologically -active lithium battery contents be recycled in a closed loop (put back to use in new batteries); but, transportation lithium battery recycling should be done in the country of product sale, at least for larger markets. Under no circumstance should lithium battery technology put the poor buggers who handle, disassemble, and re-process car batteries at risk. Note: certain lithium salts are a known human reproductive hazard - so no excuses allowed for potential drinking-water contamination resulting from battery reclamation, or component recycling.
Design, development, and the business model(s) for making and distributing transportation-deployed lithium batteries are not just "business issues." Society has to get this right.