Solid Polymer Electrolyte Research Articles

Preparation and Conductivity Analysis of LLTO Nanofiber‐Incorporated PEO‐PVDF‐HFP‐LiClO4 Solid Polymer Electrolytes for High‐Voltage Lithium Metal Batteries

ABSTRACTThis work focuses on the development of a composite polymer electrolyte (CPE) for all‐solid‐state lithium metal batteries (ASSLMBs), integrating LLTO nanofibers into a PEO (polyethylene oxide)‐PVDF‐HFP (poly(vinylidene fluoride‐cohexafluoropropylene)) matrix with LiClO4 as the lithium salt. The PEO has high ionic conductivity and flexibility, and the PVDF‐HFP has high mechanical strength and electrochemical stability. Therefore, the resulting composite has improved electrochemical performance and mechanical properties. Incorporating LLTO nanofibers enhances ionic conductivity due to the one‐dimensional ion transport pathways provided by the nanofibers while maintaining mechanical integrity and air stability, overcoming the challenges associated with conventional fillers. The prepared CPE demonstrates exceptional electrochemical stability up to 5.1 V versus Li/Li+, making it suitable for high‐voltage applications over traditional polymer electrolytes. The optimized CPE with 15 wt% LLTO provides the ionic conductivity of 1.1 × 10−5 S cm−1 at room temperature and reaches 1.46 × 10−4 S cm−1 at 80°C. The assembled LiNi1/3Mn1/3Co1/3PO4||PEO‐PVDF‐HFP‐LiClO₄‐LLTO||Li based 2032 coin cell worked in between 3 and 4.8 V versus Li/Li+ potential window without any electrolyte decomposition from 0.5 to 5 mV/s scan rates. Similarly, the fabricated LiFePO₄||PEO‐PVDF‐HFP (1:2)‐LiClO4‐LLTO (15 wt%)||Li cell provides an initial capacity of 149 mAh g−1 at 0.1 C and 85 mAh g−1 at 0.5 C, exploring its potential for lithium metal batteries. Overall, this work offers a promising pathway for developing advanced solid polymer electrolytes for next‐generation lithium metal batteries, which combine high ionic conductivity, excellent electrochemical performances, and robust mechanical properties.

Curved surface coupled structural battery composites manufactured by resin transfer molding process: Microstructure and multifunctional performance

To bridge industrial production and lab-scale research, this work demonstrates a technology to manufacture curved surface structural battery composites (CSBCs) that can simultaneously achieve electrochemical energy storage and load-bearing. The curved-surface carbon fiber structural anode and cathode are fabricated by coating the active materials on carbon fiber fabric with a vacuum-bag-assisted technique. The resin transfer molding (RTM) process is conducted to manufacture the coupled CSBCs by infusing bi-continuous phase epoxy resin electrolyte and curing at high temperatures. The microstructure of structural electrodes and CSBCs is characterized by scanning electron microscopy (SEM). Due to good interfacial compatibility between high mechanical strength carbon fiber structural electrode and high ionic conductivity solid polymer electrolyte bulk for load support, the fabricated CSBCs demonstrate a high density of 294 mWh kg−1 based on the whole mass of devices, a tensile strength of 257.4 MPa with Young's modulus of 12.9 GPa and a flexural strength of 194.1 MPa with flexural modulus of 11.1 GPa. In situ electrochemical-mechanical tests further confirm the durability of CSBCs under mechanical loads with a multifunctional efficiency of 1.07, suggesting the effectiveness of the introduced manufacturing techniques for coupled structural battery composites.

