"While a couple of challenges remain, this design brings us closer to using silicon anodes in smaller, lighter and more powerful batteries for products like cell phones, tablets and electric cars," said Yi Cui, an associate professor at Stanford and SLAC who led the research, reported today in Nature Nanotechnology.
A novel battery electrode features silicon nanoparticles clustered like pomegranate seeds in a tough carbon rind. (This is an artistic concept, not representative of the actual battery.)
Credit: Illustration by Greg Stewart/SLAC
"Experiments showed our pomegranate-inspired anode operates at 97 percent capacity even after 1,000 cycles of charging and discharging, which puts it well within the desired range for commercial operation."
The anode, or negative electrode, is where energy is stored when a battery charges. Silicon anodes could store 10 times more charge than the graphite anodes in today's rechargeable lithium-ion batteries, but they also have major drawbacks: The brittle silicon swells and falls apart during battery charging, and it reacts with the battery's electrolyte to form gunk that coats the anode and degrades its performance.
Over the past eight years, Cui's team has tackled the breakage problem by using silicon nanowires or nanoparticles that are too small to break into even smaller bits and encasing the nanoparticles in carbon "yolk shells" that give them room to swell and shrink during charging.The new study builds on that work. Graduate student Nian Liu and postdoctoral researcher Zhenda Lu used a microemulsion technique common in the oil, paint and cosmetic industries to gather silicon yolk shells into clusters, and coated each cluster with a second, thicker layer of carbon. These carbon rinds hold the pomegranate clusters together and provide a sturdy highway for electrical currents.
Although the clusters are too small to see individually, together they form a fine black powder that can be used to coat a piece of foil and form an anode. Lab tests showed that pomegranate anodes worked well when made in the thickness required for commercial battery performance.
While these experiments show the technique works, Cui said, the team will have to solve two more problems to make it viable on a commercial scale: They need to simplify the process and find a cheaper source of silicon nanoparticles. One possible source is rice husks: They're unfit for human food, produced by the millions of tons and 20 percent silicon dioxide by weight. According to Liu, they could be transformed into pure silicon nanoparticles relatively easily, as his team recently described in Scientific Reports.
"To me it's very exciting to see how much progress we've made in the last seven or eight years," Cui said, "and how we have solved the problems one by one."
The research team also included Jie Zhao, Matthew T. McDowell, Hyun-Wook Lee and Wenting Zhao of Stanford. Cui is a member of the Stanford Institute for Materials and Energy Sciences, a joint SLAC/Stanford institute. The research was funded by the DOE Office of Energy Efficiency and Renewable Energy through the Batteries for Advanced Transportation Technologies program.
Citation: N. Liu, Z. Lu et al., Nature Nanotechnology, 16 February 2014 (10.1038/nnano.2014.6)
Andy Freeberg | EurekAlert!
Engineer Improves Rechargeable Batteries with MoS2 Nano 'Sandwich'
17.04.2015 | Kansas State University
Packing Heat: New Fluid Makes Untapped Geothermal Energy Cleaner
17.04.2015 | Pacific Northwest National Laboratory
Max Planck researcher Buhalqem Mamtimin determines how much nitrogen oxide is released into the atmosphere from agriculturally used oases.
In order to make statements about current and future air pollution, scientists use models which simulate the Earth’s atmosphere. A lot of information such as...
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and the University of Konstanz are working on storing and processing information on the level of single molecules to create the smallest possible components that will combine autonomously to form a circuit. As recently reported in the academic journal Advanced Science, the researchers can switch on the current flow through a single molecule for the first time with the help of light.
Dr. Artur Erbe, physicist at the HZDR, is convinced that in the future molecular electronics will open the door for novel and increasingly smaller – while also...
Cells of the vascular system of vertebrates can fuse with themselves. This process, which occurs when a blood vessel is no longer necessary and pruned, has now been described on the cellular level by Prof. Markus Affolter from the Biozentrum of the University of Basel. The findings of this study have been published in the journal “PLoS Biology”.
The vascular system is the supply network of the human organism and delivers oxygen and nutrients to the last corners of the body. So far, research on the...
Astronomers from Chalmers University of Technology have used the giant telescope Alma to reveal an extremely powerful magnetic field very close to a supermassive black hole in a distant galaxy
Astronomers from Chalmers University of Technology have used the giant telescope Alma to reveal an extremely powerful magnetic field very close to a...
A team of physicists from MPQ, Caltech, and ICFO proposes the combination of nano-photonics with ultracold atoms for simulating quantum many-body systems and creating new states of matter.
Ultracold atoms in the so-called optical lattices, that are generated by crosswise superposition of laser beams, have been proven to be one of the most...
13.04.2015 | Event News
25.03.2015 | Event News
19.03.2015 | Event News
21.04.2015 | Life Sciences
21.04.2015 | Life Sciences
21.04.2015 | Information Technology