A Flexible Ceramic/Polymer Hybrid Solid Electrolyte for Solid-State Lithium Metal Batteries

Ceramic/polymer hybrid solid electrolytes (HSEs) have attracted worldwide attentions because they can overcome defects by combining the advantages of ceramic electrolytes (CEs) and solid polymer electrolytes (SPEs). However, the interface compatibility of CEs and SPEs in HSE limits their full function to a great extent. Herein, a flexible ceramic/polymer HSE is prepared via in situ coupling reaction. Ceramic and polymer are closely combined by strong chemical bonds, thus the problem of interface compatibility is resolved and the ions can transport rapidly by an expressway. The as-prepared membrane demonstrates an ionic conductivity of 9.83 × 10⁻⁴ S cm⁻¹ at room temperature and a high Li⁺ transference numbers of 0.68. This in situ coupling reaction method provides an effective way to resolve the problem of interface compatibility.     

High-Safety and High-Energy-Density Lithium Metal Batteries in a Novel Ionic-Liquid Electrolyte

Rechargeable lithium metal batteries are next generation energy storage devices with high energy density, but face challenges in achieving high energy density, high safety, and long cycle life. Here, lithium metal batteries in a novel nonflammable ionic-liquid (IL) electrolyte composed of 1-ethyl-3-methylimidazolium (EMIm) cations and high-concentration bis(fluorosulfonyl)imide (FSI) anions, with sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) as a key additive are reported. The Na ion participates in the formation of hybrid passivation interphases and contributes to dendrite-free Li deposition and reversible cathode electrochemistry. The electrolyte of low viscosity allows practically useful cathode mass loading up to ≈16 mg cm⁻². Li anodes paired with lithium cobalt oxide (LiCoO₂) and lithium nickel cobalt manganese oxide (LiNi_0.8Co_0.1Mn_0.1O₂, NCM 811) cathodes exhibit 99.6–99.9% Coulombic efficiencies, high discharge voltages up to 4.4 V, high specific capacity and energy density up to ≈199 mAh g⁻¹ and ≈765 Wh kg⁻¹ respectively, with impressive cycling performances over up to 1200 cycles. Highly stable passivation interphases formed on both electrodes in the novel IL electrolyte are the key to highly reversible lithium metal batteries, especially for Li–NMC 811 full batteries.     

Single-Ion Polymer Electrolyte Based on Lithium-Rich Imidazole Anionic Porous Aromatic Framework for High Performance Lithium-Ion Batteries

The low ionic conductivity and Li⁺ transference number ($t_{L{i}^{+}}$) of solid polymer electrolytes (SPEs) seriously hinder their application in lithium-ion batteries (LIBs). In this study, a novel single-ion lithium-rich imidazole anionic porous aromatic framework (PAF-220-Li) is designed. The abundant pores in PAF-220-Li are conducive to the Li⁺ transfer. Imidazole anion has low binding force with Li⁺. The conjugation of imidazole and benzene ring can further reduce the binding energy between Li⁺ and anions. Thus, only Li⁺ moved freely in the SPEs, remarkably reducing the concentration polarization and inhibiting lithium dendrite growth. PAF-220-quasi-solid polymer electrolyte (PAF-220-QSPE) is prepared through solution casting of Bis(trifluoromethane)sulfonimide lithium (LiTFSI) infused PAF-220-Li and Poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP), and possessed excellent electrochemical performance. The electrochemical property are further improved by preparing all-solid polymer electrolyte (PAF-220-ASPE) via pressing-disc method, which has a high Li⁺ conductivity of 0.501 mS cm⁻¹ and $t_{L{i}^{+}}$ of 0.93. The discharge specific capacity at 0.2 C of Li//PAF-220-ASPE//LFP reached 164 mAh g⁻¹, and the capacity retention rate is 90% after 180 cycles. This study provided a promising strategy for SPE with single-ion PAFs to achieve high-performance solid-state LIBs.     

A Crosslinked Polytetrahydrofuran‐Borate‐Based Polymer Electrolyte Enabling Wide‐Working‐Temperature‐Range Rechargeable Magnesium Batteries

A polymer‐based magnesium (Mg) electrolyte is vital for boosting the development of high‐safety and flexible Mg batteries by virtue of its enormous advantages, such as significantly improved safety, potentially high energy density, ease of fabrication, and structural flexibility. Herein, a novel polytetrahydrofuran‐borate‐based gel polymer electrolyte coupling with glass fiber is synthesized via an in situ crosslinking reaction of magnesium borohydride [Mg(BH₄)₂] and hydroxyl‐terminated polytetrahydrofuran. This gel polymer electrolyte exhibits reversible Mg plating/stripping performance, high Mg‐ion conductivity, and remarkable Mg‐ion transfer number. The Mo₆S₈/Mg batteries assembled with this gel polymer electrolyte not only work well at wide temperature range (?20 to 60 °C) but also display unprecedented improvements in safety issues without suffering from internal short‐circuit failure even after a cutting test. This in situ crosslinking approach toward exploiting the Mg‐polymer electrolyte provides a promising strategy for achieving large‐scale application of Mg‐metal batteries.     

An In Situ Cross‐Linked Nonaqueous Polymer Electrolyte for Zinc‐Metal Polymer Batteries and Hybrid Supercapacitors

This work reports the facile synthesis of nonaqueous zinc‐ion conducting polymer electrolyte (ZIP) membranes using an ultraviolet (UV)‐light‐induced photopolymerization technique, with room temperature (RT) ionic conductivity values in the order of 10^?3 S cm^?1. The ZIP membranes demonstrate excellent physicochemical and electrochemical properties, including an electrochemical stability window of >2.4 V versus Zn|Zn²⁺ and dendrite‐free plating/stripping processes in symmetric Zn||Zn cells. Besides, a UV‐polymerization‐assisted in situ process is developed to produce ZIP (abbreviated i‐ZIP), which is adopted for the first time to fabricate a nonaqueous zinc‐metal polymer battery (ZMPB; VOPO₄|i‐ZIP|Zn) and zinc‐metal hybrid polymer supercapacitor (ZMPS; activated carbon|i‐ZIP|Zn) cells. The VOPO₄ cathode employed in ZMPB possesses a layered morphology, exhibiting a high average operating voltage of ≈1.2 V. As compared to the conventional polymer cell assembling approach using the ex situ process, the in situ process is simple and it enhances the overall electrochemical performance, which enables the widespread intrusion of ZMPBs and ZMPSs into the application domain. Indeed, considering the promising aspects of the proposed ZIP and its easy processability, this work opens up a new direction for the emergence of the zinc‐based energy storage technologies.     

A Single-Ion Conducting Borate Network Polymer as a Viable Quasi-Solid Electrolyte for Lithium Metal Batteries

Lithium-ion batteries have remained a state-of-the-art electrochemical energy storage technology for decades now, but their energy densities are limited by electrode materials and conventional liquid electrolytes can pose significant safety concerns. Lithium metal batteries featuring Li metal anodes, solid polymer electrolytes, and high-voltage cathodes represent promising candidates for next-generation devices exhibiting improved power and safety, but such solid polymer electrolytes generally do not exhibit the required excellent electrochemical properties and thermal stability in tandem. Here, an interpenetrating network polymer with weakly coordinating anion nodes that functions as a high-performing single-ion conducting electrolyte in the presence of minimal plasticizer, with a wide electrochemical stability window, a high room-temperature conductivity of 1.5 × 10⁻⁴ S cm⁻¹, and exceptional selectivity for Li-ion conduction (t_Li+ = 0.95) is reported. Importantly, this material is also flame retardant and highly stable in contact with lithium metal. Significantly, a lithium metal battery prototype containing this quasi-solid electrolyte is shown to outperform a conventional battery featuring a polymer electrolyte.     

Thiol-Branched Solid Polymer Electrolyte Featuring High Strength,Toughness, and Lithium Ionic Conductivity for Lithium-Metal Batteries

Lithium-metal batteries (LMBs) with high energy densities are highly desirable for energy storage, but generally suffer from dendrite growth and side reactions in liquid electrolytes; thus the need for solid electrolytes with high mechanical strength, ionic conductivity, and compatible interface arises. Herein, a thiol-branched solid polymer electrolyte (SPE) is introduced featuring high Li⁺ conductivity (2.26 × 10⁻⁴ S cm⁻¹ at room temperature) and good mechanical strength (9.4 MPa)/toughness (≈500%), thus unblocking the tradeoff between ionic conductivity and mechanical robustness in polymer electrolytes. The SPE (denoted as M-S-PEGDA) is fabricated by covalently cross-linking metal–organic frameworks (MOFs), tetrakis (3-mercaptopropionic acid) pentaerythritol (PETMP), and poly(ethylene glycol) diacrylate (PEGDA) via multiple C S C bonds. The SPE also exhibits a high electrochemical window (>5.4 V), low interfacial impedance (<550 Ω), and impressive Li⁺ transference number (t_Li+ = 0.44). As a result, Li||Li symmetrical cells with the thiol-branched SPE displayed a high stability in a >1300 h cycling test. Moreover, a Li|M-S-PEGDA|LiFePO₄ full cell demonstrates discharge capacity of 143.7 mAh g⁻¹ and maintains 85.6% after 500 cycles at 0.5 C, displaying one of the most outstanding performances for SPEs to date.     

Achieving Ultra-Stable All-Solid-State Sodium Metal Batteries with Anion-Trapping 3D Fiber Network Enhanced Polymer Electrolyte

All-solid-state sodium metal batteries paired with solid polymer electrolytes (SPEs) are considered a promising candidate for high energy-density, low-cost, and high-safety energy storage systems. However, the low ionic conductivity and inferior interfacial stability with Na metal anode of SPEs severely hinder their practical applications. Herein, an anion-trapping 3D fiber network enhanced polymer electrolyte (ATFPE) is developed by infusing poly(ethylene oxide) matrix into an electrostatic spun fiber framework loading with an orderly arranged metal-organic framework (MOF). The 3D continuous channel provides a fast Na⁺ transport path leading to high ionic conductivity, and simultaneously the rich coordinated unsaturated cation sites exposed on MOF can effectively trap anions, thus regulating Na⁺ concentration distribution for constructing stable electrolyte/Na anode interface. Based on such advantages, the ATFPE exhibits high ionic conductivity and considerable Na⁺ transference number, as well as enhanced interfacial stability. Consequently, Na/Na symmetric cells using this ATFPE possess cyclability over 600 h at 0.1 mA cm⁻² without discernable Na dendrites. Cooperated with Na₃V₂(PO₄)₃ cathode, the all-solid-state sodium metal batteries (ASSMBs) demonstrate significantly improved rate and cycle performances, delivering a high discharge capacity of 117.5 mAh g⁻¹ under 0.1 C and rendering high capacity retention of 78.2% after 1000 cycles even at 1 C.     

Toward High-Energy-Density Lithium Metal Batteries: Opportunities and Challenges for Solid Organic Electrolytes

With increasing demands for safe, high capacity energy storage to support personal electronics, newer devices such as unmanned aerial vehicles, as well as the commercialization of electric vehicles, current energy storage technologies are facing increased challenges. Although alternative batteries have been intensively investigated, lithium (Li) batteries are still recognized as the preferred energy storage solution for the consumer electronics markets and next generation automobiles. However, the commercialized Li batteries still have disadvantages, such as low capacities, potential safety issues, and unfavorable cycling life. Therefore, the design and development of electromaterials toward high-energy-density, long-life-span Li batteries with improved safety is a focus for researchers in the field of energy materials. Herein, recent advances in the development of novel organic electrolytes are summarized toward solid-state Li batteries with higher energy density and improved safety. On the basis of new insights into ionic conduction and design principles of organic-based solid-state electrolytes, specific strategies toward developing these electrolytes for Li metal anodes, high-energy-density cathode materials (e.g., high voltage materials), as well as the optimization of cathode formulations are outlined. Finally, prospects for next generation solid-state electrolytes are also proposed.     

