Transferring Lithium Ions in Nanochannels: A PEO/Li + Solid Polymer Electrolyte Design

Microporous Materials in Polymer Electrolytes: The Merit of Order

Solid-state batteries (SSBs) have garnered significant attention in the critical field of sustainable energy storage due to their potential benefits in safety, energy density, and cycle life. The large-scale, cost-effective production of SSBs necessitates the development of high-performance solid-state electrolytes. However, the manufacturing of SSBs relies heavily on the advancement of suitable solid-state electrolytes. Composite polymer electrolytes (CPEs), which combine the advantages of ordered microporous materials (OMMs) and polymer electrolytes, meet the requirements for high ionic conductivity/transference number, stability with respect to electrodes, compatibility with established manufacturing processes, and cost-effectiveness, making them particularly well-suited for mass production of SSBs. This review delineates how structural ordering dictates the fundamental physicochemical properties of OMMs, including ion transport, thermal transfer, and mechanical stability. The applications of prominent OMMs are critically examined, such as metal-organic frameworks, covalent organic frameworks, and zeolites, in CPEs, highlighting how structural ordering facilitates the fulfillment of property requirements. Finally, an outlook on the field is provided, exploring how the properties of CPEs can be enhanced through the dimensional design of OMMs, and the importance of uncovering the underlying "feature-function" mechanisms of various CPE types is underscored.

NMR studies of lithium and sodium battery electrolytes

This review focuses on the application of nuclear magnetic resonance (NMR) spectroscopy in the study of lithium and sodium battery electrolytes. Lithium-ion batteries are widely used in electronic devices, electric vehicles, and renewable energy systems due to their high energy density, long cycle life, and low self-discharge rate. The sodium analog is still in the research phase, but has significant potential for future development. In both cases, the electrolyte plays a critical role in the performance and safety of these batteries. NMR spectroscopy provides a non-invasive and non-destructive method for investigating the structure, dynamics, and interactions of the electrolyte components, including the salts, solvents, and additives, at the molecular level. This work attempts to give a nearly comprehensive overview of the ways that NMR spectroscopy, both liquid and solid state, has been used in past and present studies of various electrolyte systems, including liquid, gel, and solid-state electrolytes, and highlights the insights gained from these studies into the fundamental mechanisms of ion transport, electrolyte stability, and electrode-electrolyte interfaces, including interphase formation and surface microstructure growth. Overviews of the NMR methods used and of the materials covered are presented in the first two chapters. The rest of the review is divided into chapters based on the types of electrolyte materials studied, and discusses representative examples of the types of insights that NMR can provide.

Lithiated Phosphoryl Cellulose Nanocrystals Enhance Cycling Stability and Safety of Quasi-Solid-State Lithium Metal Batteries

Cycling stability and safety are two of the main challenges facing lithium metal batteries with metallic lithium as anodes. Quasi-solid-state lithium metal batteries based on gel polymer electrolytes are one of the important development directions for lithium metal batteries addressing those challenges. Herein, we prepare lithiated phosphoryl cellulose nanocrystals (PCNC-Li) as a modification material for poly(vinylidene fluoride) (PVDF) gel polymer electrolyte to improve cycling stability and safety of quasi-solid-state lithium metal batteries. The synthesized PCNC-Li tends to form a uniform network structure on the surface of the PVDF membrane, in which the phosphoryl groups grafted regularly on celluloses can regulate the transport of lithium ions. As a result, a more uniform ion flux and more stable lithium anode interface support an obviously improved cycling stability for lithium metal batteries. Moreover, the introduction of the PCNC-Li coating layer makes the modified PVDF membranes have a better thermal stability and an enhanced mechanical strength, which is beneficial for improvement of safety of lithium metal batteries. This work provides a new alternative to fabricating a better composite gel polymer electrolyte for lithium metal batteries.

