Advanced Microscopy and Spectroscopy for Probing and Optimizing Anionic Redox in High Energy Lithium Batteries

The earliest developed LiCoO₂ layered oxide cathode material sparked the development of other layered cathode materials, dominating the positive electrode materials for lithium ion batteries. Within the practical operating conditions of today, the current generation layered oxide materials do not meet the future energy storage demands of 350 Wh kg^-1 per cell. This roughly translates to over 800 Wh kg^-1 at the positive electrode level. Li-excess materials have the potential to meet the high energy demands. Unlike the classical layered oxides, Li-excess materials exhibit capacities that go beyond conventional topotactic mechanistic theoretical values because of reversible and stable anionic redox.

In the past five years, our research group has made great progress on developing advanced characterization techniques (including coherent X-ray imaging, neutron pair distribution function, and resonant inelastic X-ray scattering) coupled with atomic scale modeling to properly characterize the dynamic phenomena that govern the anionic redox related performance limitations of Li-excess materials. Furthermore, our efforts have improved the material synthesis and surface modification to improve capacity retention. It is through the in-depth understanding of these anionic redox based cathode materials at atomistic and molecular level and their dynamic changes during the operation of batteries; we can successfully formulate strategies to optimize this class of cathode materials.

Highlighted Publications:

1. M. Zhang, B. Qiu, J. M. Gallardo-Amores, M. Olguin, H. Liu, Y. Li, C. Yin, S. Jiang, W. Yao, M. Elena Arroyo-de Dompablo, Z. Liu and Y. S. Meng, “High Pressure Effect on Structural and Electrochemical Properties of Anionic Redox- Based Lithium Transition Metal Oxides“, Matter, 2020, 4, 1, 164-181

2. A. Singer, M. Zhang, S. Hy, D. Cela, C. Fang, T. A. Wynn, B. Qiu, Y. Xia, Z. Liu, A. Ulvestad, N. Hua, J. Wingert, H. Liu, M. Sprung, A. V. Zozulya, E. Maxey, R. Harder, Y. S. Meng, and O. G. Shpyrko,”Nucleation of Dislocations and Their Dynamics in Layered Oxide Cathode Materials During Battery Charging‘ ,Nature Energy, 2018, 3, 641

3. B. Qiu, M. Zhang, L. Wu, J. Wang, Y. Xia, D. Qian, H.D. Liu, S. Hy, Y. Chen, K. An, Y. Zhu, Z. Liu, Y. S. Meng, “Gas–solid interfacial modification of oxygen activity in layered oxide cathodes for lithium-ion batteries“, Nature Communication 2016, 7,12108

4. Sunny Hy, H.D. Liu, M. Zhang, D. Qian, B.-J. Hwang, Y. S. Meng, “Performance and design considerations for lithium excess layered oxide positive electrode materials for lithium ion batteries“, Energy & Environmental Science, 2016, 9, 1931

Co Free Cathode Materials and Their Novel Architectures

The next generation Li-ion batteries (LIBs) need reasonable matching of electrode and electrolyte to achieve the best performance, including longer cycling and better safety. For the cathode materials, the current commercialization and research mainly focuses on lithium metal oxides (LiNi_xCo_yMn_zO₂, x+y+z=1) with layered structure. Layered lithium metal oxides have high energy densities, but the use of expensive and toxic cobalt elements greatly restricts their application in widespread commercialization of electric vehicles. In this context, a new spinel type oxide LiNi_0.5Mn_1.5O₄ (LNMO) is of great focus with a theoretical capacity of 147 mAh/g and average working voltage as high as 4.7 V. More importantly, it does not contain expensive cobalt, which makes LNMO cathode cost-effective and suitable for applications in the field of power batteries and large-scale energy storage.

