Ben Richards and Tobias Hanrath

Center for Future Energy

Systems

Feb 26, 2015

Scalable Fabrication of

Silicon Nanowire Anodes

2 cm

- scientific and engineering principles for scalable manufacturing of

semiconductor nanowires via roll-to-roll (R2R) manufacturing processes.

Scalable Fabrication of Silicon Nanowire Anodes

Nissan Leaf

[LIB] 24 kWh; 270 kg

150 miles

100

~ 7000 cells !

1320 lbs.

Limitations of currently available EV batteries:

- Performance

- Weight

- Co$t !

anode

(graphite) cathode

(Li1+xMn2O4)

Charge and Energy Storage Capacity

of next-generation battery materials.

exciting scientific breakthroughs

for new battery materials

0

1500

3000

4500

6000

2000 2002 2004 2006 2008 2010 2012

Li ion battery

scientific papers / year

scalability and integration of nanomaterials

85 kWh

~40 kg Si nanowires

Scalability Limitations of Chemical Vapor Deposition

(Thin Film Technologies)

thin film processing technologies adopted from the

microelectronics fabrication are ill-suited for manufacturing

battery materials at technologically relevant scales.

loading requirements for high capacity batteries

(a)

Al

Cu (b)

Design for nanomanufacturing:

Requirements for Si nanowire anodes in battery

applications

- scalable, high-throughput manufacturing.

- integrated material fabrication and device processing

- high loading

- stable electrochemical cycling, tolerance for mechanical

stresses due to volume dilation.

gen1: Supercritical Fluid Nanowire Synthesis

High throughput Ge nanowire synthesis in super-

critical fluid

High-pressure / high-temperature CSTR reactor

gen II: supercritical fluid Nanowire Synthesis

gen III: supercritical fluid nanowire synthesis

high throughput synthesis: 2g!

- continuous flow synthesis

- multi-zone temperature control

- integrating synthesis and surface

treatment

Nanowire growth on bulk metal films

gen IV: nanowire synthesis directly on metal surface

Chem Mater 23, 4838–4843 (2011).

Uncovering basic mechanism governing nanowire

growth from bulk metals.

1. Journal of Materials Chemistry C 2, no. 10 (2014): 1699–1678. doi:10.1039/C3TC31666A,

(i)

(iv) (ii)

nanowire growth mechanism

depth

(v)

Cu Ge

(iii)

1. Richards, B. T., Gaskey, B., Levin, B. D. A., Whitham, K., Muller, D., and Hanrath, T.

“Direct Growth of Germanium and Silicon Nanowires on Metal Films ”

Journal of Materials Chemistry C 2, no. 10 (2014): 1699–1678.

doi:10.1039/C3TC31666A,

(i)

(iv) (ii)

depth

(v)

Cu Ge

(iii)

1. Richards, B. T., Gaskey, B., Levin, B. D. A., Whitham, K., Muller, D., and Hanrath, T.

“Direct Growth of Germanium and Silicon Nanowires on Metal Films ”

Journal of Materials Chemistry C 2, no. 10 (2014): 1699–1678.

doi:10.1039/C3TC31666A,

nanowire growth mechanism

activate nanowire growth directly on the surface of the metal.

- scientific and engineering principles for scalable manufacturing of

semiconductor nanowires via R2R manufacturing processes.

Can we exploit the direct growth on metal

surfaces for a roll-to-roll process ?

electrochemical characterization of nanowire films

nanowires are in direct contact with the metal current

collector and exhibit negligible contact resistance

electrochemical characterization of nanowire films

capacity fade in wires grown directly from the metal ( ) is less

pronounced than in a wire-paste deposited onto the wire ( )

2 cm

Summary

direct growth of Si nanowires on metal foils presents an exciting

opportunity to develop scalable nanofabrication technology to

resolve impending bottlenecks in our transition towards

nanomaterials in energy storage.

outstanding scientific and technological challenges to bring the

prospect of Si-based high-capacity anodes to technological

fruition.

2 cm

Benjamin Richards

Kevin Whitham

Katie Silberstein

Barnaby Levin

Jie Gao

Bernard Gaskey

Charles Hamilton

Samuel Schraer

Eric McShane

Heather Barton

Jacob Quintana

THANKS