使用碳纳米管可显著增加锂电池容量-凯发k8官网

使用碳纳米管可显著增加锂电池容量
文章来源:未知 文章作者:meng 发布时间:2010-06-21 06:45 字体: [ ] 
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batteries might gain a boost in power capacity(功率容量) as a result of a new finding from researchers at mit. they found that using carbon nanotubes for one of the battery's electrodes produced a significant increase — up to tenfold — in the amount of power it could deliver from a given weight of material, compared to a conventional lithium-ion battery. such electrodes might find applications in small portable devices, and with further research might also lead to improved batteries for larger, more power-hungry applications. to produce the powerful new electrode material, the team used a layer-by-layer fabrication(制造,装配) method, in which a base material is alternately dipped in solutions containing carbon nanotubes that have been treated with simple organic compounds that give them either a positive or negative net charge. when these layers are alternated on a surface, they bond tightly together because of the complementary charges, making a stable and 1 film.

the findings, by a team led by associate professor of mechanical engineering and materials science and engineering yang shao-horn, in 2 with bayer chair professor of chemical engineering paula hammond, are reported in a paper published june 20 in the journal nature nanotechnology. the lead authors are chemical engineering student seung woo lee phd '10 and postdoctoral researcher naoaki yabuuchi.

batteries, such as the lithium-ion batteries widely used in portable electronics, are made up of three basic 3: two electrodes (called the anode阳极,正极, or negative electrode, and the cathode阴极, or positive electrode) separated by an electrolyte(电解质) , an electrically conductive material through which charged particles, or ions, can move easily. when these batteries are in use, 4 charged lithium ions travel across the electrolyte to the cathode, producing an electric current; when they are recharged, an external current causes these ions to move the opposite way, so they become 5 in the spaces in the 6 material(多孔材料) of the anode.

in the new battery electrode, carbon nanotubes — a form of pure carbon in which sheets of carbon atoms are rolled up into tiny tubes — "self-assemble" into a tightly bound structure that is porous at the nanometer scale (billionths of a meter). in addition, the carbon nanotubes have many oxygen groups on their surfaces, which can store a large number of lithium ions; this enables carbon nanotubes for the first time to serve as the positive electrode in lithium batteries, instead of just the negative electrode.

this "electrostatic self-assembly" process is important, hammond explains, because ordinarily carbon nanotubes on a surface tend to 7 together in bundles(捆,束) , leaving fewer exposed surfaces to undergo reactions. by incorporating organic 8 on the nanotubes, they assemble in a way that "has a high degree of 9 while having a great number of nanotubes present," she says.

lithium batteries with the new material demonstrate some of the advantages of both capacitors, which can produce very high power outputs in short bursts, and lithium batteries, which can provide lower power 10 for long periods, lee says. the energy output for a given weight of this new electrode material was shown to be five times greater than for conventional capacitors, and the total power delivery rate was 10 times that of lithium-ion batteries, the team says. this performance can be attributed to good conduction of ions and electrons in the electrode, and efficient lithium storage on the surface of the nanotubes.

in addition to their high power output, the carbon nanotube electrodes showed very good stability over time. after 1,000 cycles of charging and discharging a test battery, there was no 11 change in the material's performance.

the electrodes the team produced had thicknesses up to a few microns(微米) , and the improvements in energy delivery only were seen at high-power output levels. in future work, the team aims to produce thicker electrodes and extend the improved performance to low-power outputs as well, they say. in its present form, the material might have applications for small, portable electronic devices, says shao-horn, but if the reported high power 12 were demonstrated in a much thicker form — with thicknesses of hundreds of microns rather than just a few — it might eventually be suitable for other applications such as 13 cars(双动力汽车) .

while the electrode material was produced by alternately dipping a substrate(基质) into two different solutions — a 14 time-consuming process — hammond suggests that the process could be modified by instead spraying the alternate layers onto a moving ribbon of material, a technique now being developed in her lab. this could eventually open the possibility of a continuous manufacturing process that could be scaled up(按比例放大) to high volumes for commercial production, and could also be used to produce thicker electrodes with a greater power capacity. "there isn't a real limit" on the potential thickness, hammond says. "the only limit is the time it takes to make the layers," and the spraying technique can be up to 100 times faster than dipping, she says.

lee says that while carbon nanotubes have been produced in limited quantities so far, a number of companies are currently gearing up(在一改准备) for mass production of the material, which could help to make it a 15 material for large-scale battery manufacturing.



