Degradation of All-Solid-State Lithium-Sulfur Batteries with PEO-Based Composite Electrolyte

Lithium sulfur (Li-S) battery has been considered as one of the most promising next generation energy storage devices, especially for the emerging electric vehicles.1 Unlike the state-of-art lithium ion (Li-ion) batteries, the Li-S battery is based on the conversion reaction between lithium and sulfur instead of lithium intercalation/deintercalation mechanism, which leads to an exceptionally high theoretical energy density of over 500 Wh/kg.1 Despite the high energy density, there are still many problems to tackle for the application of Li-S battery. One of the biggest problems is the polysulfide shuttling effect. Massive improvements have been achieved recently to resolve the shuttling effect. However, since most methods are employed in conventional Li-S batteries, where liquid electrolyte is used, there is always dissolution of Li2Sxin the battery, leading to the decay of performance upon long term operation. Solid state electrolyte has attracted massive research attention recently due to their ability to block lithium dendrite growth and sustain safe operation. Garnet type LLCZN electrolyte has shown excellent performance due to its high ionic conductivity and stability.2-3 The nature of ceramic electrolyte can prevent the lithium polysulfide from reaching anode side, thus eliminating the polysulfude shuttling. Therefore, a solid state Li-S battery based on garnet electrolyte which can completely resolve the polysulfide shuttling problem can be a crucial step towards the actual application of Li-S battery. In this study, we introduce a solid-state Li-S battery based on a triple layer garnet type ceramic electrolyte, where a thin dense layer of garnet was sandwiched by two porous layer. Lithium and sulfur are molten infiltrated into the different porous sides of the garnet electrolyte and are separated by the dense layer of garnet. Therefore, it is impossible for Li2Sxto migrate to from the cathode to the sulfide, thus completely eliminating the shuttling effect. The proposed quasi solid state Li-S battery promotes a new design for high energy Li-S batteries. The tri-layer garnet structure was prepared via a tape casting technique. The dense layer is 30 µm thick while both the porous layers are 70 µm thick with a porosity of ~67%. The sintered trilayer was characterized via SEM, XRD and XPS. The product shows characteristic cubic garnet phase which ensures high ionic conductivity. The lithium can be stripped from one side of the other, thus enabling the operation of solid-state Li-S battery. The solid-state Li-S battery based on tri-layer garnet show high capacity of 1200 mAh/gsulfur and stable coulombic efficiency of nearly 100% after 50 cycles. Moreover, even with the extra weight introduce by the ceramic garnet electrolyte, the Li-S cell still delivered an impressive energy density of 250 Wh/kgcell. Such a high energy density makes the tri-layer Li-S battery superior compared to state-of-art Li-ion batteries. Moreover, the utilization of the solid-state electrolyte also prevents the growth of lithium dendrite, enabling a much safer battery operation. As far as we know, this is the first time a high energy density Li-S battery with all solid-state anode framework is developed. The high energy density, all-in-one configuration, solid-state Li-S battery introduces a new route for future energy storage system. Refrence P. G. Bruce et al., Nature Materials, 2012, 11, 19–29V. Thangadurai et al., Chem. Soc. Rev., 2014, 43, 4714-4727F. Han et al., Adv. Energy Mater. 2016, 6, 1501590

