Conductivity Of Solid Polymer Electrolytes Research Articles

Amino‐Modified Porous Aromatic Frameworks for Enhanced Lithium‐Ion Dissociation and Transport in Polymer Electrolytes

Enhancing the ionic conductivity of solid polymer electrolytes and accelerating ion transport are pivotal challenges in achieving lithium‐ion batteries with high energy density and excellent electrochemical performance. In this study, amino‐modified porous aromatic frameworks (AMPAF) are prepared. The amino group in AMPAF stabilizes the anion through hydrogen bonding to reduce the dissociation energy barrier of Li+, enabling Li+ to be more easily dissociated from lithium salts. Additionally, the abundant pores of AMPAF promote the rapid transport of Li+. The prepared quasi‐solid polymer electrolyte (AMPAF‐QSPE) exhibited a high Li+ conductivity of 7.62 × 10−5 S cm−1 and a Li+ transference number as high as 0.55, which proves the restriction of the amino group in AMPAF on the movement of anions and the ability to dissociate lithium salts. The discharge specific capacity of Li//AMPAF‐QSPE//LiFePO4 reached as high as 137 mAh g−1 at 0.2 °C, and the capacity retention rate was stable at 85% after 200 cycles. This article presents an effective attempt to enhance the overall performance of polymer electrolytes using amino‐modified PAF, offering an innovative perspective for the development of electrochemical energy storage technologies.

ИЗУЧЕНИЕ ИОННОЙ ПРОВОДИМОСТИ СМЕСЕВЫХ КОМПОЗИЦИЙ НА ОСНОВЕ ПВДФ И ГБНК

The paper studies the ways of increasing ionic conductivity of solid polymer electrolytes based on polymer blends of polyvinylidene fluoride and hydrogenated butadiene nitrile rubber with lithium bis(trifle-orosulfonyl)imide prepared by solution watering method. The influence of polymer matrix composition, polymer molecular weight and amount of residual solvent on the ionic conductivity of the electrolytes has been studied.

Synergistic effect of ceramic filler in polymer salt complex for improved ion dissociation and migration mechanism

Abstract Use of Ceramic filler is one of the most common approaches to improve the conductivity and stability properties of a solid polymer electrolyte (SPE) cum separator. Among them, active fillers like Garnet have been extensively used to enhance the stability and conductivity of SPE. However, SPE suffers from limited ion migration at room temperature acting as a bottleneck for their application in all solid-state batteries. An extensive study on these fillers' role in ion dissociation and migration can be a stepping stone for advanced SPE. In the present work, an FTIR analysis has primarily been used to identify and evaluate cation coordinate site-cation, and ion pair interactions in a Li6.5La3Zr1.75Te0.25O12 loaded polyethylene oxide-LiCF3SO3 matrix with varying ceramic concentrations. Further, the Trukhan model has been used to calculate diffusion coefficient, mobility, and charge carrier density to interpret relaxation parameters, conductivity, and FTIR results in the SPE samples. Finally, an ion migration model has been proposed based on the results obtained in experimental studies.

Accelerating Lithium‐Ion Transfer and Sulfur Conversion via Electrolyte Engineering for Ultra‐Stable All‐Solid‐State Lithium–Sulfur Batteries

AbstractOffering ultrahigh energy density and exceptional safety, all‐solid‐state lithium–sulfur batteries (ASSLSBs) can be one of the most promising energy storage systems if their inherent challenges, including slow Li+ mass transport and insufficient sulfur utilization efficiency, are completely tackled. In this work, an amide‐based electrolyte additive with a high Gutmann donor number is used to construct a deep eutectic system, a “one‐stone‐two‐birds” solution to address these issues. In particular, an acetamide is used to interact with the insulative Li2S via a strong S─H bond and Li─O bond to boost the electrochemical reaction kinetics of lithium‐sulfur (Li─S) chemistry and sulfur utilization and simultaneously form a deep eutectic LiTFSI‐acetamide system to enhance ionic conductivity of solid polymer electrolytes (SPEs). Such a seamless integration of this system into the solid‐state LSBs helps deliver a high initial discharge specific capacity of 1012 mAh g−1 at 0.05 C and attain a stable cyclability for 1300 cycles at 0.1 C. This remarkable achievement in high performance and stability can effectively facilitate the commercialization of ASSLSBs.

