Li Symmetric Cells Research Articles

A Dielectric MXene‐Induced Self‐Built Electric Field in Polymer Electrolyte Triggering Fast Lithium‐Ion Transport and High‐Voltage Cycling Stability

AbstractQuasi‐solid polymer electrolyte (QPE) lithium (Li)‐metal battery holds significant promise in the application of high‐energy‐density batteries, yet it suffers from low ionic conductivity and poor oxidation stability. Herein, a novel self‐built electric field (SBEF) strategy is proposed to enhance Li+ transportation and accelerate the degradation dynamics of carbon‐fluorine bond cleavage in LiTFSI by optimizing the termination of MXene. Among them, the SBEF induced by dielectric Nb4C3F2 MXene effectively constructs highly conductive LiF‐enriched SEI and CEI stable interfaces, moreover, enhances the electrochemical performance of the QPE. The related Li‐ion transfer mechanism and dual‐reinforced stable interface are thoroughly investigated using ab initio molecular dynamics, COMSOL, XPS depth profiling, and ToF‐SIMS. This comprehensive approach results in a high conductivity of 1.34 mS cm−1, leading to a small polarization of approximately 25 mV for Li//Li symmetric cell after 6000 h. Furthermore, it enables a prolonged cycle life at a high voltage of up to 4.6 V. Overall, this work not only broadens the application of MXene for QPE but also inspires the great potential of the self‐built electric field in QPE‐based high‐voltage batteries.

A locally solvent-tethered polymer electrolyte for long-life lithium metal batteries

Solid polymer electrolytes exhibit enhanced Li+ conductivity when plasticized with highly dielectric solvents such as N,N-dimethylformamide (DMF). However, the application of DMF-containing electrolytes in solid-state batteries is hindered by poor cycle life caused by continuous DMF degradation at the anode surface and the resulting unstable solid-electrolyte interphase. Here we report a composite polymer electrolyte with a rationally designed Hofmann-DMF coordination complex to address this issue. DMF is engineered on Hofmann frameworks as tethered ligands to construct a locally DMF-rich interface which promotes Li+ conduction through a ligand-assisted transport mechanism. A high ionic conductivity of 6.5 × 10−4 S cm−1 is achieved at room temperature. We demonstrate that the composite electrolyte effectively reduces the free shuttling and subsequent decomposition of DMF. The locally solvent-tethered electrolyte cycles stably for over 6000 h at 0.1 mA cm−2 in Li | |Li symmetric cell. When paired with sulfurized polyacrylonitrile cathodes, the full cell exhibits a prolonged cycle life of 1000 cycles at 1 C. This work will facilitate the development of practical polymer-based electrolytes with high ionic conductivity and long cycle life.

Hybrid Ceramic Polymer Electrolytes Enabling Long Cycling in Practical 1 Ah‐Class High‐Voltage Solid‐State Batteries with Li Metal Anode

AbstractSolid polymer electrolytes offer a safer alternative to organic liquid electrolytes in high‐voltage lithium metal batteries, yet challenges remain in achieving adequate cyclability, energy density, scalability, and safety. This study presents the cycling performance of 1 Ah high‐voltage lithium polymer batteries featuring a hybrid ceramic polymer electrolyte (HCPE), a lithium metal anode, and a LiNi0.8Mn0.1Co0.1O2 (NMC‐811)‐based positive electrode. The HCPE stands out for its remarkable mechanical properties, with a Young's modulus exceeding 200 MPa at room temperature, providing robust resistance against dendrite formation. The Li||Li symmetric cells exhibited outstanding performance, cycling for over 1000 hours at a capacity of 2 mAh cm−2, highlighting the exceptional attributes of HCPE. Full cell testing is conducted under practical conditions, utilizing various cell configurations, from coin cells to large pouch cells with a 1 Ah capacity, achieving an energy density of nearly 250 Wh kg−1 and promising cyclability with 80% capacity retention after 110 cycles. The study also investigated thermal runaway characteristics, showing comparability with commercial lithium‐ion batteries. This research underscores the scalability and performance of high‐voltage lithium metal polymer batteries, advancing their potential for commercial viability.

Stable Oxyhalide-Nitride Fast Ionic Conductors for All-Solid-State Li Metal Batteries.

