1. Recent Advancements in Two-Dimensional Materials for Li-Air Battery
Pedram Abbasi
LAS 493-Fall 2017

2. Agenda Motivation of research on Li-air batteries
How two dimensional materials can contribute?
Carbon based materials
Graphene
Doped-graphene
reduced-Graphene oxide
Carbon Free Materials TMDCs
h-Bn
Transition metal oxides
Conclusion and Remarks
news.mit.edu

3. Current states of Li Batteries
Production of Electric Drive Vehicle (EDV) batteries has been ~ doubling globally every year since 2010.
Economies of scale continue to push costs towards $200/kWh.
New material chemistries and lower-cost manufacturing, cost parity with (Internal Combustion Engines (ICEs)) should be reached in the next ten years.
Tesla’s battery pack in the floorpan of the Model S (Image: First Reporter)
High Energy density
Low Price
doi: /nmat3191

4. Advantages
Very high energy density compared to the Li-Ion
Cost Effective
Environmentally friendly
Energy density comparison among different Metal-Air batteries
𝐷𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑖𝑛𝑔 𝑂𝑅𝑅 𝐿𝑖 + + 2𝑒 − + 𝑂 2 → 𝐿𝑖 2 𝑂
𝐶ℎ𝑎𝑟𝑔𝑖𝑛𝑔 (𝑂𝐸𝑅) 𝐿𝑖 2 𝑂 2 →2𝐿𝑖 + + 2𝑒 − + 𝑂

5. 2D Materials in metal air battery applications:
“Two-dimensional (2D) materials are showing promise for many energy-related applications and particularly for energy storage, because of the efficient ion transport between the layers and the large surface areas available for improved ion adsorption and faster surface redox reactions.”
Five common 2D materials reported for charge storage application.
Different synthetic approaches for the preparation of 2D materials.
High Surface to volume ratio
Tunable electronic property
Scalable synthesis methods
Cheap and cost effective
DOI: /c6cc05357b
DOI: /c6cc05357b

6. a b Evolution of Carbon based 2D materials for Metal-Air batteries:
Figure1. (a) A schematic representation of the Li/02 plastic battery(b)The cycling data for a li/PAN-based polymer electrolyte/
oxygen cell at room temperature in an atmosphere of oxygen.
The cathode contained 20 w/o catalyzed Chevron carbon
black and 80 w/o polymer electrolyte. The cell was discharged at
0.1 mA/cm2 and charged at 0.05 mA/cm2
Kuzhikalail M. Abraham /
Figure2. a) Schematic illustration of a rechargeable Li-air cell based on a GNSs electrode. b) Discharge profiles of the 20 wt% Pt/CB, GNS, and acetylene black electrodes at a current density of 0.5 mA cm-2 for 24 hours, respectively. c) Correlation between cycle numbers and capacity of Li-air cells based on GNS electrodes. Reproduced with permission.
/nn200084u

7. Carbon based doped materials for Li-Air Batteries
Nitrogen Doped Graphene
Introducing dopant into the structure of graphene to tune the electronic property and morphology
Sulfur Doped Graphene
Figure4. a) Scheme of the formation for nitrogen-doped graphene sheets
derived from polyaniline and Co precursors using MWNTs as templates. (b
and c) HR-TEM images of the graphene-rich nanocomposites observed in
Co–N–MWNT catalysts. (d) RDE testing results for the ORR at 25 1C in
oxygen-saturated 0.1 M LiPF6 in 1,2-dimethoxyethane (e) Initial discharge
performance for various catalysts at a current density of 50 mA/gcat
1 in Li– O2 battery tests
Figure3. a images of (a) sulfur-doped and (b) pristine graphene discharged electrodes and the discharge/charge curves for (c) sulfur-doped and (d) pristine graphene.
/C2JM34718K
/nn303275d

8. r-GO with LiI for high cycle life lithium air Reduced Graphene Oxide
Introducing dopant into the structure of graphene to tune the electronic property and morphology
Hierarchically macroporous reduced graphene oxide (rGO)
electrodes (binder-free) are used because they are light, conductive, and have a large pore volume
that can potentially lead to large capacities.
Figure5. a) SEM image of pristine rG-O electrodes used in the Li-O 2 battery. b) Discharge/charge curves for Li-O 2 battery using mesoporous SP and TiC, and macroporous rG-O electrodes, with capacities limited to 500 mAh g −1 . Discharge/charge curves for Li-O 2 batteries using rG-O electrodes with capacity limits of: c) 1000 mAh g c −1 , d) 5000 mAh g c −1 , and e) 8000 mAh g c −1 , and f) as a function of rate. DOI: /science.aac7730.
/science.aac7730

9. Ir-rGO for lithium superoxide battery Iridium- Reduced Graphene oxide
This unique battery can cycle the Li-oxygen system through a one-electron process. This process can significantly increase the energy efficiency of the system by forming lithium super oxide instead of lithium per oxide.
Figure 6. Electrochemical tests and discharge products. a, Voltage profiles of the Ir–rGO cathode. Inset shows capacity as a function of cycle number. b, Voltage profiles of the rGO cathode. Inset shows capacity as a function of cycle number. c, Main panel, SEM image of discharge product on Ir–rGO (scale bar, 1 µm d, DEMS profile showing O2, H2 and CO2 gases released (n′ is the number of moles per second) from the cell during the charging
doi: /nature16484

