Electrolytes For Solid-state Batteries Research Articles

A locally solvent-tethered polymer electrolyte for long-life lithium metal batteries

Solid polymer electrolytes exhibit enhanced Li+ conductivity when plasticized with highly dielectric solvents such as N,N-dimethylformamide (DMF). However, the application of DMF-containing electrolytes in solid-state batteries is hindered by poor cycle life caused by continuous DMF degradation at the anode surface and the resulting unstable solid-electrolyte interphase. Here we report a composite polymer electrolyte with a rationally designed Hofmann-DMF coordination complex to address this issue. DMF is engineered on Hofmann frameworks as tethered ligands to construct a locally DMF-rich interface which promotes Li+ conduction through a ligand-assisted transport mechanism. A high ionic conductivity of 6.5 × 10−4 S cm−1 is achieved at room temperature. We demonstrate that the composite electrolyte effectively reduces the free shuttling and subsequent decomposition of DMF. The locally solvent-tethered electrolyte cycles stably for over 6000 h at 0.1 mA cm−2 in Li | |Li symmetric cell. When paired with sulfurized polyacrylonitrile cathodes, the full cell exhibits a prolonged cycle life of 1000 cycles at 1 C. This work will facilitate the development of practical polymer-based electrolytes with high ionic conductivity and long cycle life.

The role of chemo-mechanical modelling in the development of battery technology—a perspective

In the race to reduce global CO2 emissions and achieve net-zero, chemomechanics must play a critical role in the technological development of current and next-generation batteries to improve their energy storage capabilities and their lifetime. Many degradation processes arise through mechanics via the development of diffusion-induced stress and volumetric strains within the various constituent materials in a battery. From particle cracking in lithium-ion batteries to lithium dendrite-based fracture of solid electrolytes in solid-state batteries, it is clear that significant barriers exist in the development of these energy storage systems, where chemomechanics plays a central part. To accelerate technological and scientific advances in this area, multi-scale and highly coupled multiphysics modelling must be carried out that includes mechanics-based phenomena. In this perspective article, we provide an introduction to chemomechanical modelling, the various physical problems that it addresses, and the issues that need to be resolved in order to expand its use within the field of battery technology.

Lithium Superionic Conductive Nanofiber-Reinforcing High-Performance Polymer Electrolytes for Solid-State Batteries.

Although composite solid-state electrolytes (CSEs) are considered promising ionic conductors for high-energy lithium metal batteries, their unsatisfactory ionic conductivity, low mechanical strength, poor thermal stability, and narrow voltage window limit their practical applications. We have prepared a new lithium superionic conductor (Li-HA-F) with an ultralong nanofiber structure and ultrahigh room-temperature ionic conductivity (12.6 mS cm-1). When it is directly coupled with a typical poly(ethylene oxide)-based solid electrolyte, the Li-HA-F nanofibers endow the resulting CSE with high ionic conductivity (4.0 × 10-4 S cm-1 at 30 °C), large Li+ transference number (0.66), and wide voltage window (5.2 V). Detailed experiments and theoretical calculations reveal that Li-HA-F supplies continuous dual-conductive pathways and results in stable LiF-rich interfaces, leading to its excellent performance. Moreover, the Li-HA-F nanofiber-reinforced CSE exhibits good heat/flame resistance and flexibility, with a high breaking strength (9.66 MPa). As a result, the Li/Li half cells fabricated with the Li-HA-F CSE exhibit good stability over 2000 h with a high critical current density of 1.4 mA cm-2. Furthermore, the LiFePO4/Li-HA-F CSE/Li and LiNi0.8Co0.1Mn0.1O2/Li-HA-F CSE/Li solid-state batteries deliver high reversible capacities over a wide temperature range with a good cycling performance.