Rechargeable all-solid-state lithium metal batteries (ASSLMBs) utilizing inorganic solid-state electrolytes (SSEs) are promising for electric vehicles and large-scale grid energy storage. However, the Li dendrite growth in SSEs still constrains the practical utility of ASSLMBs. To achieve a high dendrite-suppression capability, SSEs must be chemically stable with Li, possess fast Li transfer kinetics, and exhibit high interface energy. Herein, a class of low-cost, eco-friendly, and sustainable oxyhalide-nitride solid electrolytes (ONSEs), denoted as LixNyIz-qLiOH (where x = 3y + z, 0 ≤ q ≤ 0.75), is designed to fulfill all the requirements. As-prepared ONSEs demonstrate chemically stable against Li and high interface energy (>43.08 meV Å-2), effectively restraining Li dendrite growth and the self-degradation at electrode interfaces. Furthermore, improved thermodynamic oxidation stability of ONSEs (>3V vs Li+/Li, 0.45V for pure Li3N), arising from the increased ionicity of Li─N bonds, contributes to the stability in ASSLMBs. As a proof-of-concept, the optimized ONSEs possess high ionic conductivity of 0.52 mS cm-1 and achieve long-term cycling of Li||Li symmetric cell for over 500h. When coupled with the Li3InCl6 SSE for high-voltage cathodes, the bilayer oxyhalide-nitride/Li3InCl6 electrolyte imparts 90% capacity retention over 500 cycles for Li||1 mAh cm-2 LiCoO2 cells.

Constructing lithiophilic sites–rich artificial solid electrolyte interphase to enable dendrite−free and corrosion−free lithium–sulfur batteries

An artificial solid electrolyte interphase (SEI) with lithiophilic sites and chemical bonds anchoring lithium polysulfides (LiPSs) has been developed as a potential solution to protect the lithium (Li) metal anode of Lithium−sulfur (Li–S) batteries. This strategy aims to guide consistent Li deposition and relieve lithium corrosion. Herein, the evolution process of lithiophilic sites based on aluminum fluoride (AlF3) in an artificial SEI is disclosed in Li–S batteries with metal−based lithiophilic sites. The polyester polymer (PMMA and PPC)/AlF3 artificial SEI (MPAF−SEI) was homogeneously anchored on Li anode by in−situ polymerization. The conversion of AlF3 into Li–Al and LiF lithiophilic sites effectively reduce the Li nucleation overpotential and prevents the formation of Li dendrites. At the same time, the polymer can anchor LiPSs by chemical bonds and prevents Li corrosion. The optimized MPAF−SEI protected Li demonstrates excellent stability for over 3000 h at a capacity of 1 mAh cm−2 in Li || Li symmetric cells. The Li–S battery with low N/P (4) exhibits a capacity of 532.6 mAh g −1 over 300 cycles lifespan at 0.5C.

An environmentally friendly and scalable manufacturing route to the high performance composite polymer electrolytes for lithium-metal batteries

Environmentally friendly manufacturing of flexible all-solid-state electrolytes in large-scale and low cost is important for market entering of lithium metal batteries. Herein, a simple and practical solvent-free route to the high performance composite polymer electrolyte is proposed by infiltrating the hot-molten polyether polymer (F127)/Li-salt (LiTFSI) slurry into a thin cellulose fibrous membrane. The good compatibility between the slurry and cellulose membrane allows the formation of a highly dense F127/LiTFSI/cellulose composite electrolyte with a thin thickness of 28 μm. The solvent-free feature without side-reaction as well as the good mechanical stability of such electrolyte makes great significance to ensure the safety and stability of the batteries. Therefore, its Li symmetric cell can stably operate with an ultralong lifespan of more than 3600 h without dendritic growth of metal lithium, and the LiFePO4//Li cell can also deliver an excellent cycling stability with an initial capacity of 130.1 mAh g−1 and a capacity retention of 84.11 % after more than 260 cycles at 0.5C and 60 °C. Additionally, the performance of high-loading cathode full cell and the flexible pouch cell further confirm its excellent stability and safety for practical use.

Electronic State‐Modulated Ni4N/Zn3N2 Heterogeneous Nanosheet Arrays Toward Dendrite‐Free and Kinetic‐Enhanced Li‐S Full Batteries

