Will Future EV Batteries Be Cobalt-Free?
MIT researchers are testing a promising material known as TAQ as a carbon-based alternative to cobalt for lithium-ion batteries used in electric vehicles.
Electric vehicles (EVs) are an important and increasingly popular way to reduce greenhouse gas emissions. However, the batteries powering them are often far from eco-friendly, largely because of their materials. Cobalt, in particular, significantly hinders EVs’ sustainability, but researchers may have found a solution.
Cobalt ore. Image used courtesy of Missouri Department of Natural Resources
A team at MIT recently developed an alternative material called TAQ that offers conductivity and storage efficiency on par with cobalt. Their discovery is one of many contributing to finding a viable replacement for cobalt.
The Trouble With Cobalt in Lithium-ion Batteries
Most EVs and rechargeable electronics rely on lithium-ion (Li-ion) batteries. Many use cobalt cathodes since cobalt’s energy density and relative stability make it ideal for rechargeable batteries.
Unfortunately, cobalt mining is environmentally destructive. Mining operations typically rely on fossil-fuel-powered equipment, leading to considerable emissions. Researchers have also found high radioactivity levels in cobalt mining areas, as many contain significant amounts of uranium. Conventional techniques also leak hazardous chemicals into the surrounding environment, jeopardizing public health and the region’s biodiversity.
Copper-cobalt mine. Image used courtesy of U.S. Geological Survey
Cobalt’s scarcity introduces further concerns. While not necessarily a rare metal, it isn’t abundant, and more than half of the world’s supply lies in the Democratic Republic of the Congo (DRC). This supply concentration makes it vulnerable to price volatility, making it difficult for engineers to produce affordable technologies with the metal.
Finally, cobalt mining carries a high social cost. Reports of child labor, unsafe working conditions, and other human rights issues are common in cobalt mines in the DRC. If engineers continue relying on the metal, it could exacerbate this mistreatment.
Recent Cobalt-Free Battery Breakthroughs
Given these drawbacks, researchers have sought ways to develop lithium batteries without cobalt. Several recent breakthroughs show promise.
At MIT, researchers developed a battery using a carbon-based material called bis-tetraaminobenzoquinone, or TAQ. TAQ consists of molecules with three fused hexagon rings. The structure is similar to graphene and allows the layers to extend in all directions to create stable hydrogen bonds. TAQ will not dissolve into the electrolyte as some organic materials do.
TAQ structure. Image used courtesy of the authors
This alternative showcased a higher energy density than most cobalt cathodes and safely went through over 2,000 charging cycles. Most importantly, TAQ is abundant and doesn’t carry the same mining complications as cobalt.
The energy density and stability mean TAQ-based lithium batteries may perform better than cobalt alternatives in real-world applications. Engineers could develop faster-charging, longer-lasting EV power systems around this technology, aiding a quicker transition to electrified transportation. It could also enable more affordable electronics design, given the reduction in material price volatility.
Other researchers have focused on lithium iron phosphate (LFP) alternatives. LFP batteries have existed for a few decades but haven’t been viable for large-scale practical applications until recently. Now, 44% of all EVs in China use LFPs, as do the latest Tesla models.
Like the TAQ battery, LFPs don’t degrade as quickly as cobalt-based cathodes and have a significantly smaller carbon footprint. Using iron phosphate also makes them a highly affordable alternative.
Remaining Challenges to Cobalt-Free Batteries
Electrical engineers hoping to capitalize on cobalt alternatives should consider a few remaining obstacles. Notably, lithium itself still presents several complications.
Lithium mining may not be as wrought with social and environmental issues as cobalt, but it still generates considerable emissions and hazardous runoff. The most commonly used lithium salt in Li-ion batteries converts to hydrogen fluoride, which is highly toxic and corrosive when it reacts to moisture. Consequently, accidents in shipping or working with these systems can create significant safety risks.
Each alternative to cobalt-based Li-ion batteries carries unique downsides, too. TAQ offers impressive performance in laboratory settings, but real-world results are still uncertain because it’s so new. Its novelty also means engineers can’t start using it today.
LFP batteries have proven real-world results, but their shortcomings have become more prominent across this usage history. Even newer, more efficient versions struggle to perform well in colder environments. They’re also harder to recycle when they reach the end of their useful life.
The Road Ahead for EV Batteries
These obstacles don’t mean engineers shouldn’t pursue cobalt-free battery systems. However, they should temper near-term expectations and inform a few operational considerations. Designing and manufacturing EVs with these batteries requires understanding where they fall short.
Supply chain transparency must improve, given lithium and other battery materials’ reliance on potentially destructive mines. Only 15% of supply chains have visibility beyond tier-one suppliers, making it hard to know if a product relies on ethically or environmentally harmful operations. Promoting transparency and trust will help engineers source materials with these factors in mind.
Thorough safety measures are also essential for developing systems around Li-ion batteries. Similarly, engineers must consider how their overall designs account for potential safety issues like moisture exposure or overcharging fire hazards.
Additional support within an EV may help offset some cobalt alternatives’ shortcomings. For example, increasing thermal insulation will help LFPs perform better in the cold. Real-time monitoring systems can help keep TAQ performance in check to uncover potential issues.
Moving Away From Cobalt Batteries
Li-ion batteries will likely still rely on cobalt until alternatives become more widely available and viable commercially. However, the market is moving in that direction. The economic, social, and environmental costs of cobalt are too significant not to.