Composite Polymer Electrolyte Research Articles

Flexible Aluminum-Air Battery Based on High-Performance Three-Dimensional Dual-Network PVA/KC/KOH Composite Gel Polymer Electrolyte.

With a large theoretical capacity and high energy density, aluminum-air batteries are a promising energy storage device. However, the rigid structure and liquid electrolyte of a traditional aluminum-air battery limit its application potential in the field of flexible electronics, and the irreversible corrosion of its anode greatly reduces the battery life. To solve the above problems, a PVA/KC/KOH (2 M) composite gel polymer electrolyte (GPE) with a three-dimensional dual-network structure consisting of polyvinyl alcohol (PVA), kappa-carrageenan (KC), and potassium hydroxide was prepared in this paper by a simple two-step method and applied in aluminum-air batteries. At room temperature, the ionic conductivity of the PVA/KC/KOH (2 M) composite GPE was found to be up to 6.50 × 10-3 S cm-1. By utilizing this composite GPE, a single flexible aluminum-air battery was assembled and achieved a maximum discharge voltage of 1.2 V at 5 mA cm-2, with discharge time exceeding 3 h. Moreover, the single flexible aluminum-air battery maintains good electrochemical performance under various deformation modes, and the output voltage of the battery remains at about 99% after 300 cycles. The construction of flexible aluminum-air batteries based on a three-dimensional dual-network PVA/KC/KOH composite GPE provides excellent safety and high-multiplication capabilities for aluminum-air batteries, making them potential candidates for various flexible device applications.

A-LLTO Nanoparticles Embedded Composite Solid Polymer Electrolyte for Room Temperature Operational Li-metal Batteries.

Solid-state batteries (SSBs) have the potential to revolutionize the current energy storage sector. A significant portion of the current development of electric vehicles and the electrification of various appliances relies on Lithium (Li)-ion batteries. However, future energy demands will require the development of stronger and more reliable batteries. This report presents a novel solid state electrolyte (SSE) composed of a self-healing composite solid polymer electrolyte (CSPE) matrix and aluminum-doped (Li0.33La0.56)1.005Ti0.99Al0.01O3 (A-LLTO) nanofillers. The CSPE contains Jeffamine ED-2003 monomer, Benzene-1,3,5-tricarbaldehyde (BTC)crosslinker dissolved in a 1:1 ratio of Dimethylformamide (DMF) to LiPF6, and a certain amount (x) of A-LLTO nanofillers (x=5, 7.5, 10, 12.5%). A CSPE containing x-amount of A-LLTO fillers (referred to as CAL-x%) demonstrates excellent ion-conducting properties and stable battery performance. The CAL-10% demonstrates 1.1×10-3Scm-1 of ionic conductivity at room temperature (RT). A-LLTO nanofillers dispersed uniformly within the polymer matrix form a percolation network, which is believed to improve ionic conductivity and the diffusion of Li+ ions. The CR-2032 cell, consisting of LiFePO4 (LFP)║CAL-10%║Li, at RT offers an initial discharge capacity of ≈165mAhg-1 at 0.1C rate for 120 cycles with 98.85% coulombic efficiency (C.E.).

Three-Dimensional Metal-Organic Framework@Cellulose Skeleton-Reinforced Composite Polymer Electrolyte for All-Solid-State Lithium Metal Battery.