Introduction Since the introduction of lithium-ion batteries in 1990, the steady growth in volume and performance of lithium-ion cell components and batteries has demonstrated their strong demand in the high-energy-density energy-storage market. The commercial lithium-ion cells adopt the stable intercalation reaction to enable the reversible insertion of lithium ions between layered oxide cathodes and graphite anodes, resulting in the high energy density (100–350 Wh kg–1) and long-term cycling capability (1,000 cycles) that outperform other rechargeable batteries. However, after three decades of research, the charge-storage capacities of the electrode active materials are approaching their theoretical values (200–300 mAh g–1), while the cost of the electrode continues to increase. This limits the improvement of the energy density of lithium-ion cells, which has reduced the annual growth rate from 7% to 2%, making it difficult to supply the energy-storage market of more than 1,500 GWh in 2030. In response to these challenges, next-generation batteries are being developed, focusing on electrochemical cells to achieve high reversible energy storage and competitive prices and solid-state electrolytes for enhanced stability and improved energy density. Both developments aim at achieving new energy density records (300–500 Wh kg–1 and 700–800 Wh L–1) that would enable electric vehicles to surpass conventional vehicles in range, while reducing cell costs. Results and Discussion In this presentation, we will present the designs of the next-generation rechargeable cells aimed at overcoming the bottleneck faced by current commercial lithium-ion cells. From the materials science point of view, the lithium–sulfur battery is the most promising candidate because of its high energy density, low cost, and low toxicity. On the other hand, from the materials engineering point of view, the solid-state electrolytes with high ionic conductivity are proposed to increase the energy density, cyclability, and safety of the batteries through configuration modification. To adopt the advantages of these two novel battery technologies, we report an integrated design of the lithium–sulfur electrochemical cell with the solid-state electrolyte as a lithium–sulfur solid-state electrolyte cell. The lithium–sulfur electrochemical cell employs a high-sulfur-loading polysulfide cathode to achieve high energy density and to form a smooth ion-transfer interface between the catholyte and the solid-state electrolyte. On the other hand, the solid-state electrolyte provides excellent stability and safety to the cells by stabilizing the polysulfide cathode and protecting the lithium anode. The resulting cell design demonstrates the new battery materials and configurations, which include the development of a high-performance polysulfide cathode, the design and synthesis of solid-state electrolytes (i.e., polymer, oxide, and sulfide-based electrolytes), and the cell integration and interface analytical method. Our battery technologies enable the design of lithium–sulfur solid-state electrolyte batteries to achieve high sulfur loadings (4–16 mg cm–2) and high sulfur contents (50–80 wt%), which are better than those of current lithium–sulfur batteries that aim to be 5–10 mg cm–2 and 70 wt%. With the high sulfur loading, the lithium–sulfur solid-state electrolyte batteries exhibit high areal capacity (5–7 mA·h cm–2) and energy density (11–15 mW·h cm–2). Both values are higher than those of commercial lithium-ion cells for electric vehicles. Moreover, the cell has a long cyclability (100–200 cycles) and high rate capability (C/20 to 1C rate). Conclusion In summary, we report in the presentation a summary of our lithium–sulfur solid-state electrolyte batteries with a high-loading polysulfide cathode. The solid-state electrolytes stabilize the polysulfide cathode and the electrochemical reaction of lithium–sulfur batteries, while the stabilized polysulfide cathode forming a stable ionic conductive interface between the cathode and the solid-state electrolytes. Our lithium–sulfur solid-state electrolyte cells demonstrate outstanding battery-design parameters, excellent cell-performance values, and advanced interface analytical method. Both are essential for the commercial development of advanced next-generation rechargeable batteries. References L.-L. Chiu, S.-H. Chung, J. Mater. Chem. A 2022, 10, 13719.Y.-J. Yen, S.-H. Chung, J. Mater. Chem. A 2023, 11, 4519.Y.-C. Huang, B.-X. Ye, S.-H. Chung, RSC Adv. 2024, 14, 4025.

Advanced lithium battery chemistries beyond lithium-ion have demonstrated high energy density (>300 Wh/kg) but need further work to improve and demonstrate cycle life, shelf life, rate capability, and safety matching or exceeding that of lithium-ion batteries. A lithium sulfur battery can theoretically reach energy densities of 2600 Wh/kg and has high potential to meet energy density needs for portable power including electric vehicles. Nevertheless, the Li-S system has not yet been implemented because of multiple obstacles: poor electrical conductivity of elemental sulfur, lack of a system that reduces the capacity robbing polysulfide shuttle (PS) effect, a suitable electrolyte that can suppress dendrite formation, and thicker cathode layers necessary to realize the energy density of a lithium sulfur couple. Past research to improve sulfur cathode conductivity and eliminate the PS effect has included infusing sulfur within electrically conductive carbon micro- and nano-scale particles. This approach addresses both the PS shuttle and sulfur’s poor electrical conductivity; however it presents a barrier for lithium ions, which slows reaction, reduces power, and limits cathode thickness1. Effective sulfur encapsulation require both electronic and ionic conduction to build thicker cathode structures that retain battery power, capacity, and cycle life. Typically liquid electrolytes facilitate high sulfur loadings and cathode capacity in a lithium sulfur battery however they also encourage the polysulfide shuttle through the porous polymer separator and don’t prevent dendrites. Excessive amounts of liquid electrolyte also reduces the practical energy density of a lithium sulfur cell. Solid-state electrolytes have the potential to play at least three significant roles in a lithium sulfur battery: (1) provide a barrier to stop PS shuttle effect, (2) prevent lithium dendrite formation, and (3) reduction of liquid electrolyte. This presentation will discuss the development of a lithium sulfur battery based on combining a solid state electrolyte, entrapped sulfur cathode, and a lithium metal anode necessary to meet needs for high energy density, rechargeable energy storage. New processing methods that improve performance of sulfur carbon composites for cathodes will be discussed. The feasibility of low cost practical carbon materials for sulfur carbon composite cathodes will also be discussed in relation to the new processing methods. Methods and results of using solid state electrolytes in lithium sulfur cell design will also be discussed related to their impact on liquid electrolyte reduction and cathode capacity improvement. Finally optimization targets for a metallic lithium anode, solid electrolyte, and sulfur cathode materials will be discussed in relation to goals for cell specific energy. 1) Manthiram, Arumugam, et al. "Rechargeable lithium-sulfur batteries." Chem. Rev 114.23 (2014): 11751-11787.