The objective of this project is to research, develop, and demonstrate a spinel type LNMO electrode and novel electrolyte formulation for use in next-generation LIBs. Our proposed cathode is 100% free of cobalt and its novel architecture will have porosity less than 20% and designed tortuosity for high rate capability. In addition, to guide our research to determine which electrolyte system is more stable and compatible for LNMO electrode materials under high voltage cycling, we will develop a series of characterization techniques such as ex-situ X-ray photoelectron spectroscopy (XPS), ex-situ cryogenic transmission electron microscopy (cryo-TEM), ex-situ cryogenic focused ion beam microscope (cryo-FIB) and in situ time-of-flight secondary-ion mass spectrometry (TOF-SIMS).

 Highlighted Publications:

1. W. Li, Y. Cho, W. Yao, Y. Li, A. Cronk, R. Shimizu, M. A. Schroeder, Y. Fu, F. Zou, V. Battaglia, A. Manthiram, M. Zhang and Y. S. Meng, “Enabling high areal capacity for Co-free high voltage spinel materials in next-generation Li-ion batteries“, Journal of Power Sources 2020, 473, 228579

2. J. Alvarado, M. A. Schroeder, M. Zhang, O. Borodin, E. Gobrogge, M. Olguin, M. S. Ding, M. Gobet, S. Greenbaum, Y. S. Meng, K. Xu, “A carbonate-free, sulfone-based electrolyte for high-voltage Li-ion batteries” “supplementary data” Materials Today, 2018, 21(4), 341

• TGC method: Titration Gas Chromatography method is invented to quantify both the metallic Li0 and SEI Li+ in the cycled Li metal anode. The insights gained from the quantification results suggests the Li metal anode Coulombic efficiency (CE) is solely related to the morphology of the deposited Li. To obtain the ideal CE, a bulky and reversible columnar structure is required.
• Pressure effect: The effect of stack pressure on the Li plating/stripping is studied by TGC and Cryo-FIB/SEM. For the first time, a reversible columnar structure of electrochemically deposited Li is demonstrated by optimizing the stack pressure on the Li metal during the plating process. The resulting Li shows less than 0.5% of porosity and is able to maintain its near 100% dense morphology for more than 30 cycles.
• Li corrosion: The key parameters in controlling the chemical corrosion of Li metal in liquid electrolyte are studied in this work. It is found that the morphology of the Li plays the most crucial role in mitigating the chemical corrosion of Li. A slow corrosion rate of 0.08%/day is demonstrated after optimizing the morphology and interface of the Li metal.

Publication list:

• W. Deng, X. Yin, W. Bao, X. Zhou, Z. Hu, B. He, B. Qiu, Y. S. Meng and Z. Liu, “Quantification of reversible and irreversible lithium in practical lithium-metal batteries“, Nature Energy, 2022, ASAP
• B. Lu, W. Bao, W. Yao, J. Doux, C. Fang and Y. S. Meng, “Editors’ Choice—Methods—Pressure Control Apparatus for Lithium Metal Batteries”, Journal of The Electrochemical Society, 2022, 169, 070537
• C. Fang, B. Lu, G. Pawar, M. Zhang, D. Cheng, S. Chen, M. Ceja, J. Doux, H. Musrock, M. Cai, B. Liaw and Y. S. Meng, “Pressure-tailored lithium deposition and dissolution in lithium metal batteries“, Nature Energy 2021, 6, 987–994
• B. Lu, E. Olivera, J. Scharf, M. Chouchane, C. Fang, M. Ceja, L. E. Pangilinan, S. Zheng, A. Dawson, D. Cheng, W. Bao, O. Arcelus, A. A. Franco, X. Li, S. H. Tolbert & Y. S. Meng, “Quantitatively Designing Porous Copper Current Collectors for Lithium Metal Anodes“, ACS Appl. Energy Mater. 2021, 4, 7, 6454–6465
• C. Fang, J. Li, M. Zhang, Y. Zhang, F. Yang, J. Z. Lee, M. Lee, J. Alvarado, M. A. Schroeder, Y. Yang, B. Lu, N. Williams, M. Ceja, L. Yang, M. Cai, J. Gu, K. Xu, X. Wang & Y. S. Meng, “Quantifying inactive lithium in lithium metal batteries“, Nature, 2019, 572, 511–515
• C. Fang, X. Wang, and Y. S. Meng, “Key Issues Hindering a Practical Lithium-Metal Anode” Trends in Chemistry, 2019, 1, 152

