With the rapid development of electric vehicles, lithium-ion battery has been widely used as an energy source. However, to avoid thermal runaway and to ensure the correct operation of lithium-ion battery system, effective battery thermal management would be required. In this study the capacity of phase change materials with different thermal-physical properties to respectively manage thermal issues associated with lithium-ion battery is theoretically investigated using computational fluid dynamics. The impacts of shell material, heat transfer coefficient, phase change material fill volume and the shape of the battery pack on the thermal performance of the lithium-ion battery/phase change material system are investigated in detail. The results show that when the ambient temperature was 20 degrees C or 30 degrees C, phase change material-RT35 shows the best temperature control ability for the proposed system, while the phase change material-RT50 has better thermal management capability when the ambient temperature is 40 degrees C. Also, higher heat transfer coefficient or shell material with higher thermal conductivity, effectively reduce the maximum temperature of the lithium-ion battery and the temperature difference within the proposed system. Specifically, the phase transition time in the lithium-ion battery/phase change material system with a heat transfer coefficient of 10 W/m2K is more than twice longer compared to that of 1 W/m2K and the maximum temperature is 47.18 degrees C after 150 min of charging and discharging. It is also observed that the phase change material with larger volume ratio leads to lower system temperature during phase transition and the continuous charging and discharging after completing transformation of the phase change material impacts negatively on the thermal management of the lithium-ion battery system. Besides, the rectangular lithium-ion battery/phase change material system surpasses the circular one by 14.78 degrees C in maximum temperature, while attaining a minimum temperature difference of 9.6 degrees C after 150 min of charging and discharging.

In recent years, bacterial cellulose (BC) has been fabricated in tubular shape as scaffold for vascular tissue engineering. However, in order to improve the blood compatibility and regenerative ability of BC, BC nano-fibres should be cross-linked with some materials which can prevent the formation of blood clot. In this work, a novel BC-chitosan (CS)/heparin (Hep) composite was prepared. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transformed infrared spectroscopy (FTIR) were used to analyse the obtained samples. It is observed by SEM and TEM that the obtained composites remain the three-dimensional (3D) network and porous structure. The results of XRD reveal that the curve of BC-CS/Hep composite assumes the characteristic absorption peaks of BC, CS and Hep. The FTIR results also confirm the presence of CS and Hep on the surface of BC nano-fibres. In conclusion, BC-CS/Hep composites were obtained by the co-synthesis technique and the cross-linking method, respectively. Furthermore, the MC3T3-E1 cells were seeded on the obtained samples to test the cell compatibility. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide results indicated that the BC-CS/Hep composites were suitable for cell proliferation and ingrowth.