It wasn’t the first time I was stuck behind a Tesla Model S in traffic searching for its tailpipe. I know it doesn’t have one; but that doesn’t stop me from searching for it, as if the Tesla engineers cleverly hid it away from prying eyes. No tailpipe means the absence of harmful exhaust emissions which contain greenhouse gases. Nothing, except frictional kinetic energy from braking; but even most of that is captured by the regenerative braking system and converted into chemical energy to the battery. Whether you’re a fan or not, the global vehicle electrification has emerged in the past decade as a challenge to the internal combustion engine. A Bloomberg survey suggests electric vehicle sales will hit 41 million by 2040 – representing 35% of all light-duty vehicle sales.
The recent U.S. Senate-backed $1.2 million infrastructure bill contains approximately $7.5 billion earmarked for electric vehicle (EV) charging stations; however, it fails to address the white elephant in the room – ”What are we going to do with these expired EV batteries at the end of their useful life of ten years?”
Repurposing EV batteries is a global engineering challenge that is already at our doorstep. The EV battery was never designed to be re-used, recycled, or repurposed. Fortunately, there are enough nervous, concerned automakers, academics, and entrepreneurs striving to give a retired EV battery a second life.
EV Batteries
Electric vehicle batteries (a.k.a. traction batteries) are rechargeable batteries designed to provide consistent power over time and used in electric vehicles, forklifts, golf carts, trucks, medical equipment, and computers. EV batteries work by releasing electrons from the anode to the cathode and then ions reverse in direction to recharge the battery.
A typical lithium-ion battery in a passenger electric vehicle may have up to 100 nested cells of batteries tightly connected, a battery management system, and a cooling circuit that is encased within a water proof box. The various construction and chemistry of different manufactured batteries make it a virtual jigsaw puzzle for recyclers to give the battery a second life.
Recycling Process
Recyclers tend to target the metals, such as cobalt and nickel, in the cathode as they tend to attract the highest prices in recovery; however, the lithium and graphite within the batteries are not cost-effective to recover. Deconstructing the battery held together by glues is no easy task. Recyclers commonly refer to the process as “searching for a needle in a haystack”. For example, Tesla is known for its indestructible and tough glues and Nissan’s leaf battery can take two hours to dismantle. Moreover, the glues represent sticky carcinogenic health and safety issues to workers. Many manufacturers would rather just construct new batteries from scratch than deal with the old ones.
Once recyclers open the battery, they may use smelting methods (such as pyrometallurgy or hydrometallurgy) to recover the metals in the cathode. Pyrometallurgy involves mechanical shredding of the cells and burning them to extract the metals; while hydrometallurgy requires an acid bath to separate the metals. Unfortunately, both processes produce extensive waste, emit unintended greenhouse gases, and can be expensive.
Direct recovery, another recycling process, keeps the cathode intact, shreds the battery cells, and removes the binders with heat or solvents. A flotation technique is then used to separate the anode and cathode materials into a powdery substance at low temperatures.
Battery makers are thinking about how to consider recycling in their original design to make the battery easier to disassemble and recycle. Standardizing batteries, materials, and cell design would also make it easier for recycling and more cost-effective in the future.
Engineering Challenges
Repurposing EV batteries to a second life can typically be used as backup storage or electrical power for solar grids, wind farms, pumps, electrical grids, emergency power, generators, and other applications.
To properly repurpose the EV battery, one must determine the health of the original battery – which requires work to disassemble, investigate, repair or replace cells, and reassemble the battery with new controls and safety equipment for reuse.
The diversity of EV battery packs on the market is a big hurdle for processing and reconfiguring the batteries for new applications and requires significant reverse-engineering. Repurpose, an engineering start-up working with Nissan Motors, is looking at finding “bad cells” and replacing them in a battery pack – to squeeze another 12 years out of the battery. Smartville Energy has designed converters and conditioners that slow down the health of the batteries to create revenue streams for backup electrical power.
Environmental Concerns
Lithium-ion batteries are made from critical minerals, including cobalt, graphite and lithium. The mining, refining, and manufacturer of battery materials require a large amount of energy and produce greenhouse gas emissions and other air pollutants from fossil fuel combustion to operate equipment. Mining tailings and their bioaccumulation and toxicity to aquatic species can be hazardous to the environment. If a battery ends up in a landfill, its cells can release toxins including heavy metals. If one were to cut too deeply into a battery or in the wrong place, it can short-circuit, combust, and release toxic fumes.
In some instances, these battery materials are mined in countries where health and safety or air pollution control is less stringent than developed countries. For example, more than half the global supply of cobalt is derived from the Democratic Republic of the Congo – as a byproduct from copper or nickel mining activities. Graphite has a high heavy metal content and is primarily imported from China; and mining tailings can have high heavy metal content which can lead to soil contamination and ecological impacts, water pollution, and crop damage downstream. Lithium, which is also imported to the U.S., relies on brine mining that can also have a negative environmental impact.
The Future Is Now
Repurposing and recycling EV batteries for a second life represent an enormous engineering hurdle for recyclers – given the diversity of the construction, chemistry, safety and environmental concerns, and the original intent of the battery as only for a single use. Economically, a second life of a battery can work provided it is less demanding (i.e., backup storage or other use).
Pilot and large scale demonstration projects are currently being conducted by manufacturers, universities, and entrepreneurs to extend the useful life of the EV battery for another 10-15 years:
- BMW tested used batteries as backup power during a 190-month pilot project for the Pacific Gas & Electric grid.
- Daimler AG is currently building a 13-megawatt-hour second-life battery storage unit at a recycling plant in Lunen, Germany.
- The UC Davis Campus in California is developing a 300-kilowatt-hour demonstration project at a winery that shifts power use to offset the facility’s on-peak energy demand.
- Smartville is working on a demonstration process at a store that sells antique books whose inventory requires precise temperatures and moisture control.
Additional innovative engineering studies and demonstration projects will need to be conducted over the next several years to find the most economical and environmentally-friendly solutions to the second-life challenges.
HETI Services
HETI can assist clients underwriting risks or working in the EV space – including manufacturers, transporters, recyclers, and other waste management operations in the global lifecycle – in evaluating repurposing options and the minimization/recycling of the original waste-stream.
References:
“Battery Second Use for Plug-In Electric Vehicles Analysis”, prepared by NREL Energy
“Electric Vehicle (EV) Battery Recycling”, Battery Recyclers of America, 2009-2020
“End of Electric Vehicle Batteries: Reuse vs. Recycle”, Energies-Yash Kotak, Carlos Machante Fernandez, Lluc Canals Casals, Daniel Koch, Christian Geisbauer, Lluis Trilla, Alberto Gomez-Nunez, and Hans-Georg Schweiger, March-April 2021
Environmental Effects of Battery Electric and Internal Combustion Engine Vehicles, Congressional Research Service, June 16, 2020
“Exclusive: Biden’s Electric Vehicle Plan Includes Battery Recycling Push”, Reuters (Trevor Hunnicutt and Ernest Scheyder, June 4, 2021
“How do Battery Electric Cars Work?”, Union of Concerned Scientists, February 25, 2015 (Updated March 12, 2018)
“Millions of Electric Cars are Coming”, What Happens to All the Dead Batteries?, Science (Ian Morse), May 20, 2021
“Second Life: Carmakers and Storage Startups Get Serious About Reusing Batteries”, prepared by GTM, Julia Pyper, June 30, 2020
“U.S., EU Rules as EV Batteries Reach End of the Road”, Wards Auto, August 10, 2021
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