Unlocking the concentration polarization for Solid-State lithium metal batteries

Ceramic-polymer composite electrolytes for solid-state batteries are promising candidates due to the combination of safe reliability and mechanical flexibility. However, the sluggish lithium-ion transport and the inadequate electrochemical stability with high-voltage cathode materials limit the practical applications. Herein, we report a garnet-polymer solid electrolyte with high ionic conductivity and Li-ion transference number, favorable elasticity and good interface stability. A galvanostatic charge-relaxation process is designed to identify the inhibition effect of high Li-ionic transference number on concentration polarization and reveal its proportion to total polarization. By additionally adding lithium difluoro(oxalato)borate as stabilizer, the electrochemical window of the garnet-polymer composite electrolyte can extend to 5.3 V. The high cation conductivity and excellent antioxidant ability of composite electrolyte contribute to long cycling performance of LiNi0.8Mn0.1Co0.1O2 cathode at threshold voltage of 4.4 V. Furthermore, the pouch cell with high mass loading cathode and limited lithium anode was demonstrated successfully. Our findings provide an effective strategy on fabricating solid-state lithium-metal batteries towards practical applications.

Hybrid Electrolyte Based on PEO and Ionic Liquid with In Situ Produced and Dispersed Silica for Sustainable Solid-State Battery

This work introduces the synthesis of hybrid polymer electrolytes based on polyethylene oxide (PEO) and electrolyte solution bis(trifluoromethane)sulfonimide lithium salt/ionic liquid 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide (LiTFSI/EMIMTFSI) with in situ produced and dispersed silica particles by the sol–gel method. Conventional preparation of solid polymer electrolytes was followed by desolvation of lithium salt in a polymer matrix of PEO, which, in some cases, additionally contains plasticizers. This one-pot synthesis is an alternative route for fabricating a solid polymer electrolyte for solid-state batteries. The presence of TFSI- reduces the crystallinity of the PEO matrix (plasticizing effect), increases the dissociation and solubility of LiTFSI in the PEO matrix because of a highly delocalized charge distribution, and reveals excellent thermal, chemical, and electrochemical stability. Tetraethylorthosilicate (TEOS) was chosen due to the slow reaction rate, with the addition of (3-glycidyoxypropyl)trimethoxysilane (GLYMO), which contributes to the formation of a silica network. FTIR studies confirmed the interactions between the silica, the polymer salt, and EMIMTFSI. Impedance spectroscopy measurements were performed in a wide range of temperatures from 25 to 70 °C. The electrochemical performance was explored by assembling electrolytes in LiCoO2 (LCO), NMC(811), and LiFePO4 (LFP) coin half-cells. The HPEf15 shows a discharge capacity of 143 mA/g for NMC(811) at 0.1 C, 134 mA/g for LCO, and 139 mA/g for LFP half-cells at 0.1 C and 55 °C. The LFP half-cell with a discharge capacity of 135 mA/g at 0.1 C (safety potential range of 2.8 to 3.8) obtained a cyclability of 97.5% at 55 °C after 100 cycles. Such a type of electrolyte with high safety and good electrochemical performance provides a potential approach for developing a safer lithium-ion battery.

Characterization of Li+ Transport through the Organic-Inorganic Interface by using Electrochemical Impedance Spectroscopy

Understanding Li+ transport at polymer||inorganic interfaces is crucial for developing composite electrolytes in solid-state batteries. In our investigation, we employed impedance spectroscopy and established a multilayer methodology for assessing Li+ transport at this interface. The inorganic phase chosen was Li6.25Al0.25La3Zr2O12 (Al−LLZO), and the organic phase comprised a Poly(ethylene oxide) (PEO) network with dangling chains. Li+ incorporation in the polymer, as a free either salt or associated with anion grafting onto the PEO network, was explored. Additionally, the PEO network was either pressure-adhered to the inorganic surface (ex-situ configuration) or synthesized onto the Al−LLZO surfaces (in situ configuration) to investigate processing effects on Li+ transport. Using a Transmission Line Model for impedance data analysis, our study identified two key elements governing Li+ transport at the interface: Ri, representing resistance along the ionic pathway, and Rt and Ct, describing distributed resistance and capacitance within the interface. We observed that Ri is influenced by the polymerization process in the presence of Al−LLZO ceramic, while Rt remains constant regardless of the synthesis method. This suggests varying Li+ concentrations at the interphase in the in situ configuration, while interface/interphase heterogeneity remains consistent across configurations. The estimated activation energy indicates more energetically favorable direct Li+ transport in the in−situ configuration.