High-safety and high-energy-density solid-state lithium metal batteries (SSLMBs) attract tremendous interest in both academia and industry. Especially, composite polymer electrolytes (CPEs) can overcome the limitations of single-component solid-state electrolytes. In this work, a strategy of combining a rigid functional skeleton with a soft polymer electrolyte to prepare reinforced CPEs was adopted. The in situ grown zeolitic imidazolate frameworks (ZIFs) with three-dimensional cellulose fiber skeleton (ZIF-67@CF) and succinonitrile (SN) plasticizer into poly(ethylene oxide) (PEO) together form ZIF-67@CF/PEO-SN CPEs. The addition of ZIF-67@CF and SN to PEO synergistically enhanced the physical and electrochemical properties of CPEs. Furthermore, the conduction mechanism of lithium-ion (Li+) in CPEs was studied using density functional theory. It is impressive that the ZIF-67@CF/PEO-SN CPEs at 30 °C exhibit a high ionic conductivity of 1.17 × 10-4 S cm-1, a competitive Li+ transference number of 0.40, a wide electrochemical window of 5.0 V, a notable tensile strength of 18.7 MPa, and superior lithium plating/stripping stability (>550 h at 0.1 mA cm2). Such favorable features endowed LiFePO4/(ZIF-67@CF/PEO-SN)/Li cell at 30 °C with a high discharging capacity (152.5 mA h g-1 at 0.2 C), a long cycling lifespan (>150 cycles with 99% capacity retention), and superior operating safety. This work provides insights and promotes the application of functionalized CPEs for SSLMBs.

Coordination polymer-reinforced composite polymer electrolyte for all-solid-state Li-metal batteries

Composite polymer electrolytes (CPEs) have garnered significant interest due to their lightweight, flexible, and suitability for large-scale processing. However, current CPEs still face challenges such as unsatisfactory ionic conductivity (σ), low Li+ transference number (t+), and poor interfacial stability. This study presents the synthesis of a coordination polymer by coordinating Co2+ with terpyridine-end-capped polyethylene glycol (Co(tpy)-PEG). The resulting Co(tpy)-PEG-reinforced PEO-based CPE exhibits exceptional properties, including a high σ of 0.22 mS cm−1, large t+ of 0.75, and superior durability in both Li|Li (1400 h at 0.2 mA cm−2) and Li|LiFePO4 cells (70 % capacity retention after 1000 cycles at 1C) at 60 °C, comparable to the best available CPEs. The incorporation of Co(tpy)-PEG filler plays a vital role in enhancing the σ by disrupting the PEO crystallinity and creating additional Li+ conducting pathways. Additionally, it can free Li+ to increase t+ through Lewis acid-base interactions between Co2+ and TFSI−/O atoms, as well as NO3− and Li+. Furthermore, Co(tpy)-PEG facilitates the formation of a stable multicomponent solid electrolyte interphase containing beneficial Li2Sx, LiF, and Li3N. This work introduces a promising strategy for designing and preparing multifunctional fillers capable of simultaneously reinforcing the σ, t+, and interfacial stability of CPEs.

Metal-Doped NASICON/Polymer Composite Solid Electrolyte for Lithium Titania Anode in Lithium-Ion Batteries

This study reports five types of metal-doped (Co, Cu, Sn, V, and Zr) NASICON-type Li1.3Al0.3Ti1.7(PO4)3 (LATP)/polymer composite solid electrolytes (CSEs) enabling Li4Ti5O12 (LTO) anodes to have high rate capability and excellent cycling performance. The high Li+-conductivity LATP samples are successfully synthesized through a modified sol–gel method followed by thermal calcination. We find that the cation dopants clearly influence the substitution of Al for Ti, with the type of dopant serving as a crucial factor in determining the ionic conductivity and interfacial resistance of the solid electrolyte. The CSE containing poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and Sn-LATP shows an ionic conductivity of 1.88 × 10−4 S cm−1 at ambient temperature. The optimum conductivity can be attributed to alterations in the lattice parameters and Li+ transport pathways owing to Sn doping. The solid-state cell equipped with the LTO-supported CSE containing Sn-LATP fillers demonstrates both excellent high rate capability at 5 C (with a capacity retention of 86% compared to the value measured at 0.2 C) and superior cycling stability, maintaining high Coulombic efficiency (>99.0%) over 510 cycles. These findings indicate that the proposed CSE is highly promising for use in solid-state lithium batteries with desirable charge–discharge properties and high durability.

