Researchers have made a breakthrough in detecting electrolyte leaks in lithium-ion batteries (LIBs) with a COF-based gas sensor.
Lithium-ion batteries power everything from smartphones to electric vehicles (EVs), but they come with a risk—flammable organic carbonate (OC) vapors, like ethylene carbonate (EC), can leak from compromised cells, increasing fire and explosion hazards. Detecting these vapors early is crucial, yet current sensors struggle with selectivity, size, and cost. Researchers are now turning to a cutting-edge material—covalent organic frameworks (COFs)—to develop a smarter, more effective gas sensor.
Lithium-ion batteries offer high energy density and long life, but their electrolyte solvents, such as EC, are highly flammable. When a battery is damaged or deteriorates over time, these vapors can escape, creating dangerous conditions. Battery-related fires and explosions have become more common, underscoring the urgent need for early detection systems.
Existing gas sensors are often bulky, require high operating temperatures, or lack the necessary selectivity to detect EC vapor accurately. The challenge is finding a solution that is sensitive, room-temperature operable, and compact enough for real-world applications.
COFs: The Key to a Smarter Sensor
COFs are porous, crystalline materials that can be engineered with precision, making them ideal for gas sensing. Researchers in this study used a combination of computational modeling and lab experiments to find the perfect COF for EC detection. First, they screened 612 different COFs using high-throughput simulations to evaluate their EC adsorption capabilities. The most promising candidates were then analyzed using density functional theory (DFT) to assess molecular interactions. One COF stood out—COF-QA-4, an imine-based framework with quaternary ammonium groups.
After synthesizing COF-QA-4, the team built a gas sensor and put it through rigorous testing. The sensor The sensor demonstrated impressive results, showcasing high selectivity by detecting EC vapor without interference from other gases. It exhibited strong adsorption capabilities, with a capacity of 5.88 mmol/g, and ultra-sensitivity, detecting EC at concentrations as low as 1.15 parts per million by volume (ppmv). Additionally, it delivered a fast response time, providing stable readings within just two minutes. The sensor also proved to be highly durable, maintaining its performance across multiple cycles.
The sensor’s effectiveness is attributed to partial charge transfer between EC molecules and the COF structure, enhancing accuracy and responsiveness. Beyond proof of concept, COF-QA-4 represents a breakthrough in battery safety monitoring. This approach could extend to detecting other hazardous gases, making COFs a versatile platform for future sensor technology. If implemented in consumer electronics and EVs, it could significantly reduce fire risks—an innovation with real-world impact.
References: Zhao L., Yu C., et al. (2025). Computational screening guiding the development of a covalent-organic framework-based gas sensor for early detection of lithium-ion battery electrolyte leakage. ACS Applied Materials & Interfaces, 17, 10108−10117. DOI: 10.1021/acsami.4c19321, https://pubs.acs.org/doi/10.1021/acsami.4c19321
