The fast-growing world of battery technology is expected to be worth over $100 billion in the coming years, thanks to the rising adoption of electric vehicles (EVs), the installation of various batteries, and the powering of data centers.
Among different types of batteries, lithium-ion is the most popular one, accounting for a massive 44% market share. Li-ion batteries are rechargeable batteries that are most regularly used in today’s world, powering our mobile phones, laptops, and other consumer electronics in addition to EVs and energy storage systems.
While lithium-ion batteries offer many benefits in terms of lightweight nature, high conductivity, and high energy density, they face issues with lifespan. Safety is another big challenge as they contain a volatile, liquid electrolyte, which can catch on fire if damaged or overheated.
As a result, solid-state batteries (SSB) have emerged as an alternative to liquid-state batteries (LSB), which leverage solid electrolytes to avoid leakage or gassing.
Besides greater safety, such batteries also offer the benefits of miniaturization, being lightweight, faster charging, excellent packaging efficiency, operation over a wide temperature range, and long shelf life.
Solid-state batteries aren’t a new discovery, though. They were first introduced in the 19th century, but despite being in existence for so long, they haven’t gained widespread application. That is finally changing with the growing trend of electrification and the need for better and safer alternatives to widely adopted Li-ion batteries.
Amidst the renewed interest in the technology, researchers are optimizing solid-state batteries through a multi-faceted approach that focuses on materials, structure, and interface design, along with utilizing data-driven AI techniques.
Ongoing Work on Making SSBs Better
Researchers around the world are hard at work on understanding and improving solid-state batteries to power the future. Some recent, prominent studies conducted in this field are as follows:
Decoding SSBs
Researchers from the University of Missouri took a deep dive into understanding issues with solid-state batteries and ways to overcome them to help SSBs become a reality.
They used 4D scanning transmission electron microscopy (STEM) to analyze the battery’s atomic structure without disassembling it and found the interphase layer to be the source of the problem.
In SSBs, a solid electrolyte touching the cathode leads to a reaction that forms a 100 nm thick interphase layer. While this layer is 1,000x thinner than our single hair, it blocks the seamless transfer of lithium ions and electrons, which increases resistance and hurts battery performance.
Having made this discovery, Assistant Professor Matthias Young is now planning to test whether his lab’s specialization, thin-films created by a process called oxidative molecular layer deposition (oMLD), can form protective coatings and help prevent the solid electrolyte and cathode materials from reacting with each other.
“The coatings need to be thin enough to prevent reactions but not so thick that they block lithium-ion flow,” he said. “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 the sake of compatibility.”
Exploring LLZO’s Potential as a Solid Electrolyte in SSLMB
A recent study by researchers at Tohoku University evaluated garnet-type solid electrolytes for solid-state lithium metal batteries (SSLMB), which are considered a promising technology due to their potential for improved energy performance and safety.
It found that energy density advantages expected from these batteries may actually be overstated.
As per this study, an all-solid-state lithium metal battery (ASSLMB) with the leading solid electrolyte candidate LLZO (lithium lanthanum zirconium oxide) only offers a marginal increase in energy density compared to current Li-ion batteries while incurring high production costs and dealing with manufacturing challenges.
According to the study, ASSLMB would achieve a gravimetric energy density of 272 Wh/kg compared to Li-ion’s 250-270 Wh/kg, making quasi-solid-state electrolytes more viable alternatives.
“All-solid-state lithium metal batteries have been viewed as the future of energy storage, but our study shows that LLZO-based designs may not provide the expected leap in energy density. Even under ideal conditions, the gains are limited, and the cost and manufacturing challenges are significant.”
– Lead study author Eric Jianfeng Cheng from WPI-AIMR, Tohoku University
While valued for its ionic conductivity and stability, a comprehensive modeling of a practical LLZO-based battery questioned the idea that it enhances energy density considerably. Even with an ultrathin LLZO ceramic separator and a high-capacity cathode, the study finds the battery’s performance to be only slightly better than the best conventional lithium-ion cells.
LLZO’s density is the key issue here, which increases the cell mass and reduces expected energy benefits. Then there’s the brittleness of the material, issues with lithium dendrites, problems with fabricating defect-free thin sheets, and voids at the interface, all of which complicate large-scale implementation. According to Cheng:
“LLZO is an excellent material from a stability standpoint, but its mechanical limitations and weight penalty create serious barriers to commercialization.”
Here, combining the material with gel or polymer-based electrolytes showed better long-term stability.
Discovering Promising Solid Electrolytes
Researchers from Tokyo University of Science also discovered new materials for safe, high-performance SSLIBs.
“Making all-solid-state lithium-ion secondary batteries has been a long-held dream of many battery researchers,” said Professor Kenjiro Fujimoto, who noted that they have discovered an oxide solid electrolyte, which is a key component of ASSLIBs.
The material (Li1.25La0.58Nb2O6F) is highly stable and shows total ionic conductivity of 3.9 mS cm⁻¹ at room temperature, which is higher than previously reported oxide solid electrolytes, while having extremely low activation energy.
