Green Car Congress  
Home Topics Archives About Contact  RSS Headlines

« Rheinmetall wins 7-year, €100M contract for electric motor housings for China | Main | California ARB opens solicitations for $17M for On-Road Advanced Technology Demonstrations Projects; Class 7, 8 trucks »

Print this post

Rice team devises Li metal anode that completely suppresses Li dendrite formation

19 May 2017

Rice University scientists have used a seamless graphene-carbon nanotube (GCNT) electrode to store lithium metal reversibly and with complete suppression of dendrite formation. The GCNT-Li capacity of 3351 mAh g-1GCNT-Li approaches that of bare Li metal (3861 mAh g-1Li)—indicating the low contributing mass of GCNT—while yielding a practical areal capacity up to 4 mAh cm-2 and cycle stability.

In a paper published in the journal ACS Nano, the team led by Dr. James Tour reports that a full battery based on GCNT-Li/sulfurized carbon (SC) exhibits high energy density (752 Wh kg-1total electrodes, where total electrodes = GCNT-Li + SC + binder), high areal capacity (2 mAh cm-2), cyclability (80% retention at > 500 cycles) and is free of Li polysulfides and dendrites that would cause severe capacity fade.

Tour
Comparison of the gravimetric capacity of GCNT-Li (with different areal capacities) with other anode materials with respect to the mass of the anode at the fully lithiated state. The areal capacities of the GCNT-Li are from 0.4 to 4 mAh cm-2, represented by GCNT-Li-0.4 to GCNT-Li-4. Credit: ACS, Raji et al.

Post-Li-ion batteries, such as Li-S and Li-air batteries, require high gravimetric capacity anodes and cathodes. Ideally, during the charging of a battery, the maximum gravimetric capacity would be achieved if Li is deposited on the anode directly as pure Li metal rather than stored in intercalation compounds such as graphite as in Li-ion batteries (LIBs). The theoretical capacity based on lithiated graphite LiC6 is ~ 339 mAh g-1 while pure Li metal can theoretically deliver 3860 mAh g-1 assuming 100% of Li usage in the discharge operation.

This enormous capacity compared to commercial Li-ion anodes explain the revisiting of Li metal after more than 30 years of the first attempts to incorporate this low density metal in high energy density batteries. However, Li metal problematically forms dendrites and related unstable structures during battery operation. This results in low coulombic efficiency (CE) and cycle life and poses serious safety concerns as the dendrites can cause short circuits.

—Raji et al.

The Rice team’s GCNT, first created at Rice in 2012, is essentially a three-dimensional carbon surface that provides abundant area for lithium to inhabit. It stores large amounts of metal homogeneously distributed as a thin coating over CNT bundles—suppressing dendrite formation during reversible plating and stripping operation.

Because of the low density of the nanotube carpet, the ability of lithium to coat all the way down to the substrate ensures maximum use of the available volume, Tour said.

The researchers had their “Aha!” moment in 2014, when co-lead author Abdul-Rahman Raji, a former graduate student in Tour’s lab and now a postdoctoral researcher at the University of Cambridge, began experimenting with lithium metal and the graphene-nanotube hybrid.

I reasoned that lithium metal must have plated on the electrode while analyzing results of experiments carried out to store lithium ions in the anode material combined with a lithium cobalt oxide cathode in a full cell. We were excited because the voltage profile of the full cell was very flat. At that moment, we knew we had found something special.

—Abdul-Rahman Raji

Within a week, Raji and co-lead author Rodrigo Villegas Salvatierra, a Rice postdoctoral researcher, deposited lithium metal into a standalone hybrid anode so they could have a closer look with a microscope. “We were stunned to find no dendrites grown, and the rest is history,” Raji said.

Electron microscope images of the GCNT-Li anodes from the full cell with a sulfur cathode after testing showed no sign of dendrites or the moss-like structures that have been observed on flat anodes. To the naked eye, anodes within the quarter-sized batteries were dark when empty of lithium metal and silver when full, the researchers reported.

Many people doing battery research only make the anode, because to do the whole package is much harder. We had to develop a commensurate cathode technology based upon sulfur to accommodate these ultrahigh-capacity lithium anodes in first-generation systems. We’re producing these full batteries, cathode plus anode, on a pilot scale, and they’re being tested.

—James Tour

This holds promise for achieving superior energy density due to the near theoretical Li storage capacity and serves as the basis for the demonstrated SC||GCNT-Li full-cell in a high concentration electrolyte to produce a safe, stable, and high performance battery, thus becoming a harbinger of future systems.

—Raji et al.

Co-authors of the paper are Rice postdoctoral researcher Nam Dong Kim, visiting researchers Xiujun Fan and Junwei Sha and graduate students Yilun Li and Gladys López-Silva. 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.

The Air Force Office of Scientific Research Multidisciplinary University Research Initiative supported the research.

Resources

  • Abdul-Rahman O. Raji, Rodrigo Villegas Salvatierra, Nam Dong Kim, Xiujun Fan, Yilun Li, Gladys A. L. Silva, Junwei Sha, and James M. Tour (2017) “Lithium Batteries with Nearly Maximum Metal Storage” ACS Nano doi: 10.1021/acsnano.7b02731

May 19, 2017 in Batteries, Li-O2, Li-Sulfur | Permalink | Comments (7)

Comments

hmmmm, me thinks the comment system is broken today LOL

And of course, now that I make fun of it, the comments work. Sigh.

Anyway, this is one of the few announcements I see on batteries that I think will make a real difference one day. The fact they did a full on battery is a great sign of how practical this is in the real world. Of course, the cost side of the equation is still a big question....but at least it exists.

Sounds promising. I will be interested to hear about durability testing, and (probably more important) cost and scalability of manufacture. Can these things be made easily/cheaply, potentially?

Kudos to the Rice team for this important breakthrough. The prospect of a 100kg battery (sans bms and pack components) for ~ 250 mile EV is incredibly exciting.

These cells could enable ~ 4 hours of 100 kts flight for a small 2 passenger aircraft. Fuel cost for the ~400 mile flight (with reserve) would be only $36 at national average electric cost, and as low as $15 with hangar-roof solar panels. $3.50 per hour of travel at 115mph.

That would totally transform the GA industry.

En la practica con este desarrollo se podrian ver baterías de Li-S con 750wh/kg. Esto seria un sueño humedo de 1er nivel coches electricos con 800km de autonomia real o aviones de 150 plazas de recorrido corto-medio alcance 1.000/2.000km. Bicis electricas con autonomias reales de 200-300km. Las aplicaciones son infinitas ¿Veremos a Oxis energy o Sion Power con celdas de este tipo y 750wh/kg?. Algo me dice que alguien se encargara de guardar bajo 1.000 llaves esta revolucionara tecnica en un cajon muy oscuro.

When you figure the 2011 Leaf has an energy density of 140 Wh/Kg and weighs 600 pounds this battery with a density of 740 Wh/kg would have a range 5 times longer, from a range of 70 miles to a range of 350 miles. And,it should never short out.

Solid state can increase safety, but if you want higher energy density lithium sulfur may be the next step.

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Working...
Your comment could not be posted. Error type:
Your comment has been posted. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.

Working...

Post a comment

Green Car Congress © 2017 BioAge Group, LLC. All Rights Reserved. | Home | BioAge Group