[Due to the increasing size of the archives, each topic page now contains only the prior 365 days of content. Access to older stories is now solely through the Monthly Archive pages or the site search function.]
Huawei Watt Lab develops graphene-assisted high-temperature Li-ion batteries
December 20, 2016
Huawei researchers recently unveiled what they said was the first long-lifespan graphene-assisted Li-ion battery able to withstand high temperatures. The announcement was made by Watt Laboratory, an organization under Huawei’s Central Research Institute, at the 57th Battery Symposium held in Japan.
Huawei’s research results show that new graphene-assisted heat-resistant technologies allow Li-ion batteries to remain functional in a 60 ˚C (140 ˚F) environment, a temperature 10 ˚C higher than the existing upper limit. The lifespan of the graphene-assisted Li-ion batteries will also be twice as long as ordinary Li-ion batteries.
Manchester team proposing graphene-based ballistic rectifier for waste heat recovery
June 03, 2016
Researchers at the University of Manchester (UK) have developed a graphene-based nano-rectifier (“ballistic rectifier”) that can convert waste heat to electricity. The nano-rectifier was built by a team led by Professor Aimin Song and Dr. Ernie Hill, in collaboration with a team at Shandong University (China).
The device exploits graphene’s phenomenally high electron mobility—a property which determines how fast an electron can travel in a material and how fast electronic devices can operate. The resulting device is the most sensitive room-temperature rectifier ever made, the researchers said. Conventional devices with similar conversion efficiencies require cryogenically low temperatures.
New silicon-sulfur battery built on 3D graphene shows excellent performance
April 28, 2016
Researchers at Beihang University in Beijing have developed a new Li-sulfur battery using honeycomb-like sulfur copolymer uniformly distributed onto 3D graphene (3D cpS-G) networks for a cathode material and a 3D lithiated Si-G network as anode.
In a paper published in the RSC journal Energy & Environmental Science, they reported that the full cell exhibits superior electrochemical performances in term of a high reversible capacity of 620 mAh g-1, ultrahigh energy density of 1147 Wh kg−1 (based on the total mass of cathode and anode), good high-rate capability and excellent cycle performance over 500 cycles (0.028% capacity loss per cycle).
New silicon oxycarbide glass/graphene anode material; lightweight, high-capacity and long cycle life
April 11, 2016
Researchers at Kansas State University have developed a new high-performance Li-ion battery anode material combining silicon oxycarbide (SiOC) glass and graphene. The self-standing (i.e., no current collector or binder) anode material comprises molecular precursor-derived SiOC glass particles embedded in a chemically-modified reduced graphene oxide (rGO) matrix.
The porous reduced graphene oxide matrix serves as an effective electron conductor and current collector with a stable mechanical structure, and the amorphous silicon oxycarbide particles cycle lithium-ions with high Coulombic efficiency. The SiOC-rGO composite electrode delivers a charge capacity of ~588 mAh g−1electrode (~393 mAh cm−3electrode) at the 1,020th cycle and shows no evidence of mechanical failure.
Researchers develop all-weather solar cell that generates power from rain as well as from sun
April 03, 2016
While many technical advances have made solar cells more efficient and affordable, a disadvantage remains in the fact that solar cells produce no power when it’s raining. Now, however, researchers from the Ocean University of China (Qingdao) and Yunnan Normal University (Kunming, China) have developed an all-weather solar cell that is triggered by both sunlight and raindrops by combining an electron-enriched graphene electrode with a dye-sensitized solar cell.
The new solar cell can be excited by incident light on sunny days and raindrops on rainy days, yielding an optimal solar-to-electric conversion efficiency of 6.53% under AM 1.5 irradiation and current over microamps as well as a voltage of hundreds of microvolts by simulated raindrops. Their work is published as a “Very Important Paper” in the journal Angewandte Chemie.
LLNL team finds certain graphene metal oxide nanocomposites increase Li-ion capacity and cycling performance
March 22, 2016
Material scientists at Lawrence Livermore National Laboratory have found that certain graphene metal oxide (GMO) nanocomposites increase capacity and improve cycling performance in lithium-ion batteries.
The team synthesized and compared the electrochemical performance of three representative graphene metal oxide nanocomposites—Fe2O3/graphene, SnO2/graphene, and TiO2/graphene—and found that two of them greatly improved reversible lithium storage capacity. The research appears on the cover of the 21 March edition of the Journal of Materials Chemistry A.
Berkeley Lab team develops new high-performance solid-state H2 storage material: graphene oxide (GO)/Mg nanocrystal hybrid
March 12, 2016
Researchers at Lawrence Berkeley National Laboratory (Berkeley Lab) have developed a new, environmentally stable solid-state hydrogen storage material constructed of Mg nanocrystals encapsulated by atomically thin and gas-selective reduced graphene oxide (rGO) sheets.
This material, protected from oxygen and moisture by the rGO layers, exhibits dense hydrogen storage (6.5 wt% and 0.105 kg H2 per liter in the total composite). As rGO is atomically thin, this approach minimizes inactive mass in the composite, while also providing a kinetic enhancement to hydrogen sorption performance.
Stanford, SLAC team cages silicon microparticles in graphene for stable, high-energy anode for Li-ion batteries
January 28, 2016
A team from Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory has developed a new practical, high-energy-capacity lithium-ion battery anode out of silicon by encapsulating Si microparticles (∼1–3 µm) using conformally synthesized cages of multilayered graphene.
The graphene cage acts as a mechanically strong and flexible buffer during deep cycling, allowing the silicon microparticles to expand and fracture within the cage while retaining electrical connectivity on both the particle and electrode level.
Graphene ultracapacitor company Skeleton Technologies secures €4M from KIC InnoEnergy; targeting 20 Wh/kg by 2020
European ultracapacitor manufacturer Skeleton Technologies received a €4-million (US$4.4-million) investment from KIC InnoEnergy, an investment company dedicated to promoting sustainable innovation and entrepreneurship in Europe’s energy industry.
The €4m investment from KIC InnoEnergy—the shareholders of which include ABB, EDF, Iberdrola and Total—will be used to further develop the competitive advantage of Skeleton Technologies’ ultracapacitors. The company aims to reach the ambitious target of 20 Wh/kg energy density for its technology by 2020.
Northwestern researchers discover crumpled graphene balls are a promising lubricant additive
January 26, 2016
Researchers at Northwestern University’s McCormick School of Engineering have found that crumpled graphene balls are an extremely promising lubricant additive. In a series of tests, a polyalphaolefin base oil with only 0.01–0.1 wt % of crumpled graphene balls outperformed a fully formulated commercial lubricant in terms of friction and wear reduction. A paper on their work is published in the Proceedings of the National Academy of Sciences.
For the average car, 15% of the fuel consumption is spent overcoming friction in the engine and transmission. While oil helps reduce this friction, researchers have long sought additives that enhance oil’s performance. Ultrafine particles are often used as lubricant additives because they are capable of reducing friction and protecting surfaces from wear. They also tend to be more stable than molecular additives under high thermal and mechanical stresses during rubbing. However, they also can aggregate, reducing the effective concentration.