As a secondary Li-ion battery with high energy density, lithium-sulfur (Li-S) batteries possess high potential development prospects. One of the important ingredients to improve the safety and energy density in Li-S batteries is the solid-state electrolyte. However, the poor ionic conductivity largely limits its application for the commercial market. At present, the gel electrolyte prepared by combining the electrolyte or ionic liquid with the all-solid electrolyte is an effective method to solve the low ion conductivity of the solid electrolyte. We present a cross-linked gel polymer electrolyte with fluoroethylene carbonate (FEC) as a solid electrolyte interface (SEI) film formed for Li-S quasi-solid-state batteries, which can be simply synthesized without initiators. This gel polymer electrolyte with FEC as an additive (GPE@FEC) possesses high ionic conductivity (0.830 × 10-3 S/cm at 25 °C and 1.577 × 10-3 S/cm at 85 °C) and extremely high Li-ion transference number (tLi+ = 0.674). In addition, the strong ability toward anchoring polysulfides resulting in the high electrochemical performance of Li-S batteries was confirmed in GPE@FEC by the diffusion experiment, X-ray photoelectron spectroscopy analysis (XPS), and scanning electron microscopy (SEM) mapping of the S element. Such a high ion conductivity (IC) gel polymer electrolyte enables a competitive specific capacity of 940 mAh/g at 0.2C and supreme cycling performance for 180 cycles at 0.5C, which is far beyond that of conventional poly(ethylene oxide)-based quasi-solid-state Li-S batteries.

Preparation and performances of the modified gel composite electrolyte for application of quasi-solid-state lithium sulfur battery

The inter- and intra-atomic interactions of molecular species in complex electrolyte solutions affect the solvation structure and dynamical in bulk solution and at electrode/electrolyte interface. A fundamental understanding of such intricate structure-property relationships in complex solutions will allow designing optimal materials for next generation energy storage devices. A major breakthrough in battery materials is required to meet the ever-increasing proliferation of portable electronic devices, electric vehicles and their variants, as well as the need for incorporating renewable energy resources into the main energy supply [1]. In this context, lithium-sulfur (Li-S) batteries attract attention owing to their very high energy density (2,600 Wh kg-1) and specific capacity (1,675 mAh g-1) and significantly lower weight and cost, compared to lithium-ion batteries (LIBs) [2]. Fully packaged, it is expected that future Li-S batteries can operate at close to 500 Wh kg-1, which is more than twice the energy density of LIBs (200 Wh kg-1) [3]. The problem of realizing the expected high energy density is defined by several issues including the dissolution of Li-Polysulfide (PS) species into the electrolyte, insulating properties of sulfur and Li-PS species, and volume change at the cathode [4]. Overcoming these challenges requires a fundamental understanding of the interplay between events scaling over wide spatial and temporal scales, and accurate prediction of electrode and electrolyte properties to obtain design metrics for new improved materials. In this talk, I will present how we are utilizing a multi-scale-data-driven approach to gain mechanistic insight into Li-S battery by combining density functional theory (DFT) with molecular dynamics (MD) simulations. I will describe our group’s newly developed computational workflow and analysis codes for generating data with high-throughput DFT and MD simulations within the framework of the Materials Project infrastructure [5]. I will discuss usage of these tools to mitigate dissolution of LiPS species by altering the atomistic interactions between electrode and electrolyte components through functionalizing the cathode material. This approach guides and accelerates our rational selection of functional groups that exhibit strong affinity with both the cathode material and LiPS moieties from a bigger set of available candidates through fully automated DFT calculations. We use the selected candidates in detailed MD studies to understand the effect of various electrolyte variables (components, PS chain length, salt concentration) on structural and dynamical properties at the functionalized interface [6, 7]. The approach allows for creating a database of well-characterized materials to be used in machine learning-based methods as well as for testing computationally identified structures in experiments. This work provides crucial information to alleviate the dissolution of PS species during cycling, which is the main reason for rapid capacity decay in Li-S batteries.References Larcher, D. and J.-M. Tarascon, Towards greener and more sustainable batteries for electrical energy storage. Nature chemistry, 2015. 7(1): p. 19.Manthiram, A., X. Yu, and S. Wang, Lithium battery chemistries enabled by solid-state electrolytes. Nature Reviews Materials, 2017. 2(4): p. 1-16.Fang, R., et al., More reliable lithium‐sulfur batteries: status, solutions and prospects. Advanced materials, 2017. 29(48): p. 1606823.Manthiram, A., Y. Fu, and Y.-S. Su, Challenges and prospects of lithium–sulfur batteries. Accounts of chemical research, 2013. 46(5): p. 1125-1134.Jain, A., et al., Commentary: The Materials Project: A materials genome approach to accelerating materials innovation. Apl Materials, 2013. 1(1): p. 011002.Rajput, N.N., et al., Elucidating the solvation structure and dynamics of lithium polysulfides resulting from competitive salt and solvent interactions. Chemistry of Materials, 2017. 29(8): p. 3375-3379.Andersen, A., et al., Structure and dynamics of polysulfide clusters in a nonaqueous solvent mixture of 1, 3-dioxolane and 1, 2-dimethoxyethane. Chemistry of Materials, 2019. 31(7): p. 2308-2319.

