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Silicon Nanowires for Rechargeable Li-Ion Batteries

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Silicon Nanowires for Rechargeable Li-Ion Batteries. Onur Ergen , Brian Lambson , Anthony Yeh EE C235, Spring 2009. Overview. Battery Technology Landscape Battery Basics Lithium Ion Battery State of the Art Silicon Nanowire Anode Why Silicon Nanowires? Experimental Results - PowerPoint PPT Presentation
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Silicon Nanowires for Rechargeable Li-Ion Batteries Onur Ergen, Brian Lambson, Anthony Yeh EE C235, Spring 2009
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Page 1: Silicon Nanowires for Rechargeable Li-Ion Batteries

Silicon Nanowires for Rechargeable Li-Ion BatteriesOnur Ergen, Brian Lambson, Anthony YehEE C235, Spring 2009

Page 2: Silicon Nanowires for Rechargeable Li-Ion Batteries

Overview Battery Technology Landscape

Battery Basics Lithium Ion Battery State of the Art

Silicon Nanowire Anode Why Silicon Nanowires? Experimental Results Technical Comparison

Economic Perspective Market Analysis Future Outlook Conclusion

Page 3: Silicon Nanowires for Rechargeable Li-Ion Batteries

Battery BasicsLithium Ion BatteryState of the Art

Battery Technology Landscape

Page 4: Silicon Nanowires for Rechargeable Li-Ion Batteries

Nanowire Batteries

Motivation: Batteries and Life

Page 5: Silicon Nanowires for Rechargeable Li-Ion Batteries

How does a battery work?

Page 6: Silicon Nanowires for Rechargeable Li-Ion Batteries

History of Batteries

Page 7: Silicon Nanowires for Rechargeable Li-Ion Batteries

Lithium-ion Batteries

J.-M. Tarascon& M. Armand. Nature. 414, 359 (2001).

How do Li-ion batteries work? Battery Parameters

Energy density: cathode and anode

E (Wh) = voltage x capacity Power density: ion intercalation

and electron transport Cycle life: strain relaxation

Advantages of Li-ion batteries High cell voltage Superior energy and power

density High cycling stability Low self-discharge No memory or lazy battery effect 100% depth of discharge possible

Page 8: Silicon Nanowires for Rechargeable Li-Ion Batteries

What we have in daily technology

Page 9: Silicon Nanowires for Rechargeable Li-Ion Batteries

How can we improve from here?

Using silicon nanowires as anode Energy capacity Peak power Endurance Manufacture cost

Page 10: Silicon Nanowires for Rechargeable Li-Ion Batteries

Why Silicon Nanowires?Experimental ResultsTechnical Comparison

Silicon Nanowire Anode

Page 11: Silicon Nanowires for Rechargeable Li-Ion Batteries

11

Silicon: an optimal anode material Graphite energy density: 372 mA h/g

Silicon energy density: 4200 mA h/g

C6LiC6

Si Li4.4Si

Page 12: Silicon Nanowires for Rechargeable Li-Ion Batteries

12

Why haven’t we been using Si anodes?

Lithiation of silicon has one major problem – it is accompanied by a 400% volume

increase!

Chan et. al, Nature Nanotech, 2007

Page 13: Silicon Nanowires for Rechargeable Li-Ion Batteries

13

Solution: Silicon Nanowires 10 x energy density of current anodes Structurally stable after many cycles

Chan et. al, Nature Nanotech, 2007

Page 14: Silicon Nanowires for Rechargeable Li-Ion Batteries

14

Experimental Technique NW growth on stainless steel by vapor-liquid-solid (VLS)

technique Crystalline Si Core-shell (core = crystalline Si, shell = amorphous Si)

Test current-voltage characteristics over many charge/discharge cycles using cyclic voltammetry

C

Si NW onStainless steel

Li metal

Electrolyte

V

Page 15: Silicon Nanowires for Rechargeable Li-Ion Batteries

15

Experimental Results

Chan et. al., Nature Nanotech, 2007

Charge and discharge capacity per cycle

Page 16: Silicon Nanowires for Rechargeable Li-Ion Batteries

16

Experimental Results

Chan et. al., Nature Nanotech, 2007

Charge and discharge capacity per cycleDramatic (~10x) improvement in charging capacity over graphite!