A novel composite solid electrolyte based on chemical bonding and physical reinforcing for all-solid-state lithium metal batteries

Sulfide electrolytes are a highly promising type of electrolyte due to their intrinsically soft properties and ultrahigh ionic conductivity. However, compatibility issues at the lithium interface have hindered their development in all-solid-state lithium metal batteries. Composite polymer electrolytes can indeed address interface issues, enhancing battery safety. Nonetheless, the incompatibility at the inorganic-organic interface within composite electrolytes can lead to reduced conductivity and diminished mechanical performance. Herein, we demonstrate a composite polymer electrolyte (CPE) composed of the Li6PS5Cl and polyethylene oxide (PEO) by the chemical bridging effect of (3-chloropropyl) trimethoxysilane (CTMS) on the 3D PET nonwoven framework to resolving the incompatibility between the inorganic and organic components, thereby reinforcing the chemical and mechanical performance of the electrolyte. The CPE shows superior characteristics, including elevated ionic conductivity (7.5 × 10−4 S cm−1), an extended electrochemical stability window (5.3 V versus Li/Li+), an expanded lithium transference number (t(Li+) = 0.52), and higher mechanical strength (9.35 MPa). The assembly of a Li/Li symmetric cell, operating steadily for 400 h at a current density of 0.3 mA cm−2 while maintaining a stable and relatively low polarization voltage (70 mV), demonstrates exceptional stability with respect to the lithium electrode. Moreover, the LiFePO4/Li cell initially exhibits a discharge-specific capacity of 163.6 mAh g−1 with a coulombic efficiency approaching 100 % after 100 cycles at 0.1C. This endeavor offers a robust, attainable, and scalable methodology for crafting composite electrolytes, thereby paving the path for the practical implementation of all-solid-state lithium metal batteries.

Ti3C2Tx Filled in EMIMBF4 Semi-Solid Polymer Electrolytes for the Zinc-Metal Battery.

Zinc-ion batteries (ZIBs) are promising candidates for safe energy storage applications. However, undesirable parasitic reactions such as dendrite growth, gas evaluation, anode corrosion, and structural damage to the cathode under an acidic microenvironment severely affected cell performance. To resolve these issues, an MXene entrapped in an ionic liquid semi-solid gel polymer electrolyte (GPE) composite was explored. The molecular-level mixing of poly(vinylidene fluoride-co-hexafluoropropylene) (PVHF), zinc trifluoromethanesulfonate (Zn(OTF)2), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) ionic liquid, and Ti3C2Tx MXene provided a controlled Zn2+ shuttle toward the anode/cathode. Ti3C2Tx/EMIBF4/Zn(OTF)2/PVHF exhibited a breaking strength of 0.36 MPa with an associated extension of 23%. The Zn//Ti3C2Tx/EMIBF4/Zn(OTF)2/PVHF//Zn symmetric cell with continuous zinc plating/stripping exhibited excellent Zn2+ ion mobility toward the anode and cathode without undesired reactions. This was confirmed by post-mortem analysis after a symmetric cell compatibility test. The as-prepared GPE with a Na3V2(PO4)3 (NVP) cathode exhibited a high chemical diffusion coefficient of 1.14 × 10-7. It also showed an outstanding reversible capacity of 89 mAh g-1 at C/10 with an average discharge plateau voltage of 1.45 V, cycle durability, and controlled self-discharge. These results suggested that the Zn2+ ions in the Ti3C2Tx/EMIBF4/Zn(OTF)2/PVHF composite are reversibly labile in the anode and cathode directions.

Lignin Derived Ultrathin All-Solid Polymer Electrolytes with 3D Single-Ion Nanofiber Ionic Bridge Framework for High Performance Lithium Batteries.

