A novel preheating method for the Li-ion battery using supercooled phase change materials

The Li-ion battery is widely used in power tools, energy storage systems, and electric vehicles. In reality, battery thermal management is essential to control the battery temperature within a specific temperature range. Although research has shown that preheating the battery at low temperatures on cold days can improve output performance significantly, few efforts have been made to study the preheating method in-depth. As a result, this research proposes two preheating designs for cylindrical batteries with supercooled phase change materials: Single-and dual-phase change material(PCM) designs. A mathematical model is developed to analyze the effect of the PCM layer’s height, thickness, and mass on the preheating effect for seven candidate PCMs with high supercooling degrees. Furthermore, the economic efficiency of the single-PCM design with different PCMs is compared. In addition, the optimal ratio of the PCMs’ height for the dual-PCM design is investigated. Eventually, the improvement of the battery’s output performance is discussed. The results reveal that the proposed designs can effectively preheat the battery with a temperature rise higher than 10°C. The single-PCM design using Li NO3·3H2O shows the best preheating ability, while CH3COONa·3H2O is the most economical. Although the dual-PCM design cannot outperform the single-PCM design, it can preheat the battery twice and show better flexibility. Compared with the battery without preheating, a 26650-format battery with the single-PCM design can prolong the operating time by 38.8 min and save the electric quantity by 2.1 A h;while they are by 42.8 min and 2.3 A h with the dual-PCM design.

Synthesis of Hydrophilic Acid-resistant Ge-ZSM-5 Membranes via Secondary Growth Method Using Silicalite-1 Zeolite as Seeds

Hydrophilic acid-resistant Ge-ZSM-5 membranes were synthesized via secondary growth method on porous a-A1203 substrates with Silicalite-1 zeolite as seeds. The membranes were characterized by means of scanning electron microscopy, X-ray diffraction and energy dispersive X-ray spectrometer to look into the microstructures and element contents of the membranes. The separation performance of the membranes was investigated for separating water from acetic acid solution by pervaporation. The results show that membranes fabricated by the conventional secondary growth method have a high flux, but the selectivity of them is rather limited. Preheating the secondary synthesis sol and using the supernatant as the secondary synthesis sol for membrane fabrication were found to be ef- fective to lower the concentration of the nutrient to constrain re-nucleation, at the same time, lower the A1 content in the membranes. The membrane obtained exhibited improved separation performance with a separation factor of 83 at a flux of 0.67 kg.rn-2.h-1 at 353 K for a feed concentration of 98% acetic acid solution.