AbstractThe applications of lithium (Li)–sulfur (S) batteries are simultaneously hampered by the unlimited dendritic Li growth and the sluggish redox kinetics of polysulfides (LiPSs). In this work, an electronic state‐modulated Ni4N/Zn3N2 heterogeneous nanosheet arrays is painstakingly fabricated on the surface of carbon cloth (CC@Ni4N/Zn3N2) as an efficient bi‐service host to promote uniform Li deposition and boost efficient LiPSs catalysis. It is found that the electronic structure of Ni4N/Zn3N2 heterostructure is modulated to realize a rational transition metal d‐band center, and its built‐in electric field (BIEF) within the heterointerfaces facilitates the interfacial charge transfer, resulting in low Li deposition/migration energy barrier and efficient LiPSs adsorption/catalytic conversion kinetics. As a result, the as‐prepared CC@Ni4N/Zn3N2‐Li anode can enable the Li||Li symmetrical cells to possess a long‐term lifespan over 500 h even at 10 mA cm−2/20 mAh cm−2, and the as‐assembled LiNi0.8Co0.1Mn0.1O2||CC@Ni4N/Zn3N2‐Li full cell also shows an excellent cycling performance (95.8% capacity retention after 100 cycles). When used for both S and Li loading, the as‐assembled CC@Ni4N/Zn3N2‐S||CC@Ni4N/Zn3N2‐Li full cell exhibits an outstanding cycling stability (744 mAh g−1 after 1000 cycles at 2C). This work highlights the great potential of heterostructures for fabricating ideal bi‐serve hosts for both Li and S electrodes.

Multipolar Conjugated Polymer Framework Derived Ionic Sieves via Electronic Modulation for Long-Life All-Solid-State Li Batteries.

Here, we build a tunable multipolar conjugated polymer framework platform via pore wall chemistry to probe the role of electronic structure engineering in improving the Li+ conduction by theoretical studies. Guided by theoretical prediction, we develop a new cyano-vinylene-linked multipolar polymer framework namely CNF-COF, which can act as efficient ion sieves to modify solid polymer electrolytes to simultaneously tune Li+ migration and stable Li anodes for long-lifespan all-solid-state (ASS) Li metal batteries at high rate. The dual-decoration of cyano and fluorine groups in CNF-COF favorably regulates electronic structure via multipolar donor-acceptor electronic effects to afford proper energy band structure and abundant electron-rich sites for enhanced oxidative stability, facilitated ion-pair dissociation and suppressed anion movements. Thus, the CNF-COF incorporation into poly (ethylene oxide) (PEO) electrolytes not only renders fast selective Li+ transport but also facilitates the Li dendrite suppression. Specifically, the constructed PEO composite electrolyte with an ultra-low CNF-COF content of only 0.5 wt % is endowed with a wide electrochemical window, a high ionic conductivity of 0.634 mS cm-1 at 60 °C and a large Li+ transference number of 0.81-remarkably outperforming CNF-COF-free counterparts (0.183 mS cm-1 and 0.22). As such, the Li symmetric cell delivers stable Li plating/stripping over 1400 h at 0.1 mA cm-2. Impressively, by coupling with LiFePO4 (LFP) cathodes, the assembled ASS Li battery under 60 °C allows for stable cycling over 2000 cycles at 1 C and over 1000 cycles even at 2 C with a large capacity retention of ~75 %, surpassing most reported ASS Li batteries using PEO-based electrolytes.

Multipolar Conjugated Polymer Framework Derived Ionic Sieves via Electronic Modulation for Long‐Life All‐Solid‐State Li Batteries

AbstractHere, we build a tunable multipolar conjugated polymer framework platform via pore wall chemistry to probe the role of electronic structure engineering in improving the Li+ conduction by theoretical studies. Guided by theoretical prediction, we develop a new cyano‐vinylene‐linked multipolar polymer framework namely CNF‐COF, which can act as efficient ion sieves to modify solid polymer electrolytes to simultaneously tune Li+ migration and stable Li anodes for long‐lifespan all‐solid‐state (ASS) Li metal batteries at high rate. The dual‐decoration of cyano and fluorine groups in CNF‐COF favorably regulates electronic structure via multipolar donor‐acceptor electronic effects to afford proper energy band structure and abundant electron‐rich sites for enhanced oxidative stability, facilitated ion‐pair dissociation and suppressed anion movements. Thus, the CNF‐COF incorporation into poly (ethylene oxide) (PEO) electrolytes not only renders fast selective Li+ transport but also facilitates the Li dendrite suppression. Specifically, the constructed PEO composite electrolyte with an ultra‐low CNF‐COF content of only 0.5 wt % is endowed with a wide electrochemical window, a high ionic conductivity of 0.634 mS cm−1 at 60 °C and a large Li+ transference number of 0.81—remarkably outperforming CNF‐COF‐free counterparts (0.183 mS cm−1 and 0.22). As such, the Li symmetric cell delivers stable Li plating/stripping over 1400 h at 0.1 mA cm−2. Impressively, by coupling with LiFePO4 (LFP) cathodes, the assembled ASS Li battery under 60 °C allows for stable cycling over 2000 cycles at 1 C and over 1000 cycles even at 2 C with a large capacity retention of ~75 %, surpassing most reported ASS Li batteries using PEO‐based electrolytes.

