Cobalt is primarily used in your phone’s battery. It’s a key ingredient in the lithium cobalt oxide cathode, the component that stores and releases energy every time you charge and use your device. Without cobalt, your phone’s battery would hold less charge, degrade faster, and potentially overheat.
Why Phone Batteries Need Cobalt
The battery inside your smartphone is a lithium-ion cell, and its most critical component is the cathode, the positive electrode where lithium ions are stored when the battery is charged. In most smartphones, this cathode is made from lithium cobalt oxide, a material that has dominated consumer electronics for decades because of its excellent cycling performance, high capacity, and high working voltage.
Cobalt’s role is structural. It stabilizes the layered arrangement of atoms inside the cathode, keeping it intact as lithium ions shuttle back and forth during charging and discharging. Without that stability, the cathode’s structure would collapse over hundreds of charge cycles, and your battery life would deteriorate much faster than it already does. Cobalt also helps the cathode conduct electricity and ions efficiently, which is why your phone can deliver bursts of power when you’re gaming or streaming video without the battery voltage dropping dramatically.
Lithium cobalt oxide delivers the highest volumetric energy density of any common cathode material. That’s a fancy way of saying it packs the most energy into the smallest space, which is exactly what phone designers need when they’re trying to fit a full day’s battery life into a device that’s less than 8 millimeters thick.
How Much Cobalt Is in a Phone
A typical smartphone battery contains roughly 5 to 10 grams of refined cobalt. That’s not much by weight, but given that over a billion smartphones ship every year, the cumulative demand is enormous. Cobalt is also one of the most expensive raw materials in a phone battery, which is part of why manufacturers have been working to reduce the amount they use or find alternatives entirely.
Cobalt’s Thermal Stability Advantage
Beyond energy density, cobalt contributes something you probably take for granted: safety. Cobalt improves the thermal stability of the cathode, meaning it’s less likely to break down and release heat during normal use or even under stress conditions like fast charging. In cathodes that blend cobalt with nickel and manganese (a common formula in newer batteries), the cobalt specifically helps prevent the cathode from transforming into unstable crystal structures when it gets hot. This is one reason phone batteries rarely catch fire despite being charged hundreds of times a year in warm pockets and hot cars.
Where Phone Cobalt Comes From
About 70% of the world’s cobalt is mined in the Democratic Republic of the Congo. The country’s mining operations range from large industrial mines run by international companies to small-scale artisanal sites where individuals dig by hand. Artisanal mining has drawn significant attention for labor and safety concerns, but its share of production has dropped considerably. A study published in PNAS estimated that artisanal mining accounted for only 9 to 11% of DRC cobalt production by 2020, down from a peak of 40 to 53% around 2008. In practical terms, a randomly sourced batch of DRC cobalt has roughly a 90% chance of coming from an industrial, non-artisanal operation.
Environmental contamination near mining areas is real, though. Research in DRC mining communities found cobalt concentrations in surface dust that were 70 times higher than in control areas, far exceeding residential soil safety standards. Interestingly, drinking water in the same communities did not show significantly elevated metal levels compared to non-mining areas, suggesting the contamination pathway is primarily through dust and soil rather than water.
Recycling and the Push Away From Mined Cobalt
The good news is that cobalt is highly recyclable. Modern recovery processes can extract up to 97% of the cobalt from spent lithium-ion batteries under relatively mild conditions, and the recovered material performs well when rebuilt into new cathodes. This makes phone batteries a valuable source of secondary cobalt rather than just electronic waste.
Apple announced a target to use 100% recycled cobalt in all Apple-designed batteries by 2025, a commitment that signals how seriously the industry is treating supply chain concerns. Other manufacturers are pursuing similar goals, though timelines vary. The combination of better recycling infrastructure and growing stockpiles of used batteries means the proportion of recycled cobalt in new phones will likely keep climbing.
Could Phones Work Without Cobalt?
Alternatives exist, but they come with trade-offs. Lithium iron phosphate (LFP) batteries have gained traction in electric vehicles because they’re cheaper and use no cobalt at all. The catch is that LFP has only about half the energy density of cobalt-based batteries. For an electric car with a large battery compartment, that’s manageable. For a smartphone where every cubic millimeter matters, halving the energy density would mean either a much thicker phone or a battery that dies by lunchtime.
Researchers are also developing cathodes that use less cobalt by increasing the proportion of nickel, and some newer formulations have brought cobalt content down significantly compared to the pure lithium cobalt oxide used a decade ago. But eliminating cobalt entirely from phone-sized batteries without sacrificing performance remains an unsolved engineering challenge. For now, cobalt is still doing the heavy lifting inside your phone.