Moreover, if damaged, it will not ignite, making the new material suitable for applications where safety is critical. Usable under high temperatures and supporting rapid recharging also makes it appropriate for high-capacity applications like EVs.
“The application of this material is promising for the development of revolutionary batteries that can operate in a wide range of temperatures, from low to high.”
– Prof. Fujimoto
Meanwhile, late last year, researchers from the Osaka Metropolitan University developed Na2.25TaCl4.75O1.25 as a new solid electrolyte.
The researchers had previously developed the solid electrolyte NaTaCl6, which is a combination of sodium chloride and tantalum chloride. This time, the team added tantalum pentoxide (Ta2O5) to it, which helped them achieve high conductivity at room temperature.
It also exhibits high formability as well as higher electrochemical stability than conventional chlorides.
“The results of this research are expected to make a significant contribution to the development of composite solid electrolytes, in addition to the glass and crystal solid electrolytes that have been developed to date.”
– Assistant Professor Kota Motohashi of the Graduate School of Engineering
They are now focusing on illustrating the ionic conduction mechanism of composite solid electrolytes as well as developing more materials.
Changing the Structure, Removing the Components
University of Illinois Urbana-Champaign researchers, meanwhile, found that helical structure significantly boosted the conductivity of solid-state peptide polymer electrolytes compared to “random coil” counterparts, with longer helices leading to higher conductivity. Additionally, the helical structure increases the material’s overall stability to voltage and temperature.
“We introduced the concept of using secondary structure – the helix – to design and improve upon the basic material property of ionic conductivity in solid materials.”
– Study lead Professor Chris Evans
This is the same helix found in peptides in biology. Being made from peptides means that once the battery reaches the end of its useful life, the material can be degraded back into individual monomer units using acid or enzymes, and the starting materials can then be recovered and reused, making it environmentally friendly.
In yet another interesting study, researchers created the first anode-free sodium solid-state battery with stable cycling for several hundred cycles. The inexpensive, high-capacity, fast-charging battery can help decarbonize the economy.
Removing the anode required an innovative architecture, so the team created a current collector using aluminum powder, which, while solid, can flow like a liquid, that surrounded the electrolyte.
“Sodium solid-state batteries are usually seen as a far-off-in-the-future technology, but we hope that this paper can invigorate more push into the sodium area by demonstrating that it can indeed work well, even better than the lithium version in some cases.”
– First author Grayson Deysher, a UC San Diego PhD candidate
Time to Use AI to Find the Best Solid Electrolyte Candidates Fast
Amidst this extensive ongoing research into different aspects of solid-state batteries, especially electrolytes, to make them better to help drive their adoption, scientists are now making use of artificial intelligence.
Electrolyte is one of the most crucial battery components. It transfers charge-carrying particles called ions back and forth between the battery’s two electrodes, causing the battery to charge and discharge.
Hence, the focus is on improving the solid-state electrolyte (SSE) performance, which involves enhancing ionic conductivity, stability, and cycle life. However, limitations of current materials have made it difficult to achieve these improvements.
Overcoming these challenges needs the development of high-performance SSE materials, which will unlock the full potential of solid-state batteries.
Metal oxides and sulfides are some of the most widely studied materials as promising SSEs. Here, looking into hydrides as SSEs that show high redox and mechanical stability and average divalent ionic conductivity at ambient temperature is particularly beneficial.
With their high ionic conductivity and low activation energy, hydrides have shown great promise in SSE development. Metal hydrides, meanwhile, offer distinct benefits because of the light mass of hydrogen atoms.
However, the light weight of hydrogen and the complex behavior of divalent hydrides present challenges in synthesis and structural characterization, highlighting the limitations in current experimental techniques.
The challenge here is that experimental SSE discovery depends on inefficient, time-consuming trial-and-error methods. To address this, we need computation-assisted research to understand ionic migration mechanisms and discover new solid-state electrolytes.
The thing is, theoretical approaches tend to offer more systematic and faster ways to explore material properties. Then there are advancements in large language models (LLMs), which are further enhancing data-driven methodologies and improving theoretical predictions.
Still, getting high accuracy in theoretical methods is challenging because of the complexity of the SSE materials. The focus of current research on a single material or method also limits the comprehensive understanding of SSEs.
So, how can we better use theoretical insights to design more efficient experiments? Also, what kind of optimal workflow seamlessly combines theoretical modeling with experimental validation? The answer lies in combining computational and experimental information.
In order to get past the obstructions with divalent SSEs, which show significant promise for high-performance All-Solid-State-Batteries (ASSBs), researchers in a new study developed an integrated workflow that combines data mining, AI-driven analysis, machine learning regression, global structure search, ab initio metadynamics (MetaD) simulations, and theory-experiment benchmarking.
This research aims to improve our understanding of divalent SSEs and provide a robust framework to predict and design new SSE candidates. In turn, it will accelerate the discovery of optimized SSE options to advance viable energy storage technologies.
Click here to learn about Princeton’s game-changing solid-state battery tech.