The lignin derived ultrathin all-solid composite polymer electrolyte (CPE) with a thickness of only 13.2µm, which possess 3D nanofiber ionic bridge networks composed of single-ion lignin-based lithium salt (L-Li) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as the framework, and poly(ethylene oxide)/lithium bis(trifluoromethanesulfonyl)imide (PEO/LiTFSI) as the filler, is obtained through electrospinning/spraying and hot-pressing. t. The Li-symmetric cell assembled with the CPE can stably cycle more than 6000h under 0.5mA cm-2 with little Li dendrites growth. Moreover, the assembled Li||CPE||LiFePO4 cells can stably cycle over 700 cycles at 0.2 C with a super high initial discharge capacity of 158.5 mAh g-1 at room temperature, and a favorable capacity of 123 mAh g-1 at -20°C for 250 cycles. The excellent electrochemical performance is mainly attributed to the reason that the nanofiber ionic bridge network can afford uniformly dispersed single-ion L-Li through electrospinning, which synergizes with the LiTFSI well dispersed in PEO to form abundant and efficient 3D Li+ transfer channels. The ultrathin CPE induces uniform deposition of Li+ at the interface, and effectively inhibit the lithium dendrites. This work provides a promising strategy to achieve ultrathin biobased electrolytes for solid-state lithium ion batteries.

Building Bulk and Interface Dual Fast Li+ Conducting Pathway in Composite Solid Polymer Electrolyte Membrane for All–Solid–State Lithium–Metal Batteries

AbstractSolid polymer electrolytes (SPEs) are considered a promising solution to the safety problems of lithium‐ion batteries (LIBs) using liquid electrolytes. However, the high crystallinity and low ionic conductivity hinder the practical application of SPEs. Herein, we design a composite solid polymer electrolyte with a dual fast Li+ conducting pathway in bulk and interface by incorporating highly Li+ conductive ceramic Li6.4Ga0.2La3Zr2O12 (LGLZO) in polyethylene oxide (PEO)/Li–bis (trifluoromethanesulfonyl) imide (LiTFSI) system. Compared to Li6.5La3Zr1.5Ta0.5O12 (LLZTO), LGLZO provides better Li+ conductivity; therefore, a fast Li+ conducting pathway will form in the bulk of LGLZO nanofillers. Besides, LGLZO nanofiller accelerates the dissociation of LiTFSI and benefits the transfer of free Li+ through the SPEs near the LGLZO surface, forming another interface fast Li+ conducting pathway in the SPEs. Benefits from the dual fast Li+ pathway design, the composite electrolyte membrane with 15 wt % LGLZO nanoparticles presents a high ionic conductivity of 8.0×10−4 S cm−1 at 60 °C. The Li−Li symmetric cells with optimized content LGLZO show good cycling stability (no short circuit even after 1000 h), and the all–solid Li/LiFePO4 batteries exhibit excellent cycling performance (remained 154 mAh g−1 after 500 cycles at 0.2 C under 60 °C).

Composite polymer electrolyte with vertically aligned garnet scaffolds for quasi solid-state lithium batteries

Structure design is of great importance for composite solid electrolytes to meet the high requirements for lithium batteries today. Herein, a novel composite polymer electrolyte with vertically aligned fast ion pathways has been constructed through the in-situ UV-induced polymerization of poly (butyl acrylate) (PBA) based gel polymer electrolyte inside the honeycomb-structure Li6.5La3Zr1.5Ta0.5012 (LLZTO) scaffolds by freeze casting. The addition of LLZTO enhances the anion adsorption through the Lewis-acid sites of the La ions and reduces the Li+ complexation by participating in the interaction of CO⋯Li+. Therefore, the interface of PBA and LLZTO scaffold serves as a continuous Li+ transport pathway and the resulting composite solid electrolyte exhibits a high ionic conductivity (5.098×10−4 S cm−1), near single-ion conducting characteristic (a transference number of 0.8) and high electrochemical stability window (5.15 V). Based on the above superior performance, the composite electrolyte promotes uniform distribution of lithium ion concentration and electrolyte potential. Thus, quasi-solid-state LiFePO4/Li cells exhibit excellent cycling performance (capacity retention of 91.7 % after 300 cycles at 0.5 C).

