Sodium Iodine batteries for utility-scale energy storage

Dr. Ron RoedelYousif AlansariGeorges NassifSEC 598 - PV Systems Engineering

Agenda

1)Introduction to Sodium Iodine (𝑁𝑁𝑁𝑁 /𝐼𝐼2) Batteries2)Analysis

a) 𝑁𝑁𝑁𝑁 /𝐼𝐼2 electrochemistryb) Power & energy densityc) Construction & manufacturingd) Strengths, weaknesses, opportunities & threats

(SWOT) Analysis for 𝑁𝑁𝑁𝑁 /𝐼𝐼23)Conclusion4)References

Quack Quack!

Where do we start?

𝑬𝑬 = 𝑪𝑪 ∗ 𝑽𝑽

𝑷𝑷 =𝑬𝑬

𝒕𝒕𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄

●High charge capacity

●Large voltage window

●Fast ionic/electronic diffusion

●Fast charge/discharge rates

●Stable SEI formation (solid electrolyte interface)

●Stable current collectors

●Mechanically stable electrodes

●Fast interfacial chemical reactions

●High coulombic efficiency

●Long cycle life

Ideally…

𝜼𝜼 =𝑪𝑪𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝑪𝑪𝒅𝒅𝒅𝒅𝒅𝒅𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄

Anode H2 Li Na Mg Al Fe Pb MH LiC6 Li4.4Si

Ah/g 26.6 3.86 1.16 2.2 2.98 0.96 0.26 0.30 0.37 4.2

g/mol 2.01 6.94 23 24.3 26.9 55.8 207.2 NA 79 58.5

V vs. SHE 0 -3.01 -2.71 -2.38 -1.66 -0.44 -0.13 -0.83 -2.8 -2.9

Valence change 2 1 1 2 3 2 2 2 1 4.4

Cathode O2 LiCoO2 LiMn2O4 LiFePO4 CuCl CuF2 I2

Ah/g 0.528 0.155 0.120 0.160 0.270 0.528 0.211

g/mol 32 98 148.8 163.8 99 101.5 253.8

V vs. SHE 1.23 1.25 1.2 0.42 0.14 3.55 0.54

Valence change 4 0.5 1 1 1 2 2

● High redox capacity● High electronegativity● Good reversibility● Earth abundant● Theoretical capacity of 211 mAh/g

Na ion vs. Li ionSodium (Na) Lithium (Li)

Abundant? Yes NoGeographically constrained? No Yes

Cost Low HighRecyclability Easy Difficult

Appropriate for utility scale storage? Yes No

Why Iodine (𝐼𝐼2)?

Why Carbon as a cathode current collector?● High conductivity● Chemical neutrality● Good ionic host● Earth Abundant

Na/I2 electrochemistry

2𝑁𝑁𝑁𝑁 ↔ 2𝑁𝑁𝑁𝑁+ + 2𝑒𝑒−(at -2.71 V vs SHE)

𝐼𝐼2 + 2𝑒𝑒− ↔ 2𝐼𝐼−(at 0.54 V vs SHE)

𝟐𝟐𝟐𝟐𝒄𝒄+ 𝑰𝑰𝟐𝟐 ↔ 𝟐𝟐𝟐𝟐𝒄𝒄𝑰𝑰Operating voltage window of 3.24 V

Theoretical charge capacity of 211 mAh/g

Na+

Na/I2 power and energy densitySodium

ion

𝑬𝑬 = 𝑪𝑪 ∗ 𝑽𝑽 = 𝟔𝟔𝟔𝟔𝟔𝟔𝑾𝑾𝒄𝒄/𝒌𝒌𝒄𝒄 𝑷𝑷 =𝑬𝑬𝒕𝒕

= 𝟕𝟕𝟐𝟐𝑾𝑾/𝒌𝒌𝒄𝒄

Na/I2

CNT:PTFE:I2 composite as cathode

0

500

1000

1500

2000

2500

3000

0 50 100Spec

ific

Cap

acity

per

gI2

(mAh

/gI2

)

Cycle Index

CNT/I2 vs Na (Cell 2)

Charge

Discharge

Theoretical capacity for Na/I2 is 211mAh/g

Free standing MWCNT, –COOHFunctionalized, mixed with PTFE binder (10%), followed by I2 PVD in Ar

CNT: inactive current collectorI2: active cathode materialPTFE: inactive binder

Cell ConfigurationCathode: I2 infiltrated carbon matrixAnode: Na metal disk Ø 5/8” thickness ~ 0.3mm

Electrolyte: 120 µL of 5M NaPF6 in solvent of 30% FEC / 70% PC vol.