Lithium-Sulfur (Li-S) batteries stand out to be one of the most promising candidates to meet the current energy storage requirement, with its natural abundance of materials, high theoretical capacity of 1672 mAhg-1, high energy density of 2600 Whkg-1, and low cost and lower environmental impact. Sulfur itself (S8), Li2S2 and Li2S formed during the discharge process, are electrical insulators and hence reduce the active material utilization and the electronic conductivity of the cathode affecting the battery performance. Combining of Carbon Super P (SP) with sulfur in cathode formulation is used to overcome these issues. In Liquid electrolyte batteries, polysulfides formed while charging and discharging, easily dissolve in liquid electrolyte and the resulting polysulfide shuttling leads to poor coulombic efficiency and cyclability. Liquid electrolytes used in the conventional Li-S batteries are easy to flow and become flammable. Further, Lithium dendrites piercing through separator causing short circuit paths leads to safety concerns. Replacement of the liquid electrolyte by a solid-state electrolyte (SSE) proves to be a strategy to overcome above mentioned issues. Sulfide based solid electrolytes have received greater attention due to their higher ionic conductivity, compatible interface with sulfur-based cathodes, and lower grain boundary resistance. Novel Li6PS5F0.5Cl0.5 due to its remarkable ionic conductivity of 3.5 x 10-4 S cm-1 makes it an excellent candidate for use in a Li-S solid state battery. However, the interface between SSEs and cathodes has become a challenge to be addressed in all solid-state Li-S batteries due to the rigidity of the participating surfaces. A hybrid electrolyte containing of SSE coupled with a small amount of ionic liquid at the interface, has been employed to improve the interface contact of the SSE with the electrodes.Cathode formulation consisting of sulfur as the active material, Super P as the conductive carbon black, acetylene carbon black as conductive carbon additive, with water based carboxymethyl cellulose (CMC) solution and Styrene butadiene rubber (SBR) as the binder was successfully developed. Thermo gravimetric analysis (TGA) studies of the cathode were carried out by the thermo gravimetric analyzer TA 2050 under N2 gas flow of 100 ml/min. Cathode surface morphology was characterized using the Field emission gun scanning electron microscope (FEI), TESCAN scanning electron microscope with energy dispersive X-ray spectroscopy (EDAX). Using a solvent-based process, Li6PS5F0.5Cl0.5 and Li6PS5F0.5Cl2 SSE were synthesized via the introduction of LiF into the argyrodite crystal structure, which enhances both the ionic conductivity and interface-stabilizing properties of the SSE. Relevant Ionic Liquids (IL) were prepared using Lithium bis(trifluoromethyl sulfonyl)imide (LiTFSI) as salt, with premixed pyrrolidinium bis(trifluoromethyl sulfonyl)imide (PYR) as solvent and 1,3-dioxolane (DOL) as diluent.SP-S cathode with 0.70 mgcm-2 sulfur loading was punched into disks of 2.0 cm2. SSE was pressed into 150 mg pellets using a stainless-steel tank. During the assembly, SSE was wetted with total of 40 μl of IL (LiTFSI dissolved in PYR and DOL solution) from both ends using a micropipette. 2032 type coin cells of Quasi-solid-state Li-S batteries (QSSLSB) consisting of SP-S based composite cathodes, Li anodes and novel Li6PS5F0.5Cl0.5 SSE were tested with an ionic liquid wetting both electrode-SSE interfaces. All the QSSLSB were cycled at 30 °C between 1.0 V and 2.8 V using an 8 channel Arbin battery testing system.Effect of IL dilution, co-solvent amount, LiTFSI concentration and C rate at which the batteries are tested, were systematically studied and optimized to develop a QSSLSB with higher capacity retention and cyclability. Optimum batteries had initial discharge capacity >1100 mAh/g and discharge capacity >400 mAh/g after 100 cycles at the C rate of C/10 with a significant coulombic efficiency. 40 μl of LiTFSI (2M) dissolved in PYR:DOL(1:1) IL was found to be optimum for high performance QSSEBs with low sulfur loading of 0.7 mg/cm2. From the C rate performance study QSSEBs have shown improved stability with the higher current rates. Next, cathodes with higher sulfur loading were studied and for sulfur loading > 4 mgcm-2, initial discharge capacity >950 mAh/g and 400 mAh/g after 60 cycles at C/20 rate were achieved with 40 μl of IL consisting of LiTFSI (3M) dissolved in PYR:DOL(1:3) for the SSE Li6PS5F0.5Cl2. Further testing is underway to improve the performance at high C rate for higher loading by incorporating SSE in the cathode to realize QSSLSB with higher capacity with improved cycle retention.