Asymmetric Solid-State Lithium-Metal-Battery Electrolytes Featuring Na Superionic Conductor-Type Ceramic and Garnet-Type Ceramic Filled Composite Polymer

Abstract In this study, Li1.3Al0.3Ti1.7(PO4)3 (LATP)-based lithium metal battery (LMB) cells are prepared using two different protection layers against Li metal: a solid polymer electrolyte (SPE) containing polyethylene oxide and lithium bis(fluorosulfonyl)imide (LiTFSI), and a composite polymer electrolyte (CPE) filled with a 14 wt% Li6.4La3Zr1.4Ta0.6O12 (LLZTO). The CPE-containing symmetric cell exhibits a smaller overvoltage than that of its SPE-containing counterpart, which is maintained for ~1000 h at 0.1 mA·cm-2 at 60 °C, owing to enhanced Li-ion transport in the CPE and at the LATP–CPE interface as well as the uniform Li deposition induced by the CPE with a higher Li+ transference number. Post-material analyses reveal that the CPE imparts long-term (~1000 h) protection to the LATP against Li metal, whereas the SPE is effective over a shorter period (~100 h). The CPE-based full cell exhibits a higher capacity (~141 mAh·g-1; with a LiFePO4) and capacity retention (~95%) than those of the SPE-based full cell (~130 mAh·g-1 and ~ 55%, respectively), for 310 cycles at 60 °C. This study recommends utilizing asymmetric solid electrolytes containing a ceramic (LATP at the cathode) and composite polymer (PEO + LLZTO at the anode) to improve cyclability and suppress Li dendrite growth in solid-state LMBs.

Flexible High Lithium-Ion Conducting PEO-Based Solid Polymer Electrolyte with Liquid Plasticizers for High Performance Solid-State Lithium Batteries.

Lithium-ion secondary batteries (LIB) with high energy density have attracted much attention for electric vehicle (EV) applications. However, LIBs have a safety problem because these batteries contain a flammable organic electrolyte. As such, all-solid secondary batteries that are not flammable have been extensively reported recently. In this study, we have focused on polymer electrolytes, which is flexible and is expected to address the safety problem. However, the conventional polymer electrolytes have low electrial conductivity at room temperature. Various attempts have been made to solve this problem, such as the addition of inorganic fillers and ionic liquids; however, these composite polymer electrolytes have not yet reached a practical level of lithium-ion conductivity. In this study, high electrical conductivity and lithium dendrite formation-free PEO based composite electrolytes are developed with both a filler of Li6,4La3Zr1.4Ta0.6O12 and liquid plasticizers of tetraethylene glycol dimethyl ether and 1,2 dimethoxyethane. The proposed flexible polymer electrolyte shows a high electrical conduciviy of 6.01×10-4 S cm-1 at 25 °C.

Constructing Robust LiF‐Enriched Interfaces in High‐Voltage Solid‐State Lithium Batteries Utilizing Tailored Oriented Ceramic Fiber Electrolytes

AbstractThe pursuit of high‐performance energy storage devices has fueled significant advancements in the all‐solid‐state lithium batteries (ASSLBs). One of the strategies to enhance the performance of ASSLBs, especially concerning high‐voltage cathodes, is optimizing the structure of composite polymer electrolytes (CPEs). This study fabricates a high‐oriented framework of Li6.4La3Zr2Al0.2O12 (o‐LLZO) ceramic nanofibers, meticulously addressing challenges in both the Li metal anode and the high‐voltage LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode. The as‐constructed electrolyte features a highly efficient Li+ transport and robust mechanical network, enhancing both electron and ion transport, ensuring uniform current density distribution, and stress distribution, and effectively suppressing Li dendrite growth. Remarkably, the Li symmetric cells exhibit outstanding long‐term lifespan of 9800 h at 0.1 mA cm−2 and operate effectively over 800 h even at 1.0 mA cm−2 under 30 °C. The CPEs design results from the formation of a gradient LiF‐riched SEI and CEI film at the Li/electrolyte/NCM811 dual interfaces, enhancing ion conduction and maintaining electrode integrity. The coin‐cells and pouch cells demonstrate prolonged cycling stability and superior capacity retention. This study sets a notable precedent in advancing high‐energy ASSLBs.

