Solid Lithium Batteries Research Articles

Solid-State Lithium Batteries with in-Situ Polymerized Acrylate-Based Electrolytes Capable of Electrochemically Stable Operation at 100 ℃

In-situ polymerized acrylate-based polymers are very appealing as solid polymer electrolytes (SPEs) in lithium (Li) batteries due to the drop-in compatibility of such in-situ polymerization with conventional battery production, the ease of acrylate polymerization and their inexpensive, facile SPE chemistry. We identified, however, that such SPEs suffer from either a low cationic transference number with dual ion conducting salts (0.12-0.2) or a low ionic conductivity with single Li-ion conducting (SLIC) salts (6·10-6 S cm-1). In this project we overcame these limitations and developed significantly improved SPE with ionic conductivity of up to 2·10-4 Scm-1 and a relatively high Li-ion transference number of 0.4. With a significantly reduced fraction of mobile anions in the hybrid SPE, in-situ polymerized SPE cells with an LiFePO4 (LFP) cathode achieve a stable performance for over 100 cycles at temperatures as high as 100 °C, which is unattainable with conventional Li salts or electrolytes. Furthermore, the motional narrowing observed in the line-shapes of solid-state nuclear magnetic resonance (SS-NMR) spectra provided additional insights of the differences in Li nucleus environments and revealed a reduced activation energy for the hybrid salt SPEs due to their more open structure. This study opens the path for the fabrication of high-performance solid polymer lithium batteries capable of operating at high temperatures using commercial battery fabrication equipment. We expect that further tuning of the acrylate based SPE composition may allow further increases in its conductivity without sacrifices in its electrochemical stability or mechanical properties.

Deciphering and Integrating Functionalized Side Chains for High Ion‐Conductive Elastic Ternary Copolymer Solid‐State Electrolytes for Safe Lithium Metal Batteries

AbstractA critical challenge in solid polymer lithium batteries is developing a polymer matrix that can harmonize ionic transportation, electrochemical stability, and mechanical durability. We introduce a novel polymer matrix design by deciphering the structure‐function relationships of polymer side chains. Leveraging the molecular orbital‐polarity‐spatial freedom design strategy, a high ion‐conductive hyperelastic ternary copolymer electrolyte (CPE) is synthesized, incorporating three functionalized side chains of poly‐2,2,2‐Trifluoroethyl acrylate (PTFEA), poly(vinylene carbonate) (PVC), and polyethylene glycol monomethyl ether acrylate (PEGMEA). It is revealed that fluorine‐rich side chain (PTFEA) contributes to improved stability and interfacial compatibility; the highly polar side chain (PVC) facilitates the efficient dissociation and migration of ions; the flexible side chain (PEGMEA) with high spatial freedom promotes segmental motion and interchain ion exchanges. The resulting CPE demonstrates an ionic conductivity of 2.19×10−3 S cm−1 (30 °C), oxidation resistance voltage of 4.97 V, excellent elasticity (2700 %), and non‐flammability. The outer elastic CPE and the inner organic–inorganic hybrid SEI buffer intense volume fluctuation and enable uniform Li+ deposition. As a result, symmetric Li cells realize a high CCD of 2.55 mA cm−2 and the CPE‐based Li||NCM811 full cell exhibits a high‐capacity retention (~90 %, 0.5 C) after 200 cycles.

Deciphering and Integrating Functionalized Side Chains for High Ion-Conductive Elastic Ternary Copolymer Solid-State Electrolytes for Safe Lithium Metal Batteries.