10. Carbon-Free Materials - TMDCs
Layered materials with strong in-plane bonding and weak out-of-plane interactions.
One transition-metal atom for every two chalcogen atoms.
For example; MoS2, TaTe2, WSe2, NbSe2, VS2.
DOI: /nnano

11. Carbon-Free Materials - TMDCs
The cell with MoS2/AuNP nanohybrids exhibits discharge and charge overpotentials of 0.21 and 1.28 V, respectively, which resulted in the highest round-trip efficiency and a specific capacity of about 4336 mA.h.g-1.
Figure7.(a) discharge/charge profiles of the Li–O2 battery with the pristine Super P, MoS2 nanoflowers, and MoS2/AuNP nanohybrids at a current density of 70 mA.g-1. (b) The first discharge/charge profiles of the Li–O2 battery with Super P, MoS2 nanoflowers, and MoS2/AuNP nanohybrids at current densities of 200 and 500 mA.g-1. (c) Curtailing capacity at a current density of 300 mA.g-1. (d) Terminal discharge voltage.
A synergistic catalytic effect between MoS2 and gold nanoparticles (AuNPs) has been achieved for a highly efficient ORR.
Zhang, Panpan, et al. "MoS2 nanosheets decorated with gold nanoparticles for rechargeable Li–O2 batteries." Journal of Materials Chemistry A 3.28 (2015).

12. Carbon-Free Materials – TMDCs
in Lithium-Air Battery
(c)
(d)
Figure 8.
SEM images of MoS2 NFs deposited on the gas diffusion layer.
(b) Dynamic light scattering and Raman spectroscopy of MoS2 NFs.
(c) Charging and discharging voltage profiles of a battery using carbon-free MoS2 NFs and an ionic liquid electrolyte saturated with 0.1M LiTFSI as a Li salt. (d) Differential electrochemical mass spectroscopy (DEMS) profiles of the cell after the 1st, 20th, and 50th cycles.
(e)
(f)
(e) An optical image of a crytalline structure of MoS2 grown by chemical vapor transport method.
(f) Synthesized TMDC NFs after 20 hours of sonication and 1 hour of centrifugation at 2000 rpm.
Asadi, Mohammad, et al. "Cathode Based on Molybdenum Disulfide Nanoflakes for Lithium–Oxygen Batteries." ACS nano 10.2 (2016).

13. Carbon-Free Materials - h–BN
From the family of “Boron Nitrates”.
Layered structure which boron and nitrogen atoms are bound by strong covalent bonds and layers are bound by weak van der Waals forces.
Wide bandgap semiconductor.
Very high thermal and chemical stability.
High thermal conductivity.
Called as “White Graphene”.
DOI: /nphoton

14. Carbon-Free Materials - h–BN
Hexagonal boron nitride as SEI Layer in Lithium-Air Battery
The problems of dendritic and mossy Li formation and its highly reactive nature cause poor safety and low cycling efficiency during charge and discharge.
Morphology studies of Li metal deposition.
Used the method of chemical vapor deposition (CVD): Copper foil was heated up to 1000°C in Ar and H2 at low pressure followed by ammonia borane (NH3−BH3) vapor.
stable cycling over 50 cycles with Coulombic efficiency ∼97%.
Figure9. Cycling performance of Li metal anode with and without h-BN protection at various current rates.
Schematic diagrams of lithium deposition.
Yan, Kai, et al. "Ultrathin two-dimensional atomic crystals as stable interfacial layer for improvement of lithium metal anode." Nano letters (2014):

15. Transition metal oxides:
RuO2 based catalyst
Figure10. SEM images of pre-prepared layered precursor (a-b) and as-prepared RuO2 nanosheets; and (c) their corresponding XRD patterns (d).HRTEM image of the asprepared RuO2 nanosheet. The left inset shows the corresponding TEM image, and the right inset is a photo of the as-prepared RuO2 sample suspended by a thin hair.
Figure11. Electrochemical impedance spectra of the Li-O2 cell with RuO2 nanosheet cathode at different states.
DOI: /C5EE01451D

16. Conclusion
Carbon based two dimensional materials such as graphene and reduced graphene oxides have been widely utilized as air cathode and catalyst for Li-air batteries, there are still lot of room for discoveries in this field.
Other two dimensional families such as TMDCs or TMOs have shown promising performance to be used as the air cathode and also SEI layer for anode protection
More in-depth modeling and predictive tools are needed to be able to find the right two- dimensional structures that can address not only the cathode interphase issues but also electrolyte and anode limitations as well.
Practical implementation of Li-air as an alternative for current Li-ion systems requires some techno economical assessments such as designing the battery pack, power densities at different charge-discharge rates etc. that are as important as catalysis development.