New battery technologies are proliferating as demand for safe and efficient energy storage solutions increases. Solid-state batteries (SSBs) represent a major advancement in energy storage technology with the potential to overcome several limitations of traditional lithium-ion batteries (LIBs). By replacing flammable liquid or gel electrolytes with solid materials such as ceramics, polymers, or sulfides, solid-state batteries offer enhanced safety, superior thermal stability, and significantly higher energy densities, reaching up to 500 Wh/kg compared to 250 Wh/kg in conventional systems. The presence of a solid electrolyte not only enables the use of lithium metal anodes and high-capacity cathodes but also mitigates risks of high flammability, dendrite formation, electrolytic decomposition at high voltages, and leaks that plague liquid electrolyte-based batteries.
With the ability to last over 1,000 cycles — compared to 500 cycles in typical LIBs — solid-state batteries also promise longer lifespans. Their smaller footprint and potential for more compact design than LIBs make them ideal for use in electric vehicles (EVs), wearable electronics, medical devices like pacemakers, and aerospace applications.
We examined the CAS Content CollectionTM, the largest human-curated repository of scientific information, to better understand the research landscape of solid-state batteries, and we found a clear shift from early-stage research to widespread scientific and commercial interest (see Figure 1).
Figure 1: Publication trends in the field of solid-state batteries. Data for 2025 is through July. Source: CAS Content Collection.
In the early 2000s, activity was minimal, indicating that solid-state batteries were limited to fundamental research. However, around 2017, academic papers and patents rose sharply, reflecting growing technological maturity, market demand, and recognition of this technology as a solution to key limitations of conventional lithium-ion batteries.
Now, the slightly higher number of patents suggests that the field is moving beyond academic research toward commercial readiness, with companies securing intellectual property. The sharp growth of patents in recent years reflects urgent demand driven by the increase in EVs, grid-level storage of renewable energy, and the need for safer, high-performance energy solutions. Current momentum indicates that solid-state batteries have reached a critical point of research and investment, often seen just before major breakthroughs and widespread adoption.
Asia leads in global battery innovation
To evaluate commercialization efforts within the SSB sector, we identified the top 15 companies based on their patenting activity (Figure 2a). Japanese firms such as Toyota and Panasonic lead with extensive patent portfolios, reflecting Japan’s early strategic investment in SSB technology and its strong alignment with the automotive industry. The presence of other major Asian companies such as LG Chem, Samsung SDI, and CATL further reinforces Asia’s leadership in global battery innovation (see Figure 2a).
The trends of commercial patent activity across countries reveal shifting innovation dynamics in the SSB field (Figure 2b). While Japan has maintained steady leadership through consistent investment and long-term research, China’s rapid rise in recent years marks a significant shift. This surge is driven not only by established firms but also by a wave of new entrants actively filing patents.
In contrast, the relatively lower patent activity from the United States and Germany, despite their strong automotive and tech industries, suggests differing strategic priorities or alternative approaches to intellectual property protection in the SSB domain.
Figure 2a: Leading commercial entities identified by their number of patent publications related to solid-state batteries. The inset pie chart shows the volume of commercial patents published by countries/regions.
Figure 2b: Yearly trends for commercial patent publications for the leading countries/regions.
Advantages of solid-state electrolytes
Solid-state electrolytes (SSEs) are the core component of solid-state batteries (SSBs), functioning as ion-conducting solids that replace traditional liquid electrolytes. They enable the transport of lithium ions or other metal ions between the battery’s electrodes while physically separating them, ensuring both ionic conductivity and electrical insulation.
A noteworthy characteristic of solid-state electrolytes is their capacity to facilitate ion transport through crystallographic sites, where mobile ions can behave like fluid phases within a solid matrix. This structural feature underpins their high ionic mobility, which is essential for efficient battery performance. Solid-state electrolytes also offer significant advantages over liquid systems, including nonflammability, non-volatility, superior mechanical strength, and resilience under extreme temperatures. These features not only enhance safety and stability but also support the use of lithium metal anodes, which can dramatically increase energy density and battery lifespan.
