Calcium chloride hexahydrate based composite phase change/thermochemical material for wide-temperature range passive battery thermal management

Battery, as the core of the electric vehicle, needs to be thermally managed and protected to avoid decreased performance and thermal runaway. In this study, calcium chloride hexahydrate based composite phase change materials are developed for passive battery thermal management and thermal protection. The composite phase change materials achieve wide-temperature range thermal management based on their high energy density, including 84.89 ∼ 195.5 J/g for pre-heating between 0 and 10 ℃, 99.93 ∼ 179.2 J/g for operation cooling between 25 and 50 ℃, and 326 ∼ 699.5 J/g for thermal runaway elimination between 50 and 120 ℃. Using ceramic fibre as a support material, strontium chloride hexahydrate as a nucleating agent, and hydroxylated cellulose nanofiber to improve the form stability of calcium chloride hexahydrate, the phase transition temperature is increased to 37.1 °C, which meets thermal management requirements. The unique dendrite structure provided by crystalline phase change material and the cross-linked fibre network enhances the tensile strength of the composite to 2.97 MPa. Compared with typical battery wrapping material, Polyvinyl chloride, the battery module based on the developed composite phase change material can reduce the peak temperature and temperature difference during operation cooling by up to 34.9 % and 50.7 %, respectively. In addition, the composite phase change material also provides excellent flame retardancy, with a limiting oxygen index value of 100 % unburned and UL-94 grade reaching V0. In the case of battery thermal runaway, the composite phase change material can absorb the 37,730 J of energy released by the first battery and eliminate the thermal runaway. The results show that the prepared composite phase change material has high performance thermal management and thermal protection, with the advantage of low cost.