Improvement of ionic conductivity of solid polymer electrolyte based on Cu−Al bimetallic metal-organic framework fabricated through molecular grafting

A composite solid electrolyte comprising a Cu−Al bimetallic metal-organic framework (CAB), lithium salt (LiTFSI) and polyethylene oxide (PEO) was fabricated through molecular grafting to enhance the ionic conductivity of the PEO-based electrolytes. Experimental and molecular dynamics simulation results indicated that the electrolyte with 10 wt.% CAB (PL-CAB-10%) exhibits high ionic conductivity (8.42×10−4 S/cm at 60 °C), high Li+ transference number (0.46), wide electrochemical window (4.91 V), good thermal stability, and outstanding mechanical properties. Furthermore, PL-CAB-10% exhibits excellent cycle stability in both Li−Li symmetric battery and Li/PL-CAB- 10%/LiFePO4 asymmetric battery setups. These enhanced performances are primarily attributable to the introduction of the versatile CAB. The abundant metal sites in CAB can react with TFSI− and PEO through Lewis acid–base interactions, promoting LiTFSI dissociation and improving ionic conductivity. Additionally, regular pores in CAB provide uniformly distributed sites for cation plating during cycling.

Non-flammable polymer electrolyte with fast ion conductivity for high-safety Li batteries

The safety and ionic conductivity of solid polymer electrolytes have hindered their large-scale application. Tetrabromobisphenol A (TBBA) is regarded as an efficient flame retardant for polymers. However, the -OH group of TBBA is active during electrochemical process and results in the sacrifice of capacity in battery cycling. Herein, a new organic filler, TBBA-dichlorobutane (TD) is generated by replacing the H of -OH in TBBA using the 1,4-dichlorobutane through copolymerization modification. The electrochemical stability of TD has been improved, which facilitates the generation of the solid electrolyte interphase (SEI) layer of LiBr, improving interface ionic conductivity. Meanwhile, the addition of TD significantly reduces the crystallinity of polyacrylonitrile (PAN), improving the ionic conductivity of the electrolyte. Furthermore, the electrochemical mechanism has been characterized by in-situ Raman and Fourier transform infrared (FT-IR) spectra, revealing the high stability and fast ion transfer ability of electrolytes. From the theoretical calculation (density functional theory (DFT), COMSOL, and molecular dynamics (MD)), the priority combination between lithium-ion and the bromine in PAN-TD (P-TD), as well as uniform lithium-ion flux, can be certified. Therefore, the LiFePO4//Li battery exhibits a specific capacity of 157 mA h g−1 at 0.5 C and maintains 154 mA h g−1 after 100 cycles. At the same time, the safety properties have been improved by the formation of the carbon layer and the capture of free radicals through bromine, exhibiting an oxygen index as high as 29 %.

Na2SO3 Salt Effect on The Ionic Conductivity of Solid Polymer Electrolyte (SPE) Based on Polyvinyl Alcohol

This research is about solid polymer electrolyte (SPE) based on polyvinyl alcohol (PVA) synthesized using a solution casting technique by adding variations of sodium sulfite salt and glycerol as fillers to reduce the samples' bulk resistance for electrochemical energy storage application. The method used is a quantitative analysis based on the test results. X-ray Diffraction (XRD) was used to determine the crystallinity and structure of the solid polymer electrolyte material. Interactions between Na+ ions from salts in SPE were analyzed using Fourier transform infrared (FTIR). The mechanical properties of the SPE samples were analyzed using tensile testing (ultimate tensile strength). Solid polymer electrolyte (SPE) ion conductivity was analyzed using electrochemical impedance spectroscopy (EIS) with temperature variations of 25, 40, 50, 60, and 70°C. The maximum SPE ionic conductivity value is 1.05 × 10-5 S cm-1 in a PVA-Glycerol-Na2SO3 15% sample at 70°C.

