Rethinking the Rechargeable Battery

What's Hot in January/February 2011

By John Emsley

It has always been believed that lithium ion batteries are slow to recharge, because the process involves the physical transport of ions, hence the hours that are needed to restore the batteries to full capacity. Paper #8 in the current list overturns this belief and reports a material through which ions like Li+ can move within seconds, and it may be that one day they will be nearly as quick to recharge as ultra-capacitors, which can be recharged in seconds and are increasingly being used to store electrical energy.

This new material is lithium iron phosphate, LiFePO4, and although it has not yet found an application, with proper engineering the next few years might well see battery-operated equipment such as cell phones, cameras, iPads, and electric shavers taking only a couple of minutes to recharge—and the advance will be thanks in large part to the remarkable work of by Byoungwoo Kang and Gerbrand Ceder of MIT.

In #8 the researchers report that LiFePO4 can transport lithium ions speedily back to the electrode so that the battery becomes fully charged. The material was made by grinding together an off-stoichiometric mix of lithium carbonate, iron oxalate, and ammonium dihydrogen phosphate in a ball-mill, and following this by heating the resulting fine powder at 600° C for 10 hours under an atmosphere of argon. The product so obtained has the remarkable ability to move lithium ions more than a hundred times faster than in a conventional lithium battery.

Gerbrand Ceder

Byoungwoo Kang
Gerbrand Ceder (top) of Byoungwoo Kang (bottom) of MIT

Not that this discovery is likely to come to market in the near future. Ceder acknowledges that to produce a quick-recharge battery will mean a lot of re-engineering because fast charging or discharging requires very high currents to deliver the full amount of energy stored in the battery in a short time. That is a river yet to be crossed.

Meanwhile more information about the structure and performance of LiFePO4 can be found in the paper by A. Kayyar, H.J. Qian, and J. Luo published in Applied Physics Letters (95: 221905, 2009), which shows micrographs of the microstructure of the new material.

Ceder tells Science Watch that while he is still working on new electrode materials for batteries which can store more charge (energy) than current materials, he is also devoting his energy to the Materials Genome project which he has started at MIT, and this promises to revolutionize inorganic materials research by computing exactly what can be expected from them, thereby directing research into those with real potential.

Says Ceder: "Ab-initio computations and the problems of solving the basic equations of quantum mechanics and statistical mechanics have made tremendous progress in the last 20 years, and we have reached the point at which many important properties of compounds can be confidently predicted." According to Ceder, the vision of the Materials Genome project is to know everything about a new material before it is even made, and they are applying their knowledge to the development of novel materials for energy storage, solar energy capture, and thermoelectrics.

Ceder is keen to see progress: "We really want to change the way materials design is done by applying the power of computing to it. The world's problems are too serious and impatient to wait for traditional Edisonian materials invention."

Meanwhile, just outside the current Hot Ten, at #13, is a paper from a group led by Elisabetta Collini and Cathy Wang of the Department of Chemistry at the University of Toronto (E. Collini, et al., Nature, 363(7281): 644-7, 4 February 2010; 18 citations this period, 25 overall). This reports on a most unexpected way in which cryptophyte algae transfer the light which they harvest to the sites where they synthesize the various chemicals they need.

The light-gathering is done via so-called antenna proteins, and these are able to transfer the light energy they gather to reaction sites that are technically too far away to flow via conventional "wiring" pathways. The algae appear to be doing the transfer by means of quantum-coherent sharing of energy states, which is a rather sophisticated mechanism for simple organisms like the algae to have developed.End

Dr. John Emsley is based at the Department of Chemistry, Cambridge University, U.K.

 
Click the tab above to view Hot Papers.
What's Hot in Chemistry
Rank Paper Cites This Period
Jul-Aug 10
Rank Last Period
May-Jun 10
X.S. Li, et al., "Large-area synthesis of high-quality and uniform graphene films on copper foils," Science, 324(5932): 1312-4, 5 June 2009. [U. Texas, Austin]     *453TF 43 2
A. Reina, et al., "Large area, few-layer graphene films on arbitrary substrates by chemical vapor deposition," Nano Letters, 9(1): 30-5, January 2009. [MIT, Cambridge]  *395IZ 40 4
3 D.C. Elias, et al., "Control of graphene’s properties by reversible hydrogenation: Evidence for graphane," Science, 323(5914): 610-3, 30 January 2009. [U. Manchester, U.K.; Inst. Microelectronics Tech., Chernogolovka, Russia; Cambridge U., U.K.; U. Nijmegen, Netherlands]   *400JB  35 3
M.D. Stoller, et al., "Graphene-based ultracapacitors," Nano Letters, 8(10): 3498-3502, October 2008. [U. Texas, Austin]  *358HD 31 5
D.V. Kosynkin, et al., "Longitudinal unzipping of carbon nanotubes to form graphene nanoribbons," Nature, 458(7240): 872-6, 16 April 2009.  [Rice U., Houston, TX] *433CS 25 6
6 L.Y. Jiao, et al., "Narrow graphene nanoribbons from carbon nanotubes," Nature, 458(7240): 877-80, 16 April 2009. [Stanford U., CA] *433CS 21 10
7 J.H. Hou, et al., "Synthesis, characterization, and photovoltaic properties of a low band gap polymer based on silole-containing polythiophenes and 2,1,3-benzothiadiazole," J. Am. Chem. Soc., 130(48): 16144-5, 3 December 2008. [U. Calif., Los Angeles; Solarmer Energy, El Monte, CA]   *406UG 20
B. Kang, G. Ceder, "Battery materials for ultrafast charging and discharging," Nature, 458(7235): 190-3, 12 March 2009. [MIT, Cambridge, MA]  *417EQ 20
9 B. Lim, et al., "Pd-Pt bimetallic nanodendrites with high activity for oxygen reduction," Science, 324(5932): 1302-5, 5 June 2009.  [Washington U., St. Louis, MO; Brookhaven Natl. Lab., Upton, NY]  *453TF 20
10 Y.Y. Liang, et al., "Highly efficient solar cell polymers developed via fine-tuning of structural and electronic properties," J. Am. Chem. Soc., 131(22): 7792-9, 10 June 1009. [U. Chicago, IL; Solarmer Energy Inc., El Monte, CA]   *460HD 20
SOURCE: Thomson Reuters Hot Papers Database. Read the Legend.

 

 

 

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