You’re charging your phone wrong. It’s not your fault.

I used to think I was good at charging stuff. My phone, for instance, almost never dies because I charge it wirelessly overnight, and then, if it’s running low in the afternoon, I blast it with juice from a fast charger. But my battery’s maximum capacity recently dropped into the 80 percent range, and I know it will only be a matter of time before I have to get a new battery — or a new phone if I’m feeling gullible. The lithium-ion batteries that power our phones, laptops, and even cars are inherently imperfect and destined to degrade over time. Almost everything we do makes this happen faster. That wireless charger I use overnight creates excess heat, which speeds up battery degradation. Ditto for fast charging. That means charging your phone correctly is practically impossible. While certain tips and tricks can speed up the process and extend your phone battery’s life, there’s nothing you can do about the limitations of the lithium-ion batteries in your devices. They all eventually stop holding a charge, which means they constantly need replacing. Lithium-ion batteries, especially the cheap ones, can also explode without warning. There is, however, new hope for a breakthrough in battery technology. A Boston-based startup called Pure Lithium recently announced a breakthrough with its lithium metal batteries. While the lithium-ion batteries in your phone start to degrade significantly after a few hundred cycles of charging and discharging, these lithium metal batteries, which use pure lithium rather than a lithium compound, can last over 2,000 cycles without significant damage degradation, an ongoing test shows. Plus, the lithium metal batteries can store twice as much energy and weigh half as much as conventional lithium-ion batteries. Pure Lithium cofounder and CEO Emilie Bodoin calls this combination of features “the holy grail of energy storage.” “We have to have a step change, because there have been many inventions in the battery space over the last 20 years,” Bodoin told me. “[But] you cannot feel it in your phone or your device.” That said, you cannot currently buy an iPhone with a lithium metal battery in it. Lithium metal batteries, along with the rest of the battery technologies that stand to replace lithium-ion, are still in development. And so even though lithium-ion batteries are imperfect, they will continue to be ubiquitous for decades. The supply chain needed to build lithium-ion batteries, especially EV batteries, is highly reliant on China, but it can also scale up in a way that experimental battery technology cannot. Global demand for lithium-ion batteries reached 700 gigawatt hours in 2022 and, largely thanks to EVs, demand is expected to grow 30 percent annually until it reaches 4,300 gigawatt hours in 2030, according to McKinsey. To put that into context, 4,300 kilowatt hours is enough to power more than 400,000 homes for a year or roughly equivalent to the annual output of the Hoover Dam. Lithium-ion batteries are key to the renewable energy transition, and because they are getting incrementally better. You can be bad at charging your phone, for instance, and yet your phone will not explode or stop working immediately. You can also drive an EV about 300 miles before needing to charge it. The ability to cram even more energy into our batteries would be revolutionary, however. “If we did have another generation of battery technology that gave you another three to five, ideally 10 times more energy density,” said Stuart Lipoff, an IEEE fellow. “It could enable a whole new generation of devices.” This kind of technological revolution could not only mean your phone’s battery lasts for days. It could lead to a device that completely replaces your phone, like ultra lightweight augmented reality glasses that never need charging. And revolutionary new batteries won’t just give us longer lasting EV batteries. We could have battery-powered planes, trains, and container ships. In the meantime, though, we’re all stuck with lithium-ion batteries, and their many faults — but there are ways we can manage them. The Handycam revolution Lithium-ion battery technology dates back to 1972, when M. Stanley Whittingham first developed it at Exxon, of all places. Exxon predicted that oil production would eventually decline, and its researchers were looking for alternative energy sources. The company even showed off Whittingham’s design at the 1977 Chicago Auto Show, decades before lithium-ion batteries helped make EVs mainstream. These batteries upended the consumer technology industry, first appearing in a Sony Handycam model, before they found their way back into EVs. All three scientists — Whittingham, Akira Yoshino, and John Goodenough — shared the 2019 Nobel Prize in Chemistry for their contributions to develop lithium-ion technology. --- How lithium-ion batteries work Batteries are made up of three essential ingredients: an anode, a cathode, and an electrolyte. (You’ll usually see the anode labeled with a + sign and the cathode a - sign.) When the battery is in use, a series of chemical reactions pushes electrons from the anode, through the electrolyte, and into the cathode. When the chemical energy between the two poles hits an equilibrium, the reaction stops, and the battery is dead, until you recharge it. Adding an electrical current