My watch list  

Recharging on stable, amorphous silicon


© Wiley-VCH

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. 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.

Original publication:

Jian Yang et al.; "Mesoporous Amorphous Silicon: A Simple Synthesis of a High-Rate and Long-Life Anode Material for Lithium-Ion Batteries"; Angewandte Chemie; 2016

Facts, background information, dossiers
  • charge-discharge cycles
  • pulverization
More about Shandong University
More about Angewandte Chemie
  • News

    What the Smell Can Tell

    Breath analysis in disease diagnostics is a promising research field, and the advances in instrumentation allows the accurate detection of metabolites. But not only the health status of patients, but also the preservation status of museum artifacts could be monitored. Heritage science resea ... more

    Water-Soluble Warped Nanographene

    Graphene and its nano-sized little sibling, nanographene, are well known for their remarkable photoelectronic properties. However, biomedical applications are hampered by the insolubility of the materials, especially in water. A Japanese team of scientists has now introduced substituted “wa ... more

    The Making of Biorelevant Nanomaterials

    The interactions of biological macromolecules such as nucleic acids, proteins, and polysaccharide–protein conjugates can be mimicked by artificial polyelectrolytes. Such synthetic polyionic complexes are expected to serve as novel platforms to stabilize and deliver drugs, proteins, or nucle ... more

Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE