Electrode–Electrolyte Interfaces in Lithium–Sulfur Batteries with Liquid

Nov 7, 2017 - (1-3) Among the commercially available battery technologies, lithium-ion (Li+-ion) batteries deliver the highest energy density and are ...
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Article Cite This: Acc. Chem. Res. 2017, 50, 2653-2660

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Electrode−Electrolyte Interfaces in Lithium−Sulfur Batteries with Liquid or Inorganic Solid Electrolytes Published as part of the Accounts of Chemical Research special issue “Energy Storage: Complexities Among Materials and Interfaces at Multiple Length Scales”. Xingwen Yu and Arumugam Manthiram* Materials Science and Engineering Program & Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States CONSPECTUS: Electrode−electrolyte interfacial properties play a vital role in the cycling performance of lithium−sulfur (Li−S) batteries. The issues at an electrode−electrolyte interface include electrochemical and chemical reactions occurring at the interface, formation mechanism of interfacial layers, compositional/structural characteristics of the interfacial layers, ionic transport across the interface, and thermodynamic and kinetic behaviors at the interface. Understanding the above critical issues is paramount for the development of strategies to enhance the overall performance of Li−S batteries. Liquid electrolytes commonly used in Li−S batteries bear resemblance to those employed in traditional lithium-ion batteries, which are generally composed of a lithium salt dissolved in a solvent matrix. However, due to a series of unique features associated with sulfur or polysulfides, ether-based solvents are generally employed in Li−S batteries rather than simply adopting the carbonate-type solvents that are generally used in the traditional Li+ion batteries. In addition, the electrolytes of Li−S batteries usually comprise an important additive, LiNO3. The unique electrolyte components of Li−S batteries do not allow us to directly take the interfacial theories of the traditional Li+-ion batteries and apply them to Li−S batteries. On the other hand, during charging/discharging a Li−S battery, the dissolved polysulfide species migrate through the battery separator and react with the Li anode, which magnifies the complexity of the interfacial problems of Li−S batteries. However, current Li−S battery development paths have primarily been energized by advances in sulfur cathodes. Insight into the electrode−electrolyte interfacial behaviors has relatively been overshadowed. In this Account, we first examine the state-of-the-art contributions in understanding the solid−electrolyte interphase (SEI) formed on the Li-metal anode and sulfur cathode in conventional liquid-electrolyte Li−S batteries and how the resulting chemical and physical properties of the SEI affect the overall battery performance. A few strategies recently proposed for improving the stability of SEI are briefly summarized. Solid Li+-ion conductive electrolytes have been attempted for the development of Li−S batteries to eliminate the polysulfide shuttle issues. One approach is based on a concept of “all-solid-state Li−S battery,” in which all the cell components are in the solid state. Another approach is based on a “hybrid-electrolyte Li−S battery” concept, in which the solid electrolyte plays roles both as a Li+-ion conductor for the electrochemical reaction and as a separator to prevent polysulfide shuttle. However, these endeavors with the solid electrolyte are not able to provide an overall satisfactory cell performance. In addition to the low ionic conductivity of solid-state electrolytes, a critical issue lies in the poor interfacial properties between the electrode and the solid electrolyte. This Account provides a survey of the relevant research progress in understanding and manipulating the interfaces of electrode and solid electrolytes in both the “all-solid-state Li−S batteries” and the “hybrid-electrolyte Li−S batteries”. A recently proposed “semi-solid-state Li−S battery” concept is also briefly discussed. Finally, future research and development directions in all the above areas are suggested. commercially available battery technologies, lithium-ion (Li+ion) batteries deliver the highest energy density and are being considered for both grid storage and electric vehicles.4−6 However, due to the limited capacity and high cost of the transition-metal oxide cathodes currently used, it is challenging for the traditional Li+-ion batteries to meet the growing needs of large-scale electrical energy storage. In this regard, lithium−

1. INTRODUCTION As the environmental concerns and the consumption of fossil fuels increase steadily, energy generated from renewable sources, such as wind and solar, are becoming increasingly desirable. However, they are intermittently harvested and need proper storage for efficient utilization. Furthermore, the environmental impact of the gasoline-based vehicles has led to an urgent need to electrify the transportation sector. Rechargeable battery technologies offer a promising solution for renewable energy storage and vehicles.1−3 Among the © 2017 American Chemical Society