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.

Au-embedded mesoporous molecular sieve enables robust organic/inorganic hybrid solid electrolyte interphase for high-performance lithium metal batteries

The solid electrolyte interphase (SEI) determines the lithium (Li) deposition behavior for long-term lithium metal batteries. However, the naturally formed fragile SEI would cause the nonuniform lithium deposition and random dendrite growth due to weak interaction of the heterogeneous distributed inorganic and organic species. Herein, we designed Au-embedded mesoporous molecular sieve as an electrolyte modifier to feasibly form a robust organic/inorganic hybrid SEI. Such hybrid SEIs, composed of Si-O interlinked polycarbonates (poly(CO3)) which is derived from the Au-induced electrocatalytic polymerization of EC (ethylene carbonate), possess an ultrahigh Young’s modulus of 11.6 GPa, achieving uniform lithium deposition and suppression of lithium dendrites. Assembled by the Au@MCM-41-modified electrolyte, the Li||Li symmetrical cells exhibit a recyclable behavior of Li deposition/dissolution over 900 h at 0.5 mA cm−2, and the Li||LFP (LiFePO4) full cells maintain a high capacity of 123 mAh g−1 even after 300 cycles at 1.0 C. This work explores a new route to in situ develop a robust and effective SEI for prospective lithium metal batteries in practical application and social requirement.

Dual-functional Separators Regulating Ion Transport Enabled by 3D-Reinforced Polyimide Microspheres Protective Layer for Dendrite-Free and High-Temperature Lithium Metal Batteries.

High-energy-density lithium metal batteries (LMBs) are confronted with crucial concerns of security and a short cycle lifespan caused by the uncontrollable formation of lithium (Li) dendrites. The poor thermal stability and heterogeneous Li deposition of conventional polyolefin separators often cause battery short circuiting and thermal runaway in LMBs. Herein, a novel dual-functional PE composite separator (PI-COOH/PE) coated by carboxyl polyimide (PI) microspheres is fabricated by an etching-acidification method. The three-dimensional (3D) high-temp PI microsphere with rich carboxyl groups on the surface improve the security of LMBs at extremely high temperatures and facilitate the formation of a stable and uniform SEI layer, which contributes to accelerating the Li+ transport and stabilizing the formation of the SEI layer. Consequently, the Li symmetric cell assembled with the (PI-COOH)/PE separator exhibits stable overpotential over 3000 h, and the corresponding Li//NCM811 full cells also show a high-level discharge capacity of 146.6 mAh g-1 at 5 C. Meanwhile, it also demonstrates outstanding cycling stability and thermal safety, which can survive continuously over 160 min at 140 °C (vs 21 min for PE). The above results indicate the (PI-COOH)/PE separator constructed by a low-cost and industrial-friendly strategy simultaneously addresses high-temperature stability and dendrite resistance.

Lithium Salt Combining Fluoroethylene Carbonate Initiates Methyl Methacrylate Polymerization Enabling Dendrite‐Free Solid‐State Lithium Metal Battery

This work demonstrates a novel polymerization‐derived polymer electrolyte consisting of methyl methacrylate, lithium bis(trifluoromethanesulfonyl)imide and fluoroethylene carbonate. The polymerization of MMA was initiated by the amino compounds following an anionic catalytic mechanism. LiTFSI plays both roles including the initiator and Li ion source in the polymer electrolyte. Normally, lithium bis(trifluoromethanesulfonyl)imide has difficulty in initiating the polymerization reaction of methyl methacrylate monomer, a very high concentration of lithium bis(trifluoromethanesulfonyl)imide is needed for initiating the polymerization. However, the fluoroethylene carbonate additive can work as a supporter to facilitate the degree of dissociation of lithium bis(trifluoromethanesulfonyl)imide and increase its initiator capacity due to the high dielectric constant. The as‐prepared poly‐methyl methacrylate‐based polymer electrolyte has a high ionic conductivity (1.19 × 10−3 S cm−1), a wide electrochemical stability window (5 V vs Li+/Li), and a high Li ion transference number () of 0.74 at room temperature (RT). Moreover, this polymerization‐derived polymer electrolyte can effectively work as an artificial protective layer on Li metal anode, which enabled the Li symmetric cell to achieve a long‐term cycling performance at 0.2 mAh cm−2 for 2800 h. The LiFePO4 battery with polymerization‐derived polymer electrolyte‐modified Li metal anode shows a capacity retention of 91.17% after 800 cycles at 0.5 C. This work provides a facile and accessible approach to manufacturing poly‐methyl methacrylate‐based polymerization‐derived polymer electrolyte and shows great potential as an interphase in Li metal batteries.