Page 17: Silicon Nanowires for Rechargeable Li-Ion Batteries

17

Experimental Results

Chan et. al., Nature Nanotech, 2007

Charge and discharge capacity per cycleNo decrease in capacity beyond first charge cycle!

Page 18: Silicon Nanowires for Rechargeable Li-Ion Batteries

18

Experimental Results

Cui et. al., Nano Letters, 2009

Core-shell nanowires may improve performance after first cycle

Page 19: Silicon Nanowires for Rechargeable Li-Ion Batteries

19

Experimental Results

Cui et. al., Nano Letters, 2009

Core-shell nanowires may improve performance after first cycleAmorphous shell thickness as a function of growth time

Crystalline core thickness

Page 20: Silicon Nanowires for Rechargeable Li-Ion Batteries

20

Experimental Results

Chan et. al., Nature Nanotech, 2007

Study of reaction dynamics:Near capacity charging at high reaction rates

Page 21: Silicon Nanowires for Rechargeable Li-Ion Batteries

21

Experimental Results

Chan et. al., Nature Nanotech, 2007

Study of reaction dynamics:Near capacity charging at high reaction rates

Even one hour cycle time is much better than a fully charged graphite anode!

Graphite

Page 22: Silicon Nanowires for Rechargeable Li-Ion Batteries

22

Technological Comparison

Li-ion batteries have proved optimal for most mobile electronics and competitive for hybrid and electric vehicles

Technology Power density

Energy density

Lifetime Efficiency

Fuel cells Low/moderate

High Low/moderate

Moderate

Supercapacitors

Very high Low High High

Nanogenerators

Very low Unlimited Unknown Low

Li-ion w/ graphite

Moderate Moderate Moderate High

Li-ion w/ Si NW Moderate High Under investigation

High

Fuel Cells:

Smithsonian Institution, 2008

Page 23: Silicon Nanowires for Rechargeable Li-Ion Batteries

23

Technological Comparison

Li-ion batteries have proved optimal for most mobile electronics and competitive for hybrid and electric vehicles

Technology Power density

Energy density

Lifetime Efficiency

Fuel cells Low/moderate

High Low/moderate

Moderate

Supercapacitors

Very high Low High High

Nanogenerators

Very low Unlimited Unknown Low

Li-ion w/ graphite

Moderate Moderate Moderate High

Li-ion w/ Si NW Moderate High Under investigation

High

Supercapacitors:

Maxwell Technologies, 2009

Page 24: Silicon Nanowires for Rechargeable Li-Ion Batteries

24

Technological Comparison

Li-ion batteries have proved optimal for most mobile electronics and competitive for hybrid and electric vehicles

Technology Power density

Energy density

Lifetime Efficiency

Fuel cells Low/moderate

High Low/moderate

Moderate

Supercapacitors

Very high Low High High

Nanogenerators

Very low Unlimited Unknown Low

Li-ion w/ graphite

Moderate Moderate Moderate High

Li-ion w/ Si NW Moderate High Under investigation

High

Piezoelectric nanogenerators:

Wang, ZL, Adv. Funct. Mater., 2008

Page 25: Silicon Nanowires for Rechargeable Li-Ion Batteries

25

Technological Comparison

Li-ion batteries have proved optimal for most mobile electronics and competitive for hybrid and electric vehicles

Technology Power density

Energy density

Lifetime Efficiency

Fuel cells Low/moderate

High Low/moderate

Moderate

Supercapacitors

Very high Low High High

Nanogenerators

Very low Unlimited Unknown Low

Li-ion w/ graphite

Moderate Moderate Moderate High

Li-ion w/ Si NW Moderate High Under investigation

High

Energy and power density Only fuel cells and batteries can be primary power supply Among those, Si NW batteries are optimal