Sintesis dan Karakterisasi Solid Polymer Electrolyte (SPE) Berbasis Nanofiber Selulosa untuk Menunjang Baterai Litium Berdensitas Tinggi dan Ramah Lingkungan

Lithium battery as one of the energy storage has two important elements, namely electrodes and electrolyte. Electrolyte is a part of the battery element that has undergone many developments. In this study, the manufacture of electrolytes in the form of Solid Polymer Electrolyte (SPE) was carried out by utilizing the abundant availability of nata de coco. The nanofibrous cellulose structure in Bacterial Cellulose (BC) nata de coco has the advantages of good porosity, flexibility in surface functionality, compact porous structure that provides abundant ion pathways and hetero atoms (oxygen atoms) with free electron pairs that facilitate ionic conduction. The SPE synthesis process was carried out by varying the soaking time of nata de coco in ethanol, namely 1, 2 and 3 days to determine the structure with optimal results. FTIR characterization results show the synthesis of cellulose nanofiber has the same groups as commercial cellulose groups in the form of O-H, C-H, C=O and C-O. CV characterization results show the SPE electrolyte has good redox properties, especially in the 2-day variation with the highest specific capacitance. The EIS test showed the lowest resistance in the 1-day variation sample with a conductivity of 0.017 ohm-1.

Porous Lithium‐Doped ZnO Nanosheets with Abundant Oxygen Vacancies for Accelerating Li+ Transport in Solid‐State Composite Electrolyte

The flexible Li‐ion conducting solid polymer electrolyte (SPE) endows a stable long‐term cycling to Li‐metal anode to significantly improve the energy density of solid‐state lithium batteries; however, the practical application of the SPE is limited by its low ionic conductivity and small critical current density for dendrite nucleation. Herein, Li+‐doped porous ZnO (LZO) nanosheets are introduced into the poly(ethylene oxide) (PEO)‐based SPE, releasing more mobile Li ions for faster Li‐ion transport due to the enhanced interaction between abundant oxygen vacancies and anions of Li‐salt. As a result, the optimized LZO/PEO composite polymer electrolyte exhibits a high Li‐ion conductivity of 3.3 × 10−4 S cm−1 at 50 °C, 4 times higher than the pure PEO electrolyte. The solid‐state LiFePO4/Li cell shows extraordinarily long‐term stable cycling, up to 1500 cycles with a high average Coulombic efficiency of 99.8%. In addition, the cycling stability of the high‐voltage LiNi0.8Mn0.1Co0.1O2 (NMC811)/Li cell was also obviously improved compared to the nondoped pure PEO electrolyte, indicating the positive contribution of the LZO on interfacial stability.

The Self‐Expanding Frame of Graphydiyne Induces Rapid Transport of Lithium Ions in All‐Solid‐State Lithium Metal Batteries

AbstractLow ionic conductivity hinders the practical application of solid polymer electrolytes. Here, an interface‐oscillating polymer electrolyte (IOPE) based on graphdiyne (GDY) is designed and prepared to enable high‐performance all‐solid‐state lithium (Li) metal batteries (ASSLMBs). The affinity of GDY to Li ions induces the competitive adsorption of Li ions, weakens the coordination ability of Li ions with electron‐rich oxygen (on ethylene oxide), and accelerates the Li‐ion migration kinetics. The weak coordination between Li+‐acetylene greatly promotes the rapid reversible transition of GDY itself, resulting in strong self‐expanding/shrinking of the GDY skeleton and the GDY/polymer interface oscillation, and the reduction of the Li‐ion diffusion energy barrier at the interfaces. Consequently, the as‐prepared IOPE shows significantly improved Li‐ion conductivity (1.5 × 10−4 S cm−1 at 35 °C) and transference number, as well as excellent stability toward Li metal anodes. The ASSLMBs assembled with LiFePO4 cathodes and IOPE exhibit excellent rate and cycling performance, capable of stable operation for more than 250 cycles with a high‐capacity retention of 98% at 0.1C (1C = 170 mA g−1). The high‐performance all‐solid‐state Li metal pouch cells are also demonstrated to show great potential for the practical application of IOPE.