Received: September 18, 2017 Published: November 7, 2017 2653

DOI: 10.1021/acs.accounts.7b00460 Acc. Chem. Res. 2017, 50, 2653−2660

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presented. The major topics discussed in this Account are outlined in Figure 1.

sulfur (Li−S) batteries are being considered as one of the most promising systems as sulfur offers a high theoretical capacity of 1675 A h kg−1.7−10 Therefore, during the past decade, the Li−S batteries have drawn overwhelming attention on the lists of candidates for next-generation energy storage technologies.11−14 Although the advantages of Li−S chemistry have depicted a beautiful blueprint, practical drawbacks of the Li−S technologies are hampering their implementation. The first disadvantage is the electronically and ionically insulating nature of elemental sulfur, which necessitates a large fraction of conducting additives in the cathode and thereby reduces significantly the practical capacity. The second drawback is the soluble nature of the long-chain polysulfides produced at the cathode during battery operation. The polysulfide species migrate from the sulfur cathode to the Li anode and induce side reactions. Such a polysulfide-shuttle phenomenon lowers the Coulombic efficiency and causes a continuous loss of the active cathode material.15−18 Currently, the mainstream Li−S battery research is focused on addressing the nonconductive nature of sulfur and the shuttling of high-order polysulfides. However, there is a significant but relatively less emphasized challenge with the interfacial behavior between the electrodes (both anode and cathode) and the electrolyte in Li−S batteries.19,20 The Limetal anode itself is actually not stable in organic electrolytes.21,22 Under electrochemical cycling conditions, it naturally forms a solid−electrolyte interphase (SEI) on the anode, like that commonly occurring on graphite in traditional Li+-ion batteries.23,24 Furthermore, there is an additional parasitic reaction between the Li anode and the diffused or migrated polysulfides.25,26 Due to these unique challenges, the knowledge of interfacial phenomena from traditional Li+-ion batteries cannot be directly adopted to the development of Li−S batteries. With progress in the development of Li+-ion conductive inorganic solid electrolytes and advances in all-solid-state Li+ion batteries, ceramic-based solid-state electrolytes have been integrated into Li−S systems to address the polysulfide-shuttle problem.27−30 One approach is based on an “all-solid-state Li− S battery” concept that the battery is fabricated with all solidphase components.31−34 Another approach is based on a “hybrid-electrolyte” concept, in which both a solid electrolyte and a liquid electrolyte are employed in the cell.35−38 The solid electrolyte plays both as a Li+-ion conductor for the electrochemical reaction and as a shield or separator to prevent the polysulfide shuttle. However, challenges with the solidelectrolyte Li−S batteries are even more severe than those with the liquid-electrolyte systems. A critical issue is how to manipulate the electrode−electrolyte interfaces. This Account first summarizes the key findings of the SEI formed on the Li-metal anode in liquid-electrolyte Li−S batteries. The interfacial layer developed on the sulfur cathode is briefly examined. The impacts from the LiNO3 additive in the electrolyte and the side reactions induced by the polysulfide shuttling is discussed. Second, the challenges at the solid/solid interface between the ceramic solid electrolyte and the electrodes in all-solid-state Li−S batteries are discussed. Afterward, approaches to enhance the ionic interface between the electrode and solid electrolyte in hybrid-electrolyte Li−S batteries are presented. Finally, the challenges and prospects for the electrode−electrolyte interfaces in Li−S batteries are

Figure 1. Major topics regarding the electrode−electrolyte interfaces in various types of lithium−sulfur (Li−S) batteries: (a) conventional Li−S batteries with nonaqueous liquid electrolytes, (b) all-solid-state Li−S batteries with ceramic solid electrolytes, and (c) hybridelectrolyte Li−S batteries.

2. ELECTRODE−ELECTROLYTE INTERFACES IN Li−S BATTERIES BASED ON LIQUID ELECTROLYTES The interfacial behavior of anode plays a key role in any type of battery based on Li anode. Improvement in interfacial properties plays a critical role for the enhancement of overall electrochemical performances of Li−S batteries in terms of cycle life, Coulombic efficiency, and voltage efficiency. The properties of the anode−electrolyte interface are usually controlled by the SEI film formed on Li metal.39,40 The SEI originates from the reaction between Li metal and the electrolyte components, organic solvents, and Li salt.41,42 Liquid electrolytes in Li−S batteries are usually based on ether solvents. The most common electrolyte is based on a binary solvent system comprising a linear ether, dimethyl ether (DME), and a cyclic ether, 1,3-dioxolane (DOL). It is generally believed that the linear DME can offer high polysulfide solubility and fast polysulfide reaction kinetics, but it is relatively more reactive with Li metal, whereas the cyclic DOL can help to form a more stable SEI on the surface of Limetal anode.43,44 LiNO3 has been widely recognized as an effective additive in the electrolyte to enhance the cycling performances of Li−S batteries. Although the details of the LiNO3 effect are still not fully clear, it is generally realized that it has a positive impact on the properties of the SEI formed on Li anode.45,46 In addition, because of the impact from the soluble polysulfides migrated from the cathode, properties of the SEI on the Li anode in Li−S batteries are more complicated than that in traditional Li+-ion batteries. The surface chemistry of Li-anode in Li−S batteries was first rigorously studied by Aurbach et al.43 Effects from the 2654

