"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!
A big nano boost for solar cells
18.01.2017 | Kyoto University and Osaka Gas effort doubles current efficiencies
Multiregional brain on a chip
16.01.2017 | Harvard John A. Paulson School of Engineering and Applied Sciences
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
20.01.2017 | Awards Funding
20.01.2017 | Materials Sciences
20.01.2017 | Life Sciences