Lithium sulfur (Li-S) batteries have emerged as one of the most promising post LIBs technologies with a remarkably high theoretical energy density and abundance of elemental sulfur. Nonetheless, there are several problems associated with Li-S batteries such as safety hazard due to lithium dendrite formation and fast capacity decay due to polysulfide dissolution effect.1 Employment of solid-state electrolytes is a promising strategy to address those issues. Among different solid-state Li-ion electrolytes, Li-garnet attracts a lot of attention as it has a wide electrochemical window (> 6 V vs. Li/Li+), and high ionic conductivity (~ 1 mS cm-1) at room temperature. However, the application of garnet is hampered by its interfacial resistance against electrodes.2 In order to the reduce the interfacial area specific resistance (ASR) of Li/garnet interface, we devised a surfactant-processed interlayer for ceramic electrolytes (SPICE) method which can uniformly deposit a layer of ZnO onto the garnet surface. This process improves the wetting of Li and reduces the interfacial ASR to 10 Ω cm2 at room temperature.3 Stable Galvanostatic cycling of Li/garnet/Li at current densities up to 0.5 mA cm−2 was conducted, which presents a compelling method to solve the Li/solid electrolyte interface problem. Another strategy we applied is incorporating garnet into polymer matrix to fabricate a flexible hybrid electrolyte. Polymer-based electrolytes possess low interfacial resistance due to its intimate contact with electrodes.4 The hybrid electrolyte merging the merits of garnet and polymer has been successfully employed in all-solid-state Li-S batteries operating at room temperature. Toward improving the energy density of the battery, we are working on tuning the cathode structure to effectively load more sulfur active materials. In this presentation, the SPICE method to tailor the interfacial resistance and the performance of all-solid-state Li-S batteries based on hybrid electrolyte will be discussed. Manthiram, A.; Fu, Y.; Chung, S.; Zu, C.; Su, Y. Chem. Rev. 2014, 114, 11751-11787.Han, X.; Gong, Y.; Fu, K.; He, X.; Hitz, G.; Dai, J.; Pearse, A.; Liu, B.; Wang, H.; Rubloff, G.; Mo, Y.; Thangadurai, V.; Wachsman, E.; Hu, L. Nat. Mater. 2016, 16, 572-579.Zhou, C.; Samson, A.; Hofstetter, K.; Thangadurai, V. Sustainable Energy & Fuels 2018, 2, 2165-2170.Zhou, C.; Bag, S.; Thangadurai, V. ACS Energy Lett. 2018, 3, 2181-2198.

The emerging lithium-sulfur (Li-S) batteries are gaining much attention as a promising next-generation energy storage technology.1 An analogous battery system with a sodium-sulfur chemistry has recently started to receive considerable attention as well.2 The electrochemical mechanism of the Li-S and Na-S batteries is quite similar and the charge-discharge processes of these two batteries involve the formation of soluble polysulfide intermediate species. Therefore, the development of both of these two battery systems is facing a critical obstacle due to the so-called “polysulfide-shuttle” behavior during cell operation.3, 4 Although a lot of efforts have been attempted to address such a challenge since it has been recognized many years ago, there is still a lack of reliable approaches that can fully prevent the polysulfide-shuttle without bringing any other negative effects to the Li-S or Na-S cell systems. Herein we present an alternative strategy to suppress the polysulfide-shuttle in Li-S and Na-S batteries with, respectively, a Li+-ion conductive and a Na+-ion conductive solid-state electrolytes.5, 6 However, the use of a solid electrolyte usually brings an additional challenge in maintaining an adequate ionic interface between the lithium or sodium anodes and the solid electrolytes. Therefore, a strategic approach by coating the solid-state electrolytes with a thin layer of a polymer has been developed. The polymer coating on the ceramic solid-state electrolyte offers a facile interface with the metal electrodes. Both the Li-S batteries and the Na-S batteries with the polymer-coated solid-electrolyte membrane show enhanced cycling stability. References X. W. Yu and A. Manthiram, Accounts Chem Res, 2017, 50, 2653-2660.A. Manthiram and X. W. Yu, Small, 2015, 11, 2108-2114.Y. X. Wang, B. W. Zhang, W. H. Lai, Y. F. Xu, S. L. Chou, H. K. Liu and S. X. Dou, Adv Energy Mater, 2017, 7, 1602829.A. Manthiram, X. W. Yu and S. Wang, Nat Rev Mater, 2017, 2, 16103.X. Yu and A. Manthiram, Adv Funct Mater, In Presss, doi.org/10.1002/adfm.201805996.X. W. Yu, Z. H. Bi, F. Zhao and A. Manthiram, Adv Energy Mater, 2016, 6, 1601392.