Three-dimensional polyimide nanofiber framework reinforced polymer electrolyte for all-solid-state lithium metal battery

The replacement of traditional liquid electrolytes with polyethylene oxide (PEO) based composite polymer electrolytes (CPEs) is an important strategy to address the current flammability and explosiveness of lithium batteries since PEO CPEs have high flexibility, excellent processability and moderate cost. However, the insufficient ionic conductivity and inferior mechanical strength of PEO CPEs do not suit the operating requirements of all-solid-state lithium metal batteries at room temperature. Herein, three-dimensional (3D) framework composed of interweaved high-modulus polyimide (PI) nanofibers along with functional succinonitrile (SN) plasticizers are employed to synergistically reinforce the ionic conductivity and mechanical strength of PEO CPEs. Impressively, benefitting from the synergistic effects of 3D PI framework and SN plasticizer, PI-PEO-SN CPEs exhibits high ionic conductivity of 1.03 × 10^-4 S cm^-1 at 30 °C, remarkable tensile strength of 4.52 MPa, and superior Li dendrites blocking ability (>400 h at 0.1 mA cm^-2). Such favorable features of PI-PEO-SN CPEs endow LiFePO₄/PI-PEO-SN/Li solid-state prototype cells with high specific capacity (151.2 mA h g^-1 at 0.2 C), long cycling lifespan (>150 cycles with 91.7 % capacity retention), and superior operating safety even under bending, folding and cutting harsh conditions. This work will pave the avenues to design and fabricate new high-performance PEO CPEs for the high energy density and safety all-solid-state batteries.

Natural Pyranosyl Materials: Potential Applications in Solid-State Batteries

Solid-state batteries have become one of the hottest research areas today, due to the use of solid-state electrolytes enabling the high safety and energy density. Because of the interaction with electrolyte salts and the abundant ion transport sites, natural polysaccharide polymers with rich functional groups such as -OH, -OR or -COO^- etc. have been applied in solid-state electrolytes and have the merits of possibly high ionic conductivity and sustainability. This review summarizes the recent progress of natural polysaccharides and derivatives for polymer electrolytes, which will stimulate further interest in the application of polysaccharides for solid-state batteries.

Probing distribution and dynamics of lithium ions in supermolecule β-CD-PEO/Li+ solid polymer electrolytes via solid-state NMR

In this work, the distribution and dynamics of Li⁺ ions in β-CD-PEO/Li⁺ (β-CD, β-cyclodextrin; PEO, polyethylene-oxides) crystalline polymer electrolytes were investigated by solid-state NMR to enlighten the ionic conduction mechanism. Specifically, ⁷Li-⁶Li REDOR NMR and variable-contact-time ¹H-⁶Li CP/MAS NMR were adopted for the study. The results demonstrate that Li⁺ ions coordinated by polymer chains have relatively compact spatial density and fast dynamics, which facilitate the improvement of the electrochemical properties. Additionally, the variation of the distribution and dynamics of the Li⁺ ions and the ionic conduction mechanism were studied and discussed by altering the amount of the Li⁺ ions. This work deepens our understanding of the distribution and dynamics of Li⁺ ions in β-CD-PEO/Li⁺ crystals and demonstrates possible future applications of solid-state NMR on the study of the polymer electrolytes.

A Review of Applications of Solid-State Nuclear Magnetic Resonance (ssNMR) for the Analysis of Cyclodextrin-Including Systems

Cyclodextrins, cyclic oligosaccharides composed of five or more α-D-glucopyranoside units linked by α-1,4 glycosidic bonds, are widely used both in their native forms as well as the components of more sophisticated materials. Over the last 30 years, solid-state nuclear magnetic resonance (ssNMR) has been used to characterize cyclodextrins (CDs) and CD-including systems, such as host-guest complexes or even more sophisticated macromolecules. In this review, the examples of such studies have been gathered and discussed. Due to the variety of possible ssNMR experiments, the most common approaches have been presented to provide the overview of the strategies employed to characterize those useful materials.

Molecular Self-Assembled Ether-Based Polyrotaxane Solid Electrolyte for Lithium Metal Batteries

Poly(ethylene oxide) has been widely investigated as a potential separator for solid-state lithium metal batteries. However, its applications were significantly restricted by low ionic conductivity and a narrow electrochemical stability window (<4.0 V vs Li/Li⁺) at room temperature. Herein, a novel molecular self-assembled ether-based polyrotaxane electrolyte was designed using different functional units and prepared by threading cyclic 18-crown ether-6 (18C6) to linear poly(ethylene glycol) (PEG) via intermolecular hydrogen bond and terminating with hexamethylene diisocyanate trimer (HDIt), which was strongly confirmed by local structure-sensitive solid/liquid-state nuclear magnetic resonance (NMR) techniques. The designed electrolyte has shown an obviously increased room-temperature ionic conductivity of 3.48 × 10^-4 S cm^-1 compared to 1.12 × 10^-5 S cm^-1 without assembling polyrotaxane functional units, contributing to the enhanced cycling stability of batteries with both LiFePO₄ and LiNi_0.8Co_0.15Al_0.05O₂ cathode materials. This advanced molecular self-assembled strategy provides a new paradigm in designing solid polymer electrolytes with demanded performance for lithium metal batteries.

