Novel Electrolytes for use in Li-Air Batteries for NASA ...
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Novel Electrolytes for use in Li-Air Batteries for NASA Electric Aircraft Rocco P. Viggiano*, Donald Dornbusch*, William Bennett*, Kristian Knudsen § , Baochau Nguyen† *NASA Glenn Research Center, 21000 Brookpark Rd, Cleveland, OH 44135; §UC Berkeley, Berkeley, CA 94720; †Ohio Aerospace Institute, 22800 Cedar Point Rd, Cleveland, Ohio 44142 Introduction The 2018 Strategic Implementation Plan sets forth the NASA Aeronautics Research Mission Directorate (ARMD) vision for aeronautical research aimed at the next 25 years and beyond. It encompasses a broad range of technologies to meet future needs of the aviation community. Two key areas of focus are the transition to ultra-efficient subsonic transports as well as the transition to safe, quiet and affordable vertical lift air vehicles. In support of these technology areas, NASA has been researching hybrid-electric as well as fully electric aircraft designs. Both designs necessitate the development of higher energy density battery systems. Lithium-oxygen batteries have been proposed as a potential enabling technology owing to its high theoretical energy density, to date the highest of any proposed battery technology. However, there are immense technical challenges facing their development, including the development of more stable cathodes and electrolytes. Through a synergistic approach utilizing computational modeling and experimental screening, several new cathode and electrolyte candidates have been screened. Concurrently, decomposition analysis of candidate electrolyte systems using nuclear magnetic resonance (NMR) spectroscopy has yielded mechanistic insight into decomposition pathway, which is vital to the development of future stable electrolyte candidates. Conclusions Linear Amides (NMA, DMA) Interestingly more 12 C x,x O is formed during charge relative to other solvents, suggesting more simple products are formed Low amounts of 12 C 18,18 O 2 is formed, suggesting solvent is relatively stable towards Li 2 O 2 and its intermediates DMA shows the best stability of the amides/ureas tested, but decomposes through a Baeyer-Villiger oxidation method Linear Urea (TMU) Relatively low amounts of 12 C 18,18 O 2 formed, is more stable towards Li 2 18,18 O 2 /Li 18,18 O 2 / 18,18 O 2 - than linear amides Cyclic Ureas (DMI and DMPU) Large amounts of 12 C 16,18 O 2 and 12 C 18,18 O 2 are formed while low amounts of 12 C 16,16 O 2 is formed This suggests an increased activation of a different pathway where CO 2 is formed from Li 2 O 2 induced solvent reduction Results Results Experimental Differential electrochemical mass spectrometry (DEMS) and nuclear magnetic resonance (NMR) spectroscopy were performed on a series of amides and ureas to elucidate the decomposition mechanism of these two classes of electrolytes. Figure 2 shows the series of amides and ureas tested. Figure 4: NMR spectra of neat DMA and the products formed after 1 cycle Figure 3: NMR spectra of neat NMA and the products formed after 1 cycle Scheme 1: Baeyer-Villiger Oxidation of acetamide electrolytes Figure 5: DEMS analysis performed for NMA and DMA in 1M LiNO 3 State-of-the-art Electrolyte Figure 2: Series of acetamide, linear urea and cyclic urea electrolyte candidates 1,3-dimethyl-3,4,5,6- tetrahydro-2-pyrimidione (DMPU) N,N-Dimethylacetamide (DMA) N-Methylacetamide (NMA) Tetramethylurea (TMU) 1,3-dimethyl-2- imidazolidinone (DMI) 1,2-dimethoxyethane (DME) LFP NMA DMA • Decomposition occurs predominantly on discharge • No difference is observed between a Li anode or LFP anode • Y Li2O2,c / Y Li2O2,d = ∼ 0.91-0.99 • Solvent degradation occurs on discharge, suggesting reductive mechanism • 1 H NMR needed to understand mechanisms DMSO A B B A C Assignment Shift (ppm) A 1.98 B 2.80 C 7.5 H 3 C N H O CH 3 DMSO A B B A C Assignment Shift (ppm) A 1.98 B 2.80 C 7.5 H 3 C N H O CH 3 C C O H H H H Assignment Shift (ppm) E F 3.48 4.80 E F E F Assignment Shift (ppm) G 2.09 G G Assignment Shift (ppm) J 2.91 K 6.98 J K J K H 2 O HDO H 2 O DMSO HDO H 3 C N O CH 3 CH 3 B A C A B C Assignment Shift (ppm) A 2.077 B 2.78 C 2.94 H 2 O DMSO HDO H 3 C N O CH 3 CH 3 B A C A B C Assignment Shift (ppm) A 2.077 B 2.78 C 2.94 C O H H H H Assignment Shift (ppm) E F 3.48 4.80 E E F F Assignment Shift (ppm) G 2.09 G G OER/ORR = 0.74 OER/ORR = 0.79 OER/ORR = 0.77 OER/ORR = 0.34 OER/ORR = 0.14 Figure 6: CO 2 evolution overview of selected amide and urea electrolytes with a focus on solvent 12 C Figure 1: OER/ORR ratio of selected electrolytes and DEMS analysis of state-of-the-art electrolyte DME
Transcript of Novel Electrolytes for use in Li-Air Batteries for NASA ...