Multiscale Polyvinylidene Fluoride/Magnesium–Aluminum Layered Double Hydroxide Gel Electrolytes for Lithium Batteries

A multiscale of porous polyvinylidene fluoride–hexafluoropropylene copolymer/magnesium–aluminum layered double hydroxides (MgAl‐LDHs) composite gel polymer electrolyte is prepared by phase separation method. It is discovered that the ionic conductivity of the electrolyte reaches a maximum value of 1.36 × 10−3 S cm−1, the lithium ions’ mobility is 0.66, and the chemical performance is steady within the 4.85 V window along with the concentration of MgAl‐LDHs up to 0.4 wt% at room temperature. The density functional theory calculations show that the adsorption energy of Li+ with MgAl‐LDH is −3.59 eV and the diffusion potential barrier is 0.37 eV, which is favorable for the dissociation and transport of Li+. Moreover, the anode's initial discharge capacity at 0.1 C achieves 144 mAh g−1, keeping 84.7% of the theoretical capacity of 170 mAh g−1, and the capacity retention and the columbic efficiency maintain 92.4% and 95.7% after 100 cycles at 0.2 C, respectively, through assembling into a Li/PVP–MgAl/LiFePO4 battery.

Li6.28La3Zr2Al0.24O12-reinforced Single-ion Conducting Composite Polymer Electrolyte for Room-Temperature Li-Metal Batteries

Composite polymer electrolytes composed of inorganic fillers and organic polymers are promising electrolyte candidates for Li metal batteries, with benefits of improved safety and suppressed lithium dendrite growth. However, a severe concentration polarization effect often occurs when using conventional dual-ion electrolytes, and the increase in internal impedance during cycling results in decreased lifespan of the battery. To address this challenge, a plasticized single-ion conducting composite polymer electrolyte (SICE) was designed and fabricated by polymerizing the monomers of lithium (4-styrenesulfonyl) (trifluoromethanesulfonyl) imide (LiSTFSI) and poly(ethylene glycol) methyl ether acrylate (PEGMEA), crosslinker poly(ethylene glycol) diacrylate (PEGDA), silane-modified Li6.28La3Al0.24Zr2O12 nanofibers (s@LLAZO NFs), along with a PEG-based plasticizer tetraethylene glycol dimethyl ether (TEGDME), by heat-initiation. The anions were restrained and delocalized so that only Li cation migration occurred during the charging/discharging process, leading to a superior lithium-ion transference number. The s@LLAZO NFs enabled direct monomer grafting with the polymer matrix, resulting in controlled formation of an organic-inorganic network with increased filler content and improved filler distribution in the SICE system. The SICE membrane exhibited high ionic conductivity at room temperature, reduced activation energy and excellent oxidation stability. Most importantly, the all-solid-state Li-metal batteries assembled with the fabricated SICE demonstrated stable long-term cycling performance and remarkable rate capability at room temperature.

