Guang Ma

Enhanced adhesion and conductivity of Cu electrode on AlN substrate for thin film thermoelectric device

The Cu thin film electrode grown on aluminum nitride (AlN) substrate is widely used in the thin film thermoelectric devices due to its high electrical conductivity. We have developed a new type of buffer layer by co-sputtering Ti and Cu forming Ti–Cu layer. The Ti–Cu layer was sputtered on the Ti buffered AlN substrate so that the adhesion and electrical conductivity properties of the Cu film electrode on AlN substrate could be improved. The interface between the thin films and the substrate were characterized by the scanning electron microscope (SEM). Nanoscratch tests were conducted on a nanomechanical test system to investigate the adhesion between the Cu film electrodes and AlN substrate. Meanwhile, accelerated ageing test under thermal cycling was conducted to evaluate the reliability of the thin film electrode. The results show that the adhesion and the reliability of Cu film electrode on AlN substrate have been greatly improved by employing Ti–Cu/Ti buffer layers.

Effect of rapid quenching on electrochemical properties of AB 5 and AB 3.5 -type hydrogen storage alloys

The energy infrastructure is facing ever more serious challenges due to limited supplies of oil, environmental concerns about CO<inf>2</inf> emissions and emissions from fossil fuels, and the ever-expanding energy demands of the growing economies in Asia. It is widely believed that hydrogen is a potential major alternative energy carrier. However, there remain problems with storage and transportation. An important aspect in the development of hydrogen as an energy carrier concerns the use of metal hydrides for hydrogen storage. Among the various types of hydrogen storage alloys, LaNi<inf>5</inf>-type hydrogen storage alloy has been the most promising materials which has been used as metal hydride electrode material for Ni-MH batteries because of their high capacity, capable of performing a high-rate charge/discharge, high resistance to overcharging and over-discharging, a long cycle life, environmental friendliness and compatibility with Ni-Cd batteries, and the nickel metal hydride (Ni-MH) rechargeable batteries have been produced in large industry scale. In this paper, effect of rapid quenching on the electrochemical properties of AB<inf>5</inf> and AB<inf>3.5</inf>-type hydrogen storage alloys was studied. The results indicated that the discharge capacities of the rapid quenching MmNi<inf>3.55</inf>Co<inf>0.75</inf>Mn<inf>0.4</inf>Al<inf>0.3</inf> alloys decrease under 25 and −35°C with the increase of the quenching rate. Comparatively, the decrease extent of the quenching alloys at − 35°C is lower than that at 25°C. The result on the study of the cycle life indicated that the quenching process is favorable to improve the cycle stabilities of the MmNi<inf>3.55</inf>Co<inf>0.75</inf> -Mn<inf>0.4</inf>Al<inf>0.3</inf> alloys under 25 and −35°C. Whereas, the effect of the quenching process on the La<inf>0.7</inf>Mg<inf>0.3</inf>(Ni<inf>0.85</inf>Co<inf>0.15</inf>)<inf>3.5</inf> alloy is different at 25°C from at −35°C. Under 25°C, the cycle life of the alloy was obviously improved by the quenching process, however, the quenching process did not improve but decreased slightly the cycle life at −35°C.

The electrochemical characterization of electrochemically synthesized MnO 2 -based mixed oxides for supercapacitor

With more challenges facing utilities and others responsible for reliable electricity service, considering the broadest range of technically and economically viable solutions is more important than ever. Electrical energy storage is a well known solution to many of the common energy problems which developed rapidly in recent years. Electrical energy storage is an emerging technology,storage devices can be used to improve power quality or mitigate reliability problems which affect sensitive equipment, optimize configuration of power grid, firm up that intermittent renewable energy resources generation capacity, and so on. It can believe that electrical energy storage will used widely in power grid in the future.