A critical challenge in solid polymer lithium batteries is developing a polymer matrix that can harmonize ionic transportation, electrochemical stability, and mechanical durability. We introduce a novel polymer matrix design by deciphering the structure-function relationships of polymer side chains. Leveraging the molecular orbital-polarity-spatial freedom design strategy, a high ion-conductive hyperelastic ternary copolymer electrolyte (CPE) is synthesized, incorporating three functionalized side chains of poly-2,2,2-Trifluoroethyl acrylate (PTFEA), poly(vinylene carbonate) (PVC), and polyethylene glycol monomethyl ether acrylate (PEGMEA). It is revealed that fluorine-rich side chain (PTFEA) contributes to improved stability and interfacial compatibility; the highly polar side chain (PVC) facilitates the efficient dissociation and migration of ions; the flexible side chain (PEGMEA) with high spatial freedom promotes segmental motion and interchain ion exchanges. The resulting CPE demonstrates an ionic conductivity of 2.19×10-3 S cm-1 (30 °C), oxidation resistance voltage of 4.97 V, excellent elasticity (2700 %), and non-flammability. The outer elastic CPE and the inner organic-inorganic hybrid SEI buffer intense volume fluctuation and enable uniform Li+ deposition. As a result, symmetric Li cells realize a high CCD of 2.55 mA cm-2 and the CPE-based Li||NCM811 full cell exhibits a high-capacity retention (~90 %, 0.5 C) after 200 cycles.

Local charge redistribution enables single ionic conductor for fast charge solid Li battery

Solid polymer electrolytes (SPEs) have been regarded as hopeful candidate electrolyte for solid-state lithium battery. However, the low Li+ transference number and poor interface stability pose great challenges for the high rate capability of SPE. Herein, inspired from the density functional theory (DFT) calculations that local positive charge distribution can be regulated by introducing strong electron-withdrawing groups, which can selectively anchor TFSI−, largely enhance the Li+ transference number. As predicted, the obtained CPE-NO2 deliver a remarkable Li+ transference number of 0.91, equal to a single-ion conductor for Li+, largely high than that of the SPE (0.31), according well with the molecular dynamics (MD) simulations and pyridine complexation experiments. Furthermore, the PEO||Li interfacial stability, flame retardant ability, and mass transfer of Li+ in interface can also be largely enhanced by interfacial by-product, which are fast Li+ conductors according to TOF-SIMS results. Impressively, the Li|CPE-NO2|Li cell exhibit superior cyclability for 2200 h at 0.1 mA cm−2, and the solid LFP|CPE-NO2|Li battery delivers prominent capacity of 127.4 mAh g−1 at a high rate 5 C (12 mins). This work breaks the fast charge limitation of solid lithium battery, and provides a feasible approach for the construction of advanced solid electrolyte.

Breaking the Trade‐Off between Ionic Conductivity and Mechanical Strength in Solid Polymer Electrolytes for High‐Performance Solid Lithium Batteries

AbstractSolid polymer electrolytes (SPEs) are among the most promising candidates for solid‐state batteries due to their easy processibility, interface compatibility, and cost efficiency. However, the trade‐off between the ionic conductivity and mechanical strength of SPEs, which has persisted for decades, hinders their application in solid‐state lithium (Li) metal batteries. In this study, the aim is to break this trade‐off by utilizing poly(p‐phenylene benzobisoxazole) (PBO) nanofibers as a mechanically strong backbone and polyethylene oxide (PEO) as an ionically conductive network. The PBO/PEO composite electrolyte reduces the crystallinity of PEO while increasing the mechanical strength (74.4 MPa, ≈14 times that of PEO). Thus, PBO/PEO simultaneously improves ionic conductivity and mechanical strength both at room temperature and elevated temperatures, enabling uniform and smooth Li deposition. Thus, a long cycle life of solid‐state Li symmetric cells for 1000 h at 60 °C is achieved, and stable cycling of solid‐state Li metal full batteries at 60 °C and even 100 °C. Furthermore, the solid‐state pouch cell using this SPE exhibits excellent performance reliably after bending. The study clearly indicates that simultaneously improving mechanical properties and conductivity is the indispensable path to the practical application of solid‐state electrolytes.

