Daniel A. Scherson, John Protasiewicz, Imre Treufeld, Andrew Shaffer, and Michael Rectenwald

Case Western Reserve University, Department of Chemistry 10900 Euclid Ave. Cleveland, Ohio 44106

Bifunctional Electrolytes for Lithium-ion Batteries

ES068

*This presentation does not contain any proprietary, confidential, or otherwise restricted information

Overview

• Start Date: April 2009 • End Date: May 2013 • Percent Complete: 75%

• Barriers addressed Abuse tolerance

• Total Project Funding $798K • FY09 - $199.5 K • FY10 - $199.7 K • FY11 - $199.5 K

Timeline

Budget

Barriers

Novolyte Technologies, Independence, OH

Partners

Relevance- Objectives • Design, synthesize, and characterize physical and electro-

chemical properties of functionalized Li salt anions containing phosphorus and boron moieties known to impart materials with flame retardant properties (Flame Retardant Ions or FRIONS) and thus improve device safety.

• Gain insight into the overall chemical and electrochemical behavior, including reactivity of these novel bifunctional electrolytes toward Li-ion charged anodes using a combination of electrochemical and in situ spectroscopic techniques.

• Develop structure-function relationships that will guide further search of optimized FRIONS and other species that contribute to enhance abuse tolerance.

Approach- Milestones Year Milestones

February 2012

(a) Prepare and fully characterize the electrochemical and flammability properties characteristics of three CTB-type compounds and one CBPO-type compound. (Oct. 11) Delayed –due Jul. 12

(b) Expand the CTB-type and CBPO-type libraries of compounds. (Mar.12) On schedule

(c) Synthesize and characterize a monocyclic FRION. (Sep. 12) On schedule

(d) Complete design, construction and testing of new cell for in situ infrared reflection absorption spectroscopy (IRAS) and impedance measurements with first (Oct. 11) (delayed to Jul. 12) and two additional Case electrolytes. (Sep. 12) On schedule

(e) Perform full testing of three Case salts as full fledge electrolytes and as additives in actual batteries at Novolyte (Oct 11), and LBNL (Sep 12) On schedule

(f) Improve cycling by at least 15% to reach the same decay/end of life vs. the control electrolyte. (Sep 12) On schedule

Approach- Strategy Incorporate flame retardant and overcharge protection chemical

groups to anionic species that display good transport properties and use these materials as salts or as additives to more conventional electrolytes.

Gain insight into modifications to the structural and physico-chemical properties of the passive on Li-ion anodes using a combination of attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and conventional electrochemical techniques including impedance spectroscopy.

Build up knowledge bases that could afford rational guidelines for the search of novel materials displaying required properties to enhance abuse tolerance of high energy density high power density Li batteries.

Accomplishment- Synthesis and NMR Characterization of FRION II1,2

OP

O

OH 2 ArMgBr

Ar PAr

OH

1) NaOH, H2O2 2) 2M HCl (aq)

Ar P Ar

OOH

THFReflux, 1 h

H2OReflux, 2 h

Ar PAr

OOH2 +

O O

OHHO+ H3BO3 + LiOH

OB

O

O P

POO

O

O

ArAr

O

ArAr

Li200oC, vac.

4 h

Ar = 2-MePh

1.Org. Lett. 2005, 7, 4277. 2.Eur. J. Org. Chem. Eur. J. Org. Chem. 2003, 4216.

Accomplishment- X-Ray Crystallography of FRION II

ORTEP diagram (50% thermal ellipsoids) of Frion II

Accomplishment-1H and 31P NMR Spectra of FRION II in DMSO- d6

Accomplishment- Flammability Testing of FRION I & II

Accomplishment- Thermogravimetric Analysis of FRIONs I and II

0 200 400 6000

20

40

60

80

100

Wei

ght P

erce

ntag

e (%

)

Temperature (0C)

FRIon 1 FRIon 2

Accomplishment- Capacity versus cycle number for 2325 coin cells

0 10 20 30 40 50 60 70 800.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

Baseline CaseX LiOxBOAr

mAh

Cycle Number

Accomplishment- Synthesis of Triol Borates3

HO OBO R'

R

LiOHO OB

OR'

R

Li

LiCRBR'

ROH

OHOH R' B

OH

OH Toluene Toluene

HO OBO R'

R

nBuLi

O OBOR'

R

Li

LiCRBR'

R=Me; R'=Me, nBu, Ph, 4-MePh, 4-MeOPh, OH R=Et; R'=Ph, OH

3. Angew. Chem. Int. Ed. 2008 47, 928

Accomplishment-Thermogravimetric Analysis of Select Triol Borates

0 100 200 300 400 500 600 7000

10

20

30

40

50

60

70

80

90

100

Wei

ght %

Temperature (οC)

O OB

OPh

Li

LiCEtBPh

O OBOPh

Li

LiCMeBPh

Routes to Compounds Under Study4

PHO OH

OH

O

P(CH2OH)4Cl-NaCl-CH2O

+ NaOHO B O

PO

Ph

OLi

NaBH4

PhB(OH)2, LiOH

H3BO3 LiOH

O B OPO

OH

OLi

O B OPO

H

ONa

When Li[PHB((OCH2)3P=O)] (TMPO) was reacted with phenyl boronic acid under the same reaction conditions as the carbon analog, no reaction was observed. TMPO is insoluble in toluene and a change in solvent has shown promising initial results. Other boron starting materials are being investigated with positive results.