Solid-state electrolytes can be broadly categorized into five main types based on their chemical composition: oxides, sulfides, polymers, nitrides, and halides. Each type exhibits distinct structural and electrochemical characteristics that influence their performance. Both organic and inorganic solid-state electrolytes have been extensively studied in recent years, leading to significant improvements in ionic conductivity, stability, and compatibility with electrodes.
Our analysis of the CAS Content Collection with tools including CAS SciFinder® illustrates the top 20 solid-state electrolytes categorized by type (Figure 3a) and year (Figure 3b). Among these, inorganic electrolytes, mainly oxides and sulfides, are leading in the publication landscape due to their superior ionic conductivity, enhanced safety, long cycle life, and excellent thermal stability.
Figure 3a: Top 20 solid-state electrolytes categorized by type within publication volume. Source: CAS Content Collection. See footnote for abbreviations.
Figure 3b: Top 10 solid state electrolytes categorized by year within publication volume. Source: CAS Content Collection. See footnote for abbreviations.
Oxide-based solid-state electrolytes
Oxide-based solid-state electrolytes (SSEs) are widely studied for next-generation solid-state batteries due to their excellent chemical, thermal, and electrochemical stability. These electrolytes are air- and moisture-stable, making them easier to handle and process. They can also withstand high operating voltages and temperatures without decomposition.
As shown in Figure 3, leading types of oxide solid state electrolytes include lithium lanthanum zirconium oxide, garnet-type (LLZO) , lithium aluminum titanium phosphate, NASICON-type (LATP), and lithium lanthanum titanium oxide, perovskite-type (LLTO), all offering high ionic conductivity (typically 10⁻⁴ to >10⁻³ S/cm) and robust mechanical properties. LLZO provides a wide electrochemical stability window and good compatibility with lithium metal, while LATP is non-toxic, cost-effective, and suitable for hybrid systems. LLTO offers high conductivity and strong mechanical strength, though its performance depends on ceramic microstructure.
Despite their promise, oxide-based electrolytes have several limitations. Their brittle and rigid structure make it difficult to process and achieve intimate contact with electrodes, often leading to high interfacial resistance and poor ionic transfer. This brittleness also makes them vulnerable to cracking under mechanical stress or volume changes during cycling. Additionally, their room-temperature conductivity is generally lower than that of sulfide-based electrolytes.
LLZO technology can suffer from moisture sensitivity and lithium dendrite formation, while LATP and LLTO are unstable in direct contact with lithium metal due to Ti⁴⁺ reduction. These issues can lead to short circuits, although they can be mitigated through interface engineering and protective coatings. Overall, oxide electrolytes are valued for their outstanding stability, safety, and compatibility with high-voltage cathodes, making them strong candidates for durable and thermally stable solid-state lithium battery systems.
Sulfide-based solid-state electrolytes
Sulfide-based electrolytes are among the most promising materials for next-generation solid-state batteries because of their exceptionally high ionic conductivity, which can reach up to 10⁻² S/cm, comparable to or even exceeding that of liquid electrolytes. Their structures, typically containing sulfur-based anions like PS₄³⁻, create a highly polarizable and flexible lattice that allows fast lithium-ion migration.
Another major advantage of sulfide electrolytes is their soft and deformable nature, which enables them to form excellent interfacial contact with cathodes and anodes under mild pressure: something difficult to achieve with brittle oxide electrolytes. They can also be processed at low temperatures, making large-scale fabrication feasible.
As seen in Figure 3a, among sulfide-based electrolytes, argyrodites, lithium-phosphorous-sulfur (Li-P-S) and lithium germanium phosphorus sulfide (LGPS) are leading candidates for solid-state batteries. Argyrodites (Li₆PS₅X, X = Cl, Br, I) and Li–P–S systems (e.g., Li₃PS₄, Li₇P₃S₁₁) offer conductivities ranging from 10⁻⁴ to >10⁻³ S/cm, while LGPS (e.g. Li₁₀GeP₂S₁₂), a thio-LISICON material, reaches up to 10⁻² S/cm, rivaling liquid electrolytes.