Direct wetting of Li7La3Zr2O12 electrolyte with molten Li anode and its application in solid-state lithium batteries

Garnet Li6.5La3Zr1.5Ta0.5O12 (LLZTO) is a promising solid electrolyte for solid-state batteries (SSBs) owing to its high ionic conductivity and high chemical/electrochemical stability. However, the solid-to-solid interface between LLZTO electrolyte and Li anode restricts its application. In this work, an in-situ integration of LLZTO electrolyte with Li anode is proposed to solve this problem. Superior to reported works, the LLZTO obtained by our self-consolidation method can be directly wetted by molten Li without any surface treatment. The self-consolidated LLZTO exhibits a dense microstructure consisting of grains and interstitial phases among them, both of which are accessible to molten Li. Removal of surface contaminants on molten Li rather than that on LLZTO is a prerequisite for direct wetting. Benefiting from direct wetting, an intimate interfacial contact between the LLZTO and Li anode is achieved and the interfacial resistance is significantly reduced. The Li symmetric cell exerts a stable Li plating/stripping cycle for 1000 h at 0.20 mA cm−2 and the solid-state battery paired with LiCoO2 cathode exhibits a capacity retention of 90.0 % at 0.2 C after 200 cycles at room temperature. This work highlights the surface chemistry of electrolyte and electrode, which is crucial for designing their integration and application.

Lithium Dendrite Propagation in Ta-Doped Li7La3Zr2O12 (LLZTO): Comparison of Reactively Sintered Pyrochlore-to-Garnet vs LLZTO by Solid-State Reaction and Conventional Sintering.

Ta-doped Li7La3Zr2O12 (LLZTO) garnet is a promising Li-ion-conducting ceramic electrolyte for solid-state batteries. However, it is still challenging to use LLZTO in Li metal batteries operating at high current densities because of the tendency for Li metal to nucleate and propagate along the grain boundaries. In this study, we carry out a detailed investigation to elucidate the effect of microstructure and grain size on the electrochemical properties and short circuit behavior in LLZTO. Pellets were prepared using reactive sintering from pyrochlore precursors (a method called pyrochlore-to-garnet, P2G) and compared with LLZTO synthesized using solid-state reaction (SSR) followed by conventional pressureless sintering. Both preparation methods were controlled to keep the phase and elemental composition, ionic and electronic conductivity, relative density, and area-specific resistance of the pellets constant. Reflection electron energy loss spectroscopy and X-ray photoelectron spectroscopy confirm that both types of LLZTO have similar band gaps and chemical states. Microstructure analysis shows that the P2G method results in LLZTO with an average grain size of around 3 μm, which is much smaller than the grain sizes (as large as 20 μm) seen in SSR LLZTO. Galvanostatic Li stripping/plating and linear sweep voltammetry measurements show that P2G LLZTO can withstand higher critical current densities (up to 0.4 mA/cm2 in bidirectional cycling and >1 mA/cm2 for unidirectional) than those seen in SSR LLZTO. Post-mortem examination reveals much less Li deposition along the grain boundaries of P2G LLZTO, particularly in the bulk of the pellet, compared to SSR LLZTO after cycling. The improved cycling behavior in P2G LLZTO despite the higher grain boundary area could be from more homogeneous current density at the interfaces and different grain boundary properties arising from the liquid-phase, reactive sintering method. These results suggest that the effect of grain size on Li dendrite propagation in LLZO may be highly dependent on the synthesis and sintering method employed.

Nanoscale Ion Transport Enhances Conductivity in Solid Polymer-Ceramic Lithium Electrolytes.