DOI: 10.1021/acs.accounts.7b00460 Acc. Chem. Res. 2017, 50, 2653−2660

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Figure 2. A schematic illustration of the contribution of the different electrolyte components to the surface chemistry of Li-metal anodes. Reproduced with permission from ref 43. Copyright 2009 The Electrochemical Society.

Figure 3. Schematic presentation of the SEI behavior on Li-metal anode cycling in different electrolytes. Reproduced with permission from ref 50. Copyright 2014 Elsevier Publisher.

formed on the Li-metal anode. The SEI film is composed of lithium sulfate, sulfite, and sulfide, as well as LiF, and suppresses parasitic reactions between the electrolyte and Li metal.56 From an additive point of view, we found that addition of a copper acetate to the electrolyte could have a significant effect to stabilize the SEI.57,58 The Li anode can be protected by an in situ formed passivation film consisting of a complex product of Li2S/Li2S2/CuS/Cu2S.57,58 In addition to the electrolyte approaches, controlling SEI through an architecture design of anode has been proposed. Cheng et al. reported a dual-phase Li-anode comprising a graphene nanoframework and a polysulfide induced SEI, which improved the Coulombic efficiency.59 In comparison to the Li-anode, the relevant SEI studies at the sulfur cathode have relatively been less emphasized. Markevich et al. proposed a “quasi-solid-state” mechanism of Li−S batteries in the case of formation of a controlled SEI-type surface film on composite S−C electrodes, as schematically demonstrated in Figure 4; for a comparison, a common charge−discharge reaction mechanism of Li−S batteries is also provided here.60 This mechanistic study and the proposed mechanism provide new insights for advancing the electrolyte systems for Li−S batteries.

electrolyte components, ether solvents, lithium salt, polysulfides, and LiNO3 additive on the formation and properties of the SEI film were proposed, as schematically illustrated in Figure 2. Through a strong oxidation by LiNO3, a SEI film comprising both organic species (ROLi and ROCOOLi) and inorganic species (LiNxOy) can be constructed on Li surface. Since then, there has been much progress in investigating the role of LiNO3 additive. An interaction between LiNO3 and polysulfide species can lead to the formation of a compact SEI film,47−51 as representatively schematized in Figure 3. To improve the properties of the SEI film on the Li-anode surface, various electrolyte approaches have been investigated. Representative examples are given here. Wu et al. proposed an ionic liquid with a binary Li salts for Li−S batteries. The Li anode was effectively protected due to the SEI-forming ability of lithium difluoro(oxalate)borate (LiODFB).52 Barghamadi et al. studied the effect of pyrrolidinium ionic liquid and LiNO3 additive on the SEI in Li−S batteries and confirmed the participation of C4mpyr-TFSI on Li-metal.53 Recently, a class of “solvent-in-salt” electrolyte has been proposed. The ultrahigh concentration of Li salt can help to form a stable SEI film to protect the Li-metal electrode.54,55 Our group recently investigated a fluorinated ether electrolyte to stabilize the SEI 2655

