Jeff Dahn and the team at Dalhousie University in Halifax, Canada signed a partnership with Tesla in 2016 to be part of the created Tesla Advanced Battery Research division. As a leader in the earliest research into Lithium-ion batteries the Jeff Dahn team had a 5-year partnership with the express focus or primary goal of making batteries last longer with increased energy density, decreased costs at the top of the wish list by Tesla.
This team created multiple patents and papers related to Tesla Battery cells and with this came the first talk by Tesla and the researchers of the million-mile battery pack. This has gained additional attention as various Tesla autos have come up for sale that have 400,000 plus miles with only single digit cell reduction loss implying that the battery packs should easily last up to a million miles.
On top of this is that Tesla with their work to bring both a full-size pickup truck to market and a class 8 semi-truck to market is how Tesla has moved from their earliest battery cells produced by Panasonic to their latest large energy dense 4680 cell.
Today, Jeff Dahn and the team of researchers have now published their latest paper on Li-Ion cells and how they can be built to last 100 years. To quote their paper, link posted at the bottom is as follows:
These include vehicle-to-grid storage, stationary energy storage and battery leasing. Li[Ni0.5Mn0.3Co0.2]O2//graphite (NMC532) pouch cells with only sufficient graphite for operation to 3.80 V (rather than ≥ 4.2 V) are presented as a low-voltage cell type for applications that require massive cycle and calendar-life. Charge-discharge cycling, ultra-high precision coulometry and impedance spectroscopy are used to characterize these cells and form a comparison with LiFePO4//graphite (LFP) pouch cells. The low-voltage NMC532 cells are shown to be superior in both capacity retention and energy density to the LFP cells. Lifetime predictions are made as a function of temperature and charging voltage, with room temperature operation beyond 100 years suggested in certain cases.
As with everything, these early research papers tend to still have much work to be done to get the products into mass production. Testing of existing Li-Ion cells was done in a range of 40c to 70c temperature range. This has allowed the researchers to find optimum upper cutoff voltage when designing cells for maximum lifetime. The benefits of this research is that sufficiently high potential capability is necessary to ensure high first cycle efficiency and low fade but too high voltage will result in excessive electrolyte oxidation, impedance growth and inventory loss.
This overall research has shown the potential in lifetime and volumetric energy density that with further research should help expand the capabilities of the battery cells as they are designed for fast charge application use while using less to no rare earth elements such as cobalt.
Attached research paper for those interested in reading the 13-page paper on Long-Lived Low Voltage Li-Ion Cells.
As with all things, while the 100-year battery cell is not here today, the potential for such a product is clearly in the researchers view of where the EV industry can go with reducing greenhouse gas due to long life battery cells.