Gels are paving the way for solid-state batteries, which aren’t quite there yet.

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How it started
As we move further into the 21st century, lithium-ion batteries have become ubiquitous, but this widespread use comes with significant risks. Incidents of e-bikes catching fire in stairwells and power banks igniting mid-flight highlight the dangers posed by traditional liquid electrolytes.

In 2025, the US Consumer Product Safety Commission (CPSC) recalled nearly 1.9 million power banks from various brands due to safety concerns. This also included recalls for thousands of e-bikes, with urgent warnings issued to stop using batteries in certain Rad Power Bikes models.

For over a decade, the anticipated solution has been the solid-state battery, which promises to eliminate combustion risks while being affordable, lightweight, quick to charge, and capable of storing vast amounts of energy in a compact form. So when Donut Lab announced a “miracle” solid-state battery ready for production, it captured everyone’s attention. We all wanted to believe!

Unfortunately, what seemed too good to be true has been debunked. However, while the hype was ongoing, a new category of batteries has emerged, making their way into power banks, e-bikes, and beyond.

These next-gen batteries are neither fully liquid nor solid; they exist in a semi-solid state. Semi-solid-state batteries offer a gel-like composition that combines some advantages of solid-state technology while significantly reducing the risk of thermal runaway associated with traditional lithium-ion batteries.

How it’s going
In April 2025, I reviewed what was touted as the “world’s first” semi-solid-state power bank from Kuxiu. Today, several brands are offering similar products. While they come at a slightly higher price, they provide more energy in the same footprint and perform better in colder conditions. Most importantly, they have a lower risk of overheating and catching fire, with lifespans two to three times longer than conventional lithium-ion power banks.

Each new product launch typically features videos of lab-coated individuals testing the batteries with hammers, drills, and other tools to see how they hold up. Spoiler alert: the volatile liquid electrolytes ignite, while the semi-solid gels remain stable.

Aside from the electrolyte, the basic design of a semi-solid-state battery remains unchanged. It consists of an anode on one side of the semi-solid electrolyte and a cathode on the other, with ions moving back and forth during charging and discharging. With minor tweaks, these batteries can be produced on the same assembly lines as their more dangerous counterparts.

In essence, semi-solid-state batteries can advance technology without dismantling the current infrastructure, and the e-bike sector is taking notice.

Ride1Up is at the forefront of this shift in the US. In early May, it unveiled the Revv1 EVO, claiming it to be “the world’s first semi-solid-state electric bike.” Its 1,040Wh battery, developed by Heyuan Lithium Inno, is designed to endure over 1,200 charging cycles—far exceeding the typical 500 cycles of standard e-bike batteries—before its capacity drops below 80 percent. It also charges in just two hours and is better equipped to handle extreme temperatures, with shipping set to begin in August 2026.

Not to be outdone, the global cycling giant Giant announced at the end of May its plans to adopt semi-solid-state batteries as well. The company is developing at least five mass-produced e-bikes featuring these batteries from Heyuan Lithium Inno. Additionally, it has partnered with T&D, a battery company that emerged from component maker Bafang. Giant claims T&D’s battery offers 50 percent more capacity than lithium-ion batteries and allows for a 21 percent reduction in frame-integrated weight.

Chinese smartphones have also been making waves with silicon-carbon batteries, some of which incorporate semi-solid electrolytes. The transition from graphite to silicon-carbon anodes enables these advanced batteries to store even more energy in a smaller space. Back in 2024, Vivo introduced the X200 series, featuring a battery that combined a semi-solid-state electrolyte with a silicon-carbon anode. This same BlueVolt-branded battery is now found in new Vivo devices like the X300 Ultra.

And this is just the beginning. Semi-solid-state batteries are being tested or rolled out in various applications, from drones to electric vehicles and large power stations designed for home backup during outages.

What happens next
The push for semi-solid-state batteries across different device categories is partly fueled by stricter regulations from Chinese authorities.

New e-bike regulations, effective December 2025, mandate that batteries undergo puncture tests to assess fire or explosion risks. While power banks aren’t subjected to the same rigorous testing, they must still pass a series of demanding evaluations to earn China’s CCC mark, which is necessary for air travel.

This creates a strong incentive for manufacturers to adopt semi-solid-state batteries, which align well with China’s stringent regulatory requirements. If this trend continues, it could lead to retooled assembly lines and reduced manufacturing costs, allowing a broader range of devices to benefit from these advanced batteries.

Given that China controls a significant portion of the global battery supply, improvements in safety could eventually extend to other countries. This would be particularly beneficial for the US, which currently grapples with a patchwork of state laws and regulations that have not effectively enhanced the safety of e-bike batteries and power banks nationwide.

As for true solid-state batteries, we’ll have to remain patient. Meanwhile, Donut Lab is still in the game.

By the way
* In the US smartphone market, Samsung, Apple, and Google dominate, but none are utilizing silicon-carbon batteries, with or without semi-solid electrolytes, resulting in a lack of innovation.
* Chinese electric vehicles are rapidly adopting semi-solid-state batteries. Notably, SAIC is following up last year’s “world’s first mass-produced semi-solid-state EV” with the $15,000 MG 4X electric SUV, set to launch in Europe later this year.
* The CEO of sports car manufacturer Lotus estimates we are still a decade away from the mass production of true solid-state batteries.