Home » Check Out This New Hyundai Patent Application For An Electrolyte For Solid-State Batteries

Check Out This New Hyundai Patent Application For An Electrolyte For Solid-State Batteries

Hyundai Solid State Battery Patent Topshot

The batteries in today’s EVs could become outdated sooner than you think. Automakers are in a race to bring energy-dense solid-state batteries to market, and some are closer than others. Hyundai is no stranger to solid-state battery patents, and the Korean automaker recently patented a solid-state electrolyte. Let’s take a look at what Hyundai’s done and why solid-state batteries are such a big deal.

[Editor’s Note: Welcome to Future Friday, a weekly series in which we highlight a patent that we’ve found. This one’s been applied for by “Hyundai Motor Co., Ltd., Kia Co., Ltd., Hanyang University Industry-University Cooperation Foundation.” Also, shoutout to patent-finding wizard Edward Grant, who helped us figure out how to find cool car patents. -DT]. 

Hyundai Solid State Battery Patent 1

Hyundai’s electrolyte is composed of lithium, sulphur, phosphorous, nitrogen, and a form of halogen. Said halogen could be chlorine, bromine, iodine, or some combination of the three. After careful mixing and crushing, everything gets baked for five hours at 550 degrees Celsius, eventually ending up with a crystalline structure. Hyundai then made a battery using this material, charged it up to 4.3 volts, and saw a discharge capacity of 117-118 mAh/g at during a ten-hour discharge test. That’s not exactly on-par with existing mass-market LFP or NMC cells, but it’s worth noting that this is a proof of concept and far from a final product. Performance may improve as Hyundai continues to develop batteries around this electrolyte.

Hyundai Solid State Battery Patent 2

Still, a functional solid-state electrolyte is great news, and Hyundai claims that this electrolyte offers improved safety over other sulphide-based electrolytes while still offering decent ionic conductivity. Call it a happy medium of sorts.

Solid-state batteries are heralded as the future for several reasons, the first of which is energy density. Weight is a huge enemy of range and solid-state batteries enable the use of pure lithium metal, shrinking overall footprint and weight of a battery pack. In addition, denser batteries could help with vehicle packaging, carving out extra space that would normally be filled with traditional batteries. The result should theoretically be roomier, lighter cars that can go longer distance before needing to be recharged. Sounds awesome, right?

Hyundai Solid State Battery Patent 3


In addition, several automakers are claiming that solid-state batteries will soon be cheap. Last year, Nissan said that it “believes all-solid-state batteries can be reduced to $75 per kWh in fiscal year 2028 and to $65 kWh thereafter.” At $75 per kWh, an 80 kWh gross battery pack suitable for powering a compact crossover would cost $6,000. That’s really cheap compared to the $138/kWh BloombergNEF saw in 2022. I know that 2028 doesn’t sound soon on paper, but it’s really just one model cycle away.

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Of course, every new technology comes with potential downsides and one of the biggest downsides to solid-state batteries is that we don’t know how safe they might be. One problem that scientists have experienced with solid-state electrolytes is the growth of dendites, little fingers that poke through the electrolyte and short-circuit battery cells. A 2022 Department of Energy study found that short-circuited solid-state batteries could reach higher temperatures than what we’re used to with current technologies. However, the thermodynamic model was done with just one type of solid electrolyte and the main conclusion drawn was the need for safety testing of future solid-state electrolytes.

Large 50245 Hyundaimotorunveilsdesignofall Electricioniq6electrifiedstreamlinerwithmindfulinteriordesign

Another manufacturer making progress on solid-state batteries is good news because EVs need to get lighter and more affordable for sustainable mass-adoption. Hyundai’s recent patent suggests that it’s on a path to the future of batteries, so let’s see what comes of this development, if anything.

(Photo credits: Hyundai)

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14 Responses

  1. Solid state batteries would be nice, but really aren’t necessary at this point. Once specific capacity passed 80 wh/kg, the technology was “good enough”. It is currently way better than that. Solid state batteries might increase by 50-100% specific capacity when compared to the batteries available today, which isn’t exactly world changing. The real concern is whether they increase longevity, so as to reduce operating costs.