In many applications, energy density and low-temperature performance are two key metrics that state-of-the-art Li-ion batteries have significant difficulty meeting. In recent years, a lot of focus has been placed on the use of the Li-metal anode in combination with high voltage cathodes to dramatically increase the energy densities of batteries. Actual use of these systems has been hampered due to the unavailability of electrolytes that are compatible with the Li-metal anode while at the same time resistant to degradation at the high voltage cathode. Our liquefied gas electrolyte work focuses on gases that are promising candidates to achieve the stability required at both the anode and cathode in these aggressive, high voltage systems. At low temperatures or moderate pressures, these gases liquefy and can dissolve lithium salts to form liquefied gas electrolytes. These electrolytes have shown impressive compatibility with the Li-metal anode, and very good stability with high voltage cathodes as well as dramatically improved low temperature performance down to -60C.

Through experimental and computational approaches, our research has focused on the interesting solvation and transport mechanisms of the bulk electrolyte as well as the interfaces formed on both anodes and cathodes. Our work has opened a new area of research in the energy storage field and we hope to see new materials and manufacturing methods developed from the idea of using these gaseous solvents.

Highlighted Publications:

1. Y. Yang, Y. Yin, D. M. Davies, M. Zhang, M. Mayer, Y. Zhang, E. S. Sablina, S. Wang, J. Z. Lee, O. Borodin, C. S. Rustomji and Y. S. Meng, “Liquefied gas electrolytes for wide-temperature lithium metal batteries“, Energy Environ. Sci. 2020, 13, 2209 – 2219

2. Y. Yang, D. M. Davies, Y. Yin, O. Borodin, J. Z. Lee, C. Fang, M. Olguin, Y. Zhang, E. S. Sablina, X. Wang, C. S. Rustomji and Y. S. Meng, “High-Efficiency Lithium-Metal Anode Enabled by Liquefied Gas Electrolytes“, Joule , 3, 1–15, 2019

3. C. S. Rustomji, Y. Yang, T. K. Kim, J. Mac, Y. J. Kim, E. Caldwell, H. Chung, Y. S. Meng, “Liquefied Gas Electrolytes for Electrochemical Energy Storage Devices“, Science, 2017, 356, 1351

With the invention of non-aqueous electrolytes which enabled the use of alkali metal anodes, the energy density of batteries exhibited a remarkable improvement. However, in order to mitigate the safety issues the energy density was compromised and Li ion batteries (LIBs) were designed and got wide popularity especially in the potable electronic market. Fast approaching saturation curves of LIB performance matrices and pressing demands for higher energy and power density energy storage systems to support high energy demanding applications viz. electric vehicles make a situation inevitable to stretch out beyond LIBs. Revisiting Li metal anodes as in Li-O₂ non-aqueous chemistry seems to be promising even though the understanding of the mechanism is in its infancy. Major bottle neck of exploiting the reversible reaction between Li⁺ and O₂ is the sluggish kinetics of the electrochemical decomposition of the discharge product viz. Li₂O₂ to Li⁺ and O₂ (Oxygen Evolution Reaction-OER). Fundamental understanding of Li-O₂ electrochemistry is believed to pave way for other alkali Metal-Air batteries.

Various approaches aiming to improve the kinetic requirements of the fast charge/discharge include, addition of redox mediators, solubilizing agents etc. Carbonaceous matrices have been nanoengineered to facilitate the discharge process (Oxygen Reduction Reaction-ORR) and mass transport, thus currently playing pivotal role beyond just as catalyst support layer. Our recent oxyhalogen-sulfur electrochemistry approach synergistically combines these two and the round-trip efficiency is remarkably improved. Multi-faceted approaches to take control over the nucleation site, size and composition of the discharge products is critical in the design and fabrication of a practically usable Metal-Air battery.