The predictive design of flexible and solvent-free polymer electrolytes for solid-state batteries requires an understanding of the fundamental principles governing the ion transport. In this work, we establish a correlation among the composite structures, polymer segmental dynamics, and lithium ion (Li+) transport in a ceramic-polymer composite. Elucidating this structure-property relationship will allow tailoring of the Li+ conductivity by optimizing the macroscopic electrochemical stability of the electrolyte. The ion dissociation from the slow polymer segmental dynamics was found to be enhanced by controlling the morphology and functionality of the polymer/ceramic interface. The chemical structure of the Li+ salt in the composite electrolyte was correlated with the size of the ionic cluster domains, the conductivity mechanism, and the electrochemical stability of the electrolyte. Polyethylene oxide (PEO) filled with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) or lithium bis(fluorosulfonyl) imide (LiFSI) salts was used as a matrix. A garnet electrolyte, aluminum substituted lithium lanthanum zirconium oxide (Al-LLZO) with a planar geometry, was used for the ceramic nanoparticle moieties. The dynamics of the strongly bound and highly mobile Li+ were investigated using dielectric relaxation spectroscopy. The incorporation of the Al-LLZO platelets increased the number density of more mobile Li+. The structure of the nanoscale ion-agglomeration was investigated by small-angle X-ray scattering, while molecular dynamics (MD) simulation studies were conducted to obtain the fundamental mechanism of the decorrelation of the Li+ in the LiTFSI and LiFSI salts from the long PEO chain.

Impact of optimised quasi-block structures on the properties of polymer electrolytes.

A set of ionic quasi-block copolymers were investigated to determine the effects of their composition and structure on their performance in their application as solid-state battery electrolytes. Diffusion and electrochemical tests have shown that these new quasi-block electrolytes have comparable performance to traditional block copolymers reaching ionic conductivities of 3.8 × 10-4 S cm-1 and lithium-ion diffusion of 4.6 × 10-12 m2 s-1 at 80 °C. It was illustrated that the mechanical properties of each quasi-block electrolyte are highly dependent on the order of monomer addition in polymer synthesis while the phase morphology hints at each of the quasi-blocks' unique compositional make up.

Understanding the role of aliovalent cation substitution on the li-ion diffusion mechanism in Li6+xP1-xSixS5Br argyrodites.

Due to their high ionic conductivity, lithium-ion conducting argyrodites show promise as solid electrolytes for solid-state batteries. Aliovalent substitution is an effective technique to enhance the transport properties of Li6PS5Br, where aliovalent Si substitution triples ionic conductivity. However, the origin of this experimentally observed increase is not fully understood. Our density functional theory (DFT) study reveals that Si4+ substitution increases Li diffusion by activating Li occupancy in the T4 sites. Redistribution of Li-ions within the lattice results in a more uniform distribution of Li around the T4 and neighboring T5 sites, flattening the energy landscape for diffusion. Since the T4 site is positioned in the intercage jump pathway, an increase in the intercage jump rate is found, which is directly related to the macroscopic diffusion and bulk conductivity. Analysis of neutron diffraction experiments confirms partial T4 site occupancy, in agreement with the computational findings. Understanding the aliovalent substitution effect on interstitials is crucial for improving solid electrolyte ionic conductivity and advancing solid-state battery performance.

Long-Cycle Stability of In Situ Ultraviolet Curable Organic/Inorganic Composite Electrolyte for Solid-State Batteries.

Lithium-ion solid-state batteries with spinel Li4Ti5O12 (LTO) electrodes have significant advantages, such as stability, long life, and good multiplication performance. In this work, the LTO electrode was obtained by the atmospheric plasma spraying method, and a composite solid electrolyte was prepared by in situ ultraviolet (UV) curing on the LTO electrode. The composite solid electrolyte was designed using a soft-hard combination strategy, and the electrolyte was prepared into a composite of a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) flexible structure and high-conductivity Li1.3Al0.3Ti1.7(PO4)3 (LATP) hard particles. The composite electrolyte exhibited a good ionic conductivity up to 0.35 mS cm-1 at 30 °C and an electrochemical window above 4.0 V. In situ and ex situ electrolytes were assembled into LTO//electrolyte//Li solid-state batteries to investigate their impact on the electrochemical performance of the batteries. As a result, the assembled Li4Ti5O12//in situ electrolytes//Li batteries exhibited excellent rate of performance, and their capacity retention rate was 90% at 0.2 mA/cm2 after 300 cycles. This work provides a new method for the fabrication of novel advanced solid-state electrolytes and electrodes for applications in solid-state batteries.