Polyester-enhanced poly (cyclic carbonate-fluoride)-based polymer electrolyte for stable circulating solid lithium batteries

Polymer solid-state electrolytes have become one of the promising materials for constructing solid-state lithium batteries due to their excellent processability and good compatibility with electrode interfaces. However, their limited electrochemical performance and mechanical strength have hindered their widespread application. Through the adoption of an in-situ thermal curing method, we successfully prepared a poly(carbonate-fluoride) solid-state electrolyte, utilizing a polyester separator with abundant polar groups as a reinforcing framework. The introduction of ionic liquid into the solid polymer electrolyte not only enhances the mobility of polymer chain segments to improve ionic conductivity but also, in synergy with trifluoromethyl, promotes lithium salt dissociation while restricting the migration of lithium salt anions. Additionally, their reaction with the lithium metal anode generates the LiF-rich SEI, regulating the deposition of lithium dendrites. The resulting 31VPIF/OZ exhibited outstanding ionic conductivity (3.58 × 10−4 S cm−1 at 25 °C), Li-ion migration number (0.52), and electrochemical window (5.4 V). Li | 31VPIF/OZ | Li battery cycled for 1000 h at 0.1 mA cm−2 without short-circuiting. Importantly, Li | | LiFePO4 battery demonstrated a high capacity retention rate of 91.5 % after 600 cycles at 0.5C (25 °C). Thus, through the synergistic interplay of polymer structure design and fillers, we have successfully achieved stable cycling in solid-state lithium batteries, providing robust support for their application in rechargeable lithium battery technology.

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).

Unveiling the effect law of carbon dots with polyfunctional groups on interface structure and ion migration in polymer electrolytes for solid lithium battery

Solid polymer electrolyte (SPE) has been considered as promising candidate electrolyte for solid-state lithium metal battery. However, the low ion conductivity and poor interface stability seriously hinder the development of SPE. Introducing the functional filler is a commonly used and effective approach to solving these issues. The poor compatibility and ambiguous mechanism of action are currently the main challenges. In this study, we design and synthesize carbon dots (NSFCDs) with quaternary functional groups, which are introduced into the SPE in the polymerization process of hybrid polymer electrolyte (HPE). The detailed effect law of polyfunctional groups on the polymer chain structure, interface structure of electrolyte/electrode and ion migration is systematically revealed. The dense polymer network endows HPE with enhanced mechanical properties. Through the regulation of polymer segments, the coordination environment of lithium ions is altered, promoting ion transport. The solid electrolyte interface (SEI) induced by NSFCDs and lithium salt anions effectively improves the morphology of lithium ion deposition and alleviates volume strain. As a result, the HPE based on polyethylene oxide (PEO) constructed by free radical polymerization of NSFCDs and polyethylene glycol diacrylate (PEGDA) exhibits excellent comprehensive performance, the assembled Li symmetric battery can cycle stably for 4000 h.

Configuration design toward sustainably-released polymer electrolytes for enhancing ionic transport and cycle stability of solid lithium batteries

Poly(vinylidene difluoride) (PVDF)-based solid polymer electrolytes (SPEs) hold great promise in the practical deployment of solid lithium batteries (SLBs), but suffer from low ionic conductivity, poor interfacial compatibility, and unstable anode interface, especially without liquid wetting. Herein, we utilize poly (propylene carbonate) (PPC), which degrades into propylene carbonate (PC) when being contacted with alkaline Li-metal to construct the PVDF-based composite SPEs. Blended and bi-layered PVDF/PPC configurations are designed, of which the sustain-release effect of PPC, the ionic transport, and the cycle stability are compared. The evenly swelling of PC on PVDF enables a high ionic conductivity (1.2 × 10−4 S cm−1) and a low interfacial resistance (42 Ω cm−2) of bi-layered SPEs at 30 °°C and contributes to the homogeneous distribution of high current density inside electrolytes. Besides, the produced PC can accelerate the dissociation and decomposition of Li-salts, leading to the generation of a stable and uniform solid electrolyte interface. Consequently, the Li/LiFePO4 and Li/LiNi0.6Co0.2Mn0.2O2 cells with bi-layered SPEs deliver a capacity of 163.1 and 151.4 mAh g−1 for 100 cycles at 0.2 C and 30 °C. This study provides a rational protocol for the design of PVDF SPEs and promotes the practical application of PVDF-based SLBs with desirable performances.

