Development boosts lithium-ion battery power by 8-fold

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Summary: Researchers at Berkeley have developed a new kind of anode polymer can absorb eight times the lithium of current designs.

Lithium-ion batteries are the most common type of rechargeable battery. They are found in laptops, smartphones, and increasingly, in electric cars and smart grids.

Although there are many advantages to lithium ion batteries–they maintain full capacity even after a partial recharge and are considered to be more environmentally safe than other battery technologies–their storage capacity can be improved.

A team of scientists at Berkeley Lab have designed a new kind of anode that can absorb eight times the lithium of current designs, and has maintained its greatly increased energy capacity after over a year of testing and many hundreds of charge-discharge cycles.

“Most of today’s lithium-ion batteries have anodes made of graphite, which is electrically conducting and expands only modestly when housing the ions between its graphene layers. Silicon can store 10 times more – it has by far the highest capacity among lithium-ion storage materials – but it swells to more than three times its volume when fully charged, ” said Gao Liu of Berkeley Lab’s Environmental Energy Technologies Division (EETD).

The swelling quickly breaks the electrical contacts in the anode, so the researchers concentrated on finding other ways to use silicon while maintaining anode conductivity. Through a combination of synthesis, spectroscopy and simulation, the team tailored a polymer that conducts electricity and binds closely to lithium-storing silicon particles, even as they expand to more than three times their volume during charging and then shrink again during discharge.

The new anodes are made from low-cost materials, compatible with standard lithium-battery manufacturing technologies.

The research team reports its findings in Advanced Materials, now available online.

Source: Berkeley Lab News Center

Christopher Jablonski is a freelance technology writer.

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LCD screen harvests light to power devices

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Summary: Keeping smartphones and laptops charged when there’s no electrical outlet in sight is a perennial challenge. A novel LCD screen developed by UCLA engineers could potentially help solve the problem.

UCLA engineers have developed an LCD screen with built-in photovoltaic polarizers that harvest and recycle energy from ambient light, sunlight, and its own backlight.

The energy-harvesting polarizer, which in technical terms is called a polarizing organic photovoltaic, can potentially boost the function of an LCD by working simultaneously as a polarizer–a photovoltaic device and an ambient light or sunlight photovoltaic panel.

“I believe this is a game-changer invention to improve the efficiency of LCD displays,” said Yang Yang, a professor of materials science at UCLA Engineering and principal investigator on the research. “In addition, these polarizers can also be used as regular solar cells to harvest indoor or outdoor light. So next time you are on the beach, you could charge your iPhone via sunlight.”

LCDs, or liquid crystal displays, shine light through a combination of liquid crystals and polarized glass to produce a visible image, albeit inefficiently. According to the UCLA researchers, a device’s backlight can consume 80 to 90 percent of the device’s power, but as much as 75 percent of the light generated is lost through the polarizers. A polarizing organic photovoltaic LCD could recover much of that lost energy.

Youssry Boutros, program director at Intel Labs, said: “The polarizing organic photovoltaic cell demonstrated by Professor Yang’s research group can potentially harvest 75 percent of the wasted photons from LCD backlight and turn them back into electricity.” Intel supported the research through its Intel Labs Academic Research Office (ARO).

“In the near future, we would like to increase the efficiency of the polarizing organic photovoltaics, and eventually we hope to work with electronic manufacturers to integrate our technology into real products”, Yang said. “We hope this energy-saving LCD will become a mainstream technology in displays.”

Below is a short clip of the UCLA team making the polarizing film using P3HT, an organic polymer widely used in solar cells.

The research is published in the online version of the journal Advanced Materials.

(Source: UCLA)

Christopher Jablonski is a freelance technology writer.

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Nuclear power plants for settlements on the Moon and Mars

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Summary: The first nuclear power plant being considered for production of electricity for manned or unmanned bases on the Moon, Mars and other planets “may really look like it came from outer space.”

On earth, nuclear reactors are under attack because of concerns over damage caused by natural disasters. In space, however, nuclear technology may get a new lease on life.

Plans for the first nuclear power plant for the production of electricity for manned or unmanned bases on the Moon, Mars and other planets were unveiled today at the 242nd National Meeting & Exposition of the American Chemical Society (ACS).

James E. Werner, the project leader at the U.S. Department of Energy (DOE), said that innovative fission technology for surface power applications is far different from the familiar terrestrial nuclear power stations, which sprawl over huge tracts of land and have cooling towers and other large structures.

An artist’s concept of a fission surface power system on the surface of the Moon. Credit: Galaxy Wire

A fission reactor itself is about 1.5 feet wide by 2.5 feet high, roughly the size of a carry-on suitcase, according to Werner. And there are no cooling towers.

“A fission power system is a compact, reliable, safe system that may be critical to the establishment of outposts or habitats on other planets. Fission power technology can be applied on Earth’s Moon, on Mars, or wherever NASA sees the need for continuous power,” said Werner.

Nuclear fission power in space is actually old news. In 1965, the U.S. launched SNAP-10A, which was a 45 kWt thermal nuclear fission reactor that produced 650 watts using a thermoelectric converter. (It operated for 43 days before it was shut down due to a satellite malfunction–but remains in orbit today.)

Nuclear fission works by splitting uranium atoms to generate heat that is then converted into electric power. A fission power system contains components that are similar to those found in the commercial reactors currently in use: a heat source, power conversion, heat rejection and power conditioning and distribution. For space applications, however, nuclear fission features a number of differences compared with commercial reactors.

“While the physics are the same, the low power levels, control of the reactor and the material used for neutron reflection back into the core are completely different,” Werner said. “Weight is also a significant factor that must be minimized in a space reactor that is not considered in a commercial reactor.”

Sunlight and fuel cells were traditionally the mainstays for generating electricity for space missions, but engineers realized that solar energy has limitations. Solar cells do a great job supplying electricity in near-Earth orbits and for satellite-borne equipment, but nuclear power offers some unique capabilities that could support manned outposts on other planets or moons.

Werner explains:

The biggest difference between solar and nuclear reactors is that nuclear reactors can produce power in any environment. Fission power technology doesn’t rely on sunlight, making it able to produce large, steady amounts of power at night or in harsh environments like those found on the Moon or Mars. A fission power system on the Moon could generate 40 kilowatts or more of electric power, approximately the same amount of energy needed to power eight houses on Earth.  Nuclear power has the ability to provide a power-rich environment to the astronauts or science packages anywhere in our solar system and that this technology is mature, affordable and safe to use.

Werner contends that once the technology is developed and validated, it may prove to be one of the most affordable and versatile options for providing long-term base power for the space exploration programs.

The team is scheduled to build a technology demonstration unit in 2012.

The project is a collaboration between NASA and DOE.

Source:  American Chemical Society

Related:

LCD screen harvests light to power devices
Wireless power from space: energy salvation?
Acts of space warfare likely by 2025

Christopher Jablonski is a freelance technology writer.

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