Mizzou’s 4D STEM Breakthrough: Enhancing Solid-State Battery Efficiency

Solid-state batteries are in focus these days. It is steadily gaining traction with consumer electronics and electric vehicles, constituting the largest share of the global solid-state battery market in 2022.

Researchers estimate that solid-state battery applications in the EV sector will grow exponentially in the next decade, reaching a market size of US$4.3 billion by 2032. There are reasons why solid-state batteries are poised for exponential growth. Essentially, they refer to a battery technology that uses a solid electrolyte instead of liquid electrolytes, as used in lithium-ion technology. 

Solid-state cells consist of a cathode, a separator, and an anode. The cathode could be made with the same compounds as a lithium-ion battery. In contrast, the separator is generally made of ceramic or solid polymer, which also works as an electrolyte. The anode is made of lithium metal. 

When charged, the lithium particles within these batteries move from the cathode through the atomic structure of the separator and the anode’s electrical contact, forming a solid layer of pure lithium. The process ensures that the anode consists solely of lithium particles and has a smaller volume than a lithium-ion technology anode with a graphite structure. 

Although these batteries are still in their developmental phase, they promise multiple improvements over the current batteries, including a greater energy density, a longer life, enhanced safety, and smaller size. The promising outlook solid-state batteries offer has made it an attractive space for scientists to explore further and see what could be done with it.

A recent news release on a University of Minnesota research claims that the researchers are “cracking the code on solid-state batteries.” In the coming segments, we look into the reasons that drive this tall claim. 

What the University of Minnesota Researchers Have Achieved

The research, titled Understanding Cathode–Electrolyte Interphase Formation in Solid State Li-Ion Batteries via 4D-STEM¹, demonstrates a simple workflow to study cathode–electrolyte interphase (CEI) formation using 4D-scanning transmission electron microscopy (4D-STEM) that does not require SS-LIB assembly.

At the contact points between the solid electrolyte and cathode active material in solid-state lithium-ion batteries, interphase layers form, increasing cell impedance. The researchers eliminate the need for SS-LIB assembly and show the benefits of MoCl5:EtOH as a chemical de-lithiating agent, along with chemically delithiated cathode LiNi0.6Co0.2Mn0.2O2 (NMC) powder in contact with Li10GeP2S12 (LGPS) SE powder, as an SS-LIB CEI surrogate.

The researchers mapped the composition and structure of the CEI layers using 4D-STEM, energy dispersive X-ray spectroscopy (EDS), and electron pair distribution function analysis (ePDF). Their findings suggest that coatings that block anion transport while allowing Lithium-ion and electron transport may prevent interphase formation and reduce impedance in SS-LIBs. 

While describing the nature of the coating, Young said:

“The coatings need to be thin enough to prevent reactions but not so thick that they block lithium-ion flow. We aim to maintain the high-performance characteristics of the solid electrolyte and cathode materials. Our goal is to use these materials together without sacrificing their performance for compatibility.”

All these may sound too technical, but there is an easier perspective to understand regarding the achievement of the research.

Click here to learn about a battery breakthrough that brings solid-state variants a step closer to reality.

Dealing With the Problem of Liquid Electrolyte

Lithium-ion batteries rely on liquid electrolytes, which can catch fire if damaged or overheated. The University of Missouri researchers addressed this problem by developing efficient techniques to replace liquids or gel electrolytes with solid electrolytes.

Elaborating how their solution works, Assistant Professor Matthias Young, who has joint appointments in Mizzou’s College of Engineering and College of Arts and Science, had the following to say:

“When the solid electrolyte touches the cathode, it reacts and forms an interphase layer that’s about 100 nanometers thick — 1,000 times smaller than the width of a single human hair. This layer blocks the lithium ions and electrons from moving easily, increasing resistance and hurting battery performance.”

The Most Significant Breakthrough

The research team’s most significant achievement, however, was their use of four-dimensional scanning transmission electron microscopy (4D STEM). What made this revolutionary was they could examine the atomic structure of the battery without disassembling it, allowing them to gain a fundamental understanding of the chemical reactions inside and determine the extent of harm the interphase layer was responsible for. 

From the perspective of the potential users of these batteries, the research and its implications hold great potential. 

Expected Real-World Benefits

Global automakers are excited about solid-state batteries because they will offer greater safety and thermal stability. The research we just discussed is a breakthrough in that direction—an immensely meaningful step forward. Moreover, the research could lead to improvements in safety, performance, lifetime of the batteries, cost, and their environmental impact. 

Battery scientists across the world are optimistic that the new breed of solid-state batteries, ones that will emerge as a result of research like these, will eventually overcome two key drawbacks of conventional lithium-ion. The nickel-rich cathodes will enable the battery industry to use less cobalt in the cathode. Second, solid-state chemistries will enable battery makers to use lithium metal in the anode.

The first factor is crucial for the growth of this sector because cobalt is scarce, expensive, and difficult to mine. It comes from countries that have weak mining laws. Researchers believe the scope of lithium use in anode is significant because it boosts energy density and promotes safety.

Speaking about the use of lithium metal, Helena Braga, an associate professor of engineering physics at the University of Porto in Portugal and a well-known researcher who worked with Nobel Prize winner John Goodenough on solid-state batteries a decade ago, said:

“This is why we started this (solid-state) journey in the first place–so we could use lithium metal.”

Altogether, this technology and research-based technique can lead to improved battery designs with enhanced performance and safety, potentially impacting consumer electronics and EVs within 3-7 years.​

However, the real value of such research would depend on how successfully companies and businesses manufacturing solid-state batteries adopt them and bring them up to scale. In the following segment, we discuss one such company, Solid Power, Inc. (SLDP -3.48%), that specializes in all-solid-state battery technology, focusing on safer and more efficient energy storage solutions.​

Solid Power, Inc. (SLDP -3.48%) 

Solid Power positions itself as a provider of all-solid-state battery cell technology that offers key improvements over today’s conventional liquid-based lithium-ion technology and next-gen hybrid cells, including high energy, enhanced safety, longer life, and cost savings. 

Solid Power’s batteries allow the use of higher-capacity electrodes like high-content silicon and lithium metal to achieve high-energy performance. It becomes safer by removing the need for the reactive and volatile liquid and gel components. Resultantly, it can withstand and deliver in extremely hot temperatures. The company believes its batteries can offer a 15-35% cost advantage over existing lithium-ion at pack level. 

In the coming segments, we discuss the three varieties of Solid Power’s solid-state batteries. 

Silicon EV Cell 

These cells come with a high-content silicon anode delivering high charge rates and lower temperature capabilities. These batteries are powered by the company’s proprietary sulfide-based solid electrolytes. Finally, its NMC cathode is industry-standard and commercially mature. 

Lithium Metal

Solid Power Lithium Metal batteries come with lithium metal and high-energy anode. This category of batteries is also powered by Solid Power’s proprietary sulfide-based solid electrolytes and industry-standard and commercially mature NMC cathodes. 

Conversion Reaction Cell 

Finally, we come to the conversion reaction cell category of batteries that come with a lithium metal, high-energy anode, sulfide-based solid electrolytes ultra-low cost, and high specific energy conversion-type cathode. 

Solid Power’s battery technology has sulfide-based solid electrolytes as one of its most formidable foundations. The technology ensures the complete removal of the flammable liquid electrolyte and polymer separator layer in a traditional lithium-ion battery and replaces it with a solid layer that, despite being thin, acts as a barrier to keep the anode and cathode from touching one another, which would short the battery. It also acts as a conductive electrolyte. The sulfide-based solid electrolyte of Solid Power comes with the best combination of conductivity, manufacturability, and cell-level performance. 

Solid Power’s core sulfide-based solid electrolyte technology uses earth-abundant materials. The company expects to scale its electrolyte production to power 800,000 electrified vehicles through its all-solid-state battery cells annually by 2028.

SLDP: Latest Updates

In December 2024, Solid Power announced the extension of its partnership with Ford through 2025. The third amendment to the joint development agreement reflected the ongoing commitment between Solid Power and Ford to push forward the boundaries of electric vehicle battery performance. 

Reports cited the extension of the partnership as a significant step for Solid Power’s work toward commercializing its solid-state battery technology. The extended partnership with Ford, a leading global automaker, underscored the potential impact of Solid Power’s technology on the automotive industry.

In January 2025, the company entered into a significant financial agreement with the U.S. Department of Energy (DOE). The company announced that it had secured up to $50 million in funding to enhance its production capabilities of sulfide-based solid electrolyte material, essential for next-generation batteries.

The funding came as part of an Assistance Agreement with an effective date of January 1, 2025, which stipulated that Solid Power would contribute $60 million of its funds as part of the cost-sharing arrangement. The investment was aimed at supporting the installation of equipment necessary for continuous production, which is expected to bolster the company’s manufacturing scale.

As part of the agreement, Solid Power was required to adhere to specific reporting requirements and compliance obligations. The DOE’s support underscored the importance of advancing battery technology for energy storage and electric vehicles, sectors that are critical for the transition to a low-carbon economy.

