Stanford team demonstrates a graphene-based thermal-to-electricity conversion technology

Researchers at Stanford University have recently demonstrated a graphene-based high efficiency thermal-to-electricity conversion technology, called thermionic energy convertor. By using graphene as the anode, the efficiency of the device is increased by a factor of 6.7 compared with a traditional tungsten anode. This technology can work in a tandem cycle with existing thermal-based power plants and significantly improve their overall efficiencies.

Stanford team creates graphene-based TEC image

Hongyuan Yuan and Roger T. Howe, among the leading researchers in the Stanford team, explain that one of the major challenges for wide adoption of TECs is high anode work function, which directly reduces the output voltage as well as the net efficiency. The theoretical maximum efficiency for a TEC with a 2 eV work function anode is 3% at a cathode temperature of 1500 K, compared to an astonishing 10-fold increment to 32% with a 1 eV work function anode.

Graphene-based system may enable imaging of electrical activity in heart and nerve cells

Researchers at the Berkeley Lab and Stanford University have used graphene as the film of an ultra-sensitive camera system designed for visually mapping tiny electric fields in a liquid. The new platform should permit single-cell measurements of electrical impulses traveling across networks containing 100 or more living cells. The researchers hope it will allow more extensive and precise imaging of the electrical signaling networks in our hearts and brains. Additional potential applications include the development of lab-on-a-chip devices, sensing devices and more.

The team explains that the basic concept was examining how graphene could be used as a general and scalable method for resolving very small changes in the magnitude, position, and timing pattern of a local electric field, such as the electrical impulses produced by a single nerve cell. Other techniques have been developed to measure electrical signals from small arrays of cells, but these can be difficult to scale up to larger arrays and in some cases cannot trace individual electrical impulses to a specific cell. In addition, this new method does not perturb cells in any way, which is fundamentally different from existing methods that use either genetic or chemical modifications of the cell membrane.

Graphene "cages" may open the door to silicon Li-ion battery anodes

A team of scientists at Stanford University and the Department of Energy's SLAC National Accelerator Laboratory has come up with a possible answer to the question of how to make lithium-ion battery anodes out of silicon, as these tend to swell and crack, as well as react with the battery electrolyte to form a coating that harms their performance.

The scientists wrapped each silicon anode particle in a custom-fit "cage" made of graphene, in a simple, three-step method for building microscopic graphene cages of just the right size: roomy enough to let the silicon particle expand as the battery charges, yet tight enough to hold all the pieces together when the particle falls apart, so it can continue to function at high capacity. The strong, flexible cages also block destructive chemical reactions with the electrolyte.

Graphene-enhanced film shuts down li-ion batteries before overheating and restarts upon cooling

Researchers at Stanford University have developed a revolutionary graphene-enhanced polyethylene film that prevents a lithium-ion battery from overheating, then restarts the battery when it cools. This new technology could prevent fires and melt-downs in a wide range of battery-powered devices.

The researchers in this study recently invented a wearable sensor to monitor human body temperature, made of a plastic material embedded with tiny particles of nickel with nanoscale spikes protruding from their surface. For the battery experiment, they coated the spiky nickel particles with graphene and embedded the particles in a thin film of elastic polyethylene. They then attached the film to one of the battery electrodes so that an electric current could flow through it. The researchers explain that in order to conduct electricity, the spiky particles have to physically touch one another, but during thermal expansion, polyethylene stretches. That causes the particles to spread apart, making the film non-conductive so that electricity can no longer flow through the battery.

Graphene may enable dense, energy-efficient memory chips

Researchers at Stanford University have recently performed three separate experiments that suggest graphene in computing and telecommunications could radically cut energy consumption. This work was done in search of post-silicon materials and technologies that enable storing more data per square inch and use a fraction of the energy of currently used memory chips.

All three experiments involve graphene, and test different ways to use it in new storage technologies. The scientists claim that graphene can have interesting mobile applications of these new technologies, but post-silicon memory chips may transform server farms that store and deliver quick access to enormous quantities of data stored in the cloud.