DOI: 10.1021/acs.accounts.7b00460 Acc. Chem. Res. 2017, 50, 2653−2660

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stress/strain at the electrode−electrolyte interface and thus increases the interfacial resistance.69,70 Therefore, a key challenge of developing all-solid-state Li−S batteries is how to minimize the stress/strain at the electrode−electrolyte interface by establishing a facile ionic pathway.71−73 To enhance the ionic conductivity at the interface between the sulfur cathode and the solid electrolyte, Lin et al. developed a core−shell structured Li2S cathode with a Li3PS4 solid electrolyte as the electrode shell (Figure 5a).30 The resulting material behaves as a lithium superionic sulfide cathode, which exhibits an ionic conductivity of about 6 orders of magnitude higher than that of bulk Li2S-particle electrode.30 Another approach developed by Lin et al. through the incorporation of sulfur atoms into the Li3PS4 solid electrolyte (as schematized in Figure 5b) also demonstrates an interesting strategy toward addressing the interfacial problems in all-solid-state Li−S batteries. These synthesized Li3PS4+5 compounds show a Li+ion conductivity of 10−6 to 10−5 S cm−1, which is almost comparable to that of insertion-type positive electrode materials of conventional Li+-ion batteries.33 From the cathode material point of view, Eom et al. demonstrated a Li2S−VGCF (Vapor Grown Carbon Fiber) nanocomposite in an all-solid-state Li−S battery. The interfacial properties between the Li2S active material, conductive matrix, and solid electrolyte are enhanced by optimization of the composition of the Li2S−VGCF

Figure 4. Schematic presentation of (a) normally observed liquid− solid reaction and (b) quasi-solid-state reaction due to the formation of an SEI at the sulfur−carbon cathode. Reproduced with permission from ref 60. Copyright 2015 The Royal Chemical Society.

3. ELECTRODE−ELECTROLYTE INTERFACES IN ALL-SOLID-STATE Li−S BATTERIES To completely eliminate the shuttle effect of polysulfides and to circumvent the concerns of Li-metal dendrite, all-solid-state Li−S batteries have drawn considerable attention.61−68 However, the use of ceramic solid electrolytes increases the

Figure 5. (a) Synthesis and electrochemical performance of a core−shell structured Li2S electrode with a Li3PS4 solid electrolyte as the electrode shell. Reproduced with permission from ref 30. Copyright 2013 American Chemical Society. (b) Schematic illustration of the chemical reactions of Li-polysulfidophosphates (LPSPs). (top) Reaction of Li3PS4 with sulfur yields Li3PS4+n. (bottom) Electrochemical discharge and charge reactions of the Li3PS4+n. Reproduced with permission from ref 33. Copyright 2013 John Wiley and Sons. (c) Schematic diagram of an all-solid-state lithium− sulfur battery. Reproduced with permission from ref 76. Copyright 2017 John Wiley and Sons. (d) Schematic diagram of a single-Li10GeP2S12 allsolid-state lithium-ion battery. Reproduced with permission from ref 77. Copyright 2015 John Wiley and Sons. 2656

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Figure 6. (a) Schematic of a Li−S battery composed of Li-metal/organic electrolyte/ceramic separator/organic electrolyte/Li2S cathode. Reproduced with permission from ref 35. Copyright 2015 The Royal Society of Chemistry. (b) Schematic of a hybrid Li∥LYZP∥Li2S6 cell with a Limetal anode, liquid/LYZP hybrid electrolyte, and dissolved lithium-polysulfide cathode. Reproduced with permission from ref 38. Copyright 2016 John Wiley and Sons.

nanocomposite and the crystallization of Li2S.74 Chen et al. have reported a sulfur−super P−Li6PS5Br composite cathode fabricated by a two-step ball milling process, which ensures yielding of a uniform composite with superfine particles. The resulting composite cathode exhibits a structure that is essential for maximizing the reactive area at the solid-electrolyte/ electrode interface.67 A “bulk type” all-solid-state Li−S battery has been reported by employing a LiBH4 solid electrolyte. In this study, a compact interface between the S/C cathode material and the LiBH4 material was manifested by a cold pressing process.75 The above studies indicate that a sufficient contact of the active sulfur to the solid electrolyte is necessary to ensure good electrochemical performance with all-solid-state Li−S batteries. Additionally, uniformly dispersing the active sulfur into a mixed (both ionically and electronically) conductive cathode matrix helps to reduce the stress and strain at the electrolyte−electrode interface. Based on the above, Yao et al. developed a rGO@S/Li10GeP2S12 composite cathode by coating a nanolayer of active sulfur on a reduced graphene (rGO) matrix to render an rGO@S composite and further uniformly dispersing the rGO@S into a Li+-ion superionic conductive Li10GeP2S12 material (as schematized in Figure 5c). Due to the small size and uniform dispersion of the active sulfur nanolayer, the volume change of sulfur during charge− discharge is consequently small and uniform. Therefore, the stress/strain induced by the volume change of sulfur is effectively controlled.76 Another interesting strategy in reducing the interfacial resistance in all-solid-state Li−S batteries has been reported based on a “single battery material” concept.77 The battery was fabricated with only one single-layer homogeneous Li10GeP2S12 material, which exhibits mixed electric/ionic conductivity after mixing with electronically conductive carbon. The Li10GeP2S12 material plays multiple roles as both a Li+-ion conductive electrolyte and active electrode material. The Ge−S components in Li10GeP2S12 act as a cathode, whereas the Li−S components serve as an anode (as schematized in Figure 5d). In other words, the working principle of this cell is likely using a GeS2 cathode and a Li2S anode. The resulting single-layer cell showed low interfacial impedance due to the modified interfacial interactions, improved interfacial contact, and released stress/strain at the interface.