Speek-Protic ionic Liquid-Based anhydrous Proton-Conducting composite polymer electrolyte membranes for High-Temperature fuel cell applications

A high-temperature polymer electrolyte membrane fuel cell (PEMFC) has enormous potential to produce clean energy with minimal environmental pollution along with high energy density and conversion efficiency. In the present work, anhydrous proton-conducting polymer electrolyte membranes for prospective high-temperature fuel cell application were successfully prepared using different protic ionic liquids (PILs) and sulfonated poly(ether ether ketone) (SPEEK). The protic ionic liquids (PILs), 2-hydroxyethylammonium formate, diethylmethyl ammonium triflate, 1-ethylimidazolium bis(trifluoromethylsulfonyl)imide, 1,2-dimethyl imidazolium bis(trifluoro methylsulfonyl)imide, and diethylmethylammonium methanesulfonate were selected based on their favorable physicochemical properties. The effect of the incorporation of the PIL on the structural, thermal, and electrical transport properties of the composite SPEEK polymer electrolyte membranes was studied. The prepared polymer electrolyte membranes (PEMs) were characterized using techniques of Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffractometry (XRD), and electrochemical impedance spectroscopy (EIS). FTIR results indicated an interaction between the PIL and the SPEEK, which resulted in homogeneous and flexible membranes. The DSC results confirmed good miscibility and elucidated plasticizing effect of the incorporated PIL on the SPEEK polymer matrix. All the PEMs showed good thermal stability and high-temperature anhydrous proton conductivity, achieving best proton conductivity, ≈8 × 10–3 S cm−1 at 120 °C and low activation energy ≈0.26 eV, making it suitable for prospective high-temperature PEMFC applications.

Rationally coordinating polymer enabling effective Li-ion percolation network in composite electrolyte for solid-state Li-metal batteries

The sluggish lithium-ion mobility and inferior electrolyte/electrode interfacial compatibility of composite solid electrolytes greatly hinder the practical application of solid-state lithium-metal batteries. Here, a novel composite polymer electrolyte (CPE) with effective Li+ percolation network is synthesized based on single-ion conductive polymer lithiated polyvinyl formal (LiPVFM) and garnet Li6.4La3Zr2Ga0.2O12 (LLZGO) nanoparticles. The supramolecular interaction between the branched hydroxyl in LiPVFM and the lattice oxygen in LLZGO fillers endows CPE with a continuous percolation structure and improved toughness. Meanwhile, the rational O-Li+ coordination in the LiPVFM random polymer significantly enhances Li+ transfer within the percolation network. Therefore, this as-prepared CPE presents a lithium-ion transference number of 0.75 and an ionic conductivity of 0.527 mS cm−1 at 30 °C, alongside an electrochemical stability window of 4.6 V and a substantial suppression of Li dendrite growth. In addition, ultra-stable interfaces between this CPE and high-voltage LiNi0.6Mn0.2Co0.2O2 (NMC) cathode during cycling can be determined by in-situ electrochemical impedance spectroscopy and in-situ differential electrochemical mass spectrometry characterization. This work is a new exploration for the structural design of CPEs and highlights the importance of “rational coordination” of alkali cation in solid batteries.

Enhancement mechanism of the comprehensive performance of all-solid-state polymer electrolytes by halloysite nanotubes: Construction of efficient lithium-ion conduction channels

Considering the current issues with poly(ethylene oxide)-based all-solid-state polymer electrolytes (PEO-ASSPEs) employed in lithium-ion batteries (LIBs), such as low ionic conductivity, low lithium-ion transference number, narrow electrochemical stability window, and poor cyclic stability. This study introduces oxygen-vacancy-rich halloysite nanotubes (HNTs) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) into the PEO matrix to fabricate a flexible composite polymer electrolyte (CPEs) via a solvent-free method. The interaction between HNTs and LiTFSI in the PEO matrix serves to mitigate the ionic solvation effect, increase the number of free lithium-ion, and reduce the lithium-ion migration energy barrier. Additionally, the internal framework formed by the mutual stacking of HNTs reduces the number of entanglements in polymer molecular chains, enhances the mobility of the chains, and generates a continuous interface effect, forming fast lithium-ion transport channels. The CPEs prepared in this study are in conformity with the Vogel-Tammann-Fulcher (VTF) empirical equation. The CPE containing 10 wt% HNTs exhibits a high ionic conductivity (7.15 × 10−4 S cm−1) at 25 °C, a high lithium-ion transference number (0.600), a wide electrochemical stability window (5.5 V), and excellent cyclic performance (capacity retention of 82.02 % after 100 cycles at 0.1C), satisfying the electrochemical performance requirements for ASSPEs in LIBs.