Two-step strategy to optimize interfacial compatibility of polyether sulfone-Li6.75La3Zr1.75Ta0.25O12 composite polymer electrolytes with Li anode for solid lithium battery with a wide working temperature range

Although composite polymer electrolytes (CPEs) are currently regarded as one of the most promising solid electrolyte systems closing to commercial application, some basic problems, including low conductivity at low temperature, serious interfacial compatibility with Li metal anode, inhibit the development of CPEs for solid state lithium batteries (SSLBs). Herein, a “polymer-in-ceramic” CPEs consisting of polyether sulfone (PESF), Li6·75La3Zr1·75Ta0·25O12 (LLZTO) and bis(trifluoromethane) sulfonimide lithium salt (LiTFSI) is reported, and a two-step strategy is proposed to optimize its conductivity and interfacial compatibility with Li metal anode. Benefitting from both the continuous porous structure to provide additional Li+ conducting pathways on internal porous interfaces and the typical heterogeneous bilayer structure to enhance compatibility with Li metal anode, the optimized CPEs delivers promising Li+ conductivities in a wide operating temperature range (>2.0 × 10−4 S cm−1 at −10 °C, >1.4 × 10−3 S cm−1 at 60 °C), improved tolerance against Li dendrites and/or pulverization. Moreover, commercial LiFePO4 cathode based SSLBs show acceptable discharge specific capacities of >160 mA h g−1 and excellent cycling stabilities of over 200 cycles at both room temperature and 60 °C at 0.2C.

Lithium iron phosphate cathode supported solid lithium batteries with dual composite solid electrolytes enabling high energy density and stable cyclability

In this research, we present a report on the fabrication of a Lithium iron phosphate (LFP) cathode using hierarchically structured composite electrolytes. The fabrication steps are rationally designed to involve different coating sequences, considering the requirements for the electrode/electrolyte interfaces. Two layers of composite solid electrolyte, consisting of poly(propylene carbonate) (PPC) + lithium bis (trifluoromethanesulfonyl)imide (LiTFSI) salt and poly(ethylene oxide) (PEO) + LiTFSI + Li7La3Zr2O12 (LLZTO), are employed as hierarchical structured composite electrolytes on the LFP cathode. Experimental results indicate that the optimal combination consists of a thinner PPC + LITFSI layer on the LFP cathode and a thicker PEO + LiTFSI + LLZTO facing Li metal. The Li-metal batteries, equipped with LFP supported hierarchical electrolytes exhibited an ultra-high specific capacity (~155 mAh g−1). Additionally, they demonstrated electrode polarization in the reduced form of −0.15 V, and an excellent cyclic stability with the retention capacity of 87.6 % even in 200 cycles. The ionic conductivity of the dual-layer electrolytes is achieved as high as 1.63–2.60 × 10−4 S cm−1 at ambient temperature. The impressive cycling performance demonstrated in this study is primarily attributed to the significance of the coating sequence in the design of dual composite solid electrolytes. The PPC + LiTFSI composite layer appears to function as a flexible filler on the LFP side. On the other hand, the PEO + LiTFSI + LLZTO composite layer, which faces the Li metal anode, not only provides excellent ionic conductivity but also serves as a barrier against the mechanical stress by the formation of Li-dendrite. The dual-layer electrolyte configuration, as demonstrated in this work, can be engineered to enable high energy density and stable cyclability of Li-metal batteries.

Synergistically enhanced roles based on 1D ceramic nanowire and 3D nanostructured polymer frameworks for composite electrolytes