Despite these benefits, sulfide-based electrolytes also face critical challenges. They are highly sensitive to air and moisture, decomposing to release toxic hydrogen sulfide (H₂S) gas, which complicates handling and processing. Their electrochemical stability window is narrow, leading to undesirable reactions at high-voltage cathodes and lithium metal anodes, which form resistive interphases and degrade performance over time. Nonetheless, with continued improvements through doping, surface coatings, and composite engineering, sulfide-based solid-state electrolytes remain at the forefront of research for achieving high-performance, safe, and energy-dense solid-state lithium batteries.
Polymer-based solid-state electrolytes
Polymer-based electrolytes are used in solid state batteries because they offer a unique combination of flexibility, processability, and safety that inorganic electrolytes often lack. Unlike brittle oxide electrolytes, polymer electrolytes are soft and deformable, allowing them to form intimate contact with electrodes. They also enable thin, lightweight, and flexible battery designs, which are ideal for wearable and portable electronics.
Among polymer-based solid-state electrolytes, polyacrylonitrile (PAN), hexafluoropropylene- polyvinylidene fluoride (HFP-PVDF), and poly(methyl methacrylate) (PMMA) are leading materials. However, their ionic conductivity is generally lower than that of inorganic electrolytes, especially at room temperature, and they may suffer from limited electrochemical stability at high voltage. Their excellent flexibility, interfacial compatibility, and scalability still make polymer-based electrolytes an attractive and practical choice for solid-state and flexible lithium battery applications.
[H3]: Nitride- and halide-based solid-state electrolytes
Nitride- and halide-based electrolytes are emerging classes of materials explored for high-performance all-solid-state LIBs due to their high ionic conductivity and favorable electrochemical stability. As seen in Figure 3b, lithium nitride (Li₃N) and LiXO (X= Cl, Br, I) are the only nitrides and halides, respectively, in the top 20 solid-state electrolytes based on publication trends.
Li₃N offers exceptionally fast lithium-ion transport, with conductivities up to 10⁻³ S/cm at room temperature, because of its open crystal structures that provide continuous pathways for Li⁺ migration. They are also thermally stable and compatible with lithium metal anodes. LiXO is generally combined with other solid electrolytes or polymers to improve interfacial contact and mechanical flexibility.
These materials also face notable drawbacks. Nitride- and halide-based solid-state electrolytes are highly reactive with moisture and air, producing toxic and corrosive byproducts like ammonia and HCl, which complicates handling and processing. Despite these limitations, nitride and halide electrolytes remain promising avenues for developing high-energy-density, and thermally robust solid-state lithium batteries, particularly when incorporated into composite electrolyte systems.
Argryodites emerge as the leading solid-state electrolyte technology
We further analyzed the publication trends for the top 10 solid-state electrolyte materials, and it revealed a fascinating shift in research focus in just the last few years (see Figure 3b). LLZO garnet-type electrolytes dominated the field until recently, attracting sustained attention from the research community due to their excellent stability against lithium metal and wide electrochemical window. However, a dramatic transformation occurred in 2021, with sulfide-based argyrodites experiencing an explosive surge in research interest that has propelled them past LLZO to become the most studied solid electrolyte system in 2024.
This remarkable ascent of argyrodites reflects several fundamental advantages that have become apparent to researchers. While LLZO requires extremely high sintering temperatures and struggles with interfacial contact issues due to its ceramic nature, argyrodites offer mechanical ductility that enables intimate contact with electrode materials through simple cold pressing. The sulfide framework provides ionic conductivities that significantly exceed those of oxide-based systems at room temperature, addressing one of the critical bottlenecks for solid-state battery commercialization.
Furthermore, the processing compatibility of argyrodites with existing battery manufacturing infrastructure has made them attractive for industrial-scale usage; they can be processed at moderate temperatures and even through solution-based methods. Meanwhile, other solid electrolyte systems like LATP and polymer-based electrolytes continue to attract steady but more modest research attention, suggesting that while these materials remain relevant, the field has identified argyrodites as offering the most promising near-term path toward practical solid-state batteries.
