Multifunctional Zeolites in Secondary Batteries.

Enhanced ionic conductivity and interface stability of hybrid solid-state polymer electrolyte for rechargeable lithium metal batteries

Renewable energy sources such as solar, wind, and tide energy have been implemented to decrease air pollution due to common fossil fuel-generated electricity [1]. However, those systems are intermittent; creating the need for an energy storage system (ESS) that stores over-generated energy for later use and effectively matches the power fluctuation generated because of the sporadic demand throughout the day [2]. A possible solution to this problem is to couple renewable sources with rechargeable batteries. The most widespread electrochemical battery in the market is Lithium-ion, owing to its high energy density and lifetime and capability to resist frequent changes in charging-discharging rates [3]. Nevertheless, the current battery industry already requires 50% of the world's available lithium [4]. Foremost, lithium-ion battery is composed of critical metals such as cobalt, nickel, and manganese. The anticipated growing demand for these metals will lead to their scarcity [5]. Therefore, this study aims to develop strategy to enable a sodium-ion battery based on soluble seawater sodium and address the electrochemical and engineering problems.Seawater batteries have an open cathode compartment that can utilizes Na+ infinite source in the ocean as the active material [6]. There are three main components in this open structure seawater battery design. First is the non-aqueous liquid electrolyte facilitating the sodium ions transfer and deposition on the anode compartment [7-8]. Subsequently, the solid-state electrolyte (SSE) enables the flow of sodium ions from the sweater cathode to the anode which is typically copper current collector [9]. Lastly, a current collector that provides reaction sites for cathode reactions that could be made of carbon-based materials, such as carbon paper, carbon felt, or carbon cloth [10].The Solid-state electrolyte is the component that requires the most attention. It must have high ionic conductivity to increase sodium-ions transfers and maintain good mechanical and physical properties as it represents the interface between cathode and anode, preventing the water from penetrating the anode compartment and short-circuiting the cell.To increase its ionic conductivity, it is necessary to reduce its thickness as much as possible. Through the palletization and sintering process, a ceramic SSE was fabricated with a thickness of ~ 250 µm and ionic conductivity of 0.62 mS/cm. Subsequently, symmetric cells (Na||SSE||Cu) were assembled to further test the pellet's performance. Cells that were tested under continuous charge/discharge cycling for 360 cycles showed stable charge capacity and high Coulombic efficiency (> 95%). Performance of full cells using seawater at the cathode was also demonstrated. Addressing various issues such as water permeation through the SSE, electrode corrosion, Na deactivation in the anode, and catalytic activity of the carbon cathodes are also investigated. Figure 1. Charge/discharge profile of a symmetric Na||SSE||Cu cell at a current density of 0.10 mA/cm2.

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.

This research investigated new materials and improvements to the performance of solid state batteries in order to achieve high performance, but with acute attention to safety and manufacturability. It is widely known that liquid-based lithium-ion batteries maintain inherent safety problems on account of solvent leakage and flammability of liquid electrolytes used in commercial lithium-ion batteries.1,2 Additionally, liquid-electrolyte-containing lithium-ion batteries must be constructed in such a way to account for their inherent danger, requiring excess weight in safety containment materials, which diminishes their overall energy density and adds to manufacturing costs. In contrast to commercialized liquid-electrolyte-based lithium-ion batteries, all-solid-state batteries offer ultimate safety and potential for high energy/power density due to increased packing efficiency in final battery designs with the elimination of unnecessary safety equipment.3,4 Unfortunately current research and development efforts have yet to unveil an all-solid-state battery that can fulfill all metrics for world-wide replacement of liquid-electrolyte based lithium-ion batteries. The key issue blocking commercial-scale deployment of all-solid-state batteries is not a lack of capable bulk materials to construct the batteries; but the interfacial reactions that happen between materials within the battery in contact with one-another that prevent maintained high performance. All-solid-state secondary batteries employing inorganic solid state electrolytes (SEs) offer a significant, inherent safety advantage over conventional liquid-electrolyte-containing batteries making them highly desirable for next generation energy storage. Key to the ultimate safety of all-solid-state secondary batteries is the SE which functions electrochemically and structurally within the battery. Much effort has gone into developing new SEs with excellent electrochemical characteristics such as high ionic conductivity and high voltage chemical stability, as well as into its structural role as the battery separator. Until recently, commercialization of all-solid-state secondary batteries has not been possible due to low conductivity of the SE as compared to batteries with liquid electrolyte. However, numerous groups have demonstrated SEs with high ionic conductivity on the order of 10-4-10-2 S cm-1 which engenders the opportunity for parallel performance between all-solid-state batteries and conventional batteries. As a final hurdle to realistically enable all-solid-state batteries as a viable, commercializable energy source it is critical to resolve the chemical instability between the SE and bulk electrode materials contained within batteries. It is now widely accepted that the interfaces of lithium-ion battery (LIB) electrode materials can be highly dynamic in nature, and are the source of performance fade problems as well as safety issues. Atomic Layer Deposition (ALD) has been widely demonstrated as an elegant technique for addressing the shortcomings of battery performance, and has recently being demonstrated as a means for enhancing safety. Here, we will discuss recent advances in ALD coatings applied to battery materials which significantly increase the performance as well as safe handling, production, and use of a final batteries.