    Sustainable mass adoption also means we need battery recycling infrastructure, and we need smaller, more aerodynamic vehicles that can get the same range with smaller battery packs. The emphasis on oversized and disposable trucks/SUVs/CUVs is what is making electric vehicles unsustainable, just the same as this emphasis has made their internal combustion engine counterparts unsustainable, as well as greatly increasing pedestrian deaths, greatly increasing purchase price, greatly increasing operating costs, an loading up landfills with toxic crap.

    There is no reason we can’t have a W123-sized wagon as an EV weighing in around 3,500 lbs that can transport 6 people in comfort with enough room to fully stretch their legs out that can also travel highway speeds while getting 6-7 miles per kWh, could be sold for well under $30k, could be repairable by a shadetree mechanic with basic tools, and be built to last a human lifetime. All of the bits and pieces of technology required to make it happen were here, two and a half decades ago. The only thing that would have to be given up is planned obsolescence, and if cars are going to ever be sustainable, it must be done anyway.

    There’s really no excuse. If I can build a one-seater vehicle in the kitchen of an apartment that gets 100+ miles per kWh, surely an industry with hundreds of billions of dollars and massive teams of engineers at its disposal can build something close to 1/10th as efficient.

    Definitely need to get the lobbyists out of government. Bribery is not free speech. They’re the ones that made all of the light truck rules and CAFE exemptions that allowed for the current state of affairs. If we get another world war, the silver lining on that dark cloud is that the supply line disruptions will completely destroy the viability of these wasteful bloated vehicles and force the government to reconsider all of the regulations that currently exist.

    1. Might not be needed for passenger cars, but is sorely needed in big trucks that can’t afford to be any heavier, and can’t afford 45 minutes of charging for every 4 hours of driving.
      And current battery tech is DOA for planes

      1. Today’s EV batteries are between 120 Wh/kg and 280 Wh/kg. Take the latter end of that range, and triple it, and IMO it still would barely be good enough for freight trucks, and certainly not good enough for long-distance commercial airplanes. This is in spite of efforts from companies like Tesla to make electric freight haulers; put the Tesla semi fully loaded into a mountainous area with lots of steep gradients, and it will have difficulty if it doesn’t start its climb with a full charge. If air travel were to become significantly slower, long-distance electric aircraft could work today(to make this happen, they’d more resemble blimps and travel at under 100 mph), but we still couldn’t replicate the range AND performance of the current 300+ mph jet airplanes that exist even if batteries were 3x as dense as what is available today.

        Pushing heavy electric vehicles up gradients and lifting them into the air both require greatly more energy than their lighter liquid-fuel powered counterparts precisely because of the heavy batteries present. And when the batteries themselves store more than an order of magnitude less energy per unit of mass, it compounds the problem further.

        Electric motors tend to have consistent efficiency regardless of load, whereas gasoline/diesel engines see their thermal efficiency increase with load. A loaded semi lifting itself up a mountain pass can easily require 5x the load as it would on flat ground at the same speed. With an ICE or diesel engine, it can end up operating with triple the thermal efficiency in that case.

    2. everyone loves to ignore WHY vehicles are so heavy. You could drop 1/3 of the weight from all the modern cars if you removed the modern safety. That is why cars are so heavy, and so full of extra crap weighing things down. Sure we could also get NVH way back up and that would reduce some weight. But you aren’t getting lighter cars until everything is carbon fiber.

      1. The modern Mazda Miata and Mitsubishi Mirage also show us that similar amounts of weight can be lost by cutting unnecessary features and luxuries out of the vehicle as well, without resorting to exotic materials or construction methods, and without too greatly compromising safety.

        Everything just has to be fully loaded from the factory without the consumer even getting to decide what they want, to pad profit margins. A modern Nissan Z car can easily be stripped of 500+ lbs of bloat and cost $5,000+ less to build without all this crap it has, and it would be a better performing car for it.

        Hundreds of pounds more mass could also be cut by making the cars slightly smaller. Modern “lightweight” Lamborghinis and Ferraris now weigh as much as the midsized SUVs of 20 years ago, and take up even more space in the road.

        Does everything available really have to be an over-computerized sensory deprivation chamber on wheels with heated/massage seats and steering wheel loaded down with hundreds of pounds of sensors and circuits and designed to comfortably fit people who are 300+ lbs, and then be totally unrepairable 30 years after manufacture when the touchscreen breaks and the manufacturer stopped making replacements and nothing else will work due to proprietary embedded systems and code all over the car’s electronics?

