ABSTRACT
A three-dimensional porous architecture makes an attractive electrode structure, as it has an intrinsic structural integrity and an ability to buffer stress in lithium-ion batteries caused by the large volume changes in high-capacity anode materials during cycling. Here we report the first demonstration of a SnO2-coated macroporous Cu foam anode by employing a facile and scalable combination of directional freeze-casting and sol-gel coating processes. The three-dimensional interconnected anode is composed of aligned microscale channels separated by SnO2-coated Cu walls and much finer micrometer pores, adding to surface area and providing space for volume expansion of SnO2 coating layer. With this anode, we achieve a high reversible capacity of 750 mAh g(-1) at current rate of 0.5 C after 50 cycles and an excellent rate capability of 590 mAh g(-1) at 2 C, which is close to the best performance of Sn-based nanoscale material so far.
ABSTRACT
This study investigates and compares the microstructure, biocompatibility, and tribological properties of two different Ti-based composites, Ti-10W and Ti-7.5TiC-7.5W, with those of pure Ti for their potential use in biomedical applications. In particular, cold and hot isostatic-pressing and arc-melting methods were utilized and compared for the microstructure of the composites. Nano-scratch measurements and pin-on-disk wear tests were employed to understand their tribological behavior. As compared to pure Ti, Ti-10W and Ti-7.5TiC-7.5W showed significantly improved nano-scratch resistance (by 85 and 77%, respectively) and wear resistance (by 64 and 66%, respectively), in good agreement with hardness measurements. For biocompatibility examination, both microculture tetrazolium test (MTT) and water soluble tetrazolium (WST-1) test were used to quantify the cell viability of human osteoblasts and mouse fibroblasts on the materials. Both of the Ti-based composites showed acceptable biocompatibility in comparison with the pure Ti control.