A major breakthrough in battery materials is required to meet the ever-increasing proliferation of portable electronic devices, electric vehicles and their variants, as well as the need for incorporating renewable energy resources into the main energy supply.1 In this context, lithium-sulfur (Li-S) batteries attract attention owing to their very high energy density (2,600 Wh kg-1) and specific capacity (1,675 mAh g-1) and significantly lower weight and cost, compared to lithium-ion batteries (LIBs).2 Fully packaged, it is expected that future Li-S batteries can operate at close to 500 Wh kg-1, which is more than twice the energy density of LIBs (200 Wh kg-1). The problem of realizing the expected high energy density is defined by several issues including the dissolution of Li-Polysulfide (PS) species into the electrolyte, insulating properties of sulfur and Li-PS species, and volume change at the cathode.3 Overcoming these challenges requires a fundamental understanding of the interplay between events occurring over wide spatial and temporal scales, and accurate prediction of electrode and electrolyte properties to obtain design metrics for new improved materials.In this talk, I will first discuss the details of a high-throughput multi-scale computational infrastructure developed by our group called MISPR (Materials Informatics for Structure-Property-Relationship).4, 5 MISPR seamlessly integrates density functional theory (DFT) calculations with classical molecular dynamics (MD) simulations and generates high-fidelity databases of computational properties and includes several fully automated workflows to compute electronic, thermodynamic, structural, and dynamical properties of electrolyte solutions.I will then discuss the usage of MISPR to design optimal electrolytes for Li-S batteries by altering the atomistic interactions between the electrolyte components through high-throughput screening of potential co-solvent molecules. This approach guides and accelerates our rational selection of co-solvents that enable optimal compromise between the solubility of PS species and the transport properties of the electrolyte through automated DFT calculations. We use the selected candidates in detailed MD studies to comprehend the relationship between the structure of the co-solvent and the electrolyte properties. The approach allows for creating a database of well-characterized materials to be used in machine learning-based methods as well as for testing computationally identified structures in experiments. We recently published the first publicly available database, ComBat (Computational Database for Li-S Batteries), which includes ~2000 properties for solvents spanning 16 different chemical classes. This work provides crucial information to alleviate the dissolution of PS species during cycling while maintaining high ionic conductivity and low viscosity.6 Reference: Larcher, D.; Tarascon, J.-M., Towards greener and more sustainable batteries for electrical energy storage. Nature chemistry 2015, 7 (1), 19-29.Manthiram, A.; Yu, X.; Wang, S., Lithium battery chemistries enabled by solid-state electrolytes. Nature Reviews Materials 2017, 2 (4), 1-16.Manthiram, A.; Fu, Y.; Su, Y.-S., Challenges and prospects of lithium–sulfur batteries. Acc. Chem. Res. 2012, 46 (5), 1125-1134.Atwi, R.; Chen, Y.; Han, K. S.; Mueller, K. T.; Murugesan, V.; Rajput, N. N., An automated framework for high-throughput predictions of NMR chemical shifts within liquid solutions. Nature Computational Science 2022, 2 (2), 112-122.Atwi, R.; Bliss, M.; Makeev, M.; Rajput, N. N., MISPR: an open-source package for high-throughput multiscale molecular simulations. Scientific Reports 2022, 12 (1), 15760.Atwi, R.; Rajput, N. N., Guiding maps of solvents for lithium-sulfur batteries via a computational data-driven approach. Patterns 2023, 4 (9). Figure 1