Sandwich-Structured Quasi-Solid Polymer Electrolyte Enables High-Capacity,Long-Cycling,and Dendrite-Free Lithium Metal Battery at Room Temperature

The insufficient ionic conductivity, limited lithium-ion transference number (t_Li+), and high interfacial impedance severely hinder the practical application of quasi-solid polymer electrolytes (QSPEs). Here, a sandwich-structured polyacrylonitrile (PAN) based QSPE is constructedin which MXene-SiO₂ nanosheets act as a functional filler to facilitate the rapid transfer of lithium-ion in the QSPE, and a polymer and plastic crystalline electrolyte (PPCE) interface modification layer is coated on the surface of the PAN-based QSPE of 3 wt.% MXene-SiO₂ (SS-PPCE/PAN-3%) to reduce interfacial impedance. Consequently, the synthesized SS-PPCE/PAN-3% QSPE delivers a promising ionic conductivity of ≈1.7 mS cm⁻¹ at 30 °C, a satisfactory t_Li+ of 0.51, and a low interfacial impedance. As expected, the assembled Li symmetric battery with SS-PPCE/PAN-3% QSPE can stably cycle more than 1550 h at 0.2 mA cm⁻². The Li||LiFePO₄ quasi-solid-state lithium metal battery (QSSLMB) of this QSPE exhibits a high capacity retention of 81.5% after 300 cycles at 1.0 C and at RT. Even under the high-loading cathode (LiFePO₄ ≈ 10.0 mg cm⁻²) and RT, the QSSLMB achieves a superior area capacity and good cycling performance. Besides, the assembled high voltage Li||NMC811(loading ≈ 7.1 mg cm⁻²) QSSLMB has potential applications in high-energy fields.     

A Polymer‐Reinforced SEI Layer Induced by a Cyclic Carbonate‐Based Polymer Electrolyte Boosting 4.45 V LiCoO2/Li Metal Batteries

Lithium (Li) metal batteries (LMBs) are enjoying a renaissance due to the high energy densities. However, they still suffer from the problem of uncontrollable Li dendrite and pulverization caused by continuous cracking of solid electrolyte interphase (SEI) layers. To address these issues, developing spontaneously built robust polymer‐reinforced SEI layers during electrochemical conditioning can be a simple yet effective solution. Herein, a robust homopolymer of cyclic carbonate urethane methacrylate is presented as the polymer matrix through an in situ polymerization method, in which cyclic carbonate units can participate in building a stable polymer‐integrated SEI layer during cycling. The as‐investigated gel polymer electrolyte (GPE) assembled LiCoO₂/Li metal batteries exhibit a fantastic cyclability with a capacity retention of 92% after 200 cycles at 0.5 C (1 C = 180 mAh g^?1), evidently exceeding that of the counterpart using liquid electrolytes. It is noted that the anionic ring‐opening polymerization of the cyclic carbonate units on the polymer close to the Li metal anodes enables a mechanically reinforced SEI layer, thus rendering excellent compatibility with Li anodes. The in situ formed polymer‐reinforced SEI layers afford a splendid strategy for developing high voltage resistant GPEs compatible with Li metal anodes toward high energy LMBs.     