  2. “capacity of 117-118 mAh/g at during a ten-hour discharge test. That’s not exactly on-par with existing mass-market LFP or NMC cells….”

    That’s pretty good actually. From what I can find, Tesla’s newer 4680 cells store 26136mAh and weigh 355grams; That comes out to about 74 mAh/g. Not exactly an apples-to-apples comparison because the 4680 has a metal-can which the prototype cell probably did not, but still significant.

    1. We’d be looking at somewhere around 400 wh/kg, in practice, for these batteries. That would mean my Triumph GT6 conversion could end up weighing 300 lbs less than stock, while getting more range than it could get on a full tank of gas when it ran on gasoline.

      This also opens the door to ultralight, ultra slippery economy cars that weigh under 2,500 lbs, and can get 200+ miles range per charge at highway speeds on a 25 kWh pack, and the lower projected cost per kWh could open the door to these cars being greatly less expensive to manufacture than any of the gasoline powered cars available in 1st world countries. By keeping the pack size small while using a modern 800V system, you also reduce the amount of time it takes to charge at a fast charge station, possibly making it comparable in time expended for fueling to a gasoline powered car as well.

      1. See this is the point at which I would actually consider an electric car. My gas car is currently cheaper and more fun than any electric car around, but if EV technology can be made cheaper than ICE technology, that’s better for everyone – so long as the cars are built to last.

        1. Making an EV last is the easy part.

          What makes it not last is loading it with all kinds of unrepairable, proprietary components intentionally designed to eventually stop working.

          It would be trivially easy to make an EV using plug and play parts. Hobbyists do it every day, and older OEM EVs from the 1990s were much closer to this ideal. But that now means you could make a car which routinely lasts one million miles and 5+ decades before needing major repairs and with minimal maintenance, and that is initially why the auto industry was so against this technology 30 years ago when it first became marginally viable.

          Now that the auto industry has figured out how to lock the DIY mechanic out of the car with software and proprietary electronics necessary for the car to function, the auto industry now embraces EV technology, assured that planned obsolescence can be maintained, with a built-in 10-15 year lifespan for their products.

          And it’s a terrible waste of this technology and all of the resources and energy that go into making it work.

          1. Nailed it 100%.

            My 2000 Insight was made out of Aluminum hand welded with a manual transmission and 1.0 68hp engine only weighing 1800lbs stock with a hybrid battery costing under 30k 23 years ago. Average 60mpg without the hybrid battery even in the car.

            Cars today should be better than that but basically they stopped actually trying. In 2000 they did and it still is the most efficient non rusting long lasting car you can buy and that is just sad.

            1. Imagine if that Insight had the drag coefficient of an EV1, was a non-hybrid, RWD, and K-swapped. You’d have a reliable 60+ mpg highway, 30+ mpg city sports car that could do 0-60 mph in under 5 seconds with a sub-$30k price tag, that would compete with cars twice its cost in performance while being the most efficient thing you could buy, and could essentially last as long as any other Honda with minimal operating costs. What could have been…

          2. “ planned obsolescence”

            I’m a design engineer who has been working for OEMs for decades. We work with a design life target of 10 years, which is to say that everything we do has to be fully functional after ten years of use. This is absolutely not the same thing as planned obsolescence, which is designing something to fail after a target time or number of cycles.

            No one want to fail an accelerated life span test, it costs a huge amount of time and money to revalidate the fix, so we design to beat the design life. Could we design to 50 years as a design life? Sure, but that comes with a financial and mass cost that the people who actually buy new cars from manufacturers won’t accept.

            Designing to meet a planned obsolescence target is hugely more complex, takes way more time and way more money. Plus it’s evil. I won’t compromise a design to make it fail earlier, it’s obscene. Plus it’s way more effort and costs more. There is no motivation for it.

            1. Mechanically, modern cars are generally built to last. The issue is with software and electronics. Major systems within modern cars are designed to be dealership-only repairable, and once parts are discontinued or software no longer available, the car is landfill fodder when even a simple and otherwise inexpensive to produce component is no longer available.

              It isn’t mechanically where modern cars typically fail.

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