Synergism of lithium acetate salt toward surface chemistry and physical properties of carboxymethyl chitosan‐based solid polymer electrolyte

Synergism of lithium acetate salt toward surface chemistry and physical properties of carboxymethyl chitosan‐based solid polymer electrolyte

Sulfur/reduced graphite oxide and dual-anion solid polymer‒electrolyte integrated structure for high-loading practical all-solid-state lithium–sulfur batteries

The demand for high-capacity batteries with long cycle life and safety has been increasing owing to the expanding mid-to-large battery market. Li–S batteries are suitable energy-storage devices because of their reversibility, high theoretical capacity, and inexpensive construction materials. However, their performance is limited by various factors, including the shuttle effect and dendrite growth at the anode. Here, an integrated electrode for use in all-solid-state (ASS) Li–S batteries was formed via hot pressing. In detail, S particles dispersed in a functionalized reduced graphite oxide (rGO) cathode with a binder-less polymer electrolyte (PE) and a dual-anion ionic liquid-containing cross-linked poly(ethylene oxide)–Li bis(fluoromethanesulfonyl)imide–N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide-based solid polymer electrolyte (SPE, PEO–LiFSI0.1(Pyr14TFSI)0.4) were hot-pressed into an integrated electrode, which serves as both the cathode and electrolyte. The resulting S/rGO-based solid-state Li–S batteries exhibited more stable performance than Li–S batteries using liquid electrolytes did, indicating that the dual-anion SPE layer effectively suppressed dendritic Li formation and the shuttle effect with high ionic conductivity. At 0.1 C, the battery discharge capacities were 957 and 576 mAh g−1 in the first cycle and after 100 cycles, respectively. At 1 C, the reversible capacity was 590 and 417 mAh g−1 in the first cycle and after 100 cycles, respectively (capacity retention = 71%). Therefore, the proposed S/rGO/PE//LiFSI0.1(Pyr14TFSI)0.4-integrated electrodes are beneficial for ASS Li–S batteries.

Solid polymer electrolytes with dual salts enhance lithium-metal interfacial stability for long cycle performance of lithium batteries

Solid-state lithium metal batteries (LMBs) are considered to be the ideal energy storage system for achieving higher energy density and high safety. However, poor physical contact at the interface between the solid-state electrolyte and lithium metal, as well as the growth of dendrites make the cycling stability of LMBs challenging. Therefore, we developed a multifunctional ionic liquid-based polymer electrolyte including montmorillonite (MMT) and double salts (NaFSI and LiTFSI). The self-concentration effect of MMT lithium ions, combined with the electrostatic shielding effect of the double salts, resulted in homogeneous ion deposition, reducing dendritic lithium generation and improving lithium battery performance, with lithium batteries achieving a stable cycling rate of 1000 cycles at 1 C. Moreover, Due to the integrated assembly of the battery assembly process using light curing, the physical interface between the positive electrode-electrolyte-negative electrode achieves good contact and wettability. NaFSI achieves the enhancement of solid electrolyte interface (SEI) by introducing NaF/LiF to SEI of lithium metal, and the optimization of ion deposition pattern at the interface can be achieved by electrostatic shielding effect. Ultimately, stable ion transport at the solid-solid interface for lithium metal solid-state batteries can be realized. Notably, the ionic liquid-based polymer electrolyte with high ionic conductivity (1.2 × 10−3 S cm−1) and high oxidative stability (5.2 V vs. Li/Li+) at room temperature. In addition, the good flame retardant properties of the electrolytes indicate that dual-salt polymer electrolytes are an effective strategy for achieving high safety and long cycle stability of LMBs.

Designing a Refined Multi-Structural Polymer Electrolyte Framework for Highly Stable Lithium-Metal Batteries.

Rational structural designs of solid polymer electrolytes featuring rich interface-phase morphologies can improve electrolyte connection and rapid ion transport. However, these rigid interfacial structures commonly result in diminished or entirely inert ionic conductivity within their bulk phase, compromising overall electrolyte performance. Herein, a multi-component ion-conductive electrolyte was successfully designed based on a refined multi-structural polymer electrolyte (RMSPE) framework with uniform Li+ solvation chemistry and rapid Li+ transporting kinetics. The RMSPEis constructed via polymerization-induced phase separation based on a rational combination of lithiophilic components and rigid/flexible chain units with significant hydrophobic/hydrophilic contrasts. Further refined by coating a robust polymer network, this all-organic design endows a homogenous micro-nano porous structure, providing a novel framework favorable for rapid ion transport in both its soft interfacial and bulk phases. The RMSPE exhibited excellent ion conductivity of 1.91 mS cm-1 at room temperature and a high Li+ transference number of 0.7. Assembled symmetrical Li cells realized stable cycling for over 2400 h at 3.0 mA cm-2. LiFePO4 full batteries demonstrated a long lifespan of 3300 cycles with a capacity retention of 93.5% and stable cycling performance at -35 °C. This innovative design concept offers a promising perspective for achieving high-performance polymer-based Li metal batteries.