Progress in Solid Polymer Electrolytes for Lithium-Ion Batteries and Beyond

Solid-state polymer electrolytes (SPEs) for high electrochemical performance lithium-ion batteries have received considerable attention due to their unique characteristics; they are not prone to leakage, and they exhibit low flammability, excellent processability, good flexibility, high safety levels, and superior thermal stability. However, current SPEs are far from commercialization, mainly due to the low ionic conductivity, low Li⁺ transference number (t_Li+ ), poor electrode/electrolyte interface contact, narrow electrochemical oxidation window, and poor long-term stability of Li metal. Recent work on improving electrochemical performance and these aspects of SPEs are summarized systematically here with a particular focus on the underlying mechanisms, and the improvement strategies are also proposed. This review could lead to a deeper consideration of the issues and solutions affecting the application of SPEs and pave a new pathway to safe, high-performance lithium-ion batteries.

Cyclodextrin-Integrated PEO-Based Composite Solid Electrolytes for High-Rate and Ultrastable All-Solid-State Lithium Batteries

Poly(ethylene oxide) (PEO)-based composite solid electrolytes (CSEs) are considered as one of the most promising candidates for all-solid-state lithium batteries (ASSLBs). However, a key challenge for their further development is to solve the main issues of low ionic conductivity and poor mechanical strength, which can lead to insufficient capacity and stability. Herein, β-cyclodextrin (β-CD) is first demonstrated as a multifunctional filler that can form a continuous hydrogen bond network with the ether oxygen unit from the PEO matrix, thus improving the comprehensive performances of the PEO-based CSE. By relevant characterizations, it is demonstrated that β-CD is uniformly dispersed into the PEO substrate, inducing adequate dissociation of lithium salt and enhancing mechanical strength through hydrogen bond interactions. In a Li/Li symmetric battery, the β-CD-integrated PEO-based (PEO-LiTFSI-15% β-CD) CSE works well at a critical current density up to 1.0 mA cm^-2 and retains stable lithium plating/stripping for more than 1000 h. Such reliable properties also enable its superior performance in LiFePO₄-based ASSLBs, with specific capacities of 123.6 and 114.0 mA h g^-1 as well as about 100 and 81.8% capacity retention over 300 and 700 cycles at 1 and 2 C (1 C = 170 mA g^-1), respectively.

Use of Solid-State NMR Spectroscopy for the Characterization of Molecular Structure and Dynamics in Solid Polymer and Hybrid Electrolytes

Solid-state NMR spectroscopy is an established experimental technique which is used for the characterization of structural and dynamic properties of materials in their native state. Many types of solid-state NMR experiments have been used to characterize both lithium-based and sodium-based solid polymer and polymer-ceramic hybrid electrolyte materials. This review describes several solid-state NMR experiments that are commonly employed in the analysis of these systems: pulse field gradient NMR, electrophoretic NMR, variable temperature T1 relaxation, T2 relaxation and linewidth analysis, exchange spectroscopy, cross polarization, Rotational Echo Double Resonance, and isotope enrichment. In this review, each technique is introduced with a short description of the pulse sequence, and examples of experiments that have been performed in real solid-state polymer and/or hybrid electrolyte systems are provided. The results and conclusions of these experiments are discussed to inform readers of the strengths and weaknesses of each technique when applied to polymer and hybrid electrolyte systems. It is anticipated that this review may be used to aid in the selection of solid-state NMR experiments for the analysis of these systems.

Structural Characterization of a Cyclodextrin/l-menthol Inclusion Complex in the Solid-state by Solid-state NMR and Vibrational Circular Dichroism

Hydrophobic and volatile flavor molecules can be encapsulated inside cyclodextrins (CyDs). Inclusion complexes are frequently used in solid or dispersed states in preserved food and cosmetics. In this study, the solid-state structures of spray-dried inclusion complexes of l-menthol in α-CyD and β-CyD were analyzed using ¹³C solid-state NMR and vibrational circular dichroism (VCD). The NMR signals of l-menthol and CyDs were identified in the physical mixture and the l-menthol inclusion complex of α- and β-CyD. The NMR signal of the isopropyl-methyl group of menthol in the α-CyD inclusion complex exhibited a large low-field shift, which suggested a steric hindrance between menthol and α-CyD. VCD exhibited specific changes in the intensity of bands corresponding to C-C vibrations in α-CyD and O-C stretching vibrations in l-menthol. Our results indicated that l-menthol specifically fitted the narrow space within α-CyD. The combined solid-state NMR and VCD analysis provided structural insights into the flavor inclusion complex in the solid-state.

