August 9th, 2019 by Steve Hanley Clean Technica
Tesla watchers know that Jeff Dahn and his team at Dalhousie University near Halifax, Nova Scotia, are world leaders in lithium-ion battery research. For years, Dahn worked exclusively for 3M, but when that arrangement ended, Tesla swooped in and signed a contract for Dahn to work for the Silicon Valley car/tech/energy company.
Credit: Jeff Dahn, et al./Nature Energy
For years, the Holy Grail of battery research has been making solid-state battery cells that replace the liquid electrolyte in conventional cells with solid materials. Solid-state batteries are believed to be cheaper to produce, have higher energy density, and have a longer lifespan than conventional lithium-ion batteries. Well, if someone can crack the final code for commercially viable cells.
In addition, solid-state batteries are less like to catch fire or explode if they get too hot. That in turn means electric car manufacturers can make simpler, less costly cooling systems for their battery packs, driving down the cost of EVs. It also reassures the public their shiny new electric cars aren’t going to explode in the garage, as recently happened to the owner of a Hyundai Kona EV in Canada.
Research published by Dahn and his team in the journal Nature Energy on July 15 reveals they have created new lithium-ion pouch cells that may outperform solid-state technology battery. Here’s the abstract of that research report:
“Cells with lithium-metal anodes are viewed as the most viable future technology, with higher energy density than existing lithium-ion batteries. Many researchers believe that for lithium-metal cells, the typical liquid electrolyte used in lithium-ion batteries must be replaced with a solid-state electrolyte to maintain the flat, dendrite-free lithium morphologies necessary for long-term stable cycling.
“Here, we show that anode-free lithium-metal pouch cells with a dual-salt LiDFOB/LiBF4 liquid electrolyte have 80% capacity remaining after 90 charge–discharge cycles, which is the longest life demonstrated to date for cells with zero excess lithium. The liquid electrolyte enables smooth dendrite-free lithium morphology comprised of densely packed columns even after 50 charge — discharge cycles. NMR measurements reveal that the electrolyte salts responsible for the excellent lithium morphology are slowly consumed during cycling.”
Those pesky dendrites are the bane of lithium-ion batteries. They are little projections like stalagmites in caves that can poke through the insulating layer inside individual cells, leading to short circuits and potential fires. Eliminating them would be a big step forward, particularly for use in electric vehicles.
Is Tesla on the verge of replacing the cylindrical cells in its battery packs with Jeff Dahn’s pouch cells? Not just yet. There is a lot of research and testing left to do before they becomes suitable for commercial production, but they may signal an important step forward for energy storage in the years ahead.
Below is a video of Dahn when he won the prestigious National Sciences and Engineering Research Council of Canada award in 2017. Here is a fellow who knows what he is talking about. If he says pouch cells can outperform solid state cells, we should pay heed.