Combining high ionic conductivity of inorganic solid electrolyte and favourable interface compatibility of polymer solid electrolyte, organic-inorganic composite electrolyte is more suitable for high-performance solid lithium battery. Herein, the polyacrylonitrile/polyvinylidene difluoride (PAN/PVDF) nanofiber membranes are prepared by electrospinning way, which can provide a strong skeleton support to improve the mechanical strength of composite electrolyte. The complexation between lithium ion and nitrile base of PAN can promote the transport of lithium ions and excellent oxidation resistance matching high-voltage cathode electrode. There are enough intermolecular hydrogen bonds between PVDF and PEO, and the presence of f in PVDF can enhance the interfacial interaction between the fiber membrane, polyethylene oxide (PEO) and lithium metal. Therefore, it can improve the conductivity of lithium ions and effectively inhibit the growth of severe lithium dendrites. Finally, the ionic conductivity of the composite electrolyte formed by introducing the Gd-doped SnO2 nanofibers (GDS NFs) into the PAN/PVDF nanofiber membranes and PEO matrix can reach 2.45 × 10−4 S cm−1 at 30 °C. In addition, the thickness of the composite electrolyte is only 65 μm, which can significantly improve the energy density of the battery. The specific capacity of the battery assembled with the electrolyte can still maintain 134.3 mA h g−1 after 300 cycles at 50 °C and 1C, and the specific capacity retention rate is up to 91.2 %. The NMC batteries also has a high reversible capacity even after 300 cycles. In conclusion, the Gd-doped SnO2 nanofibers and PAN/PVDF nanofiber membranes with excellent properties provide a novel idea for lithium metal batteries (LMBs).

Molecular Engineering of Highly Fluorinated Carbon Dots: Tailoring Li+ Dynamics and Interfacial Fluorination for Stable Solid Lithium Batteries.

Fluorinated carbon dots (FCDs) have garnered interest owing to their distinct physicochemical properties. Nevertheless, intricate synthesis procedures and quite low fluorine doping levels limit its development and application. Herein, we propose a facile approach based on the Claisen-Schmidt reaction to realize gram-scale synthesis of highly fluorinated carbon dots (up to 20.79 at. %) at room temperature and atmospheric pressure, and a comprehensive exploration of the specific reaction mechanism is conducted. Furthermore, in consideration of the high fluorine content, good dispersibility, and compatibility with polymer electrolyte, the synthesized FCDs are utilized as an additive for PEO-based solid electrolytes of a Li battery to improve its ionic conductivity, interface stability, and mechanical properties. The introduction of FCDs can not only reduce the crystallinity of PEO and enhance the interaction of polymer chains, but also facilitate the establishment of uninterrupted pathways and in situ fluorination at the interface, which is substantiated by both theoretical calculations and experimental findings. As a result, the lithium symmetrical battery can operate stably for 1000 h at a current density of 0.4 mA cm-2. Simultaneously, the LiFePO4/Li battery utilizing the composite electrolyte exhibits a capacity of 130.3 mAh g-1 over 300 cycles while maintaining a capacity retention rate of 95.10%. This study develops a strategy for synthesizing highly fluorinated carbon dots, which demonstrate a useful influence on PEO electrolytes, thus boosting the advancement of FCDs and solid-state batteries.

Surface Passivation of LiCoO2 by Solid Electrolyte Nanoshell for High Interfacial Stability and Conductivity.

The practical application of lithium cobalt oxide (LiCoO2 ) cathodes at high voltages is hindered by the instability of the surface structure and side reactions with the electrolyte. Herein, we prepared a multifunctional hierarchical core@double-shell structured LiCoO2 (MS-LCO) cathode material using a scalable sol-gel method. The MS-LCO cathode material comprised an outer shell with fast lithium-ion conductivity, a La/Zr co-doped inner shell, and a bulk LiCoO2 core. The outermost shell prevented direct contact between the electrolyte and LiCoO2 core, which alleviated the electrolyte decomposition and loss of active cobalt, while the La/Zr co-doped shell improved the structural stability at higher voltages in a half-cell with a liquid electrolyte. The MS-LCO cathode exhibited a stable capacity of 163.1 mAh g-1 after 500 cycles at 0.5 C, and a high specific capacity of 166.8 mAh g-1 at 2 C. In addition, a solid lithium battery with the surface-passivated MS-LCO cathode and a polyethylene oxide (PEO)-based inorganic/organic composite electrolyte retained 85.8 % of its initial discharge capacity after 150 cycles at a charging cutoff voltage of 4.3 V. Thus, the introduction of a surface-passivating shell can effectively suppress the decomposition of PEO caused by highly reactive oxygen species in LiCoO2 at high voltages.