Electrochemical Energy Storage with Mediator-Ion Solid Electrolytes

The Renaissance of Liquid Metal Batteries

A suitable theory is required to identify the electro-chemo-mechanical limits of Li-ion batteries performance in realistic electrode-electrolyte configurations. In all-solid cells, the battery life depends in larger measure on the mechanical integrity of the composite system[1]. The proposed fully coupled electro-chemo-mechanical model can contribute to the mesoscale optimization of such composite microstructures [2]. All-solid-state rechargeable lithium-ion batteries have attracted much interest because they have features partic- ularly favorable for large-scale application. The replacement of an organic liquid electrolyte with a non-flammable and more reliable inorganic solid electrolyte (SE) simplifies the battery design and improves safety and durability of the system[3]. However, the mechanical behavior of such electrodes will be considerably different than their liquid electrolyte counterparts. Direct stacking of solid-state cells enables the achievement of high operating voltages in a reduced volume. Furthermore, all-solid-state batteries allow the use of large-capacity electrode materials, for instance sulfur positive electrode paired with a lithium metal negative electrode, which are difficult to employ in conventional liquid electrolyte batteries. A key development to the success of all-solid-state batteries is a SE with high Li+ ion conductivity at room temperature[4, 5, 6]. In recent years, several solid electrolytes having level of conductivity comparable to organic liquid electrolytes have been discovered and tested with many active materials. The durability of a cohering solid- solid interface between electrode and electrolyte is likely to be important practical consideration. Notwithstanding the several techniques investigated to increase the contact area at the interface[7], interface cohesion and its effects on the rate capability and the overall performance throughout the expected life cycles needs to be maintained. The present research focuses on the development of a nonlinear continuum model able to account for the com- bined effects of Li diffusion and for the consequent volumetric expansion of the hosting material. The electrode and electrolyte are modeled as idealized as elastic materials, with elastic properties varying with lithium concentration. The complexity and the multi-physical nature of the problem requires numerical modeling strategies and poses several challenges. To address this, we have established a computational framework based on large deformation theory and in a thermodynamically consistent fashion. This is implemented in an in-house, object oriented C++ numerical code that incorporates three-dimensional finite element calculations. The numerical analysis allows for delamination at the interface between electrode particles and solid electrolyte. Crack formation and propagation is predicted by means of a cohesive zone model extended to include decreased Li flux across interfaces due to their loss of mechanical integrity. Our simulations indicate trends of mechanical reliability of all-solid state batteries realized with some of the most promising solid electrolyte materials (e.g. Li2S-P2S5 [1], LIPON [4], garnet SE [8]); our calculations are based on the mechanical properties available in literature. When physical values for the solid electrolyte’s mechanical behavior are not available, our calculations indicate trends of how mechanical reliability correlates with the battery design and operating conditions (i.e., charging rate). [1] Akitoshi Hayashi, Kousuke Noi, Atsushi Sakuda, and Masahiro Tatsumisago. Superionic glass-ceramic electrolytes for room-temperature rechargeable sodium batteries. Nature Communications, 3, 2012.[2] Giovanna Bucci, Yet-Ming Chaing, and W. Craig Carter. Formulation of the coupled electrochemical-mechanical boundary-value problem, with applications to transport of multiple charged species. Acta Materialia, 2015. (accepted). [3] KazunoriTakada.Progressandprospectiveofsolid-statelithiumbatteries.ActaMaterialia,61(3):759–770,2013. [4] J.B Bates, N.J Dudney, B Neudecker, A Ueda, and C.D Evans. Thin-film lithium and lithium-ion batteries. Solid State Ionics, 135(1 - 4):33 – 45, 2000.[5] Yoshikatsu Seino, Tsuyoshi Ota, Kazunori Takada, Akitoshi Hayashi, and Masahiro Tatsumisago. A sulphide lithium super ion conductor is superior to liquid ion conductors for use in rechargeable batteries. Energy Environ. Sci., 7:627–631, 2014. [6] Noriaki Kamaya, Kenji Homma, Yuichiro Yamakawa, Masaaki Hirayama, Ryoji Kanno, Masao Yonemura, Takashi Kamiyama, Yuki Kato, Shigenori Hama, Koji Kawamoto, and Akio Mitsui. A lithium superionic conductor. Nature materials, 10(9):682–6, September 2011.[7] Masahiro Tatsumisago, Motohiro Nagao, and Akitoshi Hayashi. Recent development of sulfide solid electrolytes and interfacial modification for all-solid-state rechargeable lithium batteries. Journal of Asian Ceramic Societies, 1(1):17 – 25, 2013.[8] Ezhiyl Rangasamy, Jeff Wolfenstine, and Jeffrey Sakamoto. The role of Al and Li concentration on the formation of cubic garnet solid electrolyte of nominal composition Li7La3Zr2O12. Solid State Ionics, 206(0):28 – 32, 2012.