Probing the Dynamics of Li+ Ions on the Crystal Surface: A Solid-State NMR Study

Polyethylene oxide-based solid polymer electrolytes (SPEs) are of research interest because of their potential applications in all-solid-state Li+ batteries. However, despite their advantages in terms of compatibility with the electrodes and easy processing, polyethylene oxide (PEO)/Li+ complexes often suffer from low conductivity at room temperature. Understanding the conduction mechanism and, in turn, developing strategies to improve the conductivity have long been the main objectives underlying research into PEO/Li+ complex electrolytes. Here, we prepared several special PEO/Li+ complex samples where the PEO/Li+ complex structures were located on the surfaces of PEO crystals and consisted of high content chain ends. We found two different Li+ species in the PEO/Li+ complex structures via solid-state nuclear magnetic resonance (NMR). The 2D 7Li exchange NMR showed the exchange process between the different Li+ species. The exchange dynamics of the Li+ ions provide a molecular mechanism of the Li+ transportation in the surface of PEO crystal lamella, which is further correlated with the ionic conduction mechanism of the PEO/Li+ complex structure.

Stabilizing lithium metal anode by octaphenyl polyoxyethylene-lithium complexation

Lithium metal is an ideal anode for lithium batteries due to its low electrochemical potential and high theoretical capacity. However, safety issues arising from lithium dendrite growth have significantly reduced the practical applicability of lithium metal batteries. Here, we report the addition of octaphenyl polyoxyethylene as an electrolyte additive to enable a stable complex layer on the surface of the lithium anode. This surface layer not only promotes uniform lithium deposition, but also facilitates the formation of a robust solid-electrolyte interface film comprising cross-linked polymer. As a result, lithium|lithium symmetric cells constructed using the octaphenyl polyoxyethylene additive exhibit excellent cycling stability over 400 cycles at 1 mA cm⁻², and outstanding rate performance up to 4 mA cm⁻². Full cells assembled with a LiFePO₄ cathode exhibit high rate capability and impressive cyclability, with capacity decay of only 0.023% per cycle.

Despite the large theoretical promise of Li metal anode, the dendrite growth poses a serious safety challenge. Here the authors address this issue by adding octaphenyl polyoxyethylene as an electrolyte additive which facilitates the formation of a dual-functional layer and excellent performance.

Controlling the Activation Energy for Single-Ion Diffusion through a Hybrid Polyelectrolyte Matrix by Manipulating the Central Coordinate Semimetal Atom

The diffusion of lithium ions decoupled from a solid polymer electrolyte matrix is the key for high-energy electrochemical devices with the safety needed for commercial use. This Letter reports how the ion mobility in a single-phase hybrid polyelectrolyte (SPHP) matrix can be tuned by changing an inorganic coordinating atom from silicon (Si) to germanium (Ge). Nuclear Magnetic Resonance (NMR) results show that the lithium ion activation barrier in the polyelectrolyte with Si can be modulated from 0.26 eV to the unprecedented value of 0.12 eV in the polyelectrolyte with Ge. Density functional theory is used to show that the electronic structures of both polymers are very different, although their chemical structures are very similar, except for the coordinating atom. This simple chemical substitution route will certainly increase the interest in these polymers for applications in electrochemical devices.

Monochromatic "Photoinitibitor"-Mediated Holographic Photopolymer Electrolytes for Lithium-Ion Batteries

A new polymer electrolyte based on holographic photopolymer is designed and fabricated. Ethylene carbonate (EC) and propylene carbonate (PC) are introduced as the photoinert substances. Upon laser-interference-pattern illumination, photopolymerization occurs within the constructive regions which subsequently results in a phase separation between the photogenerated polymer and unreacted EC-PC, affording holographic photopolymer electrolytes (HPEs) with a pitch of ≈740 nm. Interestingly, both diffraction efficiency and ionic conductivity increase with an augmentation of the EC-PC content. With 50 wt% of EC-PC, the diffraction efficiency and ionic conductivity are ≈60% and 2.13 × 10-4 S cm-1 at 30 °C, respectively, which are 60 times and 5 orders of magnitude larger than the electrolyte without EC-PC. Notably, the HPEs afford better anisotropy and more stable electrochemical properties when incorporating N,N-dimethylacrylamide. The HPEs exhibit good toughness under bending, excellent optical transparency under ambient conditions, and astonishing capabilities of reconstructing colored images. The HPEs here open a door to design flexible and transparent electronics with good mechanical, electrical, and optical functions.