Molecular Design of Solid Polymer Electrolytes with Enthalpy-Entropy Manipulation for Li Metal Batteries with Aggressive Cathode Chemistry.

Solid polymer electrolytes (SPEs) with high ion conductivity, high Li+ transference number, and a wide electrochemical window are promising for the next-generation high-energy Li metal batteries (LMBs). Here we describe an enthalpy-entropy manipulation strategy enabling a class of polycarbonate-based copolymeric electrolytes (PCCEs) with regulated cation/anion solvation via a molecular design of the polymer backbone. By integrating a weakly solvating linear carbonate with another strongly solvating cyclic carbonate segment in the polymer backbone, the cation-dipole coordination for Li+ ions (with two types of carbonyl groups) is weakened (low enthalpy penalty) and nondirectional (high entropy penalty), which enables a weak solvation and rapid diffusion of Li+. We further introduce a bis-acrylamide-based cross-linking segment which, other than imparting high mechanical strength, exhibits dihydrogen bonding with the difluoro(oxalate) borate anions, which is strong (high enthalpy penalty) and directional (low entropy penalty), thus restricting the migration of anions. As a result, the PCCE delivers a high ionic conductivity of 0.66 mS cm-1 with a high Li+ transference number (0.76) at 25 °C, as well as high oxidation stability. By an in situ polymerization approach, the PCCE enables LMBs using high-nikel LiNi0.8Co0.1Mn0.1O2 cathodes with a high capacity retention of 82.2% over 800 cycles with a cutoff voltage of 4.5 V and further LMBs using aggressive LiNi0.5Mn1.5O4 cathodes with a 96.4% capacity retention over 300 cycles with a cutoff voltage of 5.0 V. The described enthalpy-entropy manipulation approach offers a unique perspective for the molecular design of high-performance SPEs for high-energy Li metal batteries.

Ionic liquid supported chitosan-g-SPA as a biopolymer-based single ion conducting solid polymer electrolyte for energy storage devices

This article discusses the preparation of different grades of single-ion conducting quasi-solid polymer electrolytes (q-SPE) material (Chit-g-SPA-IL) based on biopolymer (chitosan), polyacrylic acid and DBU-acetate (DBUH+ AcO−) ionic liquid. Chit-SPA-60 %-IL exhibited the highest conductivity within the range of 10−4 S/cm. TGA analysis demonstrated the stability of electrolytes up to a temperature of 120 °C. SEM-EDS analysis unveiled the porous nature of the electrolyte and even distribution of ions throughout the matrix. It exhibited an electrochemical stability window (EWS) of 2.53 V with significant current density and an ionic transference number (ITN) of ~99.9 %. The temperature-dependent conductivity established an Arrhenius-type conduction mechanism with an activation energy of 0.149 eV for ion movement within the electrolyte matrix. The AC conductivity analysis emphasized the time-temperature independence of the ionic conduction mechanism. Dielectric analysis highlighted the capacitive nature of the electrolyte, underlining its substantial capacitance, while modulus studies indicated minimal influence from the electrode-electrolyte interface. Chit-SPA-60 %-IL at 30 °C included a self-diffusion coefficient of 4.57 × 10−5 m2/s, ionic mobility of 1.75 × 10−3 m2/Vs, and drift ionic velocity of 0.44 m/s. These findings makes SPE as a promising candidate for sodium-ion-based energy storage devices.