Separator: Ø 21 mm Whatman glass micro fiber GF/B

Compression: 0.5 mm Ø 5/8” Stainless Steel spacer and spring of 2032

3E stainless steel hardware

Solvent• PC: Propylene

Carbonate• FEC: Fluorinated

Ethylene Carbonate

SaltNaPF6 : Sodium Hexafluoro-phosphate

• Bottom Steel Disk Assembly:• 2 O-rings

(Buna & PTFE)• Sodium metal

disk Ø 5/8”, thickness 0.3mm• PTFE Smooth Ring• Plastic sleeves for bolts insulation

• Middle Steel Disk Assembly:• Teflon Ridged Ring• Separator• Electrolyte Solution• CNT/PTFE/I2 disk Ø 5/8”,

thickness 0.25mm• Steel Spacer• Spring

• Top Steel Disk Assembly:• Aluminum foil disk Ø

5/8”• 2 O-rings

(Buna & PTFE)• Stainless steel spacers

Ø 5/8”

Porous Activated Carbon & I2 composite

[6] Lu, Ke, et al. Nature Communications

● Electrolyte Decomposition

● Current collector corrosion

● Other side reactions (non-active reactions)

● Unstable SEI (solid-electrolyte interface)

● Electrode polarization

● Electrochemically-induced strain & cracking

● Coulombic hysteresis

● Capacity fading

● Short cycle life

But things can go wrong…

To address the I2 solubility, I2 must be encapsulated…

Confirmed by Cyclic Voltammetry (CV)

Side Reactions due to Iodine solubility:

Self-assembled NaI mesoparticles coated with C

NaI NPs self-assembled with PVP binder and carbonized to form C coating. Resulting in limited I2 solubility and longer cycle life.

Will be mixed into an NMP-based slurry with activated carbon and PVDF binder and cast onto Ni foil current collector by Dr Blading.

NaI

XRD analysis

Strengths:-High abundance of sodium and iodine-High energy density

Weaknesses:-Long term stability issues- Lower power density than Li-ion

Opportunities:-Low abundance of lithium and future depletion of resource

Threats:-Other sodium-ion battery technologies-Aluminum-ion batteries

SWOT

SWOT Analysis

Conclusion

●Not suitable at current state●Long term stability issues to be resolved●Market opportunities available●A lot of potential

𝟐𝟐𝟐𝟐𝒄𝒄 + 𝑰𝑰𝟐𝟐 ↔ 𝟐𝟐𝟐𝟐𝒄𝒄𝑰𝑰

References●[1]Hwang, Jang-Yeon. “Sodium-Ion batteries: present and future.” Chem Soc Rev, vol. 46, no. 12, 28 Mar. 2017.

●[2]Gong, Decai, et al. “An Iodine Quantum Dots Based Rechargeable Sodium-Iodine Battery.” Advanced Energy Materials, vol. 7, no. 3, 2016, p. 1601885., doi:10.1002/aenm.201601885.

●[3]Abate, Tom. “Sodium-Based batteries more cost-Effective than lithium.” Stanford News, Stanford University, 10 Oct. 2017.

●[4]“Faradion Leads Energy Storage Trio Into Sodium-Ion Territory.” CleanTechnica, 14 Mar. 2016.

●[5] “CNT/PTFE/I2 composite as a viable cathode for sodium ion batteries” Nanotech Lab, Yushin, Svoboda & Nassif, Georgia Tech

●[6] Lu, Ke, et al. “A rechargeable iodine-Carbon battery that exploits ion intercalation and iodine redox chemistry.” Nature Communications, vol. 8, no. 1, 2017, doi:10.1038/s41467-017-00649-7.

●[7] Linden’s Handbook of Batteries, 4th Edition, Thomas Reddy

Sodium Iodine batteries for utility-scale energy storage

Dr. Ron RoedelYousif AlansariGeorges NassifSEC 598 - PV Systems Engineering

Thanks for listening!!