We introduce a quasi-solid-state electrolyte lithium-sulfur (Li–S) battery (QSSEB) based on a novel Li-argyrodite solid-state electrolyte (SSE), Super P–Sulfur cathode, and Li-anode. The cathode was prepared using a water-based carboxymethyl cellulose (CMC) solution and styrene butadiene rubber (SBR) as the binder while Li6PS5F0.5Cl0.5 SSE was synthesized using a solvent-based process, via the introduction of LiF into the argyrodite crystal structure, which enhances both the ionic conductivity and interface-stabilizing properties of the SSE. Ionic liquids (IL) were prepared using lithium bis(trifluoromethyl sulfonyl)imide (LiTFSI) as the salt, with pre-mixed pyrrolidinium bis(trifluoromethyl sulfonyl)imide (PYR) as solvent and 1,3-dioxolane (DOL) as diluent, and they were used to wet the SSE–electrode interfaces. The effect of IL dilution, the co-solvent amount, the LiTFSI concentration, the C rate at which the batteries are tested and the effect of the introduction of SSE in the cathode, were systematically studied and optimized to develop a QSSEB with higher capacity retention and cyclability. Interfacial reactions occurring at the cathode–SSE interface during cycling were also investigated using electrochemical impedance spectroscopy, cyclic voltammetry, and X-ray photoelectron spectroscopy supported by ab initio molecular dynamics simulations. This work offers a new insight into the intimate interfacial contacts between the SSE and carbon–sulfur cathodes, which are critical for improving the electrochemical performance of quasi-solid-state lithium–sulfur batteries.

Cyclopropenium cationic-based covalent organic polymer (iCP@TFSI) was successfully prepared through the SN2 reaction and ion replacement process, which can be incorporated into the PEO/LiTFSI matrix as a filler. The obtained solid-state polymer electrolytes were utilized for an all-solid-state lithium-sulfur (Li-S) battery. Padding iCP@TFSI into the PEO matrix not only has a positive influence on both the ionic conductivity and the mechanical capacity of solid-state polymer electrolytes but also increases the stability of the lithium metal anode, which essentially improves the overall cycling ability of all-solid-state Li-S batteries. Among the membranes attained, the PEO-10%iCP@TFSI electrolyte displays the best ionic conductivity up to 1.2 × 10-3 S·cm-1 at 80 °C. The symmetrical lithium battery exhibits higher cycle stability (600 h) due to the higher mechanical properties related to more stable lithium metal interfaces. The Li-S battery based on the PEO-10%iCP@TFSI electrolyte exhibits excellent electrochemical performance with better Coulombic efficiency and outstanding cycling stability. Its capacity is maintained at 490 mAh·g-1 after 500 cycles at 1 C with a 0.032% decay rate each cycle, and the Coulombic efficiency is close to 100% during the whole cycling.

Rechargeable lithium-sulfur (Li-S) batteries are widely considered the most promising “Beyond Li-ion” candidates, notably for their high theoretical energy density. The low and moderate atomic weight of Li and S, respectively, translates to a battery chemistry pairing that is lightweight. Since each S atom can ultimately host two lithium ions (Li+), compared with 0.5–0.7 Li+ per host atom in Li-ion batteries [1], the Li-S battery chemistry offers a much higher Li storage capacity potential. Assuming a complete redox couple reaction, S8 + 16Li+ + 16e- ↔ 8Li2S, the S cathode can have a high theoretical specific capacity of 1672 mAh/g with an average discharge voltage of ~2.1V (vs. Li/Li+), which leads to a theoretical specific energy of ~2500 Wh/kg based on the active material weight of a Li-S cell [2]. Other compelling attributes of Li-S batteries include high S natural abundance, low cost of S materials and safety characteristics owing to an intrinsic tolerance to overcharge [3]. In addition, the primary constituents of Li-S batteries are non-toxic and environmentally friendly [4]. However, currently no commercial Li-S battery exists due to some significant technical challenges that have thus far prevented the realization of the tremendous energy density and performance potentials of Li-S batteries. These technical challenges include: low practical specific energy or energy density yield, significant capacity loss with cycling, high self-discharge rates, low Coulombic efficiency and safety concerns due to the use of Li metal anode [5]. We will present our efforts in the development of a high energy density and long cycle life Li-S battery technology via nanoengineered battery separators. We will show that our atomic and/or molecular level, functional material coated separators exhibit much improved physical properties including tensile strength, thermal shrinkage, and electrolyte wettability (Figure 1). When used in Li-S cells, the nanoengineered separators (coated) afforded a significant increase in specific capacity compared with the control (uncoated) separator, as illustrated in Figure 2. The enhanced Li-S cell performance suggests polysulfide blockage from the nanoscale functional material coated separators used in the resultant Li-S cells. Our study demonstrates that the nanoengineered separator approach represents a very promising strategy to develop a high energy density, long cycle life, safe and economically scalable Li-S battery technology. References Bullis, “Revisiting Lithium-Sulfur Batteries” MIT Review, May 22, 2009.Arumugam Manthiram, Yongzhu Fu, and Yu-Sheng Su, Acc. Chem. Res., 46 (5), pp 1125–1134 (2013)James R. Akridge, “Lithium Sulfur Rechargeable Battery Safety”, Battery Power Products & Technology, October 2001.Yongguang Zhang, Yan Zhao, Kyung Eun Sun and P. Chen, The Open Materials Science Journal, 5, 215-221 (2011).Monica Marinescu, Laura O’Neill, Teng Zhang, Sylwia Walus, Timothy E. Wilson, and Gregory J. Offer, J. Electrochem. Soc, 165 (1) A6107-A6118 (2018). Figure 1