Anion-Anchored Polymer-in-Salt Solid Electrolyte for High-Performance Zinc Batteries.

Solid polymer electrolytes hold promise for addressing key challenges in rechargeable zinc batteries (ZBs) utilizing aqueous electrolytes. However, achieving simultaneous high ionic conductivity, excellent mechanical strength, and a high cation transference number while effectively suppressing Zn dendrites remains challenging. Herein, we design a novel polymer-in-salt solid electrolyte (PISSE) composed of polyacrylonitrile (PAN), zinc chloride (ZnCl2), and niobium pentoxide with oxygen vacancies (Nb2O5-x) with high ionic conductivity. PAN polymer matrix provides the electrolyte good mechanical properties and solubility of Zn salt. The high concentration of ZnCl2 effectively decouples the Zn2+ from polymer chain segments and provides more ionic conduction amorphous region. Moreover, incorporating Nb2O5-x filler accelerates Zn2+ desolvation by anchoring (ZnxCly)2x-y clusters and enhances the system's mechanical properties, achieving a superior Zn2+ transference number (~0.93) and interfacial stability. Consequently, the optimized PISSE demonstrates exceptional stability during prolonged cycling periods, wide temperature range operation (-40 ℃ to 60 ℃), remarkable flexibility, and compatibility with diverse electrode materials. This study provides valuable insights into the design of solid-state electrolytes based on ZBs and elucidates their multifunctional prospects.

FFF/FDM 3D-Printed Solid Polymer Electrolytes Based on Acrylonitrile Copolymers for Lithium-Ion Batteries.

Lithium-ion batteries (LIBs) are essential in modern electronics, particularly in portable devices and electric vehicles. However, the limited design flexibility of current battery shapes constrains the development of custom-sized power sources for advanced applications like wearable electronics and medical devices. Additive manufacturing (AM), specifically Fused Filament Fabrication (FFF), presents a promising solution by enabling the creation of batteries with customized shapes. This study explores the use of novel poly(acrylonitrile-co-polyethylene glycol methyl ether acrylate) (poly(AN-co-PEGMEA)) copolymers as solid polymer electrolytes for lithium-ion batteries, optimized for 3D printing using FFF. The copolymers were synthesized with varying AN:PEGMEA ratios, and their physical, thermal, and electrochemical properties were systematically characterized. The study found that a poly(AN-co-PEGMEA) 6:1 copolymer ratio offers an optimal balance between printability and ionic conductivity. The successful extrusion of filaments and subsequent 3D printing of complex shapes demonstrate the potential of these materials for next-generation battery designs. The addition of succinonitrile (SCN) as a plasticizer significantly improved ionic conductivity and lithium cation transference numbers, making these copolymers viable for practical applications. This work highlights the potential of combining polymer chemistry with additive manufacturing to provide new opportunities in lithium-ion battery design and function.

Transference Numbers and Ion Coordination Strength for Mg2+, Na+, and K+ in Solid Polymer Electrolytes.

In solid polymer electrolytes, the transference number (T i ) is fundamental for performance as it defines the transport efficiency of the electrochemically active species. For systems "beyond Li", a lack of suitable methods to determine the T i is limiting the understanding of the ion transport in such systems. In this study, a method based on electrophoretic NMR (eNMR) and electrochemical impedance spectroscopy (EIS) is used to determine the T + for Na+, K+, and Mg2+ in poly(ε-caprolactone) (PCL), comparing this to previous results in poly(ethylene oxide). In common for all cations, a distinct correlation between strong coordination and a low T + is observed. Paradoxically, however, the divalent Mg2+ in PCL displayed a T + of 0.86 compared to ∼0.5 for the monovalent cations. Persistent clustering in this system suggests that it is better treated as a monovalent [MgTFSI]+ + TFSI- system, resulting in a T + of the [MgTFSI]+ cation of 0.43. These results serve as a door opener for the wide applicability of the eNMR/EIS method in order to provide an understanding of charge transport in multivalent systems.