All-solid-state rechargeable lithium-ion batteries have attracted much interest recently for applications of much larger scale than previous thin-film batteries. The replacement of an organic liquid electrolyte with a non-flammable inorganic solid electrolyte (SE) may simplify battery design and improve safety and durability [2]. However, in all-solid cells, the battery life depends in large measure on the mechanical integrity of the composite system [1]. A suitable theory to identify the electro-chemo-mechanical limits of Li-ion batteries performance in realistic electrode-electrolyte configurations is therefore required. In this work, a fully coupled electro-chemo-mechanical model is developed to facilitate the mesoscale optimization of such composite microstructures. A key development in all-solid-state batteries has been the discovery of solid electrolytes with high Li+ ion conductivity at room temperature comparable to that of organic liquid electrolytes [3, 4, 5]. These have been tested with numerous electrode active materials.The durability of a coherent solid-solid interface between electrode and electrolyte is likely to be an important consideration. Notwithstanding the several techniques investigated to increase the contact area at the interface [6], interface cohesion and its effects on the rate capability and the overall performance throughout the expected life cycles needs to be maintained. In the present research, we develop a nonlinear continuum model able to account for the combined effects of Li diffusion and for the consequent volumetric expansion of the hosting material. The electrode and electrolyte are idealized as elastic materials with elastic properties varying with lithium concentration. The complexity and the multi-physical nature of the problem require numerical modeling strategies and pose several challenges. To address this, we have established a computational framework based on large deformation kinematics and posed in a thermodynamically consistent fashion. The model is implemented in an in-house, object oriented C++ numerical code that incorporates three-dimensional finite element calculations. The numerical analysis allows for delamination at the interface between electrode particles and solid electrolyte. Crack formation and propagation is predicted by means of a cohesive zone model extended to include decreased Li flux across interfaces due to their loss of mechanical integrity. Our simulations indicate trends of mechanical reliability of all-solid state batteries realized with some of the most promising solid electrolyte materials (e.g. Li2S-P2S5 [1], LIPON [3], garnet SE [7]), using mechanical properties available in literature. When physical values for the solid electrolyte’s mechanical behavior are not available, the simulations indicate trends of how mechanical reliability correlates with the battery design and operating conditions (i.e., charging rate). Acknowledgments The work was supported by the grant DE-SC0002633 funded by the U.S. Department of Energy, Office of Science. Keywords Lithium ion batteries, All-solid-state batteries, Nonlinear continuum mechanics; Diffusion; Thermodynamics References [1] A. Hayashi, K. Noi, A. Sakuda, and M. Tatsumisago. Superionic glass-ceramic electrolytes for room-temperature rechargeable sodium batteries. Nature Communications, 3, 2012. [2] K. Takada. Progress and prospective of solid-state lithium batteries. Acta Materialia, 61(3):759 – 770, 2013. [3] J.B Bates, N.J. Dudney, B. Neudecker, A. Ueda, and C.D. Evans. Thin-film lithium and lithium-ion batteries. Solid State Ionics, 135(1 - 4):33 – 45, 2000. [4] Y. Seino, T. Ota, K. Takada, A. Hayashi, and M. Tatsumisago. A sulphide lithium super ion conductor is superior to liquid ion conductors for use in rechargeable batteries. Energy Environ. Sci., 7:627–631, 2014. [5] N. Kamaya, K. Homma, Y. Yamakawa, M. Hirayama, R. Kanno, M. Yonemura, T. Kamiyama, Y. Kato, S. Hama, K. Kawamoto, and A. Mitsui. A lithium superionic conductor. Nature materials, 10(9):682–6, September 2011. [6] M. Tatsumisago, M. Nagao, and A. Hayashi. Recent development of sulfide solid electrolytes and interfacial modification for all-solid-state rechargeable lithium batteries. Journal of Asian Ceramic Societies, 1(1):17 – 25, 2013. [7] E. Rangasamy, J. Wolfenstine, and J. Sakamoto. The role of Al and Li concentration on the formation of cubic garnet solid electrolyte of nominal composition Li7La3Zr2O12. Solid State Ionics, 206(0):28 – 32, 2012. Figure 1: Simulation of a composite all-solid Li-ion battery microstructure upon lithiation. The diffusion fronts (white lines) appear perturbed due to partial delamination of the interface between electrode particles and solid electrolyte. Figure 1