Novel Electrolytes for use in Li-Air Batteries for NASA Electric AircraftRocco P. Viggiano*, Donald Dornbusch*, William Bennett*, Kristian Knudsen§, Baochau Nguyen†
*NASA Glenn Research Center, 21000 Brookpark Rd, Cleveland, OH 44135; §UC Berkeley, Berkeley, CA 94720;†Ohio Aerospace Institute, 22800 Cedar Point Rd, Cleveland, Ohio 44142
IntroductionThe 2018 Strategic Implementation Plan sets forth theNASA Aeronautics Research Mission Directorate(ARMD) vision for aeronautical research aimed at thenext 25 years and beyond. It encompasses a broad rangeof technologies to meet future needs of the aviationcommunity. Two key areas of focus are the transition toultra-efficient subsonic transports as well as the transitionto safe, quiet and affordable vertical lift air vehicles. Insupport of these technology areas, NASA has beenresearching hybrid-electric as well as fully electricaircraft designs.
Both designs necessitate the development of higherenergy density battery systems. Lithium-oxygen batterieshave been proposed as a potential enabling technologyowing to its high theoretical energy density, to date thehighest of any proposed battery technology.
However, there are immense technical challenges facingtheir development, including the development of morestable cathodes and electrolytes. Through a synergisticapproach utilizing computational modeling andexperimental screening, several new cathode andelectrolyte candidates have been screened. Concurrently,decomposition analysis of candidate electrolyte systemsusing nuclear magnetic resonance (NMR) spectroscopyhas yielded mechanistic insight into decompositionpathway, which is vital to the development of futurestable electrolyte candidates.
ConclusionsLinear Amides (NMA, DMA) Interestingly more 12Cx,xO is formed during charge relative to
other solvents, suggesting more simple products are formed
Low amounts of 12C18,18O2 is formed, suggesting solvent is relatively stable towards Li2O2 and its intermediates
DMA shows the best stability of the amides/ureas tested, but decomposes through a Baeyer-Villiger oxidation method
Linear Urea (TMU) Relatively low amounts of 12C18,18O2 formed, is more stable
towards Li218,18O2/Li18,18O2/18,18O2
- than linear amides
Cyclic Ureas (DMI and DMPU) Large amounts of 12C16,18O2 and 12C18,18O2 are formed while
low amounts of 12C16,16O2 is formed
This suggests an increased activation of a different pathway where CO2 is formed from Li2O2 induced solvent reduction
Results
Results
ExperimentalDifferential electrochemical mass spectrometry (DEMS) and nuclear magnetic resonance (NMR)spectroscopy were performed on a series of amides and ureas to elucidate the decompositionmechanism of these two classes of electrolytes. Figure 2 shows the series of amides and ureastested.
Figure 4: NMR spectra of neat DMA and the products formed after 1 cycle
Figure 3: NMR spectra of neat NMA and the products formed after 1 cycle
Scheme 1: Baeyer-Villiger Oxidation of acetamide electrolytes
Figure 5: DEMS analysis performed for NMA and DMA in 1M LiNO3
State-of-the-art Electrolyte
Figure 2: Series of acetamide, linear urea and cyclic urea electrolyte candidates
1,3-dimethyl-3,4,5,6-tetrahydro-2-pyrimidione
(DMPU)
N,N-Dimethylacetamide(DMA)
N-Methylacetamide(NMA) Tetramethylurea
(TMU)
1,3-dimethyl-2-imidazolidinone
(DMI)
1,2-dimethoxyethane(DME)
LFP
NMADMA
• Decomposition occurs predominantly on discharge
• No difference is observed between a Li anode or LFP anode
• YLi2O2,c /YLi2O2,d = ∼0.91-0.99
• Solvent degradation occurs on discharge, suggesting reductive mechanism
• 1H NMR needed to understand mechanisms
DMSO
AB
BA
C
Assignment Shift (ppm)A 1.98B 2.80C 7.5
H3C NH
O
CH3
DMSO
ABBA
CAssignment Shift (ppm)
A 1.98B 2.80C 7.5
H3C NH
O
CH3
C
C O
H
H
H H
Assignment Shift (ppm)E
F
3.484.80
E F
EF
Assignment Shift (ppm)G 2.09
G
G Assignment Shift (ppm)J 2.91K 6.98
J
K
J
K
H2O HDO
H2ODMSO
HDO
H3C N
O
CH3
CH3
BA
C
ABC
Assignment Shift (ppm)A 2.077B 2.78C 2.94 H2O
DMSO
HDO
H3C N
O
CH3
CH3
BA
CABC
Assignment Shift (ppm)A 2.077B 2.78C 2.94
C O
H
H
H H
Assignment Shift (ppm)E
F
3.484.80
E
EF
FAssignment Shift (ppm)
G 2.09
G
G
OER/ORR = 0.74
OER/ORR = 0.79
OER/ORR = 0.77OER/ORR = 0.34
OER/ORR = 0.14
Figure 6: CO2 evolution overview of selected amide and urea electrolytes with a focus on solvent 12C
Figure 1: OER/ORR ratio of selected electrolytes and DEMS analysis of state-of-the-art electrolyte DME
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