The Rice University lab of chemist James Tour introduced a technique to tune the surface of anodes for batteries by simply brushing powders into them. The powder adheres to the anode and becomes a thin, lithiated coating that effectively prevents the formation of damaging dendrites.

The optical images of Li metal anodes after surface scrubbing and rubbing. (a) bare Li. (b) brushed Li. (c) PANI-Li. (d) MoS 2 -Li. (e) P 2 S 5 -Li. (f) PTFE-Li. In the context, P 2 S 5 -Li refers to P 2 S 5 scrubbed/rubbed on Li metal anodes for simplicity and the same for other powders modified anodes. Image Credit: Rice University, James Tour Lab. Click here for the press release data. There are two very short videos at the Advanced Materials link under “Supporting Information.”

A powder of phosphorus and sulfur ground into the surface of lithium metal foil demonstrated its surface energy can be tuned without the need for toxic solvents. Anodes so modified and paired with lithium-iron-phosphate-oxide cathodes in test cells showed they retained 70% more capacity after 340 charge-discharge cycles than off-the-shelf batteries.

The study appears in Advanced Materials.

Tour said, “This would simplify the manufacture of high-capacity batteries while greatly improving them. Sanding these powdered solids into a lithium metal anode dramatically reduces dendrite formation that can short circuit a battery, as well as the accelerated consumption of the materials.”

Lead author and Rice graduate student Weiyin Chen and his lab colleagues applied the necessary elbow grease to test a variety of powder candidates on their electrodes. They first brushed the surface to give it texture, then brushed in powder to create the fine film that reacts with the lithium metal and forms a solid passivation layer.

Chen and co-author Rodrigo Salvatierra, a former postdoctoral researcher and now an academic visitor in the Tour lab, constructed test batteries and determined the treated anodes retained ultralow polarization – another damaging characteristic for lithium-ion batteries – for more than 4,000 hours, about eight times longer than bare lithium anodes.

Tour said the powders effectively tune the surface energy of the electrodes, making for a more uniform behavior across the material.

“This provides a metal composite surface that prevents the loss of lithium metal from the anode, a common problem in lithium metal batteries,” Tour explained. “Lithium metal batteries far exceed the capacity of traditional lithium-ion batteries, but the lithium metal is often difficult to repeatedly recharge.”

“The powder at the lithium metal surface produces an artificial passivation layer that improves the stability throughout the charge-discharge cycles,” Chen added. “Using this brush-on method, the metal surface is stabilized so that it can be safely recharged.”

To show the technique may have wider application, the lab also ground powder into a sodium electrode and discovered the process greatly stabilized its voltage overpotential.

The study aligns with the recent discovery by Tour and Rice mechanical engineer C. Fred Higgs III that sanding certain powders into surfaces can make them superhydrophobic, or highly resistant to water.

Co-authors of the paper are Rice alums John Li and Duy Luong; graduate students Jacob Beckham, Nghi La and Jianan Xu, and academic visitor Victor Li. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of computer science and of materials science and nanoengineering at Rice.


This is the second electrode coating we’ve seen in the past few weeks. This technology surely has some legs for getting to the experiments about going to scale. One sure hopes so, a lithium metal battery would sure be welcome for the cell phone. Not there just yet, but getting much closer.


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