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CAS Researchers Encapsulate Tin Nanoparticles in Nanospheres for Li-ion Anode Materials
24 June 2008
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| The structure and the lithiation process of the tin nanoparticles encapsulated with elastic hollow carbon spheres. Click to enlarge. Image: Prof. Li-Jun Wan |
Researchers at the Chinese Academy of Sciences (CAS) Key Laboratory of Molecular Nanostructure and Nanotechnology have successfully designed and synthesized tin-based nanostructured anode materials for high-performance lithium-ion batteries. The work was published in a recent issue of the journal Advanced Materials.
Metallic tin is considered a promising anode material for lithium-ion batteries because its theoretical specific capacity (Li4.4Sn, 992 mAh/g) is much higher than that of conventional graphite (LiC6, 372 mAh/g). However, the biggest challenge for employing metallic tin as an applicable active anode material is its large variation in volume during the lithium insertion/extraction cycle. This variation leads to the pulverization of the electrode and very rapid capacity decay.
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| Large-scale SEM image of tin nanoparticles encapsulated elastic hollow carbon spheres (TNHCs). Click to enlarge. |
To solve the problem, a research team led by Prof. Li-Jun Wan, director of the CAS Institute of Chemistry, designed a new approach to synthesize tin nanoparticles encapsulated in elastic hollow carbon spheres (TNHCs) with uniform size.
Via such a approach, multiple tin nanoparticles with a diameter of less than 100 nm were encapsulated in one thin hollow carbon sphere with a thickness of only about 20 nm, with Sn content of up to more than 70% by weight and the void volume in carbon shell as high as about 70-80% by volume.
This void volume and the elasticity of the thin carbon spherical shell can efficiently accommodate the volume change of tin nanoparticles due to the Li-Sn alloying-dealloying reactions, and thus prevent the pulverization of the electrodes.
This type of tin-based nanocomposite is showing very high specific capacity of >800 mAh/g in the initial 10 cycles, and 550 mAh/g after the 100th cycle, as well as strong cycling performance, exhibiting potential as anode materials in lithium-ion batteries.
The researchers say their results successfully demonstrate the power of the strategy of using elastic hollow carbon spheres as buffer and container and could be extended to other anode and cathode materials.
The work was supported by CAS, the Chinese Ministry of Science and Technology, and the National Natural Science Foundation of China.
Dr. Wan’s team had earlier reported on the development of self-assembled vanadium pentoxide (V2O5) hollow microshperes as cathode materials for Li-ion batteries.
Resources
Wei-Ming Zhang, Jin-Song Hu, Yu-Guo Guo, Shu-Fa Zheng, Liang-Shu Zhong, Wei-Guo Song, Li-Jun Wan (2008) Tin-Nanoparticles Encapsulated in Elastic Hollow Carbon Spheres for High-Performance Anode Material in Lithium-Ion Batteries, Advanced Materials doi: 10.1002/adma.200701364
An-Min Cao, Jin-Song Hu, Han-Pu Liang, Li-Jun Wan (2005) Self-Assembled Vanadium Pentoxide (V2O5) Hollow Microspheres from Nanorods and Their Application in Lithium-Ion Batteries, Angewandte Chemie International Edition, doi: 10.1002/anie.200500946
June 24, 2008 in Batteries, China | Permalink | Comments (5) | TrackBack (0)
Comments
Posted by: John Taylor | June 24, 2008 at 06:43 PM
Witness the dawn of the Chinese leading the world in scientific (and technological) discovery....
Posted by: clett | June 25, 2008 at 01:41 AM
Hey Clet ... the dawn of the Chinese leading the world in scientific (and technological) discovery was back in ancient times. Except for the past 200 years, China has almost always been the top manufacturing center of the world.
The Neolithic village of Jiahu, in Henan province, Northern China, produced a mixed fermented beverage of rice, honey, and fruit 9,000 years ago. These were marketed in the same sort of little round vases we know as "potion bottles" ... (I think strong wine still works as a 'love-potion' if you can convince the girl to drink it).
I for one am not at all surprised to see them regain part of their old innovation and manufacturing capability.
Posted by: J T | June 25, 2008 at 04:00 AM
This is more good news for future PHEVs and BEVs.
Much higher performance 500+ Wh/Kg batteries may be around sooner than many of us think. The past 8% per year battery performance improvement may be multiplied in the next 5 -8 years.
If so, and if the mass produced price is right (below $300 KWh), very efficient PHEVs (various sizes) and practical, affordable, lightweight BEVs may be around by 201?.
Posted by: HarveyD | June 25, 2008 at 08:18 AM
If you combine this technique with materials that do not change volume so much on cycling (iron phospate) you might end up with a battery good for several thousand cycles.. and that may come in handy for a 10 mile range hybrid with a more agressive battery usage profile.. plus long term reliability.
Posted by: Herm | June 28, 2008 at 09:41 AM
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Something is causing the rather dramatic loss of capacity.
On first glance, it looks like the plastic spheres might be too full of nanoparticles.
A lower fill rate may have a reduced initial charge capacity, but a much longer life span and far more charge cycles.
Just a thought.