Towards Next-Gen SSBs for Sustainable Energy Solutions
To successfully build more powerful and sustainable solid-state batteries, the researchers at Tohoku University have built a data-driven AI framework1.
Unlike the traditional approach, which involves testing each material and then setting pathways one by one, this framework identifies potential solid-state electrolyte (SSE) candidates that could be “the one” to create the ideal sustainable energy solution.
The model developed not only selects optimal candidates but can also forecast how the reaction will occur. Moreover, it tells why a particular candidate is a good choice by providing insights into potential mechanisms, helping researchers get started even before they enter the lab.
Professor Hao Li of the Advanced Institute for Materials Research noted:
“The model essentially does all of the trial-and-error busywork for us. It draws from a large database from previous studies to search through all the potential options and find the best SSE candidate.”
The advanced AI framework from the team integrates with the Large Language Model (LLM), a type of machine learning model that is pre-trained on vast amounts of data. LLMs are known for their great ability to process, understand, and generate human language.
By incorporating other data-driven techniques, the predictive model draws from both computational and experimental data. This way, the study provides researchers with a solid option that has the most successful outcome.
Besides helping speed up the journey of developing high-performance, sustainable solid-state batteries, the study also aims to understand the complex structure-performance relationships of SSEs. This relationship covers factors like ionic conductivity, stability, and compatibility with electrodes and is often investigated through computational modeling, experimental analysis, and data-driven approaches.
The model built by the team further predicts activation energies, pins down stable crystal structure, and enhances the overall workflow of researchers. The study findings show MetaD to be a superb computational method, demonstrating substantial agreement with experimental data for complex hydride SSEs.
Researchers have also identified a new ion transfer system. The “two-step” mechanism is discovered in both SSEs that arise from the integration of neutral molecules.
So, by combining feature analysis with multiple linear regression, the team was able to successfully develop precise predictive models for the rapid evaluation of hydride SSE performance. More importantly, the framework enables accurate prediction of candidate structures without depending on experimental inputs.
Overall, the study provides great insights as well as advanced methodologies for the efficient design and optimization of next-generation solid-state batteries.
But these are just the initial steps towards building sustainable energy solutions, with the team planning to extend their framework’s application across diverse electrolyte families. The team actually expects generative AI tools to be useful in investigating ion migration pathways and reaction mechanisms, enhancing the platform’s predictive capacity.
Investing in the Solid State Batteries Market
When it comes to an investable company in the advancing solid-state battery market, QuantumScape is at the forefront, as a major player with a focus on lithium-metal technology. Its proprietary solid-state ceramic separator is designed to enhance energy density, charging speed, and safety while preventing critical issues like dendrite formation, which has been restricting lithium-metal anode adoption.
QuantumScape Corporation (QS -0.51%)
Developing SSB technology for EVs and aiming to become an original equipment manufacturer (OEM), QuantumScape Corporation has already secured partnerships with major automaker Volkswagen Group and its subsidiary, PowerCo.
While facing challenges in commercialization, QuantumScape remains a big name in the space. Last year, it started producing samples of its various SSB products and plans to make even more this year.
QuantumScape Corporation (QS -0.51%)
With a market cap of $2.2 bln, QS shares are currently trading at $3.90, down over 25% YTD. Its EPS (TTM) is -0.91, and P/E (TTM) is -4.30.
For Q1 2025, the company reported $5.8mln in capital expenditures, GAAP operating expenses of $123.6M, and a GAAP net loss of $114.4M. It ended the quarter with $860.3mln in liquidity, with the cash runway expected to last into the second half of 2028.
This year, the company aims to bring the Cobra separator process into baseline production, enhance QSE-5 samples’ quality and output, and ship QSE-5 cells to demonstrate its exceptional performance capabilities in a real-world application.
Latest on QuantumScape Corporation
Conclusion
With batteries playing a key role in powering electronics, EVs, and energy systems, there is a need for the development of next-generation energy materials in order to create a sustainable future. While solid-state batteries offer a promising solution, their development is facing significant technical challenges. What SSB development needs is to improve the solid-state electrolyte (SSE) performance.
Hence, the intense research surrounding SSEs, which is all set to accelerate at a greater pace thanks to the new data-driven AI model. Powered by vast datasets and advanced simulation techniques, the framework helps researchers identify and optimize SSEs with unprecedented speed and accuracy. This convergence of materials science and machine learning showcases huge potential in delivering high-performance and sustainable solid-state battery solutions to power the clean energy future.
Click here for a list of top solid-state battery stocks.
Studies Referenced:
1. Wang, Q., Yang, F., Wang, Y., Zhang, D., Sato, R., Zhang, L., Cheng, E. J., Yan, Y., Chen, Y., Kisu, K., Orimo, S., & Li, H. (2025). Unraveling the complexity of divalent hydride electrolytes in solid-state batteries via a data-driven framework with large language model. Angewandte Chemie International Edition, 64(22), e202506573. https://doi.org/10.1002/anie.202506573