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1 frox4     
adj.持久的,耐久的
参考例句:
  • this raincoat is made of very durable material.这件雨衣是用非常耐用的料子做的。
  • they frequently require more major durable purchases.他们经常需要购买耐用消费品。
2 bw7yd     
n.合作,协作;勾结
参考例句:
  • the two companies are working in close collaboration each other.这两家公司密切合作。
  • he was shot for collaboration with the enemy.他因通敌而被枪毙了。
3 4725dcf446a342f1473a8228e42dfa48     
(机器、设备等的)构成要素,零件,成分; 成分( component的名词复数 ); [物理化学]组分; [数学]分量; (混合物的)组成部分
参考例句:
  • the components of a machine 机器部件
  • our chemistry teacher often reduces a compound to its components in lab. 在实验室中化学老师常把化合物分解为各种成分。
4 vptxw     
adv.明确地,断然,坚决地;实在,确实
参考例句:
  • she was positively glowing with happiness.她满脸幸福。
  • the weather was positively poisonous.这天气着实讨厌。
5 lt9zts     
a.扎牢的
参考例句:
  • an operation to remove glass that was embedded in his leg 取出扎入他腿部玻璃的手术
  • he has embedded his name in the minds of millions of people. 他的名字铭刻在数百万人民心中。
6 91szq     
adj.可渗透的,多孔的
参考例句:
  • he added sand to the soil to make it more porous.他往土里掺沙子以提高渗水性能。
  • the shell has to be slightly porous to enable oxygen to pass in.外壳不得不有些细小的孔以便能使氧气通过。
7 xxfzh     
n.树丛,草丛;vi.用沉重的脚步行走
参考例句:
  • a stream meandered gently through a clump of trees.一条小溪从树丛中蜿蜒穿过。
  • it was as if he had hacked with his thick boots at a clump of bluebells.仿佛他用自己的厚靴子无情地践踏了一丛野风信子。
8 187c25e49d45ad10b2f266c1fa7a8d49     
分子( molecule的名词复数 )
参考例句:
  • the structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
  • inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里,大分子裂变为小分子。
9 07db8161708ca0fe31a7e9834d7f8c2a     
n.多孔性,有孔性
参考例句:
  • commonly the dolomite crytals form a framework with evenly distributed porosity. 通常白云石晶体构成格架,它有均匀分布的孔隙。 来自辞典例句
  • seismic velocity can occasionally be affected by porosity and temperature. 孔隙率和温度有时也能影响地震波速。 来自辞典例句
10 qukw6     
adv.稳定地;不变地;持续地
参考例句:
  • the scope of man's use of natural resources will steadily grow.人类利用自然资源的广度将日益扩大。
  • our educational reform was steadily led onto the correct path.我们的教学改革慢慢上轨道了。
11 tuxzmd     
adj.可发觉的;可查明的
参考例句:
  • the noise is barely detectable by the human ear.人的耳朵几乎是察觉不到这种噪音的。
  • the inflection point at this ph is barely detectable.在此ph值下,拐点不易发现。
12 jsgzz     
n.能力;才能;(pl)可发展的能力或特性等
参考例句:
  • she has the capability to become a very fine actress.她有潜力成为杰出演员。
  • organizing a whole department is beyond his capability.组织整个部门是他能力以外的事。
13 pcbzu     
n.(动,植)杂种,混合物
参考例句:
  • that is a hybrid perpetual rose.那是一株杂交的四季开花的蔷薇。
  • the hybrid was tall,handsome,and intelligent.那混血儿高大、英俊、又聪明。
14 bkqzs3     
adv.比较...地,相对地
参考例句:
  • the rabbit is a relatively recent introduction in australia.兔子是相对较新引入澳大利亚的物种。
  • the operation was relatively painless.手术相对来说不痛。
15 mi2wz     
adj.可行的,切实可行的,能活下去的
参考例句:
  • the scheme is economically viable.这个计划从经济效益来看是可行的。
  • the economy of the country is not viable.这个国家经济是难以维持的。
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