Chemical and Electrochemical Interaction of Halide and Sulfide-Based Electrolytes in Solid-State Batteries

Introduction Conventional lithium-ion batteries (LIBs) have found widespread small and large applications. However, safety issues and capacity degradation of the cells, in general, can occur due to the use of toxic and flammable liquid electrolytes [1]. As one of the next-generation LIBs, solid-state lithium batteries (SSBs) have the potential to replace liquid electrolyte LIBs due to their safety and potentially high energy density [2]. The key component of SSBs is the solid-state electrolyte (SSE). Sulfide and halide-based solid electrolytes are among the hot topics in solid electrolyte research for SSBs. Despite the advantages of solid electrolytes, such as good compatibility with high-voltage cathode materials and soft fabrication. However, the poor chemical and electrochemical stability of sulfide and halide-based solid electrolytes towards Li metal has a critical problem that causes the degradation of the lithium/solid electrolyte interface due to the formation of side reaction components that leads to inhibiting lithium kinetics [3]. Results and Discussion Here, we have shown that a combination of halide and argyrodite (Li6PS5Cl) solid electrolytes can lead to the prevention of the formation of unfavorable interactions between solid electrolytes and lithium metal anode. The combination of halide and argyrodite (Li6PS5Cl) in the Li/Li symmetric cell can stabilize cycle life and increase the high critical current density (CCD) from C/20 to C/2 in comparison with the pure halide and argyrodite electrolytes. Furthermore, compared to the original halide and argyrodite electrolytes, a high initial coulombic efficiency and cycle life can be maintained when combined with a full Li/NCM cell. This approach to improving halide-based SSBs can provide a fairly simple and efficient strategy. Acknowledgements This project has received funding from the European Union's Horizon Europe programme for research and innovation under grant agreement No. 101069681 (HELENA project).

(Invited) Strategies for Enhancing the Stability of the Electrode-Electrolyte Interphase in Sulfide-Based Solid-State Batteries

In recent years, all solid-state batteries (SSBs) have gained significant attention as the next-generation energy storage device due to their high energy density, improved safety, and enhanced stability. Sulfide-based solid electrolytes (SEs) have garnered significant attention among various inorganic materials for their exceptional properties, including high ionic conductivity and robust mechanical properties. These features make them promising candidates for SSBs, ensuring both manufacturability and long-term cycle life. For example, Li-argyrodites (e.g., Li6PS5X, and X = Cl, Br, I) and Na-thioantimonate (e.g., Na2.88Sb0.88W0.12S4) offer high ionic conductivities (> 10-3 S/cm) that are comparable to those of liquid electrolytes. However, its practical application is still under-achieved due to a few technical challenges. Among the various issues, our focus is on the electrode-electrolyte interphase, which degrades the cycle life of the SSBs.At the cathode-electrolyte interphase, narrow electrochemical window (1.71 V – 2.01 V) of Li6PS5X unwantedly prompt the oxidative decomposition of solid-electrolyte. At the anode-electrolyte interphase, Li-argyrodite SEs can be easily reduced by Li metal or oxidized by cathode active materials because of its narrow electrochemical window (1.71 V – 2.01 V). The resulting byproducts at electrode-electrolyte interphases can unwantedly lead to capacity fading and an increase in cell resistance. Additionally, SSBs made with the Li-argyrodite SEs suffer from Li-dendrite penetration during repeated cycles and consequent internal short circuits.To address these challenges, we propose strategies for passivating the interphases between the cathode and the solid electrolyte, as well as between the metallic anode and the electrolyte in solid-state batteries (SSBs). Through a combinatorial study, we aim to elucidate the extent and severity of interfacial side reactions in solid-state batteries (SSBs). In addition, the optimal coating strategies of LiNbO3 for cathodes and Li3N coating on metallic Li anode will be discussed. The optimized Li3N as an artificial solid electrolyte interphase (SEI) layer on the metallic Li anode enables more than 5000 cycles without failure in symmetrical cells.Furthermore, we will also highlight a strategy for passivating the electrode-electrolyte interphases of Na-based solid-state batteries (SSBs) that employ thioantimoniate as the electrolyte material. The approaches to passivate the cathode and metallic Na anode will be presented. Comprehensive electrochemical and spectroscopic studies will be conducted to identify the source of degradation and elucidate the improvement mechanisms associated with each strategy.