reverses the reaction, sending electrons back to the anode, and the battery is charged once again. Lithium-ion batteries use graphite as the anode and a lithium compound as the cathode, usually lithium cobalt oxide. (China is the world’s largest producer of graphite, and the Democratic Republic of Congo is the largest product of cobalt, which presents potential supply chain problems for the US.) The material used for the cathode also determines a battery’s energy density, which is why lithium gets all the credit. There are other battery chemistries, but lithium is widely regarded as the best material for a cathode, in part because of its high energy density. --- It was after Yoshino and Goodenough pushed lithium-ion battery technology forward in the 1980s that it became commercialized. Sony actually helped popularize the term “lithium-ion” when it released the first commercial rechargeable lithium-ion battery in 1991. “Lithium-ion batteries are really great, but they’re not perfect,” said Matthew McDowell, co-director of the Georgia Tech Advanced Battery Center. “They’re not going to be going anywhere anytime soon.” The benefits and drawbacks of lithium-ion batteries were clear from the start. They could pack a large amount of energy into a small, lightweight package, making them great for portable consumer gadgets, like camcorders and smartphones, as well as EVs. But while they can technically function for years, lithium-ion batteries can only be charged and discharged so many times before the materials inside them degrade to the point that they stop working. This is still true even today, which is why, at a certain point, tiny devices like AirPods simply have to be thrown away because their batteries no longer hold a charge and can’t be replaced. “Lithium-ion batteries are just not going to improve anymore,” Bodoin said. “They just can’t. They have a theoretical energy density that they can achieve, and you just can’t make that any bigger. That’s the problem.” The beauty of battery management Battery life is getting better, however. The latest iPhone lasts longer than last year’s iPhone on a single charge, but that’s not necessarily due to a breakthrough in lithium-ion battery technology. The software that manages how a device’s battery changes and discharges is just as important as the battery chemistry itself these days. That’s why there are so many tips and tricks to charging your phone. Done properly, you can work around your battery’s shortcomings and not only hold a charge longer but also extend the entire lifespan of the battery. To optimize battery life and lifespan, you’d ideally keep your phone between 20 and 80 percent charged in a room that’s about 65 degrees at all times. If the battery is too empty or too full, too hot or too cold, it degrades more quickly. And when you do charge it, you shouldn’t overdo it with an adaptor that’s too powerful, because that can heat up the battery and, again, cause it to degrade. (The power of a charger is measured in watts, with higher wattages corresponding to faster charging.) It’s practically impossible to meet all these conditions and live a normal life. Plus, degradation is inevitable with lithium-ion batteries, so even if you do everything right, you’re ultimately fighting a losing battle. Device manufacturers know the shortcomings of lithium-ion batteries all too well, which is why they’re constantly improving battery management software. You actually don’t have to worry too much about your battery getting too full, because that software will slow down the charging, also known as “trickle charging,” as the battery gets closer to 100 percent. It’s also hard to completely drain your battery, because the device will shut itself off when there are still a few percentage points left. These battery management features also supposedly protect your battery health when you’re using a fast charger. This all adds up to good news and bad news. The good news is, despite the many myths surrounding proper charging techniques, your phone, laptop, and even EV are designed to compensate for the shortcomings of lithium-ion battery technology. You can be bad at charging your phone these days, and your phone will take care of itself. If you’re really worried about your battery health, avoid fast charging or charging all night long, and don’t leave your phone out baking in the sun. But for the most part, you should just accept that your phone’s lithium-ion battery will simply stop working after a few hundred cycles. The bad news is that the step change in battery technology that will bring us battery-powered planes is years away. For new battery technologies, breakthroughs like the Pure Lithium experiment I mentioned earlier are just one step on the long road to commercialization. After all, it took 20 years from the invention of the first lithium-ion battery to its introduction in the Handycam. That’s long enough for the Handycam itself to become obsolete for one generation and then trendy again with their nostalgia-obsessed children. To borrow a quote, lithium-ion aren’t the batteries we deserve, but they are the batteries we need right now. A version of this story was also published in the Vox Technology newsletter. Sign up here so you don’t miss the next one!

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You’re charging your phone wrong. It’s not your fault.