In Situ Generation of a Gel Polymer Electrolyte via the Controlled Formation of Ethylene Carbonate in a Poly(ethylene carbonate)‐Hydrogenated Nitrile Butadiene Rubber Solid Polymer Electrolyte

AbstractElectrolytes play an essential role in electrochemical energy storage devices. Liquid electrolytes have good ionic conductivity but tend to be flammable, prompting some of the safety concerns that are associated with these devices. Solid polymer electrolytes (SPEs) are presented as a potential solution to this problem. These materials have higher mechanical stability and can be formulated to be non‐flammable. However, ionic conductivity in solid polymer electrolytes tends to be several orders of magnitude lower than that of liquid electrolytes, significantly limiting device performance making electrolyte safety and performance difficult to optimize simultaneously. However, gel electrolytes which combine lower flammability, higher mechanical strength, and adequate ionic conductivity may present a solution to this challenge. To this end, the melt processing of hydrogenated nitrile rubber (HNBR) with poly(ethylene carbonate) (PEC) followed by the in situ formation of ethylene carbonate (EC) is reported. Conversion of PEC to EC is confirmed via NMR spectroscopy. Electrochemical testing reveals improved ionic conductivity following the conversion of the solid polymer electrolyte to the gel polymer electrolyte. Improvements in ionic conductivity, relative to the initial SPE, are attributed to decreased salt‐polymer interactions in favor of salt‐EC interactions as observed via differential scanning calorimetry, Fourier transform infrared, and nuclear magnetic resonance spectroscopy.

A novel hyperbranched polyurethane solid electrolyte for room temperature ultra-long cycling lithium-ion batteries

Low room temperature ionic conductivity of solid polymer electrolytes (SPE) greatly constraints its application in the solid lithium-ion batteries. Hyperbranched polymer with unique topological structure as matrix of SPE is expected to solve this issue due to its low crystallinity and rich functional groups which helps dissociation of lithium salt. Herein, a hyperbranched polyurethane (HPU) solid electrolyte is prepared by the reaction of hyperbranched polyethylene glycol and isophoradione diisocyanate in the presence of lithium salt and ionic liquid for the first time. The obtained HPU1.5-IL1.5 electrolyte possesses a high room temperature ionic conductivity of 0.4 mS cm−1 and a wide electrochemical window of 4.95 V (vs Li/Li+). It is worth noting that the prepared HPU1.5-IL1.5 electrolyte can be adapted to multiple electrodes. Specifically, the assembled LFP half-cell can achieve long cycling up to 1000 cycles at 0.5 C with 83 % capacity retention at room temperature. Notably, the NCM811|HPU1.5-IL1.5|Li cells and LTO|HPU1.5-IL1.5|Li cells can deliver the initial discharge capacity of 148 mAh g−1 at 0.1 C for 160 cycles and the initial discharge capacity of 150 mAh g−1 at 0.2 C for 440 cycles at room temperature, respectively. Meanwhile, the safety of the pouch cell has been confirmed under some extreme conditions.

A Step Towards the Impossible – the Combination of High Ionic Conductivity and Mechanical Stability in Highly Crystalline Solid Polyketone Electrolytes

Implementation of solid polymer electrolytes (SPEs) is believed to be one pathway forward in the development of lithium-metal batteries (LMBs) that are both safe and possesses high capacities. This combination is possible since the free-standing SPE maintains its mechanical integrity during electrochemical and thermal exposure while utilizing lithium metal as the negative electrode, thus accessing the extremely high theoretical capacity of lithium metal. The main drawback for SPEs are however the poor ionic conductivity compared to the liquid electrolytes used in lithium-ion batteries today.[1] The low ionic conductivity for SPEs stems from the conduction mechanism of the ions, which is a slower process in SPEs compared to in liquid electrolytes. In general, the conductivity in SPEs are confined to the amorphous regions, where segmental motion of the polymer chains facilitates the ion transport; while the crystalline regions restrict the movements of the polymer chains and impairs the ion transport.[2] The highly crystalline polyketone poly(1-oxoheptamethylene) (POHM) is a material that has shown interesting characteristics for implementation as a SPE in batteries. In earlier studies, the polyketone revealed an extensive improvement of the ionic conductivity upon increasing the salt concentration, although the crystallinity remained with a high melting point.[3] Herein this study, the effect of the crystallinity on the characteristics and the performance was investigated further. To understand its effect, a second less hydrogenated version of POHM was synthesized, POHM-75, which is fully amorphous at high salt concentrations. The characteristics of the polyketones were in addition also compared with the more well-studied SPEs, that is polyethylene oxide (PEO) and poly(trimethylene carbonate) (PTMC). Focus of the presentation is on the interplay between the ionic conductivity and mechanical stability for the polyketones, for which something different to the normally observed tradeoff between the two properties is observed. The electrochemical performance of the polyketones are furthermore evaluated when implemented as SPEs in LMBs at extreme temperature environments, a possible application area for mechanically stable SPEs.[1] D. Zhou, D. Shanmukaraj, A. Tkacheva, M. Armand, G. Wang, Chem 2019, 5, 2326-2352.[2] M. A. Ratner, P. Johansson, D. F. Shriver, MRS Bulletin 2011, 25, 31-37.[3] T. Eriksson, H. Gudla, Y. Manabe, T. Yoneda, D. Friesen, C. Zhang, Y. Inokuma, D. Brandell, J. Mindemark, Macromolecules 2022, 55, 10940-10949. Figure 1