In Situ Formation of Polysulfonamide Supported Poly(ethylene glycol) Divinyl Ether Based Polymer Electrolyte toward Monolithic Sodium Ion Batteries

Sodium ion battery is one of the promising rechargeable batteries due to the low‐cost and abundant sodium sources. In this work, a monolithic sodium ion battery based on a Na₃V₂(PO₄)₃ cathode, MoS₂ layered anode, and polyether‐based polymer electrolyte is reported. In addition, a new kind of polysulfonamide‐supported poly(ethylene glycol) divinyl ether based polymer electrolyte is also demonstrated for monolithic sodium ion battery via in situ preparation. The resultant polymer electrolyte exhibits relatively high ionic conductivity (1.2 mS cm^?1) at ambient temperature, wide electrochemical window (4.7 V), and favorable mechanical strength (25 MPa). Moreover, such a monolithic Na₃V₂(PO₄)₃/MoS₂ sodium ion battery using this polymer electrolyte delivers outstanding rate capability (up to 10 C) and superior cyclic stability (84%) after 1000 cycles at 0.5 C. What is more essential, such a polymer electrolyte based soft‐package monolithic sodium ion cell can still power a red light emitting diode lamp and run finite times without suffering from any internal short‐circuit failures, even in the case of a bended and wrinkled state. Considering these aspects, this work no doubt provides a new approach for the design of a high‐performance polymer electrolyte toward monolithic sodium ion battery with exceptional rate capability and high safety.     

Simultaneous High Ionic Conductivity and Lithium-Ion Transference Number in Single-Ion Conductor Network Polymer Enabling Fast-Charging Solid-State Lithium Battery

Developing solid-state electrolyte with sufficient ionic conduction and flexible-intimate interface is vital to advance fast-charging solid-state lithium batteries. Solid polymer electrolyte yields the promise of interfacial compatibility, yet its critical bottleneck is how to simultaneously achieve high ionic conductivity and lithium-ion transference number. Herein, single-ion conducting network polymer electrolyte (SICNP) enabling fast charging is proposed to positively realize fast lithium-ion locomotion with both high ionic conductivity of 1.1 × 10⁻³ S cm⁻¹ and lithium-ion transference number of 0.92 at room temperature. Experimental characterization and theoretical simulations demonstrate that the construction of polymer network structure for single-ion conductor not only facilitates fast hopping of lithium ions for boosting ionic kinetics, but also enables a high dissociation level of the negative charge for lithium-ion transference number close to unity. As a result, the solid-state lithium batteries constructed by coupling SICNP with lithium anodes and various cathodes (e.g., LiFePO₄, sulfur, and LiCoO₂) display impressive high-rate cycling performance (e.g., 95% capacity retention at 5 C for 1000 cycles in LiFePO₄|SICNP|lithium cell) and fast-charging capability (e.g., being charged within 6 min and discharged over than 180 min in LiCoO₂|SICNP|lithium cell). Our study provides a prospective direction for solid-state electrolyte that meets the lithium-ion dynamics for practical fast-charging solid-state lithium batteries.     

A Silica‐Aerogel‐Reinforced Composite Polymer Electrolyte with High Ionic Conductivity and High Modulus

High‐energy all‐solid‐state lithium (Li) batteries have great potential as next‐generation energy‐storage devices. Among all choices of electrolytes, polymer‐based systems have attracted widespread attention due to their low density, low cost, and excellent processability. However, they are generally mechanically too weak to effectively suppress Li dendrites and have lower ionic conductivity for reasonable kinetics at ambient temperature. Herein, an ultrastrong reinforced composite polymer electrolyte (CPE) is successfully designed and fabricated by introducing a stiff mesoporous SiO₂ aerogel as the backbone for a polymer‐based electrolyte. The interconnected SiO₂ aerogel not only performs as a strong backbone strengthening the whole composite, but also offers large and continuous surfaces for strong anion adsorption, which produces a highly conductive pathway across the composite. As a consequence, a high modulus of ≈0.43 GPa and high ionic conductivity of ≈0.6 mS cm^?1 at 30 °C are simultaneously achieved. Furthermore, LiFePO₄–Li full cells with good cyclability and rate capability at ambient temperature are obtained. Full cells with cathode capacity up to 2.1 mAh cm^?2 are also demonstrated. The aerogel‐reinforced CPE represents a new design principle for solid‐state electrolytes and offers opportunities for future all‐solid‐state Li batteries.     