                Schematic depicting the mechanism of oxyhalogen-sulfur electrochemistry driven charge discharge processes

Highlighted Publications:

X. Wang, Y. Li, X. Bi, L. Ma, T. Wu, M. Sina, S. Wang, M. Zhang, J. Alvarado, B. Lu, A. Banerjee, K. Amine, J. Lu, and Y. S. Meng “Hybrid Li-Ion and Li-O2 Battery Enabled by Oxyhalogen-Sulfur Electrochemistry“, Joule. 2018, 2, 11, 2381

Research into inexpensive, long lifetime, grid energy storage options is increasingly important as we move to sustainable energy sources such as solar and wind. Sodium ion batteries are an exciting, inexpensive option for grid storage. The components of sodium ion batteries can be made with inexpensive elements such as manganese, iron, and carbon. While initial results show that sodium ion batteries have relatively high energy density, improvements in energy density and lifetime are necessary to make them a viable option.

To improve sodium ion batteries energy density and lifetime, we are studying the mechanism of energy storage in both the cathode and anode including material degradation and irreversible reactions. We are employing, including novel synthesis methods and advanced characterization techniques to advance our understanding of the systems scalability and fundamental properties. In combining advanced characterization techniques (XRD, TEM, FIB, NMR, synchrotron instruments, etc.), we can “see” what is happening inside the battery from the macro scale down to the atomic scale. On the cathode side we are researching the irreversible reactions in high capacity inexpensive materials and how to increase the capacity by utilizing oxygen redox. On the anode side we are studying the irreversible reactions and how to increase their life time. We aim to determine the mechanism of energy storage in sodium ion batteries and use this knowledge to build better ones.

Highlighted Publications:

1. H. S. Hirsh, Y. Li, D. H. S. Tan, M. Zhang, E. Zhao and Y. S. Meng, “Sodium-Ion Batteries Paving the Way for Grid Energy Storage“, Adv. Energy Mater. 2020, 2001274

2. H. Hirsh, M. Olguin, H. Chung, Y. Li, S. Bai, D. Feng, D.Wang, M. Zhang and Y. S. Meng, “Meso-Structure Controlled Synthesis of Sodium Iron-Manganese Oxides Cathode for Low-Cost Na-Ion Batteries“, Journal of The Electrochemical Society, 2019, 166 (12) A2528

3. H. Li, H. Tang, C. Ma, Y. Bai, J. Alvarado, B. Radhakrishnan, S. P. Ong, F. Wu, Y. S. Meng, and C. Wu “Understanding the Electrochemical Mechanisms Induced by Gradient Mg2+ Distribution of Na-Rich Na3+xV2–xMgx(PO4)3_C for Sodium Ion Batteries” Chem. Mater., 2018, 30 (8), 2498

4. M. D. Radin, J. Alvarado, Y. S. Meng, and A. V. der Ven “Role of Crystal Symmetry in the Reversibility of Stacking-Sequence Changes in Layered Intercalation Electrodes”,Nano Letters, 2017, 17(12), 7789

5. J. Alvarado, C. Ma, S. Wang, K. Nguyen, M. Kodur, and Y. S. Meng, “Improvement of the Cathode Electrolyte Interphase on P2-Na2_3Ni1_3Mn2_3O2 by Atomic Layer Deposition“ACS Appl. Mater. Interfaces, 2017, 9(31), 26518

6. C. Ma, J. Alvarado, J. Xu, R. J. Clément, M. Kodur, W. Tong, C. P. Grey, and Y. S. Meng,”Exploring Oxygen Activity in the High Energy P2-Type Na0.78Ni0.23Mn0.69O2 Cathode Material for Na-Ion Batteries“, J. Am. Chem. Soc., 2017, 139(13), 4835

