Researchers have recently reported a significant advance in detecting electrolyte leakage in lithium-ion batteries (LIBs) using a gas sensor built on covalent organic frameworks (COFs).
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The team focused on the early detection of organic carbonate (OC) vapors—especially ethylene carbonate (EC)—due to the heightened fire and explosion risks posed by compromised battery cells. Current detection methods for these gases in devices like smartphones and electric vehicles are limited, highlighting the urgent need for sensors that are effective, affordable, and operable at room temperature. This study presents a combined computational and experimental approach to identify COFs that are selectively responsive to EC vapor.
Background
Lithium-ion batteries are prized for their energy density and long life, but the chemicals that make them work also come with risks. Organic carbonate solvents like EC are flammable, and when a battery cell is damaged or degrades over time, these vapors can leak out.
And this isn’t just theoretical. In 2021 alone, a number of lithium-ion battery failures led to fires and explosions. Clearly, early warning systems are overdue.
The problem is that most current gas sensors either aren’t selective enough, operate at high temperatures, or are too bulky for real-world integration in compact electronics and electric vehicles. So the challenge is finding something that's highly selective, sensitive, works at room temperature, and can be made small enough to fit into portable tech.
The Solution: A Smarter Sensor with COFs
That’s where COFs come in. These are a class of porous, crystalline materials that can be engineered with great precision—down to the size and shape of their pores. That tunability makes them excellent candidates for gas sensing.
In this study, the researchers combined computational modeling with hands-on experiments to find a COF that could reliably detect EC vapor. First, they ran high-throughput simulations using a database of 612 different COFs. They looked at how well each material could adsorb EC, based on factors like pore size, surface area, and selectivity against other gases.
Once they narrowed the field, they used density functional theory (DFT) calculations to understand the chemistry between the EC molecules and the COFs. That led them to a standout candidate: COF-QA-4COF-QA-4, an imine-based COF with quaternary ammonium groups.
Putting It to the Test
After identifying COF-QA-4, the team synthesized it in the lab and built chemo resistive gas sensors using the material. Then they put the sensors through their paces.
In terms of the results, COF-QA-4 showed a strong affinity for EC vapor, with an adsorption capacity of 5.88 mmol/g. It was also highly selective—meaning it didn’t get thrown off by other gases. Even more impressive, the sensor could detect EC at levels as low as 1.15 parts per million by volume (ppmv), and it delivered a stable reading within just two minutes. Better yet, it kept working across multiple cycles.
The key to its performance lies in partial charge transfer between the EC molecules and the COF framework—basically, a kind of molecular handshake that makes the sensor more responsive and accurate.
What’s really exciting about this work is how it blends simulation and experimentation to speed up material discovery. Instead of randomly trying out materials in the lab, the researchers used data-driven screening to focus only on the most promising candidates—saving time, resources, and a lot of trial and error.
More importantly, COF-QA-4 isn’t just a proof of concept. It’s the first COF-based sensor developed specifically for detecting EC vapor, and it could be a game-changer for real-time battery safety monitoring.
The team also points out that the flexibility of COFs means this approach could extend to other gases and sensing applications. Whether it’s industrial leak detection, environmental monitoring, or improving the safety of next-gen batteries, COFs offer a customizable platform that traditional sensors just can’t match.
Wrapping Up
So, what does this all mean for the average person using a phone or driving an EV? Hopefully, safer batteries and fewer fire risks in the future. By catching leaks early—and accurately—COF-based sensors like COF-QA-4 could become an essential part of the battery safety toolkit.
The combination of smart materials, clever chemistry, and advanced simulations opens the door to a faster, more efficient way to develop gas sensors. And that’s good news for everyone.
Journal Reference
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