Solid state batteries are still not perfect, but gels are

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Lithium-ion batteries are everywhere as we enter the second half of the 21st century, and that’s a problem. From bicycles exploding on stairs to lithium-ion power banks catching fire midflight, the volatile nature of traditional liquid electrolytes has become an undeniable public safety hazard.

By 2025, the US Consumer Product Safety Commission (CPSC) issued recalls for nearly 1.9 million power banks from companies such as Anker, Baseus, and INIU. It also prompted the recall of tens of thousands of e-bikes due to fire problems, while a rare warning was issued to immediately stop using the batteries found in several models of Rad Power Bikes.

The solution, we’ve been told for at least a decade, is the solid-state battery. Its arrival is imminent and it promises to deliver non-combustible battery cells that are cheap and lightweight, charge quickly, work efficiently, and hold ungodly amounts of energy in a small space. No wonder everyone stopped in their tracks when Donut Lab said it had a “miracle” solid state battery that was available. ready for production. We want to believe!

Alas, what sounded too good to be true appears to be just that, as it has now been completely released. But while the world was in turmoil, a new class of advanced batteries was making its way into power banks, e-bikes, and more.

These next-generation batteries are neither liquid nor solid; they are something in between. Semi-solid-state batteries are the bridge of the future, with a gel-like structure that offers some of the benefits of solid-state, with much less risk of thermal runaway than 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 less but pack more power into the same space and perform better in cold weather. More importantly, they are less likely to overheat and catch fire during their lifetime, which can be two or three times longer than conventional lithium-ion power banks.

Each product launch is often accompanied by a video showing lab-worn hooligans with hammers, nails, drills, pincers, and knives doing their best to bend, puncture, and tear apart batteries. Spoiler: Flexible liquid electrolytes are flammable, but solid gels are not.

Other than the electrolyte, the basic design of a solid-state battery is otherwise unchanged. You have an anode on one side of a slightly solid electrolyte and a cathode on the other, with ions moving back and forth as the cell charges and discharges. With minor modifications, semi-solid-state batteries can be manufactured on the same assembly lines as their fire-resistant counterparts.

In other words, semi-solid-state batteries don’t need to explode now to power the future, and the e-bike industry is taking notice.

Ride1Up is arguably leading the charge towards a strong presence in the US. In early May, it announced the Revv1 EVO, or what it calls “the world’s first rugged electric bike.” The 1,040Wh battery made by Heyuan Lithium Inno is designed to withstand more than 1,200 charge cycles, not 500 like conventional bike batteries, before dropping below 80 percent of its original storage capacity. It can also be charged in two hours and is better resistant to extreme temperatures. It starts shipping in August 2026.

Not to be outdone, the global bicycle giant announced at the end of May that it will also use semi-solid state batteries. It works at least on mass-produced bikes using Heyuan Lithium Inno’s semi-solid state batteries. It also partnered with T&D, a battery company spun off from component maker Bafang. Giant says the T&D battery has 50 percent more capacity compared to lithium-ion and allows them to reduce the overall weight of the frame by 21 percent, according to Bike in Europe. We are still waiting for Giant to reveal the real ee bikes.

Chinese phones have been grabbing headlines with silicon-carbon batteries, but some also feature semi-solid electrolytes. Switching from graphite to silicon-carbon anodes allows these improved batteries to pack more power into a smaller area. Back in 2024, Vivo announced the X200 series with a battery that combines 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 beginning. Semi-solid-state batteries are being tested or sold in everything from drones to EVs and those big-ass power stations used for home backup during power outages.

The adoption of solid-state batteries in all device categories is driven, in part, by strict regulations imposed by Chinese regulators.

New regulations for e-bikes, for example, which came into effect in December 2025, require batteries to pass a puncture test to see if they cause a fire or explosion. And while power banks don’t suffer the same torture during certification, they still have to pass a series of tough tests that push liquid electrolytes to extremes. Otherwise they won’t get China’s CCC mark (like CE in Europe or UL in the US) required for air travel.

This presents a compelling situation for manufacturers to use solid-state batteries, which naturally comply with China’s strict regulatory standards. If that happens, it could cause more assembly lines to be reworked and lower production costs, paving the way for a wider range of device categories to benefit from these complex batteries.

And with China controlling the world’s supply of batteries, all countries could ultimately benefit from improved safety. That would be good news in the US in particular, with its combination of state laws, city ordinances, and voluntary UL certifications that have so far failed to make bike batteries and power banks soundly safe across the country.

As for true solid-state batteries, we’ll have to keep waiting. For now, Donut Lab says it’s still open for business.