All-solid-state batteries (ASSB) offer high energy density and are a safer alternative to conventional liquid-electrolyte-based Li-ion batteries. However, electrolyte selection is limited, and those exhibiting competitive ionic conductivities often exhibit high interfacial impedance. Thin film batteries are ASSBs with thickness of only a few micrometers, which have the benefits of solid-state batteries with the potential to be incorporated in microelectronics. Further, they provide with ideal platforms for interfacial studies due to their well-defined geometries. Thin film subgroup in LESC has been exploring new thin film battery compositions and their interfaces, along which novel characterization techniques, including cryogenic focused ion beam (cryo-FIB), cryogenic scanning/transmission electron microscopy (cryo-S/TEM), solid-state nuclear magnetic resonance (ss-NMR) and neutron depth profiling (NDP), etc. have been incorporated to facilitate the interfacial study of air-/beam-sensitive battery materials.

Recently, we have demonstrated the structural and chemical evolution across the interphase between Li metal and LiPON via cryo S/TEM, which provides valuable insights for interface engineering to further improve the interfacial stability. Another work successfully resolved the structure of amorphous LiPON by ss-NMR coupled with DFT calculation, where LiPON is shown to be a low-connectivity glass, influencing its mechanical properties and its stability with Li metal. Future work of thin film subgroup will continue the study on the cathode/solid electrolyte interface along with developing cryogenic in situ methodologies for probing dynamic changes at the beam-sensitive interfaces and in phase-change materials.

Highlighted Publications:

1. D. Cheng, T. A. Wynn, X. Wang, S. Wang, M. Zhang, R. Shimizu, S. Bai, H. Nguyen, C. Fang, M. Kim, W. Li, B. Lu, S. J. Kim and Y. S. Meng, “Unveiling the Stable Nature of the Solid Electrolyte Interphase between Lithium Metal and LiPON via Cryogenic Electron Microscopy“, Joule, 2020, 4, 11, 2484-2500

2. M. A. T. Marple, T. A. Wynn, D. Cheng, R. Shimizu, H. E. Mason, and Y. S. Meng, “Local structure of glassy lithium phosphorus oxynitride thin films: a combined experimental and ab initio approach“, Angew. Chem. Int. Ed. 2020, 59, 2–11

3. J. Z. Lee, T. A. Wynn, M. A. Schroeder, J. Alvarado, X. Wang, K. Xu, and Y. S. Meng, “Cryogenic Focused Ion Beam Characterization of Lithium Metal Anodes“ ACS Energy Letters, 2019, 4, 489

4. J. Z. Lee, T. A. Wynn, Y. S. Meng, D. Santhanagopalan, “Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing” . J. Vis. Exp, 2018, e56259

5. J. Z. Lee, Z. Wang, H. L. Xinb, T. A. Wynn, and Y. S. Meng, “Amorphous Lithium Lanthanum Titanate for Solid-State Microbatteries“, Journal of The Electrochemical Society, 2017, 164(1), 6268

6. Z. Wang, D. Santhanagopalan, W. Zhang, F. Wang, H. L. Xin, K. He, J. Li, N. Dudney, and Y. S. Meng,”In Situ STEM-EELS Observation of Nanoscale Interfacial Phenomena in All-Solid-State Batteries“, Nano Letters,   2016, 16 (6), 3760

Batteries for Extreme

Primary lithium batteries are of critical importance in devices where recharging is impractical such as implantable medical devices, military rescue devices, and space research missions. Due to their high specific energy, long storage times, and instant readiness, this class of lithium batteries holds great promise for such unique applications. Among different types of primary batteries (e.g. Li/I₂, Li/MnO₂, Li/Ag₂CrO₄, and Li/CuS), lithium fluorinated carbon (Li-CF_x) primary batteries show great promise for applications in a wide range of energy storage systems due to their high energy density (>2100 Wh kg^–1) and low self-discharge rate (<0.5% per year at 25 °C). This system, with the proposed governing reaction of CF_x + Li → LiF + C, is one of the leading candidates for a variety of applications where high energy density is required and recharging of the battery is not feasible, e.g. implantable medical devices, military and space applications or other extreme environments.

