Xinxi Li

Experimental study of a passive thermal management system for three types of battery using copper foam saturated with phase change materials

Battery thermal management (BTM) technology is vital for the development of new energy vehicle because the lithium batteries exhibit a more resistive behavior leading to extra heat generation with age. The CF/PCM (copper foam/phase change material) coupled thermal management system for different types of lithium ion batteries such as 26650, 42110 and square (105 mm × 28 mm × 71 mm) were selected comparatively to research in detail, especially at a relatively high discharge rate. To evaluate the effect of the battery generating heat close to the actual operating conditions, the thermal management system in an insulated environment were investigated at discharge rate of 5C, in comparison with a natural convection environment. Furthermore, the results show that the effect of the temperature control based PCM is improved when compared to air-based BTM under an insulated environment. Moreover, the maximum temperature of 26650, 42110 and square batteries of CF/PCM coupled with BTM can be controlled below 44.37 °C, 51.45 °C and 50.69 °C for a longer time than those of the pure PCM based case and air-based case under the same conditions, respectively. The passive system was coupled with copper foam as a skeleton net structure to improve the strength of the PCM during its melting. More importantly, a CF/PCM (copper foam/phase change material) battery thermal management system was designed and tested experimentally.

Thermal management investigation for lithium-ion battery module with different phase change materials

Lithium-ion batteries, with their advantages of high energy and power density, have attracted much attention for application in electric vehicles and hybrid electric vehicles. However, there have been increasing reports of lithium-ion batteries catching fire and exploding in recent years, so there is a need for a battery thermal management (BTM) system to ensure battery safety performance. In this study, a novel shaped stabilized structure (paraffin/expanded graphite/epoxy) of composited materials was investigated for the 18 650 batteries module. The selected batteries were evaluated at different conditions to ensure the consistency of batteries initially. Then, different kinds of PCM were applied in the batteries module for thermal management, such as PCM 1 (pure paraffin), PCM 2 (EG 20%, paraffin 80%) and PCM 3 (EG 3%, epoxy 47%, paraffin 50%). The maximum temperatures of the battery modules with PCM 2 decreased more than 10%, 12% and 20% at 1C, 3C and 5C discharge rates, respectively, while paraffin mixed with expanded graphite. Furthermore, PCM can be modified by epoxy: the temperature of the module with PCM 3 was 59.79 °C while that of the module with PCM 2 was 64.79 °C after 30 charge–discharge cycles, revealing that epoxy as a plasticizer can cure the melting paraffin, preventing PCM leakage as the cycle number of the battery increases. The composite materials provide a promising solution to control temperature and decrease temperature difference in batteries modules.

Preparation of BiOBr/BiVO4 composite and its application for photocatalytic degradation under visible light

BiOBr/BiVO4 heterojunction photocatalysts were synthesised via facile hydrothermal methods and mixed by ultrasonic treatment. The as-prepared samples were characterised by X-ray diffraction, Fourier transform infrared spectra, scanning electron microscopy, transmission electron microscopy and UV–vis diffuse reflection spectrometry. The photocatalytic activity of the samples was evaluated by degradation of Rhodamine B (RhB) under visible light irradiation (400 nm < λ < 580 nm). As a result, the as-prepared BiOBr/BiVO4 composites showed much higher photocatalytic activity for degradation of RhB as compared to many BiOBr and BiVO4-based photocatalysts. For example, the sample with a BiOBr/BiVO4 ratio of 1:1 showed the highest degradation ratio of 97%, which could stay over 84% after 15 cycles. This excellent photocatalytic activity could be attributed to the BiOBr/BiVO4 heterojunction interface that effectively narrowed the band gap and promoted the separation of photogenerated electron–hole pairs.

Experimental Investigation on Thermal Management of Electric Vehicle Battery Module with Paraffin/Expanded Graphite Composite Phase Change Material

The temperature has to be controlled adequately to maintain the electric vehicles (EVs) within a safety range. Using paraffin as the heat dissipation source to control the temperature rise is developed. And the expanded graphite (EG) is applied to improve the thermal conductivity. In this study, the paraffin and EG composite phase change material (PCM) was prepared and characterized. And then, the composite PCM have been applied in the 42110 LiFePO4 battery module (48 V/10 Ah) for experimental research. Different discharge rate and pulse experiments were carried out at various working conditions, including room temperature (25°C), high temperature (35°C), and low temperature (−20°C). Furthermore, in order to obtain the practical loading test data, a battery pack with the similar specifications by 2S 2P with PCM-based modules were installed in the EVs for various practical road experiments including the flat ground, 5°, 10°, and 20° slope. Testing results indicated that the PCM cooling system can control the peak temperature under 42°C and balance the maximum temperature difference within 5°C. Even in extreme high-discharge pulse current process, peak temperature can be controlled within 50°C. The aforementioned results exhibit that PCM cooling in battery thermal management has promising advantages over traditional air cooling.