Ultra-homogeneous dense Ag nano layer enables long lifespan solid-state lithium metal batteries

The unstable electrolyte/lithium (Li) anode interface has been one of the key challenges in realizing high energy density solid-state lithium metal batteries (LMBs) applications. Herein, a dense and uniform silver (Ag) nano interlayer with a thickness of ∼35 nm is designed accurately by magnetron sputtering technology to optimize the electrolyte/Li anode interface. This Ag nano layer reacts with Li metal anode to in-situ form Li-Ag alloy, thus enhancing the physical interfacial contact, and further improving the interfacial wettability and compatibility. In particular, the Li-Ag alloy is inclined to form AgLi phase proved by cryo-TEM and DFT, effectively preventing SN from continuously “attacking” the Li metal anode due to the lower adsorption of succinonitrile (SN) molecules on AgLi than that of pure Li metal, thereby significantly reinforcing the interfacial stability. Hence, the enhanced physical and chemical stability of electrolyte/Li anode interface promotes the homogeneous deposition of Li+ and inhibits the dendrite growth. The Li-symmetric cell maintains stable operation for up to 1700 h and the cycling stability of LiFePO4|SPE|Li full cell is remarkably improved at room temperature (capacity retention rate of 91.9% for 200 cycles). This work opens an effective way for accurate and controllable interface design of long lifespan solid-state LMBs.

Enhancing stable LiF-rich interface formation of polyester based electrolyte using fluoroethylene carbonate for quasi-solid state lithium metal batteries

Lithium metal batteries (LMBs) have attracted worldwide attention for next-generation energy storage systems. However, lithium metal anode is prone to harmful reactions with traditional liquid electrolytes (LEs) leading to oxidative decomposition. Especially uncontrolled lithium dendrite growth and unstable solid electrolyte interface (SEI), which often lead to serious capacity attenuation and safety problems, hindering the development of LMBs. Herein, a solvation structure engineering strategy based on tuning intermolecular interactions is proposed to design polymer electrolyte. The interface additive of fluoroethylene carbonate (FEC) was introduced into the electrolyte precursor. By using FEC to modify the solvation structure of the electrolyte, an enhanced LiF-rich SEI was engineered to regulate the electrode/electrolyte interface composition and prevent continuous reactions on the lithium metal surface. Li|PHTL-10%FEC|Li symmetrical cell demonstrated cycling of 200 h at 0.2 mA cm−2, while matching LiFePO4 cathode exhibited stable cyclic performance. This study enables long cycling performance and provides a guiding principle in electrolyte design for LMBs.

Pre-impregnated protective layer for high energy density Li metal batteries using aqueous electrolyte

Aqueous electrolytes have been considered as alternatives for solving thermal safety issues of batteries caused by the high flammability of non-aqueous electrolytes. However, the use of low-potential anodes for high energy density batteries using aqueous electrolytes is limited by the narrow electrochemical stability window of water (1.23 V). Therefore, an artificial protective layer is required to compensate for the potential difference between the electrolyte and anode: however, using selectively conducting Li ions while suppressing water penetration during cycling tests in batteries is a key problem that has not yet been solved. In this study, a pre-impregnated protective layer using a Li ion conductive high concentration solution in a hydrophobic polymer framework (PIPL-H) was developed for the reversible use of Li metal in batteries using aqueous electrolyte. PIPL-H minimizes hydrogen evolution reactions by preventing direct contact between the water molecules and the Li metal. PIPL-H enabled a Li symmetric cell without increasing polarization for 1000 h, as well as a full cell using LiMn2O4 with 88.2 % capacity retention for up to 60 cycles. These results provide a new perspective into protective layers that enable stable operation without being constrained by the limited cathodic stability of aqueous electrolytes.

