Nanostructured Si-C Anode for Lithium-Ion BatteriesLetian Wang
2014.1
Outline
• Li-ion Battery
• Nanostructured Si-C
• Possible research
Power Source Comparison
Energy Storage Market
• Fuel cells 5/8/09 (CNET News) – “DOE to slash fuel cell
vehicle research”
“[...] many years from being practical.”
Portable, Safety
• Supercapacitors Energy density<30 Wh/kg
Li-ion: <160 Wh/kg
• Battery NiCd: Toxic
NiMH: Expensive, Capacity, Memory
Li-ion: Best
2012 World Market Share over 38,000,000
kWh, 20 billion $http://li.itdcw.com
finance.sina.com.cn
Definition• Li-ion battery
LiC6+LixCoO2=LiCoO2+C
Anode: C
• Li battery
Li+MnO2=LiMnO2
Anode: Li
• Other Li battery
Li-S
Li-Air
Application-Current
Energy (Distributed Storage for Renewable Energy)
Model S-Tesla LIB -Tesla Household-Solar City
Macro
Application-Future
Small scale energy storage
MEMS and Microfluidic
Minituation
Flexible
Sensors Electrode
Biological Matter
Heavy Metal, Toxics
Micro
Companies
China
• Lishen力神,ATL,BYD比亚迪 全球前十锂离子电池生产厂商
• Shanshan杉杉 上海 世界最大锂离子电池综合材料供应商
• 贝特瑞 深圳 世界最大锂离子电池电极材料供应商
World
• Korea
Samsung SDI
LG LGC
• Japan
Sanyo
Sony
MBI, Maxwell, NEC
• USA
A123
Mechanism
Anode-lose e-Negative
Cathode-gain e-Positive
Cathode• Discharge
• Charge
• M: transition metal
LiMO2 - xe− ↔ Li1−xMO2 + xLi+
Li1−xMO2 + xLi+ + xe−↔LiMO2
Janina Molenda and Marcin Molenda ,InTech, 2011
Critical to:
Mass capacity
Vcell
Anode
• Discharge
• Charge
• Material-Graphite
Candidates:Silicon, Carbon, Tin
LixC6 - xe− ↔xLi+ + 6C
Charles de las Casas, Wenzhi Li, Journal of Power Source, 2012
xLi+ + xe− + 6C ↔ LixC6
Electrolyte
• Solid Electrolyte Interphase (SEI)固体电解质中间相 The decomposition of electrolyte
Prevent reaction between the electrode and the electrolyte
Ionically conductive and electronically insulating, stable
• Lithium salts
LiPF6, LiBF4 or LiClO4
• Organic solvent
ethylene carbonate(碳酸乙酯)
dimethyl carbonate(碳酸二甲酯)
diethyl carbonate(碳酸二乙酯)
Ionic liquid
Performance Characteristics
• Full Cell Characteristics Charge
Discharge
Discharge Curve(votage-discharge)
Storage
Cycle Life(capacity-cycle)
• Electrodes Capacity per mass or volume
Capacity vs Cycle
• Cost
Lithium Ion Rechargeable Batteries Technical Handbook, Sony
Risks and Safety Issues
• Linked to materials, size, chemistry.
• Common factors
Heat
Flammable: organic electrolytes and polymers
Lithium: low melt point (180℃) and react with water
Material aging, failure
Low temperature
Leakage
Toxic matter
• Stack design
O’hara et al. Battery Technologies: A General
Overview & Focus on Lithium-Ion, Intertek Co
Challenge For Li Battery
Cathode
• Limited Capacity
• Safety concern at deep charge
Anode
• Conductivity-Power density
• Fading
• SEI layer formation
Research Topics• Material
Easy transport through shorter distance and greater surface area
Durable and reliable: expansion
Phase transition
SEI formation
• Transport
Mass and charge transport
Ionic diffusion
Electron-transfer kinetic;
Nano design for energy
Portfolio of solar/thermal/electrochemical energy conversion,
storage, and conservation technologies, and their interactions
Baxter, Jason, Gang Chen et al. Energy & Environmental Science 2009
Gang Chen MIT, NSF Nanoscale Science and Engineering Grantees Conference, 2011
Nanostructured Electrodes• Benefit
Larger space and active site for Li insertion
Larger contact surface for electron conduction
Shorter diffusion length of electrons and ion
• New Challenges Reduced charge/discharge cycles
Increased side reactions of electrode and electrolyte
Higher self-discharge
Fabrication cost
• Research Issues Capacity- Insertion chemistry-Diffussion
Conductivity-Electron transport-Crystalination
Rate-Ion transport-Porosity
Cycle-Pulverization & contact-mechanical
Create unique pathways!