Understanding the Discharge Mechanism: A multiscale investigation of the CF_x discharge mechanism is performed using a novel cathode structure to minimize the carbon and fluorine additives for precise cathode characterizations. Titration gas chromatography, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, cross-sectional focused ion beam, high-resolution transmission electron microscopy, and scanning transmission electron microscopy with electron energy loss spectroscopy are utilized to investigate this system. This work deepens the understanding of CF_x as a high energy density cathode material and highlights the need for future investigations on primary battery materials to advance performance.

The schematic of the Li-CF_x discharge mechanism through depth of discharge.

Ultra-low Temperature Li-CF_x Battery: We report a liquefied gas electrolyte with an anion-pair solvation structure based on dimethyl ether with a low melting point (−141°C) and low viscosity (0.12 mPa×S, 20°C), leading to high ionic conductivity (> 3.5mScm^–1) between −70 and 60°C. Besides that, through systematic X-ray photoelectron spectroscopy integrated with transmission electron microscopy characterizations, we evaluate the interface of CF_x for low-temperature performance. We conclude that the fast transport and anion-pairing solvation structure of the electrolyte brings about reduced charge transfer resistance at low temperatures, which resulted in significantly enhanced performance of Li/CF_x cells (1690 Wh kg^–1, −60°C; 1172 Wh kg^–1, −70°C based on active materials). Utilizing 50 mg cm^-2 loading electrodes, the Li/CF_x still displayed1530 Wh kg^–1 at −60°C. This work provides insights into the electrolyte design that may overcome the operational limits of batteries in extreme environments.

The electrochemical performance of free-standing 50 mg/cm² CF_x electrode in novel LGE electrolyte at -60°C. This result is also compared to the state of the art data in the literature.

Highlighted Publications:

1. Yijie Yin, John Holoubek, Alex Liu, Baharak Sayahpour, Ganesh Raghavendran, Guorui Cai, Bing Han, Matthew Mayer, Noah Schorr, Timothy N Lambert, Katharine L Harrison, Weikang Li, Zheng Chen, Ying Shirley Meng “Ultra-Low Temperature Li/CFx Batteries Enabled by Fast-transport and Anion-pairing Liquefied Gas Electrolytes” Advanced Materials (2022).
2. Baharak Sayahpour, Hayley Hirsh, Shuang Bai, Noah B Schorr, Timothy N Lambert, Matthew Mayer, Wurigumula Bao, Diyi Cheng, Minghao Zhang, Kevin Leung, Katharine L Harrison, Weikang Li, Ying Shirley Meng “Revisiting Discharge Mechanism of CFx as a High Energy Density Cathode Material for Lithium Primary Battery” Advanced Energy Materials5 (2022) 2103196.
3. Baharak Sayahpour, Shuang Bai, Diyi Cheng, Minghao Zhang, Weikang Li, Ying Shirley Meng “Elucidation of Discharge Mechanism in CFx As a High Energy Density Cathode Material for Lithium Primary Battery” The Electrochemical Society (ECS) meeting 2022, MA2022-01 335, Vancouver, BC.

Fuel cells convert the chemical energy from fuels (such as hydrogen) to electrical energy. Solid oxide fuel cells (SOFCs) are one of the most attractive systems due to their high conversion efficiency; since they are electrochemical devices, their efficiency far surpasses combustion-based energy conversion. However, the operating temperature of current commercial SOFCs is around 800-950°C; at such temperatures, problems arise such as slow startup, reduced device durability, and limited material selection. To mitigate these issues, lower temperature operation is desired (550-700°C), and thus, interest has been growing in thin-film SOFCs (TF-SOFCs). By reducing the electrolyte layer thickness to a few micrometers, the electrolyte conductivity is maintained at lower temperatures and thus so is SOFC operation. Recently, we have developed a TF-SOFC (that contains a LSCF-YSZ cathode, GDC interlayer, YSZ electrode, and Ni-YSZ anode) fabricated completely by sputtering, in collaboration with Prof. Eric Fullerton’s group and Dr. Nguyen Q. Minh from Center for Energy Research. The cell demonstrated high power densities of 1.7 and 2.5 W/cm² at 600 and 650°C, respectively.