Solid-State Polymer Battery: Manufacturing Process and Characterization

Solid-state batteries are a promising technology that could provide higher energy density, better safety, longer cycle life and a wider operating temperature range than current commercial LiBs [1] .The solid electrolyte is the main component of all-solid-state batteries. It can be ceramic, glass, polymer, or a mixture. Solid Polymer Electrolyte (SPEs) have received distinctive attention, especially by industry, owing to their potential advantages such as safety, lightweight, high flexibility, and realistic processability. However, despite fast growing interest in solid-state technology, reports on the scalable production of all-solid-state lithium-ion batteries using electrodes with meaningful areal capacities are rather scarce [2] . Moreover, chemical, and mechanical challenges remain. The intimate contact between the electrode and the solid electrolyte is difficult due its non-infiltrative nature. This lack of intimate contact severely limits the cycling properties [3] . The development of effective strategies to alleviate the issue of physical contact is imperative in the engineering of solid-state batteries [4] .In the frame of SAFELiMOVE (Advanced all Solid stAte saFE Lithium Metal technology tOwards Vehicle Electrification) project, we assemble a solid-state pouch based on lithium metal anode, a solid polymer electrolyte layer and a compatible cathode. In work, we report on a reliable fabrication process of large-scale all-solid-state lithium-ion batteries using cathodes prepared by CIDETEC, lithium anode provided by Hydro-Quebec, polymers provided by CICe, inorganic filler provided by SCHOTT and a solid polymer electrolyte manufactured at SAFT.All-solid-state lithium-ion battery pouch cells have been successfully built with consistent electrochemical performance. Cycling that shows the good performance of those cells and the lesson learned regarding their cycling conditions will be presented. [1] J. Motalli, “A solid future Nature, 526, S96 (2015) [2] Ningxin Zhang et al “Scalable preparation of practical 1Ah all-solid-state lithium-ion batteries cells and their abuse tests”, Journal of Energy Storage 59 (2023) 106547 [3] Li et al.“Atomically Intimate Contact between Solid Electrolytes and Electrodes for Li Batteries” Mater 1, 1001-1016, October 2, 2019. [4] Theodosios Famprikis, Pieremanuele Canepa, James A. Dawson, M. Saiful Islam and Christian Masquelier“Fundamentals of inorganic solid-state electrolytes for batteries” Nature Materials-August 2019. Figure 1

Electrical and ionic conductivity of Li2O-B2O3-Al2O3 glass electrolyte for solid-state batteries

Solid-state electrolyte is a key component for all-solid-state lithium-ion batteries. The Li2O-B2O3-Al2O3 has been prepared, which is co-sinterable with electrode due to its low sintering temperature (520 °C). The as-prepared Li2O-B2O3-Al2O3 reveals glass transition temperature of 420 °C and crystallization temperature of 462 °C. The Li2O-B2O3-Al2O3 possess the reasonable electrochemical performances such as lithium-ion conductivity of 3.075 × 10−5 S/cm, activation energy of 0.72 eV, electronic conductivity of 4.102 × 10−5 S/cm. It is attributed to the particle morphology, grain-to-grain bonding and non-bridging oxygen. Our finding demonstrates that Li2O-B2O3-Al2O3 is an effective breakthrough in solid electrolyte for good electrochemical performances as well as excellent interfacial contact through co-sintering.