Leading combinations of solid-state materials
Our analysis of the publication landscape also explored different types of solid-state batteries (SSBs) and the top solid-state electrolytes (SSEs) associated with them (see Figure 4). LIBs dominate the landscape with the highest volume of documents, representing approximately 80% of all research activity for solid-state batteries. The nearly equal split between journal publications and patent families indicates a mature field transitioning from fundamental research toward commercialization.
Figure 4: Distribution of solid-state battery research across different battery chemistries and associated solid-state electrolytes. Individual pie charts indicate the proportion of journal (J) and patent (P) publications for the respective batteries. Heat map tables show the most prevalent solid-state electrolytes associated with their respective solid-state batteries. Source: CAS Content Collection. See footnotes for abbreviations.
The top solid-state electrolytes for lithium systems show interesting diversity. The oxide-based electrolytes LLZO and LATP receive the highest attention, followed by polymer electrolytes like PAN, sulfide-based argyrodites, and Li-P-S systems. This variety suggests the field hasn't converged on a single winning technology, with different solid-state electrolytes being explored for various application requirements.
Sodium-ion solid-state batteries come second in document volume, though they are still trailing lithium systems significantly. The patent-to-journal ratio favors journal publications slightly, indicating this field remains more research-focused than commercially driven. The electrolyte preferences for sodium systems show notable differences from lithium: NaZPSi (sodium super ionic conductor) leads the pack, while polymer electrolytes (PAN, PMMA) feature prominently. Some lithium-focused electrolytes like LATP and LLZO are also present, suggesting researchers are exploring cross-compatibility between systems.
Zinc-ion batteries represent the third significant player, showing a much higher proportion of journal publications compared to patents. This journal-heavy distribution suggests zinc solid-state batteries are still in the fundamental research phase, with researchers working to understand and optimize these systems before commercial development. The solid-state electrolyte landscape for zinc batteries is dominated by polymer electrolytes (PAN, PEO, PMMA), which makes sense given zinc's compatibility with aqueous and quasi-solid systems.
Emerging battery chemistries like magnesium and potassium show balanced research and patent activity despite lower overall numbers, indicating early stage but promising development. These systems could represent future alternatives as researchers seek to diversify beyond lithium, particularly for specific applications where their unique properties offer advantages.
The heat map intensities across different electrolytes, shown in Figure 4, reveal that while certain electrolytes show versatility across multiple battery types, others remain chemistry specific. This highlights the importance of tailored solid-state electrolyte development for each battery system's unique requirements.
Patent trends show promising applications for solid-state batteries
Our analysis of publication volumes across application sectors for solid-state batteries (SSBs) reveals distinct patterns in research focus and commercialization maturity (see Figure 5).
Figure 5: Number of journal publications and patents for solid-state battery applications. Source: CAS Content Collection.
Electronics and vehicles clearly dominate the field, representing approximately 75% of all application research. However, their development trajectories differ significantly. Electronics shows a notable gap between journal publications and patents, suggesting ongoing fundamental research challenges in adapting these batteries for consumer electronics. This could be related to miniaturization, cost, or manufacturing complexity. In contrast, the vehicle sector displays remarkable parity between publications and patents. Such findings indicate a mature field transitioning from laboratory to market, driven by the growth of EVs and the urgent need for safer, higher energy-density batteries.
Emerging application sectors show promise but remain predominantly research focused. Biomedical applications demonstrate substantial academic interest with limited patent activity, suggesting researchers are still exploring fundamental feasibility rather than pursuing commercialization. This could reflect the stringent regulatory requirements and biocompatibility challenges unique to medical devices.
Wearables show an even more pronounced research-to-patent gap, indicating that while the concept of flexible, safe solid-state batteries for wearable technology is academically intriguing, significant technical hurdles remain before commercial viability.