Cathode
• Current Material
Material Struc
ture
Capacity(mAh/g
)/Conductivity
(S cm-1)
Benefit Drawback
LiCoO2 Layer 274(140)/10-4 Capacity,
lifecycle
Fabrication
Unstable
Cost
Toxic
LiMn2O4
LiMnO2
Spinel
Layer
200(100)/10-3
285(100)
Capacity
Cost
Cycle life(Mn2O4 fading)
Unstable
LiNO2 Layer 200() Capacity
Cost
Untoxic
Fabrication
Unstable (successive
phase transformation)
Cycle life
LiNixCoy
MnzO
Layer 250(160) Cost Capacity
LiFePO4 Olivin
e
140(100)/10-9 Cost
Stable
Cycle life
Low temperature
Packing density
Capacity
Stability vs CapacityClose to chemistry & quantum effects
Bottleneck!!
Anodes• Graphite and Hard Carbon
Low capacity (372mAh/g)
Low ion transport(10-6cm2 /s-1)
• Other Candidates Metal Oxide- LTO(钛酸锂)
Zero volumetric change
Low capacity
Alloy-Si Sn High capacity
Large Volumetric change
Metal Nitride/Sulfide Normal-MS2
• New Si-C
MO-C
Si-Polymer
Research Trend
5 years of Web of Knowledge Institutions
Anode Total 14951
Carbon 5224
Silicon 1247 Stanford
Si&C 457 (354/188) Stanford,
Gatech
Cathode Total 16,100
LiFePO4 998
LiFePO4&C 430(200/90)
Full Cell NiSn-LiMnO2 2013 UIUC,2013
Si-Graphene 2013 Gatech,2014
Key words: Li ion battery; carbon; anode; cathode; silicon; LiFePO
Silicon Anodes
Benefit
• High theoretical capacity
• Low discharge potential: below 0.5V
• Low cost
Drawback
• Pulverization, electrical contact↓, capacity fading
5Si + 22Li+ + 22e- ↔ Li22Si5
⇒ 4200 mAh/g
Boukamp, Lesh, & Huggins, J. Electrochem. Soc. 1981 Yi Cui, Nature Letters, 2007
Silicon Composite
Doping: C, B, Ni
Coating: C, SiO2
Nano matrix composite
Graphite
MgO/C
TiO2
Polymer
Terranova et al. Journal of Power Source 2013
Researchers-Anodes
Yi Cui -Stanford
• Lithium-Ion Battery
Si Nanowire Anode (2007)
Silicon-Carbon (2009)
Silicon-Polymer (2013)
• Other
Photovoltaic
Printable Energy Device
Nanowire filters
Nanoscale Tools: In-situ TEM
Gelb Yushin -Gatech
• Carbon Materials
Lithium-ion Anodes
Lithium-Sulfur
Supercapacitor
Researcher-Full Cell
• UIUC-3D microelectronic full cell
Pikul et al. Nature Communication 2013
William P. King
Sihan Chen(Lab Alumnus)
AFM-based tDPN (thermal dip-pen nano lithography) Silicon-based devices and circuits.
Tsinghua LIB• 核研院202室:
• 姜长印,万春荣,何向明,李建军,王莉,任建国
• 电极材料(全面),全电池
• 物理系&富士康纳米中心
• 范首善(院士),王佳平
• 碳材料以及氧化物(MO)负极
• 材料学院
• 伍晖(Stanford Yi Cui博士后),唐子龙,朱静(院士)等
• 水凝胶与硅基负极,碳材料,全固态锂电及其锂离子传输
• 深圳研究院
• 康飞宇(材料学院),李宝华
• 碳材料出发,碳硅电极
Object:Si-C Anodes
• Anodes
Transport is more important
Less chemistry & quantum effect
• Carbon Nanotubes and Graphene
Electric, thermal and photonic properties
Mechanical strength, flexibility and resiliency
• Silicon
Semiconductor properties: PV and TPV
Why Si-C?