Nanoscale Solid-State Separator/Electrolyte for3D All-Solid-State Batteries

This STTR Phase I research program was on the development of high temperature (400 to 650 C), secondary batteries with roundtrip efficiency > 90% for integration with a 3 to 10 kW solid oxide fuel cell (SOFC) system. In fulfillment of this objective, advanced planar high temperature rechargeable batteries, comprised of an alkali metal ion conducting, highly refractory, beta'' alumina solid electrolyte (BASE) sandwiched between liquid sodium (or potassium) anode and liquid metal salt cathode, were developed at MSRI. The batteries have been successfully demonstrated at a working temperature as high as 600 C. To our knowledge, so far no work has been reported in the literature on planar rechargeable batteries based on BASE, and results obtained in Phase I for the very first time demonstrated the viability of planar batteries, though relatively low temperature tubular-based sodium-sulfur batteries and ZEBRA batteries have been actively developed by very limited non U.S. companies. The results of this Phase I work have fulfilled all the goals and stated objectives, and the achievements showed much promise for further, substantial improvements in battery design and performance. The important results of Phase I are briefly described in what follows: (1) Both Na-BASE and K-BASE discs and tubes have been successfully fabricated using MSRI's patented vapor phase process. Ionic conductivity measurements showed that Na-BASE had higher ionic conductivity than K-BASE, consistence with the literature. At 500 C, Na-BASE conductivity is 0.36 S/cm, which is more than 20 times higher than 8YSZ electrolyte used for SOFC at 800 C. The activation energy is 22.58 kJ/mol. (2) CuCl{sub 2}, FeCl{sub 2}, ZnCl{sub 2}, and AgCl were identified as suitable salts for Na/metal salt or K/metal salt electrochemical couples based on thermochemical data. Further open circuit voltage measurements matched those deduced from the thermochemical data. (3) Tubular cells with CuCl{sub 2} as the cathode and Na as the anode were constructed. However, it was discovered that CuCl{sub 2} was somewhat corrosive and dissolved iron, an element of the cathode compartment. Since protective coating technology was beyond this Phase I work scope, no further work on the CuCl{sub 2} cathode was pursued in Phase I. Notwithstanding, due to its very high OCV and high specific energy, CuCl{sub 2} cathode is a very attractive possibility for a battery capable of delivering higher specific energy with higher voltage. Further investigation of the Na-CuCl{sub 2} battery can be done by using suitable metal coating technologies developed at MSRI for high temperature applications. (4) In Phase I, FeCl{sub 2} and ZnCl{sub 2} were finalized as the potential cathodes for Na-metal salt batteries for delivering high specific energies. Planar Na-FeCl{sub 2} and Na-ZnCl{sub 2} cells were designed, constructed, and tested between 350 and 600 C. Investigation of charge/discharge characteristics showed they were the most promising batteries. Charge/discharge cycles were performed as many as 27 times, and charge/discharge current was as high as 500 mA. No failure was detected after 50 hours testing. (5) Three-cell planar stacks were designed, constructed, and evaluated. Preliminary tests showed further investigation was needed for optimization. (6) Freeze-thaw survival was remarkably good for planar BASE discs fabricated by MSRI's patented vapor phase process.

Solid-state electrolytes (SSEs) are the key materials in the new generation of all-solid-state lithium ion/metal batteries. Metal-organic frameworks (MOFs) are ideal materials for developing solid electrolytes because of their structural diversity and porous properties. However, there are several significant issues and obstacles involved, such as lower ion conductivity, a smaller ion transport number, a narrower electrochemical stability window and poor interface contact. In this review, a comprehensive analysis and summary of the unique ion-conducting behavior of MOF-based electrolytes in rechargeable batteries are presented, and the different design principles of MOF-based SSEs are classified and emphasized. Accordingly, four design principles for achieving these MOF-based SSEs are presented and the influence of SSEs combined with MOFs on the electrochemical performance of the batteries is described. Finally, the challenges in the application of MOF materials in lithium ion/metal batteries are explored, and directions for future research on MOF-based electrolytes are proposed. This review will deepen the understanding of MOF-based electrolytes and promote the development of high-performance solid-state lithium ion/metal batteries. This review not only provides theoretical guidance for research on new MOF-based SSE systems, but also contributes to further development of MOFs applied to rechargeable batteries.

Status of rechargeable potassium batteries

[Introduction] The development of high-performance all-solid-state Li-ion batteries are strongly required for high safety and reliability. The properties of solid-state electrolytes are crucial to the performance of all-solid-state Li-ion batteries. However, the conventional solid-state electrolytes with sufficient ion conductivity and high stabilities during battery operation are limited to few cases. Here, we propose a new idea to fabricate new type of solid-state hybrid electrolytes using mixture of room temperature ionic liquids (RTILs)-Li-salts and oxide nanoparticles. Presently, RTILs-Li salts mixture are considered as a potential candidate electrolyte material because of its promising properties, such as high ion conductivity, high stability and wide potential window. Recently, some researches revealed that RTILs-Li-salts are quasi-solidified incorporating with oxide particles attributed to the strong interaction between the oxide particles surfaces and RTILs-Li-salts. These composite materials maintain the liquid-like properties of RTILs-Li-salts. Our group have reported about a favorable soft sheet hybrid electrolyte based on RTILs-Li-salt and 7 nm-SiO2 nanoparticles. The liquid-like properties of hybrid electrolytes was proved to be beneficial. However, the insufficient power density of hybrid electrolytes became the problem. To solve this problem, we seek to sufficiently increase the power density of hybrid electrolytes incorporating with different nanoparticles. Therefore, the outstanding point of this study is that various commercial oxide nanoparticles were utilized to fabricate quasi-solid-state hybrid electrolytes with RTILs-Li-salt.[Experimental] The quasi-solid-state powders were prepared by mixing nanoparticles (CeO2: 15-30 nm, ZrO2: 30-60 nm and gamma-Al2O3: 5 nm) with RTIL-Li-salt mixture. Nanoparticles were preheated to 80℃ for 24h to rule out effects due to physicsorbed water. RTIL-Li-salt mixture was prepared by mixing equimolar concentration of tetraethylene glycol dimethyl ether (tetraglyme, G4) and lithium bis(trifluoromethanesulfonyl)amide (Li-TFSA) powder. The resultant solution was mixed with the above-mentioned nanoparticles in methanol for 3h. The quasi-solid-state powders were achieved by evaporating the mixture on a hot plate. The volume ration of nanoparticles reached 75, 60 and 75 vol%, respectively. Self-assembled hybrid electrolyte sheets were obtained by further mixing the powder of polytetrafluoroethylene (PTFE) with the quasi-solid-state powder at 5 wt%. All of the raw materials were used without any further treatment, but stored in the argon-filled glove box. The ion conductivities of quasi-solid-state hybrid electrolytes were measured by the ac impedance method over the frequency range from 1 × 106 to 1 Hz.[Results and discussion] White quasi-solid-state powders were successfully achieved incorporating various nanoparticles with G4/LiTFSA solution. Self-assembled electrolyte sheets were obtained mixing quasi-solid-state powders with 5 wt.% PTFE as final samples. The ionic conductivity of CeO2, Al2O3, ZrO2 – x vol% G4/LiTFSA composites were measured as a function of inverse temperature, respectively. Considered with the ionic conductivity of SiO2, it was found that all the samples had liquid-like high ion conductivities although the conduction paths, i.e. RTIL-Li-salts, are quasi-solidified. Additionally, CeO2, Al2O3 and ZrO2-based quasi-solid-state electrolytes displayed higher ion conductivities than that of SiO2-based one. The reason can be attributed to the enhancement of interaction between RTIL and nanoparticle surfaces. Thus, the higher performance of the Li-ion battery composed of the above-mentioned quasi-solid-state electrolytes can be expected. From applications point of view, the hybrid electrolytes might be potentially applied to various electrochemical devices, such as bipolar all-solid-state Li-ion batteries with wider electrical potential ranges.

As an anode material, Li metal is a most promising because of a low electrochemical potential(−3.045 V vs the standard hydrogen electrode), high theoretical capacity(3860 mAh/g), low density (0.534 g/cm3 ), and high electrical conductivity. However, a Li-metal anode battery is limited to use because of poor safety and electrochemical instability because of dendritic growth and “dead-lithium” outbreak during cycling in a flammable liquid electrolyte system. 1-3 The dendrite growth on the electrode surface is mainly caused by the localization of current due to the heterogeneous SEI film on the surface and the high current rate during cycling. 4 In order to overcome a dendrite growth behavior, there are many trials reported such as, Li metal morphology change(ref), coating the metal surface(ref), or adding a surfactant in the electrolyte. In addition, applying a solid state electrolyte (SSE) instead of a liquid electrolyte, it may overcome the disadvantage of a flammable electrolyte in the Li-metal battery.5There are two types of solid state electrolyte systems, such as a sulfidic electrolyte (i.e. LGPS(Li10GeP2S12)) and an oxide-based electrolyte(i.e. LLZO(Li7La3Zr2O12)). The former has very high ionic conductivity (12x10-3Scm-1). 6 Also, due to its ductile mechanical properties, it doesn’t require high pressure and temperature to manufacture the efficient solid state electrolyte pellet. 7, but it causes byproduct when exposed to reactive gases, humidity and lithium metal. 8Otherwise, an oxide-based electrolyte like LLZO has high ionic conductivity and is chemically and electrochemically stable with lithium metal anode. 9,10 However, high energy (1100oC, 300Mpa) is required to fabricate the efficient LLZO electrolyte. 11 and it also has the disadvantage of poor contact with the electrode due to its rigid mechanical properties.To be a true meaning of the Li-metal all solid state battery (ASSB), the Li-anode metal should be an energy (or ion) source. Therefore, non-lithiate materials such as sulfur or O2 should be coupled as a cathode material. Though they are still more works to use in the cell, Sulfur and O2 are attracting attention as a next-generation cathode material for lithium metal batteries due to their high theoratical capacity. 15,16 Instead, the LiV3O8 may be a proper non-lithiated cathode material to test a Li-metal ASSB, because its stability and electrochemical properties are already reported. 17, 18major obstacles at each constituents are numbered: (1) dendritic growth on the Li metal anode surface, (2) inappropriate contact at the anode/solid electrolyte interface, (3) poor ionic conductivity caused by less compacted solid electrolyte materials, (4) inappropriate contact at the solid electrolyte/ cathode interface, (5) poor ionic and electronic conductivity caused by less compacted cathode materials. Of course, more problems such as by-products due to every reactions, intervention of side reaction, and enhanced mechanical properties of the electrode materials also overcome to be a commercial Li-metal ASSB.The major purpose of the this research, however, builds a Li-metal ASSB system in which Li-metal used as an anode and understands the electrochemical performances of the Li/LLZO/LVO secondary batteries.

An Agar gel modulation with melamine foam skeleton for flexible Zn-air batteries