Photo-Thermal Mediated Li-ion Transport for Solid-State Lithium Metal Batteries.

The development of lithium-based solid-state batteries (SSBs) has to date been hindered by the limited ionic conductivity of solid polymer electrolytes (SPEs), where nonsolvated Li-ions are difficult to migrate in a polymer framework at room temperature. Despite the improved cationic migration by traditional heating systems, they are far from practical applications of SSBs. Here, an innovative strategy of light-mediated energy conversion is reported to build photothermal-based SPEs (PT-SPEs). The results suggest that the nanostructured photothermal materials acting as a powerful light-to-heat converter enable heating within a submicron space, leading to a decreased Li+ migration barrier and a stronger solid electrolyte interface. Via in situ X-ray diffraction analysis and molecular dynamics simulation, it is shown that the generated heating effectively triggers the structural transition of SPEs from a highly crystalline to an amorphous state, that helps mediate lithium-ion transport. Using the assembled SSBs for exemplification, PT-SPEs function as efficient ion-transport media, providing outstanding capacity retention (96% after 150 cycles) and a stable charge/discharge capacity (140mAg-1 at 1.0C). Overall, the work provides a comprehensive picture of the Li-ion transport in solid polymer electrolytes and suggests that free volume may be critical to achieving high-performance solid-state batteries.

ИССЛЕДОВАНИЕ ТВЕРДЫХ ЭЛЕКТРОЛИТОВ НА ОСНОВЕ СМЕСИ ПОЛИМЕРОВ ПОЛИВИНИЛИДЕНФТОРИДА И ГИДРИРОВАННОГО БУТАДИЕН-НИТРИЛЬНОГО КАУЧУКА

The paper discusses the preparation of solid polymer electrolytes based on a blend of polyvinylidene fluoride and hydrogenated butadiene nitrile rubber with lithium bis(trifluorosulfonyl)imide prepared by solution casting technique. The films were characterized by X-ray diffraction analysis, FTIR spectroscopy, scanning electron microscopy, and differential scanning calorimetry. The influence of the polymer blend composition on the ionic conductivity of electrolytes was studied. According to the impedance spectroscopy data, it was found that the ionic conductivity of solid polymer electrolytes increases from 10-5 to 10-4 S/cm at room temperature with increasing the content of hydrogenated butadiene nitrile rubber up to 50 wt. % in the polymer blend matrix.

Ionic conductivity of solid polymer electrolytes depending on elongation

Research on solid polymer electrolytes (SPEs) based on poly(ethylene oxide) (PEO) is essential to propose an alternative to the conventional liquid electrolyte in order to increase both the mechanical properties and the ionic conductivity. Strategies to increase the ionic conductivity of SPEs are typically based on the development of new polymer architectures, lithium salt natures, plasticizers, or additives. In addition, applying an external field such as magnetic, electric, pressure, or a mechanical deformation onto the SPEs can alter the resulting ionic transport properties. For the later one, the main difficulty lies in obtaining the instantaneous evolution of the ionic conductivity coupled with the mechanical deformation and its geometrical change, especially when a striction domain appears. For this, a dedicated sample environment was designed to perform tensile tests in an inert atmosphere on SPE membranes at different temperatures (below and above the PEO melting temperature). Moreover, a methodology to calculate the instantaneous in-plane ionic conductivity is proposed based on COMSOL simulations to back out the sample geometrical changes during elongation. A strong impact on the in-plane ionic conductivity is observed when comparing PEO electrolyte architectures; from homopolymer to crosslinked single-ion conducting via binary conducting block copolymer electrolytes. Below the PEO melting temperature, a striction domain appears upon elongation whose conductivity is higher than the one of the bulk by a factor 1.7 and 18 for PEO homopolymer and binary conducting PEO-based block copolymer electrolytes, respectively.