Polymers Based on Cyclic Carbonates as Trait d'Union Between Polymer Chemistry and Sustainable CO2 Utilization

Given the large amount of anthropogenic CO₂ emissions, it is advantageous to use CO₂ as feedstock for the fabrication of everyday products, such as fuels and materials. An attractive way to use CO₂ in the synthesis of polymers is by the formation of five-membered cyclic organic carbonate monomers (5CCs). The sustainability of this synthetic approach is increased by using scaffolds prepared from renewable resources. Indeed, recent years have seen the rise of various types of carbonate syntheses and applications. 5CC monomers are often polymerized with diamines to yield polyhydroxyurethanes (PHU). Foams are developed from this type of polymers; moreover, the additional hydroxyl groups in PHU, absent in classical polyurethanes, lead to coatings with excellent adhesive properties. Furthermore, carbonate groups in polymers offer the possibility of post-functionalization, such as curing reactions under mild conditions. Finally, the polarity of carbonate groups is remarkably high, so polymers with carbonates side-chains can be used as polymer electrolytes in batteries or as conductive membranes. The target of this Review is to highlight the multiple opportunities offered by polymers prepared from and/or containing 5CCs. Firstly, the preparation of several classes of 5CCs is discussed with special focus on the sustainability of the synthetic routes. Thereafter, specific classes of polymers are discussed for which the use and/or presence of carbonate moieties is crucial to impart the targeted properties (foams, adhesives, polymers for energy applications, and other functional materials).

Review of Recent Nuclear Magnetic Resonance Studies of Ion Transport in Polymer Electrolytes

Current and future demands for increasing the energy density of batteries without sacrificing safety has led to intensive worldwide research on all solid state Li-based batteries. Given the physical limitations on inorganic ceramic or glassy solid electrolytes, development of polymer electrolytes continues to be a high priority. This brief review covers several recent alternative approaches to polymer electrolytes based solely on poly(ethylene oxide) (PEO) and the use of nuclear magnetic resonance (NMR) to elucidate structure and ion transport properties in these materials.

Supramolecular Self-Assembly of Methylated Rotaxanes for Solid Polymer Electrolyte Application

Li⁺-conducting solid polymer electrolytes (SPEs) obtained from supramolecular self-assembly of trimethylated cyclodextrin (TMCD), poly(ethylene oxide) (PEO), and lithium salt are investigated for application in lithium-metal batteries (LMBs) and lithium-ion batteries (LIBs). The considered electrolytes comprise nanochannels for fast lithium-ion transport formed by CD threaded on PEO chains. It is demonstrated that tailored modification of CD beneficially influences the structure and transport properties of solid polymer electrolytes, thereby enabling their application in LMBs. Molecular dynamics (MD) simulation and experimental data reveal that modification of CDs shifts the steady state between lithium ions inside and outside the channels, in this way improving the achievable ionic conductivity. Notably, the designed SPEs facilitated galvanostatic cycling in LMBs at fast charging and discharging rates for more than 200 cycles and high Coulombic efficiency.

Room-Temperature Performance of Poly(Ethylene Ether Carbonate)-Based Solid Polymer Electrolytes for All-Solid-State Lithium Batteries

Amorphous poly(ethylene ether carbonate) (PEEC), which is a copolymer of ethylene oxide and ethylene carbonate, was synthesized by ring-opening polymerization of ethylene carbonate. This route overcame the common issue of low conductivity of poly(ethylene oxide)(PEO)-based solid polymer electrolytes at low temperatures, and thus the solid polymer electrolyte could be successfully employed at the room temperature. Introducing the ethylene carbonate units into PEEC improved the ionic conductivity, electrochemical stability and lithium transference number compared with PEO. A cross-linked solid polymer electrolyte was synthesized by photo cross-linking reaction using PEEC and tetraethyleneglycol diacrylate as a cross-linking agent, in the form of a flexible thin film. The solid-state Li/LiNi_0.6Co_0.2Mn_0.2O₂ cell assembled with solid polymer electrolyte based on cross-linked PEEC delivered a high initial discharge capacity of 141.4 mAh g^-1 and exhibited good capacity retention at room temperature. These results demonstrate the feasibility of using this solid polymer electrolyte in all-solid-state lithium batteries that can operate at ambient temperatures.

