Nav: Home

Recharging on stable, amorphous silicon

October 11, 2016

Next-generation anodes for lithium ion batteries will probably no longer be made of graphite. Silicon, which is a related material, can provide a much higher capacity than graphite, but its crystallinity poses problems. In the journal Angewandte Chemie, Chinese scientists have introduced a porous silicon form that is amorphous, not crystalline, and has the potential to outstrip the other materials in rechargeable battery applications.

Although carbon in its graphite form is the most common anode material today in lithium ion batteries, its capacity is relatively low. Other long-standing issues of lithium ion batteries are poor cycle life, increasing internal resistance with cycling, ageing, and safety concerns. Silicon offers a theoretical capacity almost ten times higher than that of graphite. However, silicon does not like cycling: Its crystalline structure expands and shrinks with every charge-discharge cycle, which leads to pulverization and capacity loss. Jian Yang and his team at Shangdong University in China have now a prepared a porous amorphous silicon modification that compensates for the disadvantages.

Yang said that investigation of the amorphous state was the logical consequence because silicon would loose crystallinity anyway. The authors wrote: "As silicon eventually becomes amorphous during electrochemical lithiation/delithiation, the attempt to use amorphous silicon ... from the beginning draws intense interest." On the other hand, amorphous silicon structures are rather difficult to prepare and the preparation conditions have to be carefully chosen. The scientists eventually came up with a relatively simple process, using safe substances as the starting materials, as they pointed out. For example, they used cheap and common glyme as the solvent, and liquid silicon tetrachoride as the silicon precursor, which would be easier to handle than other substances. All this makes their procedure "very attractive for the mass production," as they put it.

The resulting porous amorphous silicon material exhibited excellent electrochemical characteristics with a capacity three times better than graphite, and much longer cycling stability than crystalline silicon. Yang and his colleagues explained this stability by the presence of large, solvent-filled pores in the material and by the partial oxidation of the silicon surface in air. And there is more potential for the future. Yang proposes that a pinch of carbon in the structure would even further enhance its electrochemical performance.
-end-
About the Author

Dr. Yang is the Professor of Chemistry at Shandong University, China. His main specialty is the synthesis of novel inorganic nanomaterials and their applications in next-generation secondary batteries. He is recipient of grants from the Taishan Scholars Program, and Distinguished Young Scientists from Shandong in China.

mailto:yangjian@sdu.edu.cn

Wiley

Related Carbon Articles:

The carbon dioxide loop
Marine biologists quantify the carbon consumption of bacterioplankton to better understand the ocean carbon cycle.
Transforming the carbon economy
A task force commissioned in 2016 by former US Secretary of Energy Ernest Moniz has proposed a framework for evaluating R&D on recycling carbon dioxide and removing large amounts of CO2 from the atmosphere.
Closing the carbon loop
Research at the University of Pittsburgh's Swanson School of Engineering focused on developing a new catalyst that would lead to large-scale implementation of capture and conversion of carbon dioxide (CO2) was recently published in the Royal Society of Chemistry journal Catalysis Science & Technology.
An overlooked source of carbon emissions
Nations that pledged to carry out the Paris climate agreement have moved forward to find practical ways to reduce greenhouse gas emissions, including efforts to ban hydrofluorocarbons and set stricter fuel-efficiency standards.
Enabling direct carbon capture
Researchers have developed a solid material that can capture carbon dioxide from the atmosphere, even at very low concentrations.
Development of a novel carbon nanomaterial 'pot'
A novel, pot-shaped, carbon nanomaterial developed by researchers from Kumamoto University, Japan is several times deeper than any hollow carbon nanostructure previously produced.
Unraveling truly one-dimensional carbon solids
Elemental carbon appears in many different forms, including diamond and graphite.
Carbon leads the way in clean energy
Groundbreaking research at Griffith University is leading the way in clean energy, with the use of carbon as a way to deliver energy using hydrogen.
Consumers care about carbon footprint
How much do consumers care about the carbon footprint of the products they buy?
Assessing carbon capture technology
Carbon capture and storage could be used to mitigate greenhouse gas emissions and thus ameliorate their impact on climate change.

Related Carbon Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Setbacks
Failure can feel lonely and final. But can we learn from failure, even reframe it, to feel more like a temporary setback? This hour, TED speakers on changing a crushing defeat into a stepping stone. Guests include entrepreneur Leticia Gasca, psychology professor Alison Ledgerwood, astronomer Phil Plait, former professional athlete Charly Haversat, and UPS training manager Jon Bowers.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".