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Researchers Synthesize Tin Oxide Nanosheets with High Lithium Storage Capacity and Cyclability

Wangsn02
(a) SEM image and (b) TEM image of the as-prepared SnO2 nanosheets. Source: Wang et al./ACS. Click to enlarge.

A team of researchers from Zhejiang University (China) and the Austrian Academy of Sciences has successfully synthesized a new SnO2 nanoarchitecture: extremely thin sheets, with minimum thicknesses of 1.5-3.0 nm. The assemblies of these sheets have a high BET surface area of 180.3 m2/g and extraordinarily large pore volume of 1.028 cm3/g.

The sheets exhibit a high lithium storage capacity and excellent cyclability due to the nanometer-sized frame and breathable characteristic, making them a promising candidate for a higher capacity lithium-ion anode material. A paper on their work appeared online 9 December in the Journal of the American Chemical Society.

With a high theoretical gravimetric lithium storage capacity of 782 mAh g-1—more than twice that of the currently commercialized graphite (372 mAh g-1)—and low potential of lithium ion intercalation, SnO2 is regarded as a promising anode material for lithium-ion batteries.

Tin oxides, however, can suffer from severe capacity loss, first due to a formation of electrochemically inactive Li2O during the first few cycles and then due to pulverization stemming from drastic volume changes.

To enhance the cyclability of the electrode, hybridizing SnO2 with carbon is effective, but this approach sacrifices the capacity itself due to the introduction of carbon and is usually complicated in fabrication. It is suggested that if single SnO2 was used as an active material, it should be in a nanometer-sized frame to shorten the pathway lengths of the lithium ion and should possess interior hollow spaces to accommodate large volume change. Herein, we report highly porous SnO2 nanometer-sized sheets synthesized from a hydrothermal reaction.

—Wang et al.

Performance tests of the material as a lithium-ion anode material found that it exhibited a high discharge capacity of 559 mAh g-1 after 20 cycles with the retention of 57%. The Coulombic efficiency kept steadily at more than 95%.

Recently, Park et al. reported a SnO2/graphene hybridization, which also exhibited enhanced cyclic performance. The introduction of graphene plays dual roles; i.e., it increases the electrode conductivity and acts as a buffer layer to contain stresses induced by volume change. In comparison, the charge capacity of SnO2/graphene remains ~593 mAh g-1 after 20 cycles which is slightly higher than our results of 559 mAh/g. Nevertheless, considering we applied a wider cutoff window and larger constant current which are prone to create relatively harsher destruction and resistance of the electrode, the material reported here is very attractive due to its facile, economical, and high purity synthesis. Its performance via hybridization will be further studied.

—Wang et al.

Resources

  • Cen Wang, Yun Zhou, Mingyuan Ge, Xiaobin Xu, Zaoli Zhang and J. Z. Jiang (2009) Large-Scale Synthesis of SnO2 Nanosheets with High Lithium Storage Capacity. J. Am. Chem. Soc., Article ASAP doi: 10.1021/ja909321d

Comments

HarveyD

Another interesting development towards an improved rechargeable battery for future PHEVs and BEVs.

Wonder when somebody will come out with a 500Wh/Kg unit?

Mannstein

According to ecomii.com, around half of an EV’s manufacturing cost comes from its lithium ion battery. Mass adoption of EVs depends largely on improving the competitiveness of their batteries. But lithium is also used in batteries for other electrical technologies including laptop computers, digital cameras and cell phones. As demand rises faster than supply, price increases. Unfortunately the supply of lithium is limited by both geological and political factors.

While Lithium is a naturally occurring element, it is a finite natural resource: only so much of it exists in the world. And here’s the crunch point for many environmentalists - half of the world’s known Lithium supply is located in Bolivia, in a nature reserve.

The world will go from peak oil to peak lithium overnight.

SJC

If you can recycle and reprocess the lithium, it is not as finite. Oil is finite, so going to batteries could be a more sustainable future. This may be one of the considerations for battery design.

Peace Hugger


Isn't lithium tin battery still inferior to zinc air?

Mannstein

In terms of energy density yes.

Darius

Mannstein,

Too early to worry about Lithium reserves. See water contains lot of it. Battery efficiency per kg of Lithium is rapidly increasing. Nobody was seriously investigated conventional Lithium reserves. More over - Lithium not the only available option of battery chemistry. Other's will come.

SJC

It is obvious the HEVs lead to PHEVs and eventually EVs. The amount of batteries required increases also. As prices come down and capacities go up, we may see more and more of them used. This is a natural evolution in the transformation of personal transport.

Stan Peterson

Lithium is about 6% of the Earths crust. That is much more common than Aluminum for example.

There is no limitiations on on Lithium availability. There never has been. And the World's largest reserves of Lihtium are in the good old USA.

Ole Grampa

@ Stan:
The largest known lithium deposits are in Bolivia, which presently has a very nationalist political orientation.
Even though lithium is a common element, there are only a few places where it is economical to extract it.

TexasT

As the demand increases new lithium sources will be found:
http://www.physorg.com/news179999592.html
Re-cycled resources is the key verses use it and throw it away

Mannstein

Shares of global lithium supply by country

Production Reserves

Chile 39.30 percent 22.10 percent
China 13.30 percent 16.20 percent
Australia 11.00 percent 2.40 percent
Russia 10.80 percent n/a
Argentina 9.80 percent 14.70 percent
United States 8.40 percent 0.60 percent
Bolivia 0.00 percent 39.70 percent

Source: Meridian International Research, 2005 levels

DaveD

It takes about 80 grams of lithium per kWh of lithium ion battery. So a car like the Volt uses about 1.2kg of lithium. Considering that there are between 24-150 million metric tons of known lithium reserves today (depending on who's numbers you believe)...so we could build between 25 BILLION to 150 BILLION chevy volts.

We need to stop scaring everyone with the lithium "shortage crisis". It's taking on a life of it's own like all the other internet urban legends.

There are many sources of lithium. It's never been a big deal so people haven't looked for it or even developed the ones we have. Here's another one announce this week in Mexico:

http://www.laht.com/article.asp?CategoryId=14091&ArticleId=345461

There are other sources of lithium we're now discovering all over, even here in the US. Geothermal and even the brine left over from different types of mining (even oil field brines) have lots of lithium that nobody has ever bothered to even look at and measure.

http://lithiumabundance.blogspot.com/

Mannstein

Reclaiming Lithium from sea water is not aa inexpensive proposition.

DaveD

Here's another one from this morning:

http://green.autoblog.com/2009/12/14/domestic-lithium-source-could-be-geothermal-waste-water/#comments

As Darius said earlier, there are plenty of other paths to get batteries besides lithium as well such as zinc-air.

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