Every week, we hear reports of research breakthroughs that promise better, cheaper lithium ion batteries are coming soon. Here at CleanTechnica we try to filter these reports to keep our readers informed without subjecting them to battery breakthrough overload. Here’s one report that seems to merit your attention.
One of the persistent issues that bedevils lithium ion battery cells is the formation of dendrites. Think of them as microscopic cousins to the stalagmites and stalactites found in caves. They are little hair-like formations that form inside the cell and push their way through the various layers, short circuiting the way electrons are supposed to flow within the cell. In some cases, they can lead to cell failure, fires, or even explosions.
Dendrite formation becomes more of an issue when high power charging methods are employed. EV manufacturers naturally want to reduce the time it takes to recharge their vehicles in order to address any range anxiety issues their customers might have. But the higher the charging power, the more dendrite formation increases.
Researchers at Penn State University say they may have found a solution — a three-dimensional, cross-linked polymer sponge that attaches to the metal plating of a battery anode. “Our approach was to use a polymer on the interface of the lithium metal,” says Donghai Wang, professor of mechanical engineering at Penn State, tells Science Daily.
The material acts as a porous sponge that not only promotes ion transfer, but also inhibits deterioration. “This allowed the metal plating to be free of dendrites, even at low temperatures and fast charge conditions,” he says. The research was published November 12 in the journal Nature Energy. Below is the abstract of the report.
“The cycle life and energy density of rechargeable metal batteries are largely limited by the dendritic growth of their metal anodes (lithium, sodium or zinc). Here we develop a three-dimensional cross-linked polyethylenimine lithium-ion-affinity sponge as the lithium metal anode host to mitigate the problem. We show that electrokinetic surface conduction and electro-osmosis within the high-zeta-potential sponge change the concentration and current density profiles, which enables dendrite-free plating/stripping of lithium with a high Coulombic efficiency at high deposition capacities and current densities, even at low temperatures.
“The use of a lithium-hosting sponge leads to a significantly improved cycling stability of lithium metal batteries with a limited amount of lithium (for example, the areal lithium ratio of negative to positive electrodes is 0.6) at a commercial-level areal capacity. We also observed dendrite-free morphology in sodium and zinc anodes, which indicates a broader promise of this approach.”
The transition from lab to commercial applications is always a tricky one. In this instance, that transition will be aided by the fact that the discovery does not require new manufacturing techniques, only an adaptation of existing production technology. Professor Wang has high expectations for the discovery he and his team have made.
“In an electric vehicle, it could increase the range of a drive before needing a charge by hundreds of miles,” said Wang. “It could also give smartphones a longer battery life. We want to push these technologies forward. With this work, I’m positive we can double the life cycle of these lithium metal batteries.”
Longer lasting batteries with greater range? This discovery could have significant implications for the electric vehicle revolution. In this case, the future can’t get here fast enough.