Greatly Improved Conductivity of Double‐Chain Polymer Network Binder for High Sulfur Loading Lithium–Sulfur Batteries with a Low Electrolyte/Sulfur Ratio

Binders have been considered to play a key role in realizing high‐energy‐density lithium–sulfur batteries. However, the accompanying problems of limited conductivity and inferior affinity of soluble polysulfide intermediates bring down their comprehensive performance for practical applications. Herein, the synthesis of a novel double‐chain polymer network (DCP) binder by polymerizing 4,4′‐biphenyldisulfonic acid connected pyrrole monomer onto viscous sodium carboxymethyl cellulose matrix, yielding a primary crystal structure is reported. Consequently, the resulted binder enables superior rate performance from 0.2 C (1326.9 mAh g^?1) to 4 C (701.4 mAh g^?1). Moreover, a high sulfur loading of 9.8 mg cm^?2 and a low electrolyte/sulfur ratio (5:1, µL mg^?1) are achieved, exhibiting a high area capacity of 9.2 mAh cm^?2. In situ X‐ray diffraction analysis is conducted to monitor the structural modifications of the cathode, confirming the occurrence of sulfur reduction/recrystallization during charge–discharge process. In addition, in situ UV–vis measurements demonstrate that DCP binder impedes the polysulfide migration, thereby giving rise to high capacity retention for 400 cycles.     

High-Performance Solid Lithium Metal Batteries Enabled by LiF/LiCl/LiIn Hybrid SEI via InCl3-Driven In Situ Polymerization of 1,3-Dioxolane

The use of poly(1,3-dioxolane) (PDOL) electrolyte for lithium batteries has gained attention due to its high ionic conductivity, low cost, and potential for large-scale applications. However, its compatibility with Li metal needs improvement to build a stable solid electrolyte interface (SEI) toward metallic Li anode for practical lithium batteries. To address this concern, this study utilized a simple InCl₃-driven strategy for polymerizing DOL and building a stable LiF/LiCl/LiIn hybrid SEI, confirmed through X-ray photoelectron spectroscopy (XPS) and cryogenic-transmission electron microscopy (Cryo-TEM). Furthermore, density functional theory (DFT) calculations and finite element simulation (FES) verify that the hybrid SEI exhibits not only excellent electron insulating properties but also fast transport properties of Li⁺. Moreover, the interfacial electric field shows an even potential distribution and larger Li⁺ flux, resulting in uniform dendrite-free Li deposition. The use of the LiF/LiCl/LiIn hybrid SEI in Li/Li symmetric batteries shows steady cycling for 2000 h, without experiencing a short circuit. The hybrid SEI also provided excellent rate performance and outstanding cycling stability in LiFePO₄/Li batteries, with a high specific capacity of 123.5 mAh g⁻¹ at 10 C rate. This study contributes to the design of high-performance solid lithium metal batteries utilizing PDOL electrolytes.     

Rational Design of Statically and Dynamically Stable Lithium–Sulfur Batteries with High Sulfur Loading and Low Electrolyte/Sulfur Ratio

The primary challenge with lithium–sulfur battery research is the design of sulfur cathodes that exhibit high electrochemical efficiency and stability while keeping the sulfur content and loading high and the electrolyte/sulfur ratio low. With a systematic investigation, a novel graphene/cotton‐carbon cathode is presented here that enables sulfur loading and content as high as 46 mg cm^?2 and 70 wt% with an electrolyte/sulfur ratio of as low as only 5. The graphene/cotton‐carbon cathodes deliver peak capacities of 926 and 765 mA h g^?1, respectively, at C/10 and C/5 rates, which translate into high areal, gravimetric, and volumetric capacities of, respectively, 43 and 35 mA h cm^?2, 648 and 536 mA h g^?1, and 1067 and 881 mA h cm^?3 with a stable cyclability. They also exhibit superior cell‐storage capability with 95% capacity‐retention, a low self‐discharge constant of just 0.0012 per day, and stable poststorage cyclability after storing over a long period of six months. This work demonstrates a viable approach to develop lithium–sulfur batteries with practical energy densities exceeding that of lithium‐ion batteries.