• Broad Future of Si-C
Cost: abundance and massive fabrication
Application: Energy conversion and storage, Sensors
Flexibility: Next generation wearable electronics
• To be consistent with our groups other projects
Si nanowire (Sihan Chen)
CNT fabrication (Dong Liu)
C coated with Si
Carbon
black
CNT
Graphene
Si coated with C• Carbon on Si NP
• Carbon on Si NW
Carbon particle on Si NW (2009)
3324mAh/g (highest ever)
Tsinghua MSE Jing Zhu
CNT on Si NW (2012)
Core-void-shell
• Nanopaticle
• Nanotube
• Nanowires
• Liqiang Mai
Combination & Hierarchical
Advanced methods
• 2D+1D
• Encapsulation
Design Strategy• Operation:
Addition
Coating
Encapsulating
Voiding
• Material Matrix
Si, C NP
Si, C NW
Si, C Sheet Carbon black-Si coating- Encapsulation
?Create Hierarchy and Void
Silicon + Carbon AnodesName Fabrication Benefit Drawbacks
Nanoparticle (0D) Simple Milling Agglomeration
2004 Porous C-Si Pyrolysis,Carbonization,CVD
Massive fabrication
Core-Shell
Yolk-shell
Nanowire (1D) Simple
2007 Core-shell
(Coating)
C-Si
Si-C
C-Si-C
Cracking and
nanopore
Core-void-shell Void Separate & buffer
Graphene (2D) Coating/Multi
Coating
C-Si-C
Combination
&Hierarchical
NW+NP
NW+NW
NP+NP
Hierachical both electrical and
thermal conductivity
flexible and strong
Micro-nano-
sphere
Encapsulating, Separate Si
Problems• Solid Electrolyte Interface (SEI)
Not too thick
Object:
Hui Wu, Yi Cui et al. Nature Nanotechnology 2012
Li-ion batteries show limited calendar and
cycle life--less than 2 years
Problems
• Nanopore
Liangbing Hu, Anyuang Cao, Yi Cui, Advanced Energy Material 2011
Problems
• Cracking
(In Situ)
Research Direction
• Material fabrication
Design New Structure
Optimization: the size and distance
Massive Fabrication
In situ Studies
• Mechanism
Ion diffusion
Thermal
Electron
Lithiation caused Structural Change
Research Proposal• Phase 1
Fabrication of Si-Carbon anode
• Phase 2
In situ characterization using AFM or TEM
Ionic Transport during the Li loading process
Thermal properties for lithium-loaded anodes.
• Phase 3
Full Cell with integration of cathode (LiFePO4/C)
Conclusion• Silicon-Carbon anode is ready for research due to
its importance as well as our lab’s experience
• 2. Research proposal and schedule
• 3. Possible topics regarding the transport and thermal properties
• 4. Discussion for next step
Liqiang Mai Note• Na离子电池
• 单纳米线电池
• 包覆
• 三维,纳米卷,膨胀
• 看物象,看成分
• Li-air电池
Power Source 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
nanogenerat
ors:
Wang, ZL, Adv. Funct. Mater., 2008
45
Next Generation LIB
Nanostructures of the cell• Nanostructured architectures
• 1.1 Three dimensional thin–films
• 1.2 Interdigitated electrodes
• 1.3 Concentric electrodes
• 1.4 Inverse opal
• 1.5 Nanowires and nanotubes
• 1.6 Aperoidic electrodes
AnodesName Benefit Drawbacks Researcher
Metal Oxide
(MO)
LTO
(Ti)
Surface area
Zero volume change
Capacity (500-1000)
lower inherent
voltage,low energy
density
Tsinghua-核研院商业化
MnO
LVO
Carbon Graphene/CNT/Ha
rd carbon
Commercialized
Low cost
核研院商业化
Alloy Si High capacity(>1000)
Low charge potential
Safety
Volumetric change Stanford
中科院化学所Tsinghua-核研院
Sn UIUC
Metal
Nitride/Sulfide
MS2(Mo W Ga Nb
Ta)Li7MnN4
Good capacity
(500-1000)
Defect-volumetric
change
Expensive
Nano
Composite
Si-C Yi Cui Stanford
Yushin,Gatech
材料学院,深研院(973),核研院
MO-C Tsinghua-physics
Si-Polymer Berkely Stanford
Tsinghua MSE
Nano Energy Portfolio• Storage
Batteries
High Energy Density
Capacitors
High Power Density
Portfolio of solar/thermal/electrochemical energy
conversion,
storage, and conservation technologies, and their
interactions
Baxter, Jason, Gang Chen et al. Energy & Environmental Science 2009
Thermal
Transpo
rt
&
Interfac
e
Material
Thermal
Storage
Material
Thermophysics Current Focus
• Tradition-Heat conduction Now: Electron-Phonon
Goodson, Li Shi, C Dames
• Tradition-Radiation Now: Photon-Phonon
Gang Chen, Zhuoming Zhang, Sheng Shen
• Tradition-Phase Change Now: Hydrophobic Surface, Nanofluid, Nano porous
material
S. V. Garimella, EN Wang
• Others Chemical
Cui Yi, Xiaolin Zheng
Origin Current
Focus
Applicati
on
Researchers
Goodson, Li Shi, C Dames, Fisher
Gang Chen, Zhuoming Zhang,
Sheng Shen
S. V. Garimella, EN Wang, Fisher
Cui Yi, Xiaolin Zheng
Nanoscale design• Conversion
Wavelength
• Transport
Mean Free Path
Baxter, Jason, Gang Chen et al. Energy & Environmental Science 2009