4. J. Am. Chem. Soc. 1963 85, 79

Accomplishment- NMR Evidence for LiPOBOH in CD3OD

0 .00 .51 .01 .52 .02 .53 .03 .54 .04 .55 .05 .56 .06 .57 .07 .58 .08 .5ppm

6.00

0.48

3.47

3.52

8.25

31P NMR δ = 36.0 ppm

O B OPO

O

Li

HO

LiPOBOH

Spectroelectrochemical Cell for in situ Infrared Reflection-Absorption FTIR of Highly Reactive Interfaces

Main Attributes: Cell is filled directly from septum type electrolyte container without need of using a glove box. Anode is charged in situ avoiding exposure to the atmosphere in the glove box. All operations within the cell are performed with custom made leak free manipulators including approach of the working electrode to the diamond window of the ATR-FTIR attachment.

Li reference electrode

Li counter electrode

Ni working electrode

CaF 2 window

IR beam

In situ Reflection Absorption Infrared Spectroscopy of the Passive Film on Lithium

Overlay of the in situ IRAS spectra showing the spectrum of the Ni electrode pressed against the CaF2 window before (red) and after (blue) Li deposition on it. The regions between 1830 to 1700 cm-1 and 1330 to 1250 cm-1 contain peaks in the deposit (blue) spectrum that differ from the background (red).

1900 1800 1700 1600 1500 1400 1300 1200 1100-0.2

0.0

0.2

0.4

0.6∆

R/R

Wavenumber

pure electrolyte vs empty cell Li deposit vs pure electrolyte

Collaborations with Other Institutions

i. Dr. Alexander Morgan of the Dayton University Research Institute in Dayton, OH has agreed to determine the inherent flammability of materials developed under this program by consumption calorimetry using their unique microscale combustion calorimeter. This organization is outside the VT program.

ii. ii. Novolyte Technologies of Independence, OH to conduct coin cell tests using materials developed under this program in combination with their specialty chemicals in actual coin cells. This company is outside the VT program.

Future Work

•Continue design, synthesis, purification and full characterization of FRIONS and other safety enhancing bifunctional materials aimed at building knowledge base toward the rational search of materials that will enhance abuse tolerance without affecting adversely overall battery performance. •Attention will be focused only on materials displaying optimized characteristics even if obtained in small yields leaving development of more effective synthetic routes to a second stage. •Recent experimental results toward the synthesis of a new class of materials appear to be encouraging enough to warrant further research. • Should a class of materials be found to be inferior to an earlier developed class, any further efforts will be abandoned and focus will be centered on the design and synthesis of new classes of yet unexplored materials. •The results obtained with in situ ATR-FTIR will point to ways to improve the sensitivity and specificity of the instrumentation developed. • Synthesis and scale up of LiPOBR compounds and functionalized derivatives

• FRION I and II were successfully synthesized from the dehydration of oxalic acid and diphenylphosphinic acid with boric acid. This compound displays water and air stability as well as no visible decomposition in propylene carbonate at elevated temperatures. Decomposition occurs above 450º C by pyrolysis combustion flow calorimetry. • Several lithium cyclic triol borates have been isolated.

• Synthesis of cyclic borate phosphine oxides is underway

Summary- Conclusions

O B OPO

Ph

O

PHO OH

OH

O

+ PhB(OH)2 -3 H2O+ LiOH Li

LiO Li

O

O POB

OPOPOB

O P

THF

THF

O

OArAr

ArAr

ArAr

ArAr

O

OO

O

OO

Ar= 2-MePh

O OBOR'

R

Li

LiCRBR'

FRION II was successfully synthesized from inexpensive, commercially available substrates and characterized using a wide array of techniques.

Thermogravimetric analysis shows the high stability of both FRION I and II.

Pyrolysis combustion flow calorimetry shows decomposition of FRIONS in temperatures in excess of 450º C.

The synthesis of cyclic borate-phosphine oxides is underway as a means of generating another entry point for the formation of FRIONs containing phosphorus and boron moieties.

A unique spectroelectrochemical cell for performing in situ ATR-FTIR measurements of highly reactive systems was designed and constructed.

Addition of FRION I to conventional electrolyte does not affect adversely battery performance.

Summary- Conclusions