Currently widely used Lithium ion batteries are based on metal oxides or phosphates and carbon systems with theoretical specific capacity of about 400 Wh/Kg. However to meet the ever growing energy demand of modern society, specifically for extended range electric vehicles, high energy density batteries are required [1, 2]. From this viewpoint, the use of sulfur as a cathode material is highly beneficial since its theoretical specific capacity corresponding to 1675 mAh/g could generate high energy density of 2600 Wh/Kg which is 3x105 folds higher than the state-of-the art Lithium ion batteries [3]. However, research on lithium sulfur (Li/S) batteries using liquid electrolytes faces several problems such as the loss of the active material in the form of soluble polysulfide reaction products [4, 5]. Hence, for the development of next generation high performance power sources with high energy densities substantial emphasis has be laid on rechargeable all solid-state Li/S batteries. All solid state Li/S batteries include a solid electrolyte that offers several benefits such as good flexibility, potentially high electrochemical stability window and low flammability. The solid state nature could be very beneficial to Li/S batteries as they can prevent polysulfide dissolution and efficiently lessen dendrite penetration [6]. In this work, two kind of sulfur carbon composite electrodes were prepared by mechanical activation and thermal activation technique and the performance was evaluated by incorporating in a solid state battery. A composite solid polymer electrolyte prepared by dispersing the Li1.3Al0.3Ti1.7(PO4)3 (LATP) ceramic fillers in the blend of high and low molecular weights polymer matrix was used as a solid electrolyte. The solid state battery using thermally activated composite electrode showed good electrochemical performance and cycle stability due to intimate contact between the sulfur and the carbon. [1] Morris, R. Scott, et al. "High-energy, rechargeable Li-ion battery based on carbon nanotube technology." Journal of Power Sources 138.1 (2004): 277-280. [2] Thackeray, Michael M., Christopher Wolverton, and Eric D. Isaacs. "Electrical energy storage for transportation—approaching the limits of, and going beyond, lithium-ion batteries." Energy & Environmental Science 5.7 (2012): 7854-7863. [3] Aurbach, Doron, et al. "On the surface chemical aspects of very high energy density, rechargeable Li–sulfur batteries." Journal of the Electrochemical Society 156.8 (2009): A694-A702. [4] Hayashi, Akitoshi, et al. "All-solid-state Li/S batteries with highly conductive glass–ceramic electrolytes." Electrochemistry communications 5.8 (2003): 701-705. [5] Kobayashi, Takeshi, et al. "All solid-state battery with sulfur electrode and thio-LISICON electrolyte." Journal of Power Sources 182.2 (2008): 621-625. [6] Machida, Nobuya, et al. "Electrochemical properties of sulfur as cathode materials in a solid-state lithium battery with inorganic solid electrolytes." Solid State Ionics 175.1 (2004): 247-250.

Lithium-sulfur (Li-S) batteries have attracted tremendous interest because of their high theoretical energy density and cost effectiveness. The target of Li-S battery research is to produce batteries with a high useful energy density that at least outperforms state-of-the-art lithium-ion batteries. However, due to an intrinsic gap between fundamental research and practical applications, the outstanding electrochemical results obtained in most Li-S battery studies indeed correspond to low useful energy densities and are not really suitable for practical requirements. The Li-S battery is a complex device and its useful energy density is determined by a number of design parameters, most of which are often ignored, leading to the failure to meet commercial requirements. The purpose of this review is to discuss how to pave the way for reliable Li-S batteries. First, the current research status of Li-S batteries is briefly reviewed based on statistical information obtained from literature. This includes an analysis of how the various parameters influence the useful energy density and a summary of existing problems in the current Li-S battery research. Possible solutions and some concerns regarding the construction of reliable Li-S batteries are comprehensively discussed. Finally, insights are offered on the future directions and prospects in Li-S battery field.