Viscoelastic inorganic glass as solid-state electrolyte for batteries

A most recent exciting research result in the area of solid-state batteries that has been accepted for publication by the journal Nature Energy is highlighted. The research designed a new type of inorganic solid electrolyte named “viscoelastic inorganic glass (VIGLAS)” electrolyte with the compositions of LiAlCl2.5O0.75 and NaAlCl2.5O0.75. The newly developed solid electrolyte material showcases an exceptional degree of deformability at room temperature, high ionic conductivity (>1 mS/cm at room temperature) and high oxidation stability (up to 4.3 V vs. Li+/Li or Na+/Na). Using it as a catholyte enables a facile fabrication and a stable operation under practical stack pressure (＜0.1 MPa) of all-solid-state batteries. VIGLAS represents a new path in the design of promising solid electrolytes for realizing high performance all-solid-state batteries.

Lithium Transport Studies on Chloride-Doped Argyrodites as Electrolytes for Solid-State Batteries.

In this study, the activation energy and ionic conductivity of the Li6PS5Cl material for all-solid-state batteries were investigated using solid-state nuclear magnetic resonance (NMR) spectroscopy and electrochemical impedance spectroscopy (EIS). The results show that the activation energy values estimated from nuclear relaxation rates are significantly lower than those obtained from impedance measurements. The total ionic conductivities for long-range lithium diffusion in Li6PS5Cl calculated from EIS studies depend on the crystal size and unit cell parameter. The study also presents a new sample preparation method for measuring activation energy using temperature-dependent EIS and compares the results with the solid-state NMR data. The activation energy for a thin-film sample is equivalent to the long-range lithium dynamics estimated from NMR measurements, indicating the presence of additional limiting processes in thick pellets. Additionally, a theoretical model of Li-ion hopping based on results obtained using density-functional theory methods in comparison with experimental findings was discussed. Overall, the study emphasizes the importance of sample preparation methods in determining accurate activation energy and ionic conductivity values for solid-state lithium batteries and the significance of solid-state electrolyte thickness in new solid-state battery design for faster Li-ion diffusion.

Influence of the LLZO–PEO interface on the micro- and macro-scale properties of composite polymer electrolytes for solid-state batteries

Li7La3Zr2O12 (LLZO) garnets offering high ionic conductivity and electrochemical stability are among the most promising ceramic materials for lithium metal solid-state batteries. Although their application in composite polymer electrolytes (CPEs) with poly(ethylene oxide) (PEO) has been widely studied, their surface chemistry which is influenced by their hygroscopic nature is often neglected. This work reports on how the thermal treatment and the consequent elimination of secondary phases at the LLZO–PEO interface impacts the microstructure of the garnet-rich CPEs, which in turn affects their mechanical and ion-transport properties. It is shown that LLZO heat treatment restricts local polymer chain motions, indicating reinforcement of PEO/LLZO interactions which enhances the mechanical strength and homogeneity of the CPEs. These micro-scale modifications of CPEs eventually increase their ionic conductivity and improve the solid electrolyte/lithium metal interface. Thus, the Li+ exchange at the PEO/LLZO interface was studied by using 7Li–7Li exchange spectroscopy– nuclear magnetic resonance , and it was observed that after LLZO heat treatment, the interfacial Li+ exchange has significantly decreased, in line with a lower LiOH content. This result confirms the role of LiOH as an intermediate in the Li+ exchange reaction and that surface chemistry plays a more important role in the Li+ exchange than the local Li mobilities in the individual phases.

A Review of Solid-State Proton-Polymer Batteries: Materials and Characterizations.

The ever-increasing global population necessitates a secure and ample energy supply, the majority of which is derived from fossil fuels. However, due to the immense energy demand, the exponential depletion of these non-renewable energy sources is both unavoidable and inevitable in the approaching century. Therefore, exploring the use of polymer electrolytes as alternatives in proton-conducting batteries opens an intriguing research field, as demonstrated by the growing number of publications on the subject. Significant progress has been made in the production of new and more complex polymer-electrolyte materials. Specific characterizations are necessary to optimize these novel materials. This paper provides a detailed overview of these characterizations, as well as recent advancements in characterization methods for proton-conducting polymer electrolytes in solid-state batteries. Each characterization is evaluated based on its objectives, experimental design, a summary of significant results, and a few noteworthy case studies. Finally, we discuss future characterizations and advances.