Compositional dependence of electrochemical properties in biopolymer blend-based solid electrolytes doped with sodium perchlorate for EDLC applications

Biopolymer-based blends of solid electrolytes capable of conducting sodium ions were prepared via solution casting by incorporating sodium carboxymethyl cellulose (NaCMC) and polyvinyl alcohol (PVA) with varying concentrations of sodium perchlorate monohydrate (NaClO4.H2O), which was used as the dopant. The prepared electrolytes were characterized to reveal their structural, vibrational, electrical, and electrochemical properties that make them promising as solid polymer electrolytes (SPEs). X-ray diffraction (XRD) analysis showed that the amorphous nature of the sample increased with the addition of NaClO4.H2O salt concentrations of up to 30 wt.%. The complexation between the polymers and salt was confirmed by Fourier-Transform Infrared (FTIR) analysis. The SPE exhibited an optimal ionic conductivity of (1.90 ± 0.05) ×10−5 S cm−1, which is three orders higher than that of the pristine polymer blend with (5.31 ± 0.61) ×10−8 S cm−1, as determined by electrochemical impedance spectroscopy (EIS) analysis. Scaling studies conducted based on AC conductivity and tangent loss revealed that these measurements could be represented by a single master curve, which suggests that the optimal sample adheres to the time-temperature superposition principle (TTSP). The temperature dependence of Jonscher's exponent indicates that the conduction mechanism can be effectively represented by the Quantum Mechanical Tunneling model (QMT). Both transference number measurement (TNM) and linear sweep voltammetry (LSV) analyses validated the electrolyte's suitability for energy device applications by demonstrating its high ion transference number and electrochemical potential window of 3.93 V. The optimized SPE film was subsequently utilized in an electrochemical double-layer capacitor (EDLC) device to evaluate its performance as both an electrolyte and separator. The supercapacitor exhibited an impressive energy density of 15.18 Wh kg−1 and a power density of 4512.5 W kg−1, along with remarkable stability in terms of cycle life.

Твёрдые полимерные электролиты на основе нафиона для литий-ионных и натрий-ионных аккумуляторов

The use of solid polymer electrolytes is a novel and promising approach for enhancing the safety of lithium-ion and sodium-ion batteries. A number of publications on manufacturing electrolytes with lithium-ion and sodium-ion conductivity based on Nafion-like polymers have appeared in recent decade. The present mini-review analyses various methods of the synthesis of such electrolytes and their properties, as well as the information on laboratory lithium-ion and sodium-ion batteries using such electrolytes. The conclusion is made that the use of Nafion-based solid polymer electrolytes with Li+ and Na+ cation conductivity opens the way to creation of a new generation of lithium-ion and sodium-ion batteries. The principal advantage of Nafion-based solid polymer electrolytes over traditional PEO-based electrolytes is a fairly high cation transport number, which provides a sharp decrease in concentration polarization and, consequently, the increase in the energy efficiency of batteries.

In Situ Fabrication of Solvent-Free Solid Polymer Electrolytes for Wide-Temperature All-Solid-State Lithium Metal Batteries.

All-solid-state lithium metal batteries (ASSLMBs) have been regarded as promising candidates to settle the safety issues of liquid electrolytes for rechargeable lithium batteries. However, the currently reported gel polymer electrolytes still have flammable liquid solvents, thus leading to the potential safety hazard. Here, solvent-free deep eutectic solid polymer electrolytes (SPEs) are designed and fabricated via an in situ polymerization, which are composed of a poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) electrospun membrane, succinonitrile (SN), poly(ethylene glycol) diacrylate (PEGDA200, Mn = 200 g mol-1), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium difluoro(oxalato)borate (LiDFOB). The deep eutectic solvent (DES) with SN/LiTFSI provides a superior room-temperature ionic conductivity, while the PEGDA200 precursor acts as cross-linking network to form SPEs under thermal initiation for free radical polymerization, and LiDFOB can form a stable solid electrolyte interface (SEI) layer. The PVDF-HFP electrospun membrane with a three-dimensional nanofibrous network structure for SN/PEGDA200/LiTFSI/LiDFOB SPEs exhibits a wide electrochemical stability window, high lithium-ion transference number, and good compatibility with the lithium metal anode. Furthermore, the obtained SPEs assembled with Li//LiMn0.6Fe0.4PO4, Li//LiFePO4, and Li//LiNi0.8Co0.1Mn0.1O2 asymmetric cells show excellent cycling performance and rate capability at a wide temperature. This strategy provides a promising path in designing high-energy-density ASSLMBs for practical application.