Two Players Make a Formidable Combination: In Situ Generated Poly(acrylic anhydride-2-methyl-acrylic acid-2-oxirane-ethyl ester-methyl methacrylate) Cross-Linking Gel Polymer Electrolyte toward 5 V High-Voltage Batteries

Electrochemical performance of high-voltage lithium batteries with high energy density is limited because of the electrolyte instability and the electrode/electrolyte interfacial reactivity. Hence, a cross-linking polymer network of poly(acrylic anhydride-2-methyl-acrylic acid-2-oxirane-ethyl ester-methyl methacrylate) (PAMM)-based electrolyte was introduced via in situ polymerization inspired by "shuangjian hebi", which is a statement in a traditional Chinese Kungfu story similar to the synergetic effect of 1 + 1 > 2. A poly(acrylic anhydride) and poly(methyl methacrylate)-based system is very promising as electrolyte materials for lithium-ion batteries, in which the anhydride and acrylate groups can provide high voltage resistance and fast ionic conductivity, respectively. As a result, the cross-linking PAMM-based electrolyte possesses a significant comprehensive enhancement, including electrochemical stability window exceeding 5 V vs Li⁺/Li, an ionic conductivity of 6.79 × 10^-4 S cm^-1 at room temperature, high mechanical strength (27.5 MPa), good flame resistance, and excellent interface compatibility with Li metal. It is also demonstrated that this gel polymer electrolyte suppresses the negative effect resulting from dissolution of Mn²⁺ ions at 25 and 55 °C. Thus, the LiNi_0.5Mn_1.5O₄/Li and LiNi_0.5Mn_1.5O₄/Li₄Ti₅O₁₂ cells using the optimized in situ polymerized cross-linking PAMM-based gel polymer electrolyte deliver stable charging/discharging profiles and excellent rate performance at room temperature and even at 55 °C. These findings suggest that the cross-linking PAMM is an intriguing candidate for 5 V class high-voltage gel polymer electrolyte toward high-energy lithium-on batteries.

A Superior Polymer Electrolyte with Rigid Cyclic Carbonate Backbone for Rechargeable Lithium Ion Batteries

The fabricating process of well-known Bellcore poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP)-based polymer electrolytes is very complicated, tedious, and expensive owing to containing a large amount of fluorine substituents. Herein, a novel kind of poly(vinylene carbonate) (PVCA)-based polymer electrolyte is developed via a facile in situ polymerization method, which possesses the merits of good interfacial compatibility with electrodes. In addition, this polymer electrolyte presents a high ionic conductivity of 5.59 × 10^-4 S cm^-1 and a wide electrochemical stability window exceeding 4.8 V vs Li⁺/Li at ambient temperature. In addition, the rigid cyclic carbonate backbone of poly(vinylene carbonate) endows polymer electrolyte a superior mechanical property. The LiFe_0.2Mn_0.8PO₄/graphite lithium ion batteries using this polymer electrolyte deliver good rate capability and excellent cyclability at room temperature. The superior performance demonstrates that the PVCA-based electrolyte via in situ polymerization is a potential alternative polymer electrolyte for high-performance rechargeable lithium ion batteries.

In Situ Generation of Poly (Vinylene Carbonate) Based Solid Electrolyte with Interfacial Stability for LiCoO2 Lithium Batteries

Nowadays it is extremely urgent to seek high performance solid polymer electrolyte that possesses both interfacial stability toward lithium/graphitic anodes and high voltage cathodes for high energy density solid state batteries. Inspired by the positive interfacial effect of vinylene carbonate additive on solid electrolyte interface, a novel poly (vinylene carbonate) based solid polymer electrolyte is presented via a facile in situ polymerization process in this paper. It is manifested that poly (vinylene carbonate) based solid polymer electrolyte possess a superior electrochemical stability window up to 4.5 V versus Li/Li+ and considerable ionic conductivity of 9.82 × 10-5 S cm-1 at 50 °C. Moreover, it is demonstrated that high voltage LiCoO2/Li batteries using this solid polymer electrolyte display stable charge/discharge profiles, considerable rate capability, excellent cycling performance, and decent safety characteristic. It is believed that poly (vinylene carbonate) based electrolyte can be a very promising solid polymer electrolyte candidate for high energy density lithium batteries.

