Whenever projections of future electric vehicle demand come up, the conversation will inevitably turn to battery recycling. And for good reason: It takes a lot of expensive, difficult-to-acquire metals and materials to make the big lithium-ion batteries that power EVs, making it environmentally and financially prudent to recover them.
But there is a lot of other infrastructure, materials, and ephemera that come with a big transition to EVs, collectively known as EV supply equipment, or EVSE. Just think of all the charging stations and charging cables that have sprung up around the world, and which will reach the end of their lives sooner than you might think.
The question of what to do with them is the subject of a new partnership between business and academia. XCharge North America, a producer of DC fast chargers, has begun to send its busted and beat-up EV chargers and modules to the recycling group Grensol, which has partnered with researchers at Worcester Polytechnic Institute to find better, cheaper ways to recycle materials that otherwise would have been sent to the landfill.
“EVSEs have a particularly short useful life due to constant wear and tear, so the need for a recyclable material solution is the driving force behind this partnership,” Grensol’s Rajiv Singhal told me.
EVSE leads a difficult life. The stuff inside the cable endures rapid heating and cooling cycles as electricity races through day after day. This leads to premature degradation, explains Akanksha Gupta, a postdoctoral researcher at WPI. Meanwhile, the polymer material on the outside of the cable, which insulates the electrical components within, is subject to rain, cold, being walked on and run over — whatever the outside world can throw at it.
As a result, Gupta said, EV charging cables last just five to 15 years before they need to be replaced. EV stations are more durable, since their parts are tucked inside metal housing. But even there, specific components that are subject to high stresses wear down and fail after years of heavy usage, sending the entire charging stall to the great beyond.
Some parts we already know how to deal with. The exterior housing of an EV charger is typically made of aluminum or steel, materials that recyclers can already recover in their entirety. Gupta told me there are also existing techniques to recycle cables by (mostly) separating the plastic parts from the valuable metals, like copper.
The materials that are most important to recover, however — because they’re valuable, and because there is a limited supply of them to mine from the Earth’s crust — are also the hardest to get. Gold and silver, which have excellent electrical conductivity and corrosion resistance, are used in printed circuit boards inside the power electronic modules. Tantalum and rare earth elements can be found in capacitors, while tin is used in solders on printed circuit boards.
The electronic module found inside the charging station is a particularly thorny problem, Gupta said.
“Rare earth elements and some critical materials like tantalum and silicon carbide are found in trace amounts and bonded with other metals or plastic components,” she told me. “It is hard to recover and recycle these materials without sufficient economic incentives.” (Estimates for the value of the recycled metals industry vary widely but coalesce around the hundreds of billions of dollars, currently.) “Moreover, during the separation and recovery stages, the elements present in trace amounts can get easily discarded or landfilled, lowering the recovery rate for such materials, which are often of high value.”
The researchers at WPI are investigating new techniques for separating materials and recycling the polymers present in EV charging equipment. Though neither side of the partnership was willing to put a dollar figure or a timeframe to their partnership, the work at hand is as much economic as it is scientific, if indeed it will become economically viable to recycle EVSE. Precious tantalum, for instance, can be recovered as tantalum pentoxide or tantalum chloride depending on the chemical process used, and those two materials each have different markets.
“Our aim is to compare recovery processes for an EVSE station … in terms of both economic and ecological considerations,” Gupta said. “There will be several markets for recovered materials, including the steel and aluminum industry for base metals, the semiconductor industry for silicon, tantalum, and gallium-related products, and the petrochemical industry for polymer-based products, among other industries.”
