Polymer Lithium Will Win The Solid-State Battery Race?
| Jerry Huang
Editor's note: There are four electrolyte types for solid-state lithium batteries: polymer, oxide, sulfide, and halide, each with distinct characteristics:
Polymer Lithium Electrolytes
Utilizing polymer materials as electrolytes, these offer both flexibility and high ionic conductivity, making them suitable as a transitional solution for semi-solid batteries. They exhibit good processability, though long-term cycling stability remains to be validated.
Lithium Oxide Electrolytes
Based on materials like lithium oxide, these electrolytes offer lower cost and good stability but exhibit relatively low ionic conductivity.
Lithium Sulfide Electrolytes
Centered on lithium sulfide compounds, these electrolytes feature high room-temperature conductivity and excellent interface compatibility, positioning them as the most commercially promising technology among all. However, sulfide materials suffer from poor chemical stability and high production costs.
Lithium Halide Electrolytes
Halide solid-state electrolytes exhibit high conductivity and oxidation resistance, but it remains in the laboratory level with unclear commercialization prospects.
Common Features
All-solid-state batteries replace traditional liquid electrolytes with inorganic powder materials, significantly enhancing safety and energy density. However, different technical routes exhibit substantial differences in cost and process maturity. For instance, while the sulfide route offers high conductivity, it suffers from poor chemical stability, whereas the polymer route faces challenges in cycle life performance.
Solid-state battery technology is now undergoing a critical transition from laboratory prototypes to industrialization, which is strongly looking forward to a systematic overhaul of its evaluation framework. The laboratory phase primarily focuses on electrochemical performance metrics (such as energy density, cycle life, and rate capability), while industrial-scale solid-state battery technology requires the establishment of multidimensional evaluation criteria:
Expanded Evaluations: Industrial applications must involve systemic factors including: scalability feasibility (involving process compatibility, yield control, etc.), supply chain maturity (encompassing critical raw material stability, specialized equipment support capabilities, etc.), and total lifecycle cost (covering raw material procurement, manufacturing, recycling, etc.);
Technology-Cost Optimization: Industrialization demands an optimal balance between technical data and cost, including dynamic balance between electrochemical performance and manufacturing costs; impact of material system selection and its supply chain resilience; and balance between production process complexity and scalability;
Systematic evaluation: Compliance with key requirements including mass production consistency (6σ quality control standard), safety certifications (e.g., compliance with UL 9540A and other international standards), and single-line production capacity design ≥2GWh, etc.
Professor Guo has a different view for polymer lithium's winning on solid-state battery race over lithium sulfide electrolytes. Let's take a look at the research from Xin Guo team. Thanks so much to those great efforts from all researchers.
Abstract
Solid-state batteries (SSBs) promise to revolutionize energy storage by offering enhanced safety, higher energy density, and improved cycle lifespan over conventional lithium-ion batteries. Among the various solid electrolytes, polymers stand out for their unique combination of processability, mechanical compliance, and chemical versatility. This review explores why polymers are poised to lead the race toward commercial SSBs. Their intrinsic advantages—such as superior interfacial contact with electrodes, tunable ionic conductivity, and compatibility with scalable manufacturing methods—as well as the key technical challenges they face, including limited thermal stability, narrow electrochemical windows, and interfacial degradation, are examined. This study highlights emerging solutions from recent research, including polymer molecular design, polymer–ceramic composites, and in situ polymerization strategies. In contrast to oxide and sulfide systems, which face significant barriers in cost, manufacturability, and integration, polymer-based electrolytes offer a realistic and economically viable path to large-scale deployment. With continuing advances in materials design and industrial processing, polymers are not only competitive—they are leading the transition to next-generation solid-state batteries.
References
https://doi.org/10.1002/advs.202510481