The Deep Eutectic Solvent in Used Batteries as an Electrolyte Additive for Potential Chitosan Solid Electrolyte Membrane

The electrolyte or ion conductor acts as a bridge to transfer the ions the electrodes generate. In general, electrolytes are in the form of liquids. However, liquid electrolytes have drawbacks, including needing to be more practical and leaking quickly. Therefore, people switch to solid matrix electrolytes as battery electrolytes. An ideal solid electrolyte membrane must have chemical stability, thermal stability, high ionic conductivity, high flexibility, low cost, and abundant material availability. Lithium extraction from used batteries using Deep Eutectic Solvent (DES) was found to be an intelligent solvent. Mixing the method with lithium salt on a chitosan membrane can increase conductivity. This study aims to determine the lowest resistance value and highest conductivity of solid polymer electrolytes using Li2CO3 from used batteries. After separating the Lithium-Cobalt component from the used battery, it was extracted with deep DES solvent and precipitated using Na2CO3 to produce the Li2CO3 compound. Polymer electrolyte was synthesized by mixing polyvinyl alcohol and adding 0.2 grams, 0.4 grams, 0.6 grams, 0.8 grams, and 1 gram of chitosan. Li2CO3 variables are 0.2 grams, 0.4 grams, 0.6 grams, 0.8 grams, and 1 gram. The results showed that the higher content of chitosan and Li2CO3 led to an increase in ionic conductivity. These results concluded that the best solid electrolyte membrane was obtained with a variation ratio of 0.2 grams of chitosan with the addition of 1 gram of Li2CO3.

Inorganic Composites Improving Conductivities of Solid Polymer Electrolytes for Lithium Batteries: A Review

AbstractFor high‐energy‐density lithium batteries, the research and development of solid‐state electrolytes is crucial. Inorganic‐organic composite electrolytes with high mechanical strength and ionic conductivity of inorganic ceramic electrolytes, as well as high interfacial compatibility of polymer electrolytes, have become a current research hotspot. Based on a brief discussion of lithium dendrite growth and Li+ ion transport mechanisms, this article provides a comprehensive review of the nanostructure design and performance of inorganic‐organic composite electrolytes in recent years, and focuses on the mechanism of homogeneous monolayer composite electrolytes and heterogeneous multilayer composite electrolytes to enhance the performance of electrolytes. In addition, the future prospect of inorganic‐organic composite electrolytes is discussed, providing practical guidance for researchers in this field.

Measuring the ionic conductivity of solid polymer electrolyte powders

Ex-situ characterization of solid polymer electrolytes plays an important role in their development as materials for energy applications, with ionic conductivity being a crucial parameter to quantify. Conventional measurements of ionic conductivity often require the formation of a free-standing polymer film which in many instances is difficult to fabricate, thus there may be a need to quantify their ionic conductivity in powder form. In this work, we present a practical and reproducible method for measuring the ionic conductivity of solid polymer electrolytes (SPEs) in their powder form. By using a modified configuration of a through-plane cell, demonstrated with both a proton conducting- and an anion conducting-solid polymer electrolyte powder (SPEP), we are able to obtain ionic conductivity values under variable conditions in order to explore the influence of external parameters on the ionic conductivity of powders. Two types of SPEs in insoluble powder form were employed in this work: (1) a proton-exchange material (SPEP-H+) based on a hyperbranched, sulfo-phenylated poly(phenylene) SPEP (HB-sPPT-H+), with measured ionic conductivity of ⁓ 210 mS cm−1 at 80 °C and 95 % of relative humidity (RH); (2) an anion-exchange conducting polymer in its chloride form (SPEP-Cl-), consisting of a radiation-grafted ultra-high density polyethylene insoluble SPEP containing covalently-bonded benzyltrimethylammonium (BTMA) head-groups, with measured ionic conductivity of ⁓ 53 mS cm−1 at 80 °C and 95 % RH.

Nanoscale Confinement Effects on Ionic Conductivity of Solid Polymer Electrolytes: The Interplay between Diffusion and Dissociation.