Anisotropic charge transport in ion-conductive photoresponsive polyethylene oxide-based mesomorphic materials

The mechanism of charge motion in conductive and photosensitive mesogenic block copolymers containing polyethylene oxide (PEO) segments is investigated over a wide frequency and temperature range with the broadband dielectric spectroscopy technique. It is found that the ultraviolet (UV) irradiation, the UV intensity, and the anchoring conditions of mesogenic unit in the cells produce changes in conductivity properties and in the molecular arrangement. The anisotropic nature of the conductivity is established.

Potential of polymethacrylate pseudo crown ethers as solid state polymer electrolytes

The association of kinetic studies, DFT calculations and ¹H–⁷Li NMR analyses allowed the control of the cyclo-ATRP of PEG₉DMA and the production of polymethacrylate pseudo crown-ethers of various molar masses.

Novel Organic-Inorganic Hybrid Electrolyte to Enable LiFePO4 Quasi-Solid-State Li-Ion Batteries Performed Highly around Room Temperature

A novel type of organic-inorganic hybrid polymer electrolytes with high electrochemical performances around room temperature is formed by hybrid of nanofillers, Y-type oligomer, polyoxyethylene and Li-salt (PBA-Li), of which the T_g and T_m are significantly lowered by blended heterogeneous polyethers and embedded nanofillers with benefit of the dipole modification to achieve the high Li-ion migration due to more free-volume space. The quasi-solid-state Li-ion batteries based on the LiFePO₄/15PBA-Li/Li-metal cells present remarkable reversible capacities (133 and 165 mAh g^-1 @0.2 C at 30 and 45 °C, respectively), good rate ability and stable cycle performance (141.9 mAh g^-1 @0.2 C at 30 °C after 150 cycles).

Lithium Ion Pathway within Li7 La3 Zr2 O12 -Polyethylene Oxide Composite Electrolytes

Polymer-ceramic composite electrolytes are emerging as a promising solution to deliver high ionic conductivity, optimal mechanical properties, and good safety for developing high-performance all-solid-state rechargeable batteries. Composite electrolytes have been prepared with cubic-phase Li7 La3 Zr2 O12 (LLZO) garnet and polyethylene oxide (PEO) and employed in symmetric lithium battery cells. By combining selective isotope labeling and high-resolution solid-state Li NMR, we are able to track Li ion pathways within LLZO-PEO composite electrolytes by monitoring the replacement of (7) Li in the composite electrolyte by (6) Li from the (6) Li metal electrodes during battery cycling. We have provided the first experimental evidence to show that Li ions favor the pathway through the LLZO ceramic phase instead of the PEO-LLZO interface or PEO. This approach can be widely applied to study ion pathways in ionic conductors and to provide useful insights for developing composite materials for energy storage and harvesting.

Grafting modification of epoxidized natural rubber with poly(ethylene glycol) monomethylether carboxylic acid and ionic conductivity of graft polymer composite electrolytes

A novel polymer was synthesized via a grafting reaction of epoxidized natural rubber (ENR) with poly(ethylene glycol) monomethylether carboxylic acid (mPEG-COOH), which can improve the conductivity as a matrix of CPE.

Flexible thin-film battery based on graphene-oxide embedded in solid polymer electrolyte

Enhanced safety of flexible batteries is an imperative objective due to the intimate interaction of such devices with human organs such as flexible batteries that are integrated with touch-screens or embedded in clothing or space suits. In this study, the fabrication and testing of a high performance thin-film Li-ion battery (LIB) is reported that is both flexible and relatively safer compared to the conventional electrolyte based batteries. The concept is facilitated by the use of solid polymer nanocomposite electrolyte, specifically, composed of polyethylene oxide (PEO) matrix and 1 wt% graphene oxide (GO) nanosheets. The flexible LIB exhibits a high maximum operating voltage of 4.9 V, high capacity of 0.13 mA h cm(-2) and an energy density of 4.8 mW h cm(-3). The battery is encapsulated using a simple lamination method that is economical and scalable. The laminated battery shows robust mechanical flexibility over 6000 bending cycles and excellent electrochemical performance in both flat and bent configurations. Finite element analysis (FEA) of the LIB provides critical insights into the evolution of mechanical stresses during lamination and bending.