Boosting the rate performance of all-solid-state batteries with a novel double layer solid electrolyte

When compared to traditional liquid electrolytes, solid electrolytes face significant challenges due to insufficient ionic conductivity and poor interfacial contact. To overcome these challenges, a cathode-supported double layer gradient structured solid polymer electrolyte membrane is developed. This innovative design enhances the wetting ability of the solid electrolyte on the cathode, leading to improved rate performance. Furthermore, the double layer solid electrolyte enhances mechanical strength, ensuring excellent cycling performance. As a result, the LiFePO4/Li solid state battery demonstrates superior battery performances, for instance, it can achieve a discharge capacity of 121 mAh g−1 at a current rate of 5C, with a capacity retention of 99 % after 380 cycles. This work offers a promising strategy for further enhancing the performance of all solid-state batteries.

Advanced Crosslinked Solid Polymer Electrolytes: Molecular Architecture, Strategies, and Future Perspectives

AbstractSolid‐state batteries (SSBs) have attracted much attention for high‐energy‐density and high‐safety energy storage devices. Solid polymer electrolytes (SPEs) have emerged as a critical component in the advancement of SSBs, owing to the compelling advantages of strong molecular structure‐designability, low cost, easy manufacturing, and no liquid leakage. However, linear SPEs usually have low room‐temperature ionic conductivity due to crystallization, and melting at high temperature. Thus, crosslinked SPEs have been proposed in that the chemical bonding between internal molecule chains can maintain solid state to expand operational temperature, disrupt regularity of segment, and diminish crystalline degree, leading to an enhancement of room‐temperature ionic conductivity. Furthermore, the integration of functional groups within crosslinked SPE network can significantly augment the electrochemical performance of SPEs. Herein, according to the network structure, crosslinked SPEs are categorized into four types: simple network, AB crosslinked polymers (ABCP), semi‐interpenetrating network (semi‐IPN), and interpenetrating network (IPN), then the structure features and advantages and disadvantages of commonly used polymers for these types of crosslinked SPEs are reviewed. In addition, crosslinked SPEs with self‐healing, flame‐retardant, degradable, and recyclability are introduced. Finally, challenges and prospects of crosslinked SPEs are summarized, hoping to provide guidance for the molecular design of SPEs in the future.

A Super-Ionic Solid-State Block Copolymer Electrolyte.

Polymer solid-state electrolytes offer great promise for battery materials with high energy density, mechanical stability, and improved safety. However, their low ion conductivities have so far limited their potential applications. Here, it is shown for poly(ethylene oxide) block copolymers that the super-stoichiometric addition of lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) as lithium salt leads to the formation of a crystalline PEO block copolymer phase with exceptionally high ion conductivities and low activation energies. The addition of LiTFSI further induces block copolymer phase transitions into bi-continuous Fddd and gyroid network morphologies, providing continuous 3D conduction pathways. Both effects lead to solid-state block copolymer electrolyte membranes with ion conductivities of up to 1·10-1Scm-1 at 90°C, decreasing only moderately to 4·10-2Scm-1 at room temperature, and to >1·10-3Scm-1 at -20°C, corresponding to activation energies as low as 0.19eV. The co-crystallization of PEO and LiTFSI with ether and carbonate solvents is observed to play a key role to realize a super-ionic conduction mechanism. The discovery of PEO super-ionic conductivity at high lithium concentrations opens a new pathway for fabrication of solid polymer electrolyte membranes with sufficiently high ion conductivities over a broad temperature range with widespread applications in electrical devices.