(a) Schematic of TF-SOFC, (b) STEM cross-section image of the cell, and (c) magnified STEM image of the LSCF-YSZ cathode

For synthesis of the TF-SOFCs, the sputtering technique is utilized. Compared to atomic layer deposition (ALD), sputtering can enable control of the porosity of films by tuning the synthesis parameters. Pulsed laser deposition (PLD) is also a popular technique for ceramic-based film fabrication, but sputtering is superior in terms of cost and scalability. To characterize the SOFCs, along with electrochemical methods, we explore the morphology and chemistry in each layer of the cell through techniques such as scanning electron microscope (SEM, in conjunction with the focused ion beam (FIB)), (scanning) transmission electron microscope (TEM), and electron energy loss spectroscopy (EELS).

Highlighted Publications

1. Y. H. Lee, H. Ren, E. Wu, E. E. Fullerton, Y. S. Meng and N. Q. Minh, “All-Sputtered, Superior Power Density Thin-Film Solid Oxide Fuel Cells with a Novel Nanofibrous Ceramic Cathode“, Nano Lett. 2020, 20, 5, 2943–2949

2. H. Ren, Y. H. Lee, E. A. Wu, H. Chung, Y. S. Meng, E. E. Fullerton and N. Q. Minh, “Nano-Ceramic Cathodes via Co-sputtering of Gd−Ce Alloy and Lanthanum Strontium Cobaltite for Low-Temperature Thin-Film Solid Oxide Fuel Cells“, ACS Appl. Energy Mater. 2020, 3, 9, 8135–8142

Silicon anodes can provide high theoretical specific capacity (~3579 mAh/g) but suffer from large volume expansion (~300%) and subsequent contraction during lithiation and de-lithiation, that severely affects its capacity retention. The silicon anode subgroup works on qualitative tools as well as quantitative tools such as Titration Gas Chromatography (TGC), developed at LESC to understand these issues and proposed solutions to these fundamental issues through binder engineering, state of charge control, particle size reduction, pre-lithiation strategies and exploring silicon oxide as an alternative solution for stable capacity retention. Our team also has the capability to investigate fundamental problems and unanswered questions in the field of silicon-based anodes with the help of thin film architecture. Additionally, our team explores the realm of both half-cell and full cell (coin-cell format and single layer pouch cell format) configurations to understand the effects that arise from limited and unlimited Lithium source as well as stack pressure.

Titration Gas Chromatography Work Flow for Silicon Electrode

Understanding Lithium Inventory Losses in Binder Free, Conductive Agent Free Silicon Electrode

Understanding Lithium Inventory Losses in Practical Silicon Electrodes

Highlighted Publications:

1. Bao, C. Fang, D. Cheng, Y. Zhang, B. Lu, D. H. S. Tan, R. Shimizu, B. Sreenarayanan, S. Bai, W. Li, M. Zhang and Y. S. Meng, “Quantifying lithium loss in amorphous silicon thin-film anodes via titration-gas chromatography“, Cell Reports Physical Science, 2021,2,100597
2. Sreenarayanan, D. H. S. Tan, S. Bai, W. Li, W. Bao, Y. S. Meng, “Quantification of lithium inventory loss in micro silicon anode via titration-gas chromatography“, Journal of Power Sources, 2022, 531 231327
3. Parikh, M. Sina, A. Banerjee, X. Wang, M. Savio D’Souza, J.-M. Doux, E. A. Wu, O. Y. Trieu, Y. Gong, Q. Zhou, K. Snyder, and Y. S. Meng, “Role of Polyacrylic Acid (PAA) Binder on the Solid Electrolyte Interphase in Silicon Anodes” Chemistry of Materials, 2019, 31 (7), 2535

