Sunday, April 21, 2013

Nanometer an enabling technology

According to Prof. Yi Cui, Dept. of Materials, Science & Engineering, Stanford University, nanometer is an enabling technology. We can do applications such as electronics, energy, environment and health. Some examples are high energy batteries, printed energy storage devices on paper, textile and sponge, etc. He was delivering the inaugural address at the Globalpress Electronics Summit 2013, being held in Santa Cruz, USA.

High energy battery has portable and stationary applications. In portable, energy density, cost and safety are important. In stationary, cost, power, energy efficiency and ultra-long life are important. The standard is 500 cycles at 80 percent. One of the challenges of silicon anodes is that Si has 4200 mAh/g of silicon, 10 times more than carbon.

Nanowires can offer shorter distance for Li diffusion (high power), good strain release and interface control (for better cycle life), and continuous electron transport pathway (high power). In-situ transmission electron microscopy (TEM). Double walled hollow structure provides stable solid electrolyte interphase (SEI). The outer surface is static. Amprius, where Prof. Cui is CTO,  is a $6 million US government funded enterprise. Amprius China started in Nanjing, in April 2012.

Another example is printed energy storage devices on paper, textile and sponge. For low-cost scaffold, paper, textile and sponge, are used. There is cellulose paper and synthetic textile, besides sponge, as well.

There can be transparent batteries. It is actually very hard to develop those. The challenges for making a transparent battery are Al film, cathode, electrolyte, etc. An idea: dimension smaller than eye’s detection limit (50-100 um). Also, grids are well aligned.

Transparent conducting electrodes provide electrical and allow light to pass through. Apps include solar cells, etc. Indium tin oxide (ITO) has a low abundance of indium, brittleness when bent, and sputtering at high cost. Electrospinning of nanofibers is done for transparent electrodes. An example is the trough-shaped nanowires.

Yet another example is the water nanofilters for killing pathogens. The processes available for killing bacteria include chemical disinfection, UV disinfection, boiling, etc.

The first generation product is currently ready at Amprius. Amprius licensed the IP from Stanford. Stanford is also an investor in Amprius.

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