Solid polymer electrolytes (SPEs) are attractive for next-generation lithium metal batteries but still suffer from low ionic conductivity. Nanostructured materials offer design concepts for SPEs with better performance. Using molecular dynamics simulation, we examine SPEs under nanoscale confinement, which has been demonstrated to accelerate the transport of neutral molecules such as water. Our results show that while ion diffusion indeed accelerates by more than 2 orders of magnitude as the channel diameter decreases from 15 to 2 nm, the ionic conductivity does not increase significantly in parallel. Instead, the ionic conductivity shows a nonmonotonic variation, with an optimal value above, but on the same order as, its bulk counterparts. This trend is due to enhanced ion association with decreasing channel size, which reduces the number of effective charge carriers. This effect competes with accelerated ion diffusion, leading to the nonmonotonicity in ion conductivity.

Versatile Zn-salt additive enabling superior solid polymer electrolyte for dendrite-free all-solid-state Li metal batteries

The development of all-solid-state rechargeable batteries is plagued by low ionic conductivity of solid polymer electrolytes and large interfacial resistance between electrolyte and Li metal anode. The introduction of versatile zinc bis(trifluoromethanesulfonyl)imide (Zn(TFSI)2) into polyethylene oxide (PEO) solid polymer electrolyte reduces the parasitic reaction with Li anode, increases the cycle life and allows a high rate performance of dendrite-free batteries. The competitive ion-dipolar interaction of Zn2+ promotes free Li+ transportation in PEO and enhances ion transfer number. Furthermore, the Zn2+ makes Li-Zn alloy in the solid electrolyte film by in-situ chemical reaction, this improves the mechanical modulus from 1.94 GPa to 38.47 GPa, homogenizes Li+ deposition and makes close electrolyte/Li metal contact. Benefiting from the structure and functional advantages, the Li/Li symmetric cell with a Zn(TFSI)2-contained electrolyte can achieve stable cycling over 600 h at a current density of 0.2 mA cm−1. The LiFePO4/Li cell can stably cycle over 900 cycles at 1 C rate at 60 °C. The idea of introducing Zn-salt for modifying PEO electrolytes may be extended to other all-solid-state batteries.

Poly (vinylidene fluoride) solid polymer electrolyte structure revealed by secondary ion mass spectrometry

Due to the processability safety, polymer-matrix composites can be considered as a solid polymer electrolytes and have attracted widespread attention. However, their electrical properties, as low ionic conductivity cannot meet the requirements of practical applications. Using the high energy mixing technique, the ionic conductivity was increased from 1.6 × 10 −6 to 9.4 × 10 −5 S cm −1 . The application of the Secondary Ion Mass Spectrometry technique revealed the distribution of lithium ions in the structure of the polymer matrix, which allows to directly connect the conductive properties and the homogeneity of the polymer composite. • High energy mixing technique increased conductivity of solid polymer electrolytes. • Increased conductivity results from changes in the structure of the composites. • Changes were detected and confirmed using the SIMS technique. • Secondary Ion Mass Spectrometry technique is an effective tool to assess charge carriers localization in composite materials.

Bifunctional LiI additive for poly(ethylene oxide) electrolyte with high ionic conductivity and stable interfacial chemistry

The development of polymer-based solid-state batteries is severely limited by the low ionic conductivity of solid polymer electrolyte and the instable interface between polymer electrolyte and Li-metal anode. In this work, lithium iodide (LiI) as a bifunctional additive was introduced into the poly(ethylene oxide) (PEO)-based electrolyte to improve the ionic conductivity and to construct a stable interphase at the Li/PEO interface. I− anions offer a strong electrostatic interaction with hydrogen atoms on PEO chains (HPEO) and forming massive I–H bonds that cross-link PEO chains, decrease crystallinity of PEO, and thus improve Li+ interchain transport. In addition, LiI participates in the formation of an inorganic-rich interphase layer, which decreases the energy barrier of Li+ transport across the interface and thus inhibits the growth of lithium dendrites. As a result, the composite PEO electrolyte with 2 wt% LiI (PEO-2LiI) presents a very high ionic conductivity of 2.1 × 10−4 S cm−1 and a critical current density of 2.0 mA cm−2 at 45 °C. Li symmetric cell with this PEO-2LiI electrolyte exhibits a long-term cyclability over 600 h at 0.2 mA cm−2. Furthermore, solid-state LiFePO4 and LiNi0.8Mn0.1Co0.1O2 batteries with the PEO-2LiI electrolyte show an impressive electrochemical performance with outstanding cycling stability and rate capability at 45 °C.