4. ELECTRODE−ELECTROLYTE INTERFACES IN Li−S BATTERIES BASED ON HYBRID ELECTROLYTES The all-solid-state approach has created promise for Li−S batteries. However, from the cycling results reported in previous studies, the all-solid-state Li−S batteries under development were not able to provide decent electrochemical performances in terms of sulfur utilization, rate capability, and overall cyclability. Furthermore, sometimes the batteries must be operated at elevated temperatures due to the low ionic conductivity of the solid-state electrolyte at ambient temperature. Other major problems are the poor kinetics of the ionic transport in the sulfur cathode and at the electrode−electrolyte interface (as discussed in the last section). On the other hand, in conventional Li−S batteries, the solubility of polysulfide species in nonaqueous electrolytes is a “double-edged sword”. Apart from the commonly recognized polysulfide-shuttling negative effect, the dissolution of polysulfides from the bulk sulfur brings a positive effect, enhancing the electrochemical utilization of the electronically insulating sulfur cathode. In a regular sulfur cathode, without a continuous polysulfidedissolution process, the electrochemical reduction of sulfur would only occur on the surface of a sulfur particle and the bulk sulfur cannot be efficiently utilized. To combine the advantages from the liquid electrolyte and solid electrolyte, a particularly interesting strategy with a “hybrid electrolyte” approach has been proposed, as schematically demonstrated in Figure 6a.35−38,78 The solid electrolytes that have been employed for these studies include Li 1+x Al x Ge 2−x (PO 4 ) 3 (LAGP), Li 1+x Al x Ti 2−x (PO 4 ) 3 (LATP), and Li 1+x Y x Zr 2−x (PO 4 ) 3 (LYZP).35−38,78 In a hybrid-electrolyte Li−S battery, the solid electrolyte plays multiple roles. First it serves as a separator to insulate the sulfur cathode and the Li-metal anode. Second, the Li+-ion conductive solid electrolyte provides an ionic path to sustain the electrochemical reactions at the cathode and anode. Third, it acts as a shield to prevent the polysulfide shuttling. The liquid electrolyte in the sulfur cathode not only provides an ionic medium for the redox reactions of sulfur but also helps to maintain a facile ionic path at the interface of sulfur electrode and solid electrolyte. At the anode side, to address the technical challenge of constructing a favorable Li+-ion transporting path at the solid−solid interface between the solid electrolyte and the Li-metal, quite a few approaches have been attempted. The most successful approach is applying a liquid-electrolyte-soaked polymer interlayer between the Li anode and the solid 2657

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Li-metal anode dynamically impact the interfacial properties in all-solid-state Li−S batteries. The interfacial problems between the Li anode and the solid electrolyte can be mitigated in parallel to the conventional all-solid-state Li+-ion batteries (with conventional insertion-type cathodes). At the cathode side, the key points are to minimize the particle size of sulfur, to uniformly disperse sulfur into a conductive matrix, and to ensure a sufficient contact between sulfur and the solid electrolyte. Based on these, there has been continuous progress recently in the cathode design toward reducing interfacial impedance in all-solid-state Li−S batteries. However, there is still a lack of exhilarating developments so far. Future research efforts to overcome the interfacial challenges in all-solid-state Li−S batteries are suggested as follows: (1) fundamentally understanding the interfacial behavior of cathode/solid-electrolyte with both experimental and theoretical calculation approaches; (2) development of proper material synthesis and process techniques that are able to critically tailor the interfacial structure of sulfur, conductive matrix, and solid electrolyte; (3) integration of the elastic additives into the cathode to minimize the strain/stress effects due to the volume expansion and shrink of sulfur cathodes during cell operation. The “hybrid-electrolyte Li−S battery” and the “semi-solidstate Li−S battery” represent two interesting approaches for the development of Li−S batteries. These novel strategies combine the advantages from the liquid electrolytes and solid electrolytes. The liquid electrolyte in the cathode ensures utilization of sulfur, and the solid electrolyte prevents polysulfide shuttling. However, interfacial problems in these battery systems still exist. Tackling the interfacial challenges can be drawn from the experience in both conventional liquid-electrolyte Li−S batteries and all-solid-state Li−S batteries.