Attributed as the first practical battery developed, Zinc batteries have the known benefits of low material cost, non-toxicity, and a high theoretical energy density. Zinc-based batteries are commercially implemented in the medical and stretchable electronics industry and have great promise in grid storage. In our lab, we focus on high throughput, printable, low cost, and energy dense batteries with superior power densities when powering Bluetooth and wireless devices. Shown below from our group’s recent publication, with our all-printed and stacked configuration, our Zinc-based batteries show superior areal capacities and can handle higher current densities than reported in literature. These performances are best illustrated from the images and video below in which our printed Zinc batteries power the high current pulse required of a Bluetooth enabled flexible display.

The development of this high-performance battery is largely due to our arsenal of advance characterization techniques that allow us to recognize failure modes and optimize our materials design. Shown below is an example of how micro-scale X-ray Computed Tomography (micro-CT), used in our work, can shed light on our battery’s structure, in which each layer can be non-destructively probed to obtain 3D reconstructions. Future work will showcase improved performances through our advance characterization and will shed light on how such techniques can aid the battery community for the future of high performance and low-cost batteries.

Highlighted Publications:

1. L. Yin, J. Scharf, J. Ma, J. Doux, C. Redquest, V. L. Le, Y. Yin, J. Ortega, X. Wei, J. Wang and Y. S. Meng, “High Performance Printed AgO-Zn Rechargeable Battery for Flexible Electronics“, Joule, 2020, 5, 1-21 [Video content: YouTube Link]

2. R. Kumar, J. Shin, L. Yin, J.-M. You, Y. S. Meng, Joseph J Wang, “All-Printed, Stretchable Zn-Ag2O Rechargeable Battery via, Hyperelastic Binder for Self-Powering Wearable Electronics“, Adv. Energy Materials, 2017, 1602096

3. A. Bandodkar, W. Jia, J. Ramirez, Y. S. Meng and J. Wang, “An epidermal alkaline rechargeable Ag-Zn printable tattoo battery for wearable electronics”, J. Mater. Chem. A, 2014, 2(38), 15788

4. J.W. Shin, J.-M. You, J. Z. Lee, R. Kumar, L. Yin, J. Wang, and Y. S. Meng,”Deposition of ZnO on bismuth species towards a rechargeable Zn-based aqueous battery” , Phys. Chem. Chem. Phys., 2016, 18, 26376 (Front Cover)

The Computational Materials Science Group at LESC uses atomistic scale modeling to provide predictive understanding of Li-ion battery materials physicochemical properties.

We employ highly accurate first-principles and classical molecular dynamics techniques to study the electronic structure and energetics of anode, bulk electrolyte, cathode, and interface systems on massively parallel supercomputers. These computational chemistry approaches are performed in close collaboration with experimentalists via a complimentary research strategy with the aim of designing functional state-of-the-art battery materials.

Highlighted Publications:

1. Y. S. Meng, M. E. A.-d. Dompablo, (invited review) “First principles computational materials design for energy storage materials in lithium ion batteries“, Energy & Environmental Science, 2009, 2, 589

2. B. Xu, C. R. Fell, M. Chi, and Y. S. Meng, “Identifying surface structural changes in layered Li-excess nickel manganese oxides in high voltage lithium ion batteries: A joint experimental and theoretical study“, Energy & Environmental Science, 2011, 4, 2223

3. T. A. Wynn,  C. Fang,  M. Zhang,  H. Liu,  D. M Davies,  X. Wang,  D. Lau, J. Z Lee,  B.-Y. Huang,  K. Z. Fung,  C.-T. Ni  and  Y. S. Meng “Mitigating Oxygen Release in Anionic-Redox-Active Cathode Materials by Cationic Substitution through Rational Design“, JMCA 2018, 6, 24651

4. I.-H. Chu, M. Zhang, S. P. Ong, and Y. S. Meng, “Handbook of Materials Modeling-Battery Electrodes, Electrolytes, and Their Interfaces“