‘Cold’ Manufacturing Could Be The Breakthrough Point for Solid-State Batteries
Alex Kimani

Massive advances in Li-ion battery technology have been at the center of the global electrification drive, including the EV revolution. To wit, over the past decade, lithium-ion (Li-ion) battery cell costs have declined ~28% for every cumulative doubling of units produced, allowing rapid mainstream adoption. 

However, like any other technology out there, Li-ion batteries come with a suite of drawbacks, including the ability to deliver peak charge deteriorating over time; they generate a lot of heat, necessitating weighty cooling systems and also come with a risk of explosion or catching fire if damaged in an accident.  

EV makers consider solid-state batteries the “Holy grail” in the battery industry, often quoting insane performance and range. Unlike liquid electrolytes or polymer gel found in conventional lithium-ion batteries, solid-state batteries use a solid electrolyte including ceramics, glass, sulfides, or solid polymers. Solid-state batteries promise 2-10x the energy density of lithium-ion batteries, meaning more powerful batteries that don’t take up extra space and are also safer and more stable. They are also expected to charge faster. 

And now, scientists have unveiled a novel manufacturing method that will bring solid-state batteries closer to becoming an everyday reality. Researchers at Penn State have demonstrated a manufacturing technique known as cold sintering which operates at significantly lower temperatures than traditional sintering. 

According to Hongtao Sun, assistant professor of industrial and manufacturing engineering at Penn State, traditional ceramic-based solid-state electrolytes are typically composed of polycrystalline grains separated by grain boundaries. However, these grain boundaries hinder the transport of conductive ions, reducing the conductivity of the electrolyte. 

To overcome these barriers, Sun's team used a novel method: co-sintering a poly-ionic liquid gel (PILG) with lithium aluminum titanium phosphate (LATP) ceramics. The result? A polymer-in-ceramic composite electrolyte with high ionic conductivity — all achieved at just 150°C.

That’s a huge improvement over traditional sintering methods, which require extreme temperatures of up to 900–1,000°C— hot enough to destroy polymer additives before the ceramic forms correctly.

"One of the fabrication challenges of LATP-based composite SSEs is that the sintering temperature for ceramic is very high, to the point that traditional sintering would actually burn up any additives such as the polymer compound before the ceramic could be properly densified," Sun said. "This is why we had to implement cold sintering, to keep temperatures much lower."

Sun and his team believe that the applications of this cold sintering technology will one day go beyond manufacturing more efficient solid-state batteries, saying it could have major implications for how companies use ceramic composite materials in general manufacturing, including for industries like semiconductor manufacturing.

However, in the final analysis, it’s probably going to be years before solid-state batteries become mainstream, having failed to do so due to a combination of technical challenges, high costs, and the existing dominance of lithium-ion technology. While promising in terms of energy density and safety, solid-state batteries face difficulties in scaling production and achieving the necessary performance at acceptable price points.

Toyota (NYSE:TM) is one of the biggest investors in solid-state batteries and even holds the highest number of SSB patents. Back in 2023, the world’s largest automaker raised the stakes further after announcing its intention to invest over $13.5 billion by 2030 to develop next-generation solid-state batteries. Toyota announced a goal to lower the cost of its batteries by 30% or more. More importantly, the company provided a prototype vehicle running on solid-state batteries, something many solid-state battery startups lack.

San Jose, California-based QuantumScape Corporation (NYSE:QS) is a development-stage company. QuantumScape is regarded as a leader in solid-state batteries and is backed by Volkswagen (OTCPK:VWAGY), Bill Gates, and SAIC Motors. The company’s batteries feature a cathode and solid-state ceramic separator that connects to an anode electric contact. The company is still in the development and early commercialization phase of its solid-state battery technology. While they have shipped samples of their QSE-5 battery to automotive customers for testing, they have not yet commercialized their batteries and are not generating any revenue.

Meanwhile, Louisville, Colorado-based Solid Power (NASDAQ:SLDP) sells its proprietary sulfide-based solid electrolyte and also licenses its solid-state cell designs. Unlike QuantumScape, Solid Power is already generating revenue: the company reported  FY 2024 revenue of $20.14M (+15.7% Y/Y), beating the Wall Street consensus by $2.64M while FY GAAP EPS of -$0.54 missed by $0.05. The company has projected 2025 cash investments in the range of $100 million to $120 million, excluding any potential DOE grant.

With Penn State’s cold sintering breakthrough, the race toward commercial solid-state batteries takes a step forward. If researchers and manufacturers can clear the remaining hurdles, the “holy grail” of EV power may soon leave the lab and hit the road.

By Alex Kimani for Oilprice.com

Alex Kimani is a veteran finance writer, investor, engineer and researcher for Safehaven.com. 

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