electrolyte as schematically illustrated in Figure 6b. Other approaches, such as physically attaching Li metal to the solid electrolyte by a mechanical pressing or applying a liquid-phase buffer to the interface, do not provide a significant positive effect for the enhancement of the ionic properties at the solidelectrolyte/anode interface. Recently, a “semi-solid-state Li−S battery” has been operated with a solid electrolyte separator.79,80 A semisolid cathode exhibiting electrochemical activity is distributed throughout the volume of the electrode rather than being confined to a surface of stationary current collector. Gu et al. demonstrated a semisolid-state Li−S battery study with a FDE−LAGP (FDE: 1,3-(1,1,2,2-tetra- uoroethoxy)propane) hybrid electrolyte, in which the interfacial resistance between LAGP solid electrolyte and electrodes is reduced by the liquid-phase FDE.79 In this cell configuration, the interfacial problems between the solid electrolyte and the semisolid electrode can be minimized.79,80

5. CONCLUSIONS AND OUTLOOK This Account provides a brief survey of the research and development with respect to electrode−electrolyte interfaces (EEI) in lithium−sulfur (Li−S) batteries, including the conventional liquid-electrolyte Li−S batteries, all-solid-state Li−S batteries, and hybrid-electrolyte Li−S batteries. For the conventional liquid-electrolyte Li−S batteries, we summarized the key findings in understanding the SEI formed on the Li-anode and how the resulting chemical and physical properties of the SEI affect the overall Li−S battery performance. Apart from the effects from the basic electrolyte components, ether solvent, and lithium salt, the formation and properties of the SEI film on the Li-anode are particularly influenced by a commonly used LiNO3 additive in the electrolyte and polysulfide species migrating from the cathode. It is generally considered that the LiNO3 additive brings a positive impact to the properties of the SEI, although the relevant mechanistic details are not yet well understood. The involvement of polysulfide species magnifies the complexity of the formation and properties of the SEI film. According to the unique discharge/charge characteristics of the Li−S batteries, a few electrolyte approaches have been investigated to improve the properties of the SEI film on the Li-anode surface. However, there is no significant breakthrough. At the cathode side, the relevant SEI studies on the sulfur cathode have relatively been less emphasized. Although interfacial theories have relatively been well developed for the traditional Li+-ion batteries, we are not able to simply adopt that knowledge from the traditional Li+-ion batteries into Li−S batteries due to the unique operating features of the Li−S batteries. Currently, there is a severe lack of fundamental and practical knowledge for modulating the interfacial layers in Li−S batteries. Future efforts in the following aspects are suggested: (1) in-depth understanding of the composition, structure, formation mechanism, and property of SEI films, including those formed on both the Limetal anode and the sulfur cathode; (2) understanding the functionalities of SEI; (3) investigation of the dynamic features of the SEI including the formation kinetics of SEI and Li+-ion transport process in the SEI layer; and (4) development of controllable methods for modulating the SEI layers. For the all-solid-state Li−S batteries, the most important issue is how to build a favorable ionic interface between the electrodes and the solid electrolyte. Furthermore, the volume change in the sulfur cathode and the dendrite formation on the

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AUTHOR INFORMATION

Corresponding Author

* Email: [email protected]. ORCID

Arumugam Manthiram: 0000-0003-0237-9563 Funding

This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award Number DE-SC0005397. Notes

The authors declare no competing financial interest. Biographies Xingwen Yu is a research associate at the Texas Materials Institute at the University of Texas at Austin. He has 12 years of R&D experience in the battery and fuel cell technologies. He is currently working on multiple research programs in the field of electrochemical energy storage and conversion. Arumugam Manthiram is a Professor and holder of the Cockrell Family Regents Chair in Engineering in the Materials Science and Engineering Program and Department of Mechanical Engineering at the University of Texas at Austin. He is also the Director of the Texas Materials Institute and the Materials Science and Engineering Program. His research interests are in the area of rechargeable batteries, fuel cells, and solar cells, including novel synthesis approaches for nanomaterials and nanocomposites. 2658

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