High power and energy density graphene phase change composite materials for efficient thermal management of Li-ion batteries

Abstract

The safety concern of Li-ion battery cells, mainly caused by thermal runaway, has become a fundamental bottleneck that restricts their wider adoption in energy sector. Phase change material system is an available thermal management strategy to suppress the thermal runaway of batteries, however, the unresolved trade-off between high power and energy density greatly limits its practical applications. Here we present an efficient thermal management system with high power and energy density by hyperbolic graphene phase change material, preventing the rapid heat accumulation of Li-ion battery cells. This composite material consists of hyperbolic graphene framework and paraffin, exhibiting the overwhelming thermal conductivity of ∼30.75 W/mK at 12.5 wt% graphene loading and ultrahigh retention (90%) of latent heat, beyond than most of reported phase change composites. We demonstrate our paraffin-graphene composite (PGC) shows almost three-folds improvement of efficient energy density at high power density compared with commercial paraffin. The temperature of a battery pack in series at 3.75 C rate capability is less than 60℃ with protection of PGC system, far below ∼120℃ of bare battery pack. Our PGC system expands the usability and safety of Li-ion batteries and provides a reliable battery thermal management strategy towards extreme fast-charging goals.