Recent Advances and Perspectives in Single-Ion COF-Based Solid Electrolytes

The rapid growth of renewable energy sources and the expanding market for electric vehicles (EVs) have escalated the demand for safe lithium-ion batteries (LIBs) with excellent performance. But the limitations of safety issues and energy density for LIBs continue to be obstacles to their future use. Recently, single-ion covalent-organic-framework-based (COF-based) solid electrolytes have emerged as a promising avenue to address the limitations of traditional liquid electrolytes and enhance the performance of LIBs. COFs have a porous structure and abundant electron-donating groups, enabling the construction of an available ionic conductive network. So, COFs are the subject of extensive and in-depth investigation, especially in terms of the impacts their adjustable porous structure and tunable chemistry on the research of ionic transport thermodynamics and transport kinetics. In this perspective, we present a comprehensive and significant overview of the recent development progress of single-ion COF-based solid electrolytes, highlighting their rare performance and potential applications in solid lithium batteries. This review illustrates the merits of single-ion conducting solid electrolytes and single-ion COF conductor-based solid electrolytes. Furthermore, the properties of anionic, cationic, and hybrid single-ion COF-based conducting electrolytes are discussed, and their electrochemical performance is also compared when applied in Li-ion batteries. Finally, to solve challenges in COF-based Li-ion batteries, strategies are provided to obtain a high lifespan, rate performance, and stable and safe batteries. This work is promising to offer valuable insights for researchers and the energy storage industry.

In-situ constructing of dual bifunctional interfacial layers of garnet-type Li6.4La3Zr1.4Ta0.6O12 solid electrolyte towards long-cycle stability for flexible solid metal lithium batteries

Lithium metal batteries are used widely because of their high security and high energy density. However, the solid electrolytes and electrodes have incompatible interfaces, and the lithium anode is also hindered by dendrite growth. Herein, a bifunctional stable electrode interface layer is constructed by in-situ polymerization of polyester-based monomers and organic solvent, revealing the strong correlation between cathode electrolyte interphase (CEI) on cathode and solid electrolyte interface (SEI) on Li metal anode. The sandwich-like composite electrolyte prepared with garnet Li6.4La3Zr1.4Ta0.6O12 (LLZTO) active fillers and polymer electrolyte composed of (poly(ethylene glycol) dimethyl ether (PEGDME), trimethylolpropane trimethyllacrylate (TMPTMA), 1,6-hexanediol diacrylate (HDDA)(named as P(PF)1TH) exhibits excellent flexibility, wide electrochemical window, and good thermal stability. Moreover, P(PF)1TH-10%LLZTO electrolyte has satisfactory ionic conductivity (1.42 × 10−3) at 50 °C and high Li+ transference number (0.547) at 25 °C, and symmetrical Li|P(PF)1TH-10%LLZTO|Li cells can run stably for more than 1000 h at 0.1 mA cm−2 at 50 °C. The assembled LiFePO4(LEP)|P(PF)1TH-10%LLZTO |Li cell shows high discharge capacity of 139.9/122.8 mAh g−1 with capacity retain of 90.64%/97.96% after 200 cycles at 1C/2C. This work introduces a dual functional interface layer between electrolyte and electrode through in-situ polymerization, which brings a new idea for electrode interface compatibility.

Insights into the effects of different inorganic fillers on the electrochemical performances of polymer solid electrolytes

Compared with polymer electrolyte, organic/inorganic composite solid electrolyte (CSE) shows greater advantage in solid lithium battery. The choice of inorganic filler in composition, morphology and conductivity determines the different electrochemical performance of CSE, which affects the ion migration and interface compatibility of electrolyte. Therefore, we compared inorganic fillers (LLZO particles, LLZO fibers, Al2O3 particles and Al2O3 fibers) into the polypropylene oxide (PPO) polymer to study the different effects of these four fillers on the properties of CSE. The results show that fibrous fillers have a long-distance ion transport path compared with particles, the active filler LLZO fiber has higher conductivity than the inert filler Al2O3 fiber, which greatly improves the ionic conductivity of the composite electrolyte (4.59 × 10−4 S cