Application performance of three common solid-state electrolytes in batteries

Nanoscale Mapping of Extrinsic Interfaces in Hybrid Solid Electrolytes

Stringent requirements for safe, fast and long-life rechargeable lithium battery technologies are ever increasing with the rapid development of electronics and energy industries. Recently, solid-state lithium batteries have been regarded as one of the most promising technologies to achieve these requirements, because they can provide higher energy/power densities, longer lifetime and better safety than the state-of-the-art lithium ion batteries which contain organic electrolytes.1-3 However, the lack of advanced solid-state electrolytes with the high ionic conductivity, wide electrochemical window, and good thermal and mechanical stability, has delayed the battery’s application in many large autonomous devices, such as electric vehicles and intelligent grids.4-6 Herein, we propose a new approach to develop solid-state lithium battery technology, using an ionogel nanocomposite electrolyte composed of porous oxide matrices with in-situ immobilizing ionic liquid salt solutions. In such composites, the ionic liquid salt solutions maintain the liquid dynamics, so they are responsible for the ionic conducting and other electrochemical properties; the porous oxide matrices provide abundant channels to confine ionic liquid solutions while maintaining good mechanical properties, thus, the composites have a solid-state glassy structure. For example, a SiO2/[BMI][TFSI]/LiTFSI ionogel electrolyte system, which shows a high ionic conductivity (1.2~3.6 × 10‒3 S cm‒1 at room temperature), good electrochemical stability (3.9 ± 0.1 V vs Li+/Li), and excellent mechanical strength (Fracture strength: 0.8 ± 0.1 MPa). The solid-state cells tested with the various cathodes (LiCoO2, LiNi1/3Co1/3Mn1/3O2, and LiFePO4) exhibit good electrochemical properties, including high specific capacities, long cycling stability, and excellent high temperature performance. Therefore, the ionogel electrolytes exhibit the superior performance to conventional organic electrolytes with regard to safety and cycle-life. This solid-state battery technology will provide new avenues for the rational engineering of advanced lithium batteries and other electrochemical devices. The nanocomposite electrolytes (NEs) look like glass monoliths (Fig. 1A), which are transparent, smooth, and homogeneous. They have high room-temperature ionic conductivities of 1.2‒3.6 × 10‒3 S cm‒1 and stable electrochemical windows of 3.9 ± 0.1 V vs Li+/Li (Fig. 1C). They can be easily processed into thin-film electrolytes, allowing their flexible incorporation into a solid-state battery configuration (Fig. 1B), where we use the NEs as the solid-state electrolyte, a lithium foil as the anode, and cathode material of LiCoO2, LiNi1/3Co1/3Mn1/3O2, or LiFePO4. Figs. 1D‒I show the electrochemical performance of NEs with four NEs compositions in these half cells. It is noteworthy that the specific capacities and cycling performance of all these cells are gradually increasing with higher ionic liquid content in NEs. This finding is mainly attributed to the improved charge transfer in the electrode−electrolyte interface by increasing their wetting properties. In a word, these solid-state cells exhibit good electrochemical performance. Fig. 1 Electrochemical characterization of nanocomposite electrolytes (NEs). (A) Optical photograph of NEs. (B) Schematic showing the solid-state battery configuration. (C) Ionic conductivities, activation energies, and electrochemical windows of NEs. (D-F) Initial charge-discharge profiles, and (G-I) cycling performance of LiCoO2/NEs/Li cells, LiCo1/3Ni1/3Mn1/3O2/NEs/Li cells, and LiFePO4/NEs/Li cells cycled at C/10 rate and at 30 °C.

Stabilizing Solid Electrolyte-Anode Interface in Li-Metal Batteries by Boron Nitride-Based Nanocomposite Coating

Enormous commercial interest in upcoming new energy storage application fields such as electric vehicles (EVs) and smart portable electronics has continuously pushed us to search for high-energy density rechargeable power sources. Bipolar cell configuration (in particular, lithium-ion battery applications) has garnered a great deal of attention as a promising way to achieve this goal. In comparison to the simple connection of monopolar cells in series, the bipolar batteries can offer several advantageous performances, including low internal resistance through the reduced terminal connections in a cell pack assembly and, more importantly, high volumetric energy density due to the minimal use of electrically-inert cell components such as current collectors and packaging substances. A key components to realize the bipolar batteries is solid-state electrolytes, which play a crucial role as a separator membrane and also an electrolyte in electrodes. In case the adjacent cells inside the bipolar batteries are ionically connected, they lose the advantageous features (in particular, voltage build-up arising from the accumulated cells), eventually behaving like a single unit cell. Therefore, solid-state electrolytes without fluidic characteristics are urgently needed to secure reliable electrochemical performance. To date, inorganic electrolytes, including LiSICON, perovskite, garnet and sulfide types, have been extensively investigated for potential use in bipolar batteries, however, their intrinsic limitations such as low ionic conductivity, grain boundary resistance and mechanical brittleness have posed a formidable challenge in their practical development. To overcome these problems, recently, a few works suggested inorganic/organic hybrid electrolytes, wherein inorganic electrolytes were mixed with polymeric (gel) electrolytes. Some possibility for resolving the grain boundary issue was suggested, however, numerous technical issues have been still unresolved. Most notably, taking into consideration continuous manufacturing process and also application versatility, the mechanical fragility and stiffness of bipolar batteries should be urgently overcome. To the best of knowledge, no works have reported bipolar batteries with mechanical flexibility and safety tolerance, in addition to offering reliable/sustainable electrochemical performance. Here, as a facile and efficient strategy to address the aforementioned longstanding issues, we demonstrate a new class of printed flexible bipolar lithium-ion batteries (referred to as “PFBB”). A distinctive feature of the PFBBs, compared to previously-reported bipolar batteries, is the use of printable inorganic/organic (I/O) solid-state electrolytes (fabricated via ultraviolet (UV) curing process) with good electrochemical performance, robust thermal stability and mechanical deformability. Due to such unusual printable characteristic, the I/O solid-state electrolyte can be seamlessly integrated with electrodes comprising the I/O solid-state electrolyte, active materials and conductive additives, eventually leading to the simple and facile fabrication of all-solid-state bi-polar batteries without interfacial resistance concerns. Specifically, within an extremely short time (less than 30 min), PFBBs comprising 5 cells can be successfully prepared. The I/O electrolytes were composed of LSTP (Li2O-SiO2-TiO2-P2O5) inorganic electrolytes and gel polymer electrolyte (GPEs) containing glyme-based ionic liquids. The GPEs act as an ionic bridge between the LSTP particles, thereby alleviating the grain boundary resistance. Also, due to their ionic liquid-like behavior, excellent thermal stability can be achieved. More notably, the GPEs exploit semi-IPN (interpenetration polymer network) matrix based on UV-cured triacrylate (as a crosslinked polymer network) and PVdF-HFP (as a linear polymer), thus enabling exceptional mechanical flexibility. Meanwhile, to further improve the mechanical flexibility of the electrodes, current collectors with a diversity of pattern were employed. Owing to the well-defined microscale pattern, the electrode components (i.e., active materials, conductive additives and I/O electrolytes) were tightly adhered to the pattern current collectors, contributing to the improvement of mechanical deformability. Driven by the material/architecture uniqueness mentioned above, the PFBBs provided unprecedented improvements in mechanical flexibility and thermal stability with reliable/sustainable electrochemical performance (above operating voltage of 10.0 V) which lie far beyond those accessible with conventional bipolar battery technologies.

An effective solid-electrolyte interphase for stable solid-state batteries

Toward an Atomistic Understanding of Solid-State Electrochemical Interfaces for Energy Storage

Pseudo-solid State Batteries See the Light

Nickel phosphate nanorod-enhanced polyethylene oxide-based composite polymer electrolytes for solid-state lithium batteries

Solid-state lithium batteries exhibit high-energy density and exceptional safety performance, thereby enabling an extended driving range for electric vehicles in the future. Solid-state electrolytes (SSEs) are the key materials in solid-state batteries that guarantee the safety performance of the battery. This review assesses the research progress on solid-state electrolytes, including polymers, inorganic compounds (oxides, sulfides, halides), and organic-inorganic composites, the challenges related to solid-state batteries in terms of their interfaces, and the status of industrialization research on solid-state electrolytes. For each kind of solid-state electrolytes, details on the preparation, properties, composition, ionic conductivity, ionic migration mechanism, and structure-activity relationship, are collected. For the challenges faced by solid-state batteries, the high interfacial resistance, the side reactions between solid-state electrolytes and electrodes, and interface instability, are mainly discussed. The current industrialization research status of various solid electrolytes is analyzed in regard to relevant enterprises from different countries. Finally, the potential development directions and prospects of high-energy density solid-state batteries are discussed. This review provides a comprehensive reference for SSE researchers and paves the way for innovative advancements in regard to solid-state lithium batteries.

Theoretical and experimental design in the study of sulfide-based solid-state battery and interfaces

The mechanical properties of electrode materials and solid-state electrolytes in solid-state batteries (SSBs) have an important influence on the mechanical stabilties of SSBs. Mechanical failures in SSBs on different scales and in different components will occur once the stress inside SSBs exceeds the materials’ strengths, which seriously deteriorates the electrochemical performances of SSBs. From the perspective of stabilizing the mechanical stabilities of SSBs, in this review we describe the influences of the mechanical properties of each component in SSBs on the mechanical stabilites of SSBs, and we analyze the factors that affect the mechanical properties of materials. In addition, we also discuss the mechanical failures of SSBs during cycle, including electrode materials’ or solid-state electrolytes’ fractures, electrode-electrolyte contact losses, and short-circuits due to lithium dendrites. Finally, we summarize some common strategies to mitigate the mechanical failures in SSBs, and look forward to the future research directions in this field. Overall, the mechanical failures in SSBs and their strategies discussed in this review will help researchers build SSBs with higher energy density, longer life and higher safety.

The escalating demand for high-performance, safe energy storage devices has propelled the advancement of solid-state battery (SSB) technology. SSBs can supplant traditional liquid electrolyte-based Li-ion batteries by offering higher theoretical capacities and enhanced safety through solid-state electrolytes. However, challenges like dendritic lithium growth and inadequate solid-solid interfaces impede their practical application. This study aims to overcome these barriers by enhancing the ionic conductivity of ceramic-based solid-state electrolytes by incorporating nanoscale multicomponent halides. Utilizing green chemistry principles, we synthesized composite electrolytes based on Li₃InCl₆, doped with fluorine (F), cerium (Ce), and molybdenum (Mo). Among these, the F-, Ce-, and Mo-doped Li₃InCl₆ electrolytes contributed uniquely to enhancing ionic conductivity. Mo-doping improved most substantially, reaching an average ionic conductivity modal value of 0.30 S cm⁻1 (Rangle 0.15,0.46) S cm−1;± 0.13 S cm⁻1, comparable to commercial liquid electrolytes. F doping enhanced lattice stability and facilitated Li⁺ ion mobility, while Ce doping improved structural integrity and reduced interfacial resistance. Comprehensive structural characterization confirmed the successful incorporation of dopants and favorable modification of the crystal lattice, facilitating enhanced Li⁺ ion mobility. Electrochemical performance evaluations using symmetrical half-cells demonstrated reduced charge transfer resistance and improved cycling stability, particularly in the Mo-doped variants. These findings underscore the effectiveness of molybdenum doping in mitigating interfacial resistance and promoting reliable ion transport in SSBs. Toxicity assessments revealed that using water as a solvent and natural extracts minimized the environmental footprint, aligning with sustainable synthesis practices. Our green nano-engineering approach not only advances the performance of solid-state electrolytes but also aligns with sustainable synthesis practices, paving the way for developing efficient and eco-friendly energy storage solutions. Additionally, our green nano-engineering approach was evaluated against traditional synthesis methods, demonstrating a 40% reduction in energy consumption and a 75% decrease in hazardous waste generation. This manuscript highlights the pivotal role of doped Li₃InCl₆ electrolytes in addressing current limitations of SSB technology, thereby contributing to the future of safe and high-capacity energy storage systems.

Solid-state lithium-ion batteries are a promising type of batteries for future applications. While replacing flammable liquid electrolytes with solid alternatives gives advantage to improved safety, the higher density of these solids compared to the currently used liquids is detrimental to the gravimetric energy density. Therefore, for sufficient battery cell performance thin and dense electrolyte layers of highly Li+ conductive material are needed. Currently, materials investigated for solid electrolyte application include ceramics, glasses and polymers. Ceramic Li7La3Zr2O12 (LLZO) with cubic garnet like crystal structure has emerged as one of the most promising materials as electrolyte. Its advantages include high Li+ conductivity and chemical stability vs. lithium metal anodes. The material can be synthesised by solid state reactions as well as various wet chemistry routes. The product usually obtained from all methods is a powder. Processing this powder into a thin electrolyte layer that is suitable for battery production proofs to be difficult. Physical vapour deposition methods (e.g. pulsed laser deposition or sputtering) have been used to create thin film layers of LLZO, but these methods are limited and not suitable for large scale production. Easier processing techniques (e.g. tape casting and extrusion) are found for solid polymer electrolytes, but so far ionic conductivities of solid polymer electrolytes fall short of ceramic and glass electrolytes. The objective of this study is to combine the advantages of ceramic and polymer electrolytes by fabrication of a hybrid solid state electrolyte. The hybrid mainly consists of LLZO and employs a polymer electrolyte as a binder. The aim is to produce a hybrid electrolyte for easier processing of solid-state batteries. Therefore, LLZO powder obtained from a facile wet chemistry synthesis route is mixed with solid polymer electrolyte. Thin hybrid electrolyte membranes are obtained using the tape casting method. Ceramic content of the hybrid electrolyte is varied up to 80-wt %. Both LLZO powders and the hybrid electrolytes are characterized in regard to structure and electrochemical performance. Phase composition and crystal structure of the prepared powder are checked using X-ray diffraction (XRD). Morphology of powders and microstructure of the hybrid electrolytes are investigated with scanning electron microscopy (SEM). Thermal behavior of the hybrid electrolytes is examined using differential scanning calorimetry (DSC). Electrochemical impedance spectroscopy (EIS) is used to evaluate the ionic conductivity and special attention is paid to the ceramic polymer interaction. Its influence on lithium ion transport is discussed in detail. We show that the combination of LLZO with polymer greatly simplifies the production of thin solid state electrolytes for lithium-ion batteries with only small losses in conductivity.

This review focuses on the promising technology of solid-state batteries (SSBs) that utilize lithium metal and solid electrolytes. SSBs offer significant advantages in terms of high energy density and enhanced safety. This review categorizes solid electrolytes into four classes: polymer, oxide, hybrid, and sulfide solid electrolytes. Each class has its own unique characteristics and benefits. By exploring these different classes, this review aims to shed light on the diversity of materials and their contributions to the advancement of SSB technology. In order to gain insights into the latest technological developments and identify potential avenues for accelerating the progress of SSBs, this review examines the intellectual property landscape related to solid electrolytes. Thus, this review focuses on the recent SSB technology patent filed by the main companies in this area, chosen based on their contribution and influence in the field of batteries. The analysis of the patent application was performed through the Espacenet database. The number of patents related to SSBs from Toyota, Samsung, and LG is very important; they represent more than 3400 patents, the equivalent of 2/3 of the world’s patent production in the field of SSBs. In addition to focusing on these three famous companies, we also focused on 15 other companies by analyzing a hundred patents. The objective of this review is to provide a comprehensive overview of the strategies employed by various companies in the field of solid-state battery technologies, bridging the gap between applied and academic research. Some of the technologies presented in this review have already been commercialized and, certainly, an acceleration in SSB industrialization will be seen in the years to come.

The emerging electrical applications and transportation electrification call for safe and energy-dense batteries with long lifespans and considerable power outputs. For the current graphite-majority LIBs, the anode takes up more than 30% of the mass ratio and around 50% of the volume ratio within the cell unit because of the low specific capacity of the graphite (theoretical capacity ~372 mAh g-1), leading to a low energy density around 200 Wh kg-1. Replacing the insertion-type graphite anode with the conversion-type Si anode (theoretical capacity ~3579 mAh g-1) [1] or the Li-metal anode (theoretical capacity ~3860 mAh g-1) could help reduce the mass and volume portion to less than 5% and 10%, respectively, which is thus of great significance for further promotion of the energy density (>350 Wh kg-1) at the cell level. Aside from the performance-related issues, the safety concerns of LIBs should also be well addressed. Therefore, solid state electrolytes have triggered worldwide interest in the past few years for its incomparable safety of anti-combustion and no leakage. Besides, the solid-state electrolytes could also boost the promotion of battery energy density.However, most of the current research about solid-states electrolytes adopt Li-metal as the anode. Though solid-state Li-metal batteries (SSLMBs) are acclaimed to have the highest gravimetric specific energy density theoretically, it is challenged by several critical issues. First, the Li-metal anode could not well address the dendrite issue, which limits the critical current density (< 0.5 mA cm-2) and areal capacities (< 0.5 mA cm-2) of the battery [2]. Secondly, most of the reported SSLMBs are carried out at high-temperature (60℃ or above) or with incredibly huge pressure (fabrication at > 200 MPa; operation at > 50 MPa) [3][4], which is not realistic in the common scenarios. Besides, nearly all the reported SSLMBs are tested with large Li-excess (low reversibility of Li-plaiting and stripping) and limited cathode loadings (inefficient conductivity), leading to unacceptable energy densities of the cells.Herein, we present that the Si-anode, which is not as widely as Li-metal studied in solid-state batteries, is a well-qualified candidate for the Li-metal for practical solid batteries. The pure Si anode (~2.1 mAh cm-2) with the solid electrolyte can be stably cycled at room temperature without external pressure for more than 150 cycles with no sharp capacity fade and a remained capacity over 1800 mAh g-1. The Si||LiFePO4 full cell adopting this electrolyte could achieves 120 stable cycles with high Coulombic efficiencies (>99.9%). This study shows that the in-situ polymerized solid electrolyte could be well matched with Si-anode for practical high energy density battery configuration. Acknowledgement The work described in this paper was fully supported by a grant from the Research Grants Council of the Hong Kong Special Administrbative Region, China (Project No. R6005–20). Reference [1] M.S. Kang, I. Heo, S. Kim, J. Yang, J. Kim, S.-J. Min, J. Chae, W.C. Yoo, High-areal-capacity of micron-sized silicon anodes in lithium-ion batteries by using wrinkled-multilayered-graphenes, Energy Storage Mater. 50 (2022) 234–242.[2] Q. Zhao, S. Stalin, C.Z. Zhao, L.A. Archer, Designing solid-state electrolytes for safe, energy-dense batteries, Nat. Rev. Mater. 5, (2020) 229–252.[3] D.H.S. Tan, Y.-T. Chen, H. Yang, W. Bao, B. Sreenarayanan, J. Doux, W. Li, B. Lu, S. Ham, B. Sayahpour, J. Scharf, E.A. Wu, G. Deysher, H.E. Han, H.J. Hah, H. Jeong, J.B. Lee, Z. Chen, Y.S. Meng, Carbon-free high-loading silicon anodes enabled by sulfide solid electrolytes, Science 373 (2021) 1494–1499.[4] Y. Ren, Z. Cui, A. Bhargav, J. He, A. Manthiram, A Self-Healable Sulfide/Polymer Composite Electrolyte for Long-Life, Low-Lithium-Excess Lithium-Metal Batteries, Adv. Funct. Mater. 2106680 (2021) 1–10. Figure 1