The aerospace sector features a nearly equal distribution of journal articles and patents. This balanced ratio, despite a lower overall volume of documents, mirrors the pattern observed in the vehicle sector. It suggests active commercial engagement driven by several compelling technical advantages of solid-state batteries in aerospace applications, such as nonflammability and better performance at high altitudes.
Challenges and opportunities with solid-state batteries
Although solid-state batteries (SSBs) show great promise, several challenges prevent them from achieving large-scale commercialization. A major technical limitation is the relatively low ionic conductivity of many solid electrolytes at room temperature compared to liquid ones. Oxide-based electrolytes like LLZO require high sintering temperatures for dense microstructures, making processing complex and costly. Sulfide electrolytes offer high conductivity but are sensitive to air and moisture, necessitating inert conditions.
Another challenge is instability at the electrode–electrolyte interfaces. Unlike liquid electrolytes, solid–solid contact often results in poor interfacial contact and high resistance. Chemical reactions at these interfaces can form resistive layers, especially with lithium metal, worsening over cycles and degrading performance. The mechanical rigidity of solid electrolytes further contributes to stress, gaps, and delamination during volume changes, increasing impedance and performance decay.
Lithium dendrite formation remains a concern, as lithium filaments can propagate through microstructural defects in solid-state electrolytes under high current densities, causing short circuits. Additionally, large-scale production is costly — processing these materials requires high temperatures, high pressure, precise engineering, and dry conditions (especially for sulfides). These material and integration challenges, along recyclability issues and immature supply chains, hinder the transition from lab-scale prototypes to industrial-scale solid-state batteries.
Despite these hurdles, solid-state batteries are evolving toward a future where materials design, interface engineering, and scalable processing converge to deliver safer, denser, and longer-lasting energy storage. The next generation of these batteries will feature hybrid and composite electrolytes that combine the high conductivity of ceramics with the flexibility of polymers, ensuring stable interfaces and mechanical integrity during cycling. Advances in low-temperature fabrication, such as cold sintering and transient-liquid-assisted processing, will make manufacturing more efficient and compatible with large-scale production.
Recent prototypes reflect this momentum: Chery has unveiled a solid-state battery module with an energy density of 600 Wh/kg targeting 1,300 km range, more than double that of conventional lithium-ion batteries. Similarly, Sunwoda introduced a polymer all solid-state battery with 400 Wh/kg and a cycle life of 1,200 cycles under ultra-low pressure. This could give EVs ranges over 1,000 km and 1,200 cycles, enabling more than a decade of use, assuming annual driving of 20,000 km.
Meanwhile, data-driven approaches and AI-assisted materials discovery will accelerate optimization and quality control in this field. Beyond lithium, solid-state conceptsextend to other metal ions such as sodium, zinc, magnesium, and potassium systems, broadening sustainability and resource accessibility. These continuous advancements and hybrid approaches are steadily closing the performance gap between traditional battery technology and new solid-state options.
Though full-scale deployment may still be years away, the convergence of scientific and industrial advances indicates that solid-state batteries are on track to reshape energy storage across industries in the coming decade.
Abbreviations used: LLZO, Lithium Lanthanum Zirconium Oxide; LATP, Lithium Aluminum Titanium Phosphate; LLTO, Lithium Lanthanum Titanium Oxide; LiPON, Lithium Phosphorus Oxynitride; LAGP, Lithium Aluminum Germanium Phosphate; NaZPSi, Sodium Zirconium Phosphate Silicate; GLiZnO, Germanium Lithium Zinc Oxide; Li-P-S, Lithium-Phosphorous-Sulfur; LGPS, Lithium Germanium Phosphorus Sulfide; LSnPS, Lithium Tin Phosphorus Sulfide; Na-P-S, Sodium-Phosphorous-Sulfur; PAN, Polyacrylonitrile; HFP-PVDF, Hexafluoropropylene-Poly(vinylidene fluoride); PMMA, Polymethyl Methacrylate; PEO, Polyethylene Oxide; PC , Polycarbonate; PDMS, Polydimethylsiloxane
