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Lithium-ion batteries are everywhere as we enter the second quarter of the 21st century, and that’s a problem. From exploding e-bikes in stairwells to lithium-ion power banks combusting midflight, the volatile nature of traditional liquid electrolytes has become an undeniable public safety hazard.

In 2025, the US Consumer Product Safety Commission (CPSC) issued recalls for almost 1.9 million power banks from companies like Anker, Baseus, and INIU. It also prompted recalls for tens of thousands of e-bikes over fire concerns, while issuing a rare warning to immediately stop using batteries found in several Rad Power Bikes models.

The solution, we’ve been told for at least a decade, is the solid-state battery. Its arrival is perpetually imminent and promises to deliver combustion-free battery cells that are cheap and lightweight, charge quickly, run cool, and hold ungodly amounts of energy in less space. It’s no wonder that everyone stopped in their tracks when Donut Lab claimed to have a “miracle” solid-state battery that was ready for production. We want to believe!

Alas, what sounded too good to be true appears to be exactly that, having now been thoroughly debunked. But while the world was distracted, a new class of improved batteries has been making its way into power banks, e-bikes, and more.

These next generation batteries aren’t liquid and they’re not solid; they’re something in between. Semi-solid-state batteries are a bridge to the future, with a gel-like composition that offers some benefits of solid-state, with far less risk of the thermal runaway exhibited by traditional lithium-ion batteries.

In April 2025, I reviewed the “world’s first” semi-solid-state power bank from a company called Kuxiu. Today, several additional brands sell similar products. They cost a little more but pack more energy into the same space and perform better in cold weather. More importantly, they are less likely to overheat and catch fire over their lifetimes, which can be two to three times longer than traditional lithium-ion power banks.

Each product launch is usually accompanied by a video showing lab-coated hooligans with hammers, nails, drills, pliers, and knives doing their best to bend, puncture, and tear the batteries. Spoiler: Volatile liquid electrolyte ignites, but the semi-solid gels do not.

Aside from the electrolyte, the fundamental design of a semi-solid-state battery is otherwise unchanged. You have an anode on one side of the semi-solid electrolyte and a cathode on the other, with ions scrambling back and forth as the cell charges and discharges. With minor adjustments, semi-solid-state batteries can be manufactured on the same assembly lines as their fire-prone peers.

In other words, semi-solid-state batteries don’t need to blow up the present to power the future, and the e-bike industry has taken notice.

Ride1Up is arguably leading the charge toward semi-solid state in the US. In early May, it announced the Revv1 EVO, or what it calls “the world’s first semi-solid-state electric bike.” The 1,040Wh battery made by Heyuan Lithium Inno is meant to withstand over 1,200 charging cycles, not 500 like typical e-bike batteries, before dropping below 80 percent of its original storage capacity. It can also charge in two hours and better withstand extreme temperatures. It begins shipping in August 2026.

Not to be outdone, global bicycling giant Giant announced at the end of May that it would also be adopting semi-solid-state batteries. It’s working on at least five mass-produced e-bikes using Heyuan Lithium Inno’s semi-solid-state batteries. It has also partnered with T&D, a battery company spun out of component maker Bafang. Giant says T&D’s battery has 50 percent more capacity compared to lithium-ion and allows them to reduce the frame-integrated weight by 21 percent, according to Bike Europe. We’re still waiting for Giant to reveal the actual e-bikes.

Chinese phones have been capturing headlines with silicon-carbon batteries, but some also feature semi-solid electrolytes. The switch from graphite to silicon-carbon anodes allows these advanced batteries to pack even more energy into less space. Way back in 2024, Vivo announced the X200 series with a battery that combined a semi-solid-state electrolyte with a silicon-carbon anode. This same BlueVolt-branded battery can be found in new Vivo devices like the X300 Ultra.

And that’s just the start. Semi-solid-state batteries are being tested or commercialized in everything from drones to EVs and those big-ass power stations used for home backup during a power outage.

The adoption of semi-solid-state batteries across device categories is being driven, in part, by stricter rules imposed by Chinese regulators.

New rules for e-bikes, for example, which came into force in December 2025, require batteries to pass a puncture test to see if it triggers a fire or explosion. And while power banks aren’t subjected to the same torture during certification, they still need to pass a series of rigorous tests that push liquid electrolytes to their extreme. Otherwise they won’t get China’s CCC mark (analogous to the CE mark in Europe or UL in the US) required for air travel.

This presents a compelling case for manufacturers to adopt semi-solid-state batteries, which naturally align with China’s rigorous regulatory standards. Should that happen, it would cause more assembly lines to retool and drive down the manufacturing costs, paving the way for a wider range of device categories to benefit from these sophisticated batteries.

And since China controls the world’s battery supply, all countries could eventually benefit from the improved safety. That’d be good news for the US especially, with its patchwork of state laws, city ordinances, and optional UL certifications that have so far failed to make e-bike batteries and power banks meaningfully safer nationwide.

As for true solid-state batteries, well, we’ll just have to keep waiting. In the meantime, Donut Lab says it’s still open for business.