Sandwich-type composited solid polymer electrolytes to strengthen the interfacial ionic transportation and bulk conductivity for all-solid-state lithium batteries from room temperature to 120 °C

The insurmountable charge transfer impedance at the Li metal/ solid polymer electrolytes (SPEs) interface at room temperature as well as the ascending risk of short circuits at the operating temperature higher than the melting point, dominantly limits their applications in solid-state batteries (SSBs). Although the inorganic filler such as CeO2 nanoparticle content of composite solid polymer electrolytes (CSPEs) can significantly reduce the enormous charge transfer impedance at the Li metal/SPEs interface, we found that the required content of CeO2 nanoparticles in SPEs varies for achieving a decent interfacial charge transfer impedance and the bulk ionic conductivity in CSPEs. In this regard, a sandwich-type composited solid polymer electrolyte with a 10% CeO2 CSPEs interlayer sandwiched between two 50% CeO2 CSPEs thin layers (sandwiched CSPEs) is constructed to simultaneously achieve low charge transfer impedance and superior ionic conductivity at 30 °C. The sandwiched CSPEs allow for stable cycling of Li plating and stripping for 1000 h with 129 mV polarized voltage at 0.1 mA cm−2 and 30 °C. In addition, the LiFePO4/Sandwiched CSPEs /Li cell also exhibits exceptional cycle performance at 30 °C and even elevated 120 °C without short circuits. Constructing multi-layered CSPEs with optimized contents of the inorganic fillers can be an efficient method for developing all solid-state PEO-based batteries with high performance at a wide range of temperatures.

The Versatile Establishment of Charge Storage in Polymer Solid Electrolyte with Enhanced Charge Transfer for LiF‐Rich SEI Generation in Lithium Metal Batteries

AbstractThe solid‐state electrolyte interface (SEI) between the solid‐state polymer electrolyte and the lithium metal anode dramatically affects the overall battery performance. Increasing the content of lithium fluoride (LiF) in SEI can help the uniform deposition of lithium and inhibit the growth of lithium dendrites, thus improving the cycle stability performance of lithium batteries. Currently, most methods of constructing LiF SEI involve decomposing the lithium salt by the polar groups of the filler. However, there is a lack of research reports on how to affect the SEI layer of Li‐ion batteries by increasing the charge transfer number. In this study, a porous organic polymer with “charge storage” properties was prepared and doped into a polymer composite solid electrolyte to study the effect of sufficient charge transfer on the decomposition of lithium salts. The results show in contrast to porphyrins, the unique structure of POF allows for charge transfer between each individual porphyrin. Therefore, during TFSI− decomposition to the formation of LiF, TFSI− can obtain sufficient charge, thereby promoting the break of C−F and forming the LiF‐rich SEI. Compared with single porphyrin (0.423 e−), POF provides 2.7 times more charge transfer to LiTFSI (1.147 e−). The experimental results show that Li//Li symmetric batteries equipped with PEO‐POF can be operated stably for more than 2700 h at 60 °C. Even the Li//Li (45 μm) symmetric cells are stable for more than 1100 h at 0.1 mA cm−1. In addition, LiFePO4//PEO‐POF//Li batteries have excellent cycling performance at 2 C (80 % capacity retention after 750 cycles). Even LiFePO4//PEO‐POF//Li (45 μm) cells have excellent cycling performance at 1 C (96 % capacity retention after 300 cycles). Even when the PEO‐base is replaced with a PEG‐base and a PVDF‐base, the performance of the cell is still significantly improved. Therefore, we believe that the concept of charge transfer offers a novel perspective for the preparation of high‐performance assemblies.