Composite Electrolytes with Li2CO3‐Free Garnets Achieved by One‐Step Poly(propylene carbonate) Treatment for High‐Rate and Long‐Life Solid Lithium Batteries

AbstractGarnet‐based composite electrolytes show great potential in building high‐energy‐density solid lithium batteries. However, naturally formed Li2CO3 on garnets owing to air exposure hinders the Li‐ion transport and triggers undesirable performance deterioration. Based on the reaction between basic Li2CO3 and poly(propylene carbonate) (PPC) with a product of propylene carbonate (PC), composite electrolytes with homogeneously distributed Li2CO3‐free garnets as well as PC are fabricated in one step without the post‐treatment of garnet powders in both polyethylene oxide (PEO) and polyvinylidene fluoride (PVDF)‐based electrolytes. The formed PC component further decreases the crystallization of PEO and reduces the grain size of PVDF, leading to improved ion transport in PEO and the suppression of PVDF dehydrofluorination. Consequently, the PPC‐treated garnets enable high ionic conductivities of 3.40 × 10−4 and 1.75 × 10−4 S cm−1 at 30 °C, respectively, in PEO:garnet and PVDF:garnet electrolytes, as well as great electrochemical stability against Li‐metal with a lifespan over 1000 h in Li symmetrical cells at 0.1 mA cm−2. Superior stable cycles are thus realized in both LiFePO4|PEO:garnet|Li and LiNi0.6Co0.2Mn0.2O2|PVDF:garnet|Li cells. These above results demonstrate that the one‐step treatment used here helps the enhancement of Li‐ion transport in composite electrolytes, thus essential for building high‐rate and long‐life solid lithium batteries (SLBs).

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).

Eutectogel Electrolyte Constructs Robust Interfaces for High-Voltage Safe Lithium Metal Battery.

Dramatic growth of lithium dendrite, structural deterioration of LiCoO2 (LCO) cathode at high voltages, and unstable electrode/electrolyte interfaces pose significant obstacles to the practical application of high-energy-density LCO||Li batteries. In this work, a novel eutectogel electrolyte is developed by confining the nonflammable eutectic electrolyte in a polymer matrix. The eutectogel electrolyte can construct a robust solid electrolyte interphase (SEI) with inorganic-rich LiF and Li3N, contributing to a uniform Li deposition. Besides, the severe interface side reactions between LCO cathode and electrolyte can be retarded with an in situ formed protective layer. Correspondingly, Li||Li symmetrical cells achieve highly reversible Li plating/stripping over 1000h. The LCO||Li full cell can maintain 72.5% capacity after 1500 cycles with a decay rate of only 0.018% per cycle at a high charging voltage of 4.45V. Moreover, the well-designed eutectogel electrolyte can even enable the stable operation of LCO at an extremely high cutoff voltage of 4.6V. This work introduces a promising avenue for the advancement of eutectogel electrolytes, the nonflammable nature and well-regulated interphase significantly push forward the future application of lithium metal batteries and high-voltage utilization of LCO cathode.

ZnO Substitution in Argyrodite Li5.5+3xZnxP1‐xOxS4.5‐xBr1.5 Electrolyte with Enhanced Interface Performance for All‐Solid‐State Battery

AbstractArgyrodite sulfide solid electrolytes (SSEs) have been attracting more concentration in ionic conductivity, crystal structure, and mechanical properties. Nevertheless, shortcomings of SSEs like poor air‐vapor stability and interface reactions limit the wider application in batteries. Herein, a double‐element ZnO substitution strategy is applied to enhancing Li5.5PS4.5Br1.5 Argyrodite electrolyte structure stability and property, Li5.5PS4.5Br1.5 electrolyte with a small amount of ZnO substitution to P and S. Li5.5+3xZnxP1‐xOxS4.5‐xBr1.5 solid electrolytes have achieved improved performance, interface composition also has changed, and crystal structure is becoming more stable. Specifically, LPSBr1.5‐4 %ZnO exhibits the most promising comprehensive properties, more expanded lithium pathway and crystal cell size, 2.25 mS cm−1 ionic conductivity at 25 °C, 65 % electronic conductivity decline, and air stability enhancement. Moreover, LPSBr1.5‐4 %ZnO show decent lithium compatibility and dendrite suppression capability, LPSBr1.5‐4 %ZnO can continue cycling for more than 800 h at 0.1 mA cm−2 in Li symmetric cell, and critical current density has reached 1.4 mA cm−2. More importantly, an all‐solid‐state battery (ASSB) with LPSBr1.5‐4 %ZnO electrolyte can cycle with 130 mAh g−1 capacity and more than 120 cycles in LiCoO2|SSE|In‐Li cell. Our work might provide a strategy to promote structure stability and electrochemical durability, and how element substitution affects ionic transport pathway and crystal structure.