The Race to Put a Solid-State Battery on the Road
Automotive patents don’t always focus on a new product that is about to hit showrooms. More often, they give us a peek at the real issues carmakers face in the background – especially for upcoming breakthroughs. Solid-state batteries are a perfect example of that right now.
In a nutshell, solid-state batteries replace the liquid electrolyte in today’s lithium-ion batteries with a solid material. On paper, that means more energy, quicker charging, better safety, and longer lifespan. That’s why they’re often hyped as the next big thing for EVs. We’ve already seen some bold claims – like Donut Lab’s supposed five-minute recharge battery.
Honda and Toyota were some of the first legacy automakers, among others, to say they were all-in on solid-state batteries. Fast forward a few years, and you still won’t find a production-ready pack in any of their cars. Two new separate patents help explain what’s holding things up – and yes, both companies are working on these problems that will decide if solid-state batteries actually work in the real world.
Donut Lab
Honda’s Problem: Keeping the Battery From Destroying Itself
Honda is zeroing in on durability. Its latest patent, filed in the US Patent and Trademark Office in September 2025 (patent no. 20260024768, if you want to check) and published in January 2026, delves into how solid-state batteries hold up as they age.
The main headache with solid-state batteries is internal stress. Every time the battery charges or discharges, the materials inside expand and contract. Liquid electrolytes can handle that movement, but solid materials can’t. That leads to cracks, layers pulling apart, and increased resistance, all of which slowly erode performance.
So, how does Honda plan to solve this? The Japanese automaker is looking at the battery’s structure, especially how the negative electrode connects with the solid electrolyte. Rather than inventing a new chemistry, Honda is tweaking the way the layers are built so they can handle stress and avoid long-term damage. The aim isn’t to break records for charging speed or energy capacity, but to ensure the battery can withstand daily use without coming apart inside.
In short, Honda is tackling the longevity problem first. It’s prioritizing cycle life and reliability for now.
Honda
Toyota’s Problem: Making Solid-State Batteries at Scale
On the other hand, Toyota’s patent addresses a different roadblock. Filed in July 2025 (patent no. 20260024805) and published on the same day as Honda’s, it’s all about making sure solid-state batteries can be built consistently, not just in the lab but in the factory.
Toyota’s concerns are moisture, contamination, and variation in resistance during production. Apparently, solid-state batteries are extremely sensitive to even small amounts of surface moisture, which can ruin performance before they even reach customers. In a lab, that’s manageable. On a mass-production line, it’s a nightmare.
Toyota’s patent outlines methods for controlling variables during lamination and pressing. It’s not a moonshot. It’s more like a set of instructions for the factory floor, all about improving yield and ensuring every battery comes out the same. That lines up with the automaker’s usual approach. Instead of rushing to be first, it’s making sure solid-state batteries can be built reliably, at scale, and at a price that works for everyday cars.
Like any patent, these filings don’t guarantee the tech will ever make it to production. But together, they show why solid-state batteries are still a work in progress. Honda is working on making them last. Toyota is working on making them buildable. Until both sides crack their problems, solid-state batteries will stay more of a promise than a real product.
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