Lifetime and efficiency Batteries last about as long as typical electronic components Energy efficiency of electrochemical devices is generally high

Page 26: Silicon Nanowires for Rechargeable Li-Ion Batteries

Market AnalysisFuture OutlookConclusion

Economic Perspective

Page 27: Silicon Nanowires for Rechargeable Li-Ion Batteries

27

Portable Electronics

Lighter Phones

Longer-lasting Laptops

More powerful PDAs

2002 2003 2004 2005 2006 2007 2008 2009 2010 20110

100200300400500600700800900

1000

Worldwide Total Available Market for Portable Rechargeable Electronics

PDAsLaptopsCamcordersDigital camerasMobiles

Year (2008-2011 projected)

Mill

ions

of

Uni

ts

P. Agnolucci, “Economics and market prospects of portable fuel cells”

Page 28: Silicon Nanowires for Rechargeable Li-Ion Batteries

28

Hybrid/Electric Vehicles Emerging market for H/EV batteries Batteries are the main roadblock

Energy density (range) Power density (acceleration)

Li-ion poised to be biggest contender

http://www.chemetalllithium.com/index.php?id=56

Page 29: Silicon Nanowires for Rechargeable Li-Ion Batteries

29

Competing Technologies Other battery technologies

NiMH NiCd other Li-ion

Fuel cells 5/8/09 (CNET News) – “DOE to

slash fuel cell vehicle research” “[...] many years from being

practical.” Portable fuel cells

Supercapacitors <30 Wh/kg Li-ion: <160 Wh/kg

P. Agnolucci, “Economics and market prospects of portable fuel cells”

Page 30: Silicon Nanowires for Rechargeable Li-Ion Batteries

30

Economics of Nanowire Batteries Silicon is abundant and cheap

Leverage extensive silicon production infrastructure

Don’t need high purity (expensive) Si Nanowire growth substrate is also current

collector Leads to simpler/easier battery

design/manufacture (one step synthesis) Nanowire growth is mature and scalable

technique J.-G. Zhang et al., “Large-Scale Production of Si-

Nanowires for Lithium Ion Battery Applications” (Pacific Northwest National Laboratory)

9 sq. mi. factory = batteries for 100,000 cars/day

GM-Volt.com, “Interview with Dr. Cui, Inventor of Silicon Nanowire Lithium-ion Battery Breakthrough”K. Peng et al., "Silicon nanowires for rechargeable lithium-ion battery anodes," Applied Physics Letters, 2008

Page 31: Silicon Nanowires for Rechargeable Li-Ion Batteries

Can you really get 10x?Si nanowire anode ~3541 Ah/kgAdjust anode/cathode mass ratio

Capacity Issues

J.-M. Tarascon, M. Armand, "Issues and challenges facing rechargeable lithium batteries"

Cathode materialsLithium Cobalt OxideLithium Iron Phosphate

Page 32: Silicon Nanowires for Rechargeable Li-Ion Batteries

32

Lifetime Issues Initial capacity loss after first cycle (17%)

Cause still unknown? Capacity stable at ~3500 Ah/kg for 20

cycles Can’t yet maintain theoretical 4200 Ah/kg

Crystalline-Amorphous Core-Shell Nanowires (2009) Energy Density: ~1000 Ah/kg (3x)

90% retention, 100 cycles Power Density: ~6800 A/kg (20x)

Y. Cui, “High-performance lithium battery anodes using silicon nanowires”Y. Cui, “Crystalline-Amorphous Core-Shell Silicon Nanowires for High Capacity and High Current Battery Electrodes”

Page 33: Silicon Nanowires for Rechargeable Li-Ion Batteries

33

Conclusion Summary

Motivation Technology

landscape Silicon nanowire

battery advantages

Market Prospects

Time to market ~5 years (Cui)


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