CPCM Optimizes Battery Performance and Longevity

Researchers from North China Electric Power University presented a Composite Phase Change Material (CPCM) made of expanded graphite (EG) and Na₂SO₄-10H₂O in a study published in the journal Energy Storage and Saving.

Lithium-ion batteries (LIBs) are important for electric vehicles and energy storage systems due to their high energy density and stable operation. However, they are sensitive to temperature and can experience thermal runaway when charged quickly. Conventional thermal management systems often require complex and costly cooling solutions that may fail under extreme conditions.

Composite phase change materials (CPCMs) offer a passive thermal management solution to address these issues, helping to improve battery performance and safety in challenging environments.

This hydrated salt material increases thermal conductivity, facilitating efficient heat absorption and release. The CPCM uses a two-stage temperature management approach to reduce overheating, lowering peak LIB temperatures from 66 °C to 34 °C during normal use. Its melting point is 29 °C. Additionally, by delaying the onset of thermal runaway events, this passive method provides time for cooling measures to take effect.

By absorbing energy through high-latent-heat phase transitions and maintaining stability through improved thermal conductivity, the CPCM's two-stage temperature management effectively controls LIB heat.

Important characteristics such as a high latent heat (183.7 J·g−1), an excellent melting point, and robust thermal conductivity (3.926 W·m−1·K−1) support consistent temperature decreases. Under typical circumstances, it keeps LIB temperatures within acceptable bounds by absorbing peak heat produced by high-rate discharges.

During thermal runaway situations, the dehydration phase of the material extends the time to critical temperatures by up to 187 seconds. Additionally, the CPCM design addresses phase separation issues that have affected conventional thermal management materials.

CPCM-10 % EG has demonstrated long-term stability and effective temperature control in high-stress applications based on tests conducted under cyclic and dynamic conditions.

Effective temperature control is vital for preventing failures in high-demand applications like electric vehicles. This CPCM offers a unique, energy-efficient solution that reduces dependency on complex active systems and bolsters battery safety. Its dual-stage control demonstrates strong potential as a passive thermal safeguard, especially in cases where active management might be unreliable or too costly.

Dr. Xing Ju, Study Lead Researcher, North China Electric Power University

This development in CPCM technology has potential applications in various sectors reliant on LIBs. It could provide an important layer of thermal stability to electric vehicles, reducing the risk of battery explosions or fires in demanding environments.

In addition to automotive applications, CPCMs show promise for energy storage systems, where reliable temperature control is crucial. This innovative CPCM offers a scalable and effective approach to ensuring the long-term, safe use of high-energy-density batteries as LIBs continue to expand in both personal and commercial sectors.

Journal Reference:

Zhang, J., et al. (2024) Passive battery thermal management and thermal safety protection based on hydrated salt composite phase change materials. Energy Storage and Saving. doi.org/10.1016/j.enss.2024.08.003.