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BATTERY ELECTRIC VEHICLES have hitherto been few and far between. But environmental goals around the world are increasing BEV presence and impact.
True, these are clean-air vehicles, even with mixed renewable/fossil fuel electrical generation. But their batteries don’t last forever, and battery recycling presents significant technical challenges.
Here are tidbits gleaned from “A Dead Battery Dilemma,” by Ian Morse, in Science, May 21, 2021, together with my usual Internet sleuthing.
Today and Tomorrow. PEV (BEV and hybrid) sales have been almost trivial in the U.S. (2.2 percent in 2020). But because of consumer demand, market prices, charging infrastructure, and government policies, this is expected to grow significantly—and quickly. For instance, GM has said that 40 percent of its models will be BEVs by 2025, with an all-electric lineup by 2035.
What’s more, in this regard the U.S. has lagged behind much of the developed world. In 2020, PEV market shares were 13.5 percent in Germany, 24.6 percent in the Netherlands, 32.2 percent in Sweden, and 74.7 percent in governmental-BEV-favored Norway.
BEV Recycling. Batteries are more complex to recycle than components of traditional cars. In the Science article, Ian Morse notes, “The battery pack of a Tesla Model S is a feat of intricate engineering. Thousands of cylindrical cells with components sourced from around the world transform lithium and electrons into enough energy to propel the car hundreds of kilometers, again and again, without tailpipe emissions.”
“But when the battery comes to the end of its life,” Morse says, “its green benefits fade…. Cut too deep into a Tesla cell, or in the wrong place, and it can short-circuit, combust, and release toxic fumes.”
A Multiplicity of Configurations. One challenge of recycling is a still evolving battery technology. A basic cell contains an anode and cathode separated by electrolyte. These cells can be glued together in rectangular modules (most BEVs) or in cylinders (Tesla). Modules are assembled into a battery pack, typically located low in the BEV for considerations of packaging and center of gravity.
Whether to Recycle. Morse writes, “It’s often cheaper for batterymakers to buy freshly mined metals than to use recycled materials…. Now, recyclers primarily target metals in the cathode, such as cobalt and nickel, that fetch high prices. (Lithium and graphite are too cheap for recycling to be economical.) But because of the small quantities, the metals are like needles in a haystack: hard to find and recover.”
How to Disassemble a Battery. Today, there are two approaches to extracting these valuable needles from the haystack: Morse says, “The more common is pyrometallurgy, in which recyclers first mechanically shred the cell and then burn it, leaving a charred mass of plastic, metals, and glues. At that point, they can use several methods to extract the metals, including further burning.”
Pyromet is likened to treating a battery as though it’s an ore straight from a mine.
The other technique is hydrometallurgy. The battery materials are treated to selective acids producing what Morse calls “a metal-laden soup.” For example, a mixture of acids and bases called a deep eutectic solvent can dissolve everything but the sought-after nickel.
Pyromet/Hydromet Tradeoffs. Pyromet doesn’t care about a battery’s design or configuration, but generating the necessary combustion is energy-intensive. Hydromet may use particularly nasty chemicals posing health risks.
Design for Direct Recycling. Morse says, “The ideal is direct recycling, which would keep the cathode mixture intact. That’s attractive to batterymakers because recycled cathodes wouldn’t require heavy processing.” Plus, Science notes, “The cathode typically holds the most valuable recyclable material, made of many metals.” The anode, by comparison, is composed of graphite, carbon, or silicon-based components.
Efficient battery recycling is a balancing act involving resource abundance, electrochemistry, and the environment. With a market share of two percent, the game may not be worth the candle. With forecasts of BEVs being more than half the global market by 2040, it’s a new game entirely. ds
© Dennis Simanaitis, SimanaitisSays.com, 2021