Rice technique shows creating films on lithium anodes gives them longer life

A little brushing can be the top secret to making better rechargeable lithium batteries.

The Rice University lab of chemist James Tour has introduced a procedure for setting the surface of battery anodes by simply applying powders to them. The powder adheres to the anode and becomes a thin lithium coating that effectively prevents the formation of harmful dendrites.

A powder of phosphorus and sulfur crushed on the surface of a sheet lithium metal has demonstrated that its surface energy can be tuned without the need for toxic solvents. The anodes thus modified and associated with lithium-iron-phosphate-oxide cathodes in take a look at cells have shown that they retain 70% of capacity in more after 340 charge-discharge cycles than regular batteries.

Study appears in Highly Developed Supplies.

“This would simplify the manufacture of high-capacity batteries while significantly improving them,” said Tour. “Grinding these powdered solids into a lithium metal anode dramatically reduces the formation of dendrites that can short out a battery, as well as accelerated material consumption.”

Weiyin Chen, lead author and Rice graduate student, and his lab colleagues applied the elbow grease needed to test a variety of candidate powders on their electrodes. They first brushed the surface area to give it texture, then powder brushed to create the thin film that reacts with the metallic lithium and forms a strong passivation layer.

Chen and co-author Rodrigo Salvatierra, a former postdoctoral researcher and now academic visitor in the Tour lab, built test batteries and determined that the treated anodes retained ultra-low polarization – another damaging characteristic for batteries lithium-ion – for over 4 000 hours, approximately eight times longer than bare lithium anodes.

Tour said the powders effectively tune the area energy of the electrodes, allowing for more uniform behavior across the material.

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

“The powder at the surface of lithium metal produces an artificial passivation layer that improves stability throughout demand-discharge cycles,” Chen said. “Using this method of brushing, the metal surface is stabilized so that it can be relined safely.”

To show that the technique may have more massive application , the lab also ground powder in a sodium electrode and found that the process significantly stabilized its pressure surge.

Study aligns with recent finding of Tour and Rice mechanical engineer C. Fred Higgs III that sanding certain powders onto surfaces can make them superhydrophobic or highly water resistant.

The co-authors of the article are Rice alumni John Li and Duy Luong graduate students Jacob Beckham, Nghi La and Jianan Xu, and Academic Visitor Victor Li. Tour holds the TT and WF Chao Chair in Chemistry as well as Professor of Computing and Materials Science and Nano-Engineering at Rice.

The Air Pressure Office environment of Scientific Study (FA9550-19-1- 0296) supported the search.

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