The partnership of the company with the DOE was a strategic step in accelerating the commercialization of solid-state batteries, which promised higher energy density, enhanced safety, and longer life compared to conventional lithium-ion batteries.

On the financial front, Solid Power delivered $20.1 million in revenue during 2024, an increase of $2.7 million compared to 2023. Operating expenses were $125.5 million in 2024, up from $108.0 million in 2023, driven by increased research and development costs to improve the performance of its electrolyte and cell designs, electrolyte production, equipment purchases supporting the SK On agreements, and scaling operations, including establishing Korean operations. The operating loss for 2024 was $105.3 million, while the net loss was $96.5 million, or $0.54 per share.

“In 2025, Solid Power will continue to push the development of ASSB technology forward by improving electrolyte performance through feedback from our cell development team, executing partner requirements and customer requests, continuing to innovate on both electrolyte and cell technologies, and maintaining financial discipline while strategically investing in development and capabilities.”

– John Van Scoter, President and Chief Executive Officer of Solid Power

Solid-State Battery: Looking into the Future

The future of solid-state batteries appears exciting, replete with innovation potential. In 2024, for instance, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) developed a new lithium metal battery that could be charged and discharged at least 6,000 times — more than any other pouch battery cell — and could be recharged in a matter of minutes.

According to Xin Li, Associate Professor of Materials Science at SEAS and senior author of the paper that detailed the research and was published in Nature Materials:

“Lithium metal anode batteries are considered the holy grail of batteries because they have ten times the capacity of commercial graphite anodes and could drastically increase the driving distance of electric vehicles.”

In their research, Li and his team stopped dendrite formation by using micron-sized silicon particles in the anode to constrict the lithiation reaction and facilitate homogeneous plating of a thick layer of lithium metal. When lithium ions moved from the cathode to the anode during charging, the lithiation reaction was constricted at the shallow surface, and the ions were attached to the surface of the silicon particle without penetrating further. 

“In our design, lithium metal gets wrapped around the silicon particle, like a hard chocolate shell around a hazelnut core in a chocolate truffle.”

– Li

The coated particles formed a homogenous surface, ensuring an even distribution of current density and preventing the growth of dendrites. And because plating and stripping could happen quickly on an even surface, the battery could recharge in only about 10 minutes. 

The researchers developed a postage stamp-sized pouch cell version of the battery, 10 to 20 times larger than the coin cell made in most university labs. The battery retained 80% of its capacity after 6,000 cycles, outperforming other pouch cell batteries belonging to the same league. In the process, researchers revealed dozens of other materials that could potentially yield similar performance. According to Li:

“Previous research had found that other materials, including silver, could serve as good materials at the anode for solid-state batteries.”

To make the process universal, a team of researchers published a paper on benchmarking the reproducibility of all-solid-state battery cell performance.² The researchers observed that the interlaboratory comparability and reproducibility of all-solid-state battery cell cycling performance were poorly understood due to the lack of standardized set-ups and assembly parameters.

The researchers suggested a set of parameters for reporting all-solid-state battery cycling results and advocated for reporting data in triplicate. For instance, an initial open circuit voltage of 2.5 and 2.7 V vs. Li+/Li was a good predictor of successful cycling for cells using these electroactive materials.

Standardization of solid-state battery manufacturing is crucial because its usability is diverse. While EV manufacturers are among the most interested in developing efficient solid-state batteries, even NASA researchers reported making progress with developing an innovative battery pack that was lighter, safer, and performed better than batteries commonly used in vehicles and large electronics today. 

NASA researchers experimented with innovative new materials that had not yet been used in batteries. The team was early to realize that solid-state architecture allowed them to change battery construction and packaging, reducing weight while increasing energy storage capacity. They demonstrated that solid-state batteries could power objects at the huge capacity of 500 watt-hours per kilogram—twice that of an electric car.

“Not only does this design eliminate 30 to 40 percent of the battery’s weight, but it also allows us to double or even triple the energy it can store, far exceeding the capabilities of lithium-ion batteries that are considered to be state of the art.”

– Rocco Viggiano, principal investigator of SABERS

SABERS is an acronym for NASA’s designated activity, ‘Solid-state Architecture Batteries for Enhanced Rechargeability and Safety.’

As the name suggests, the future of solid-state batteries would thrive on these aspects of fast rechargeability and safety. Manufacturers will increasingly look for developing batteries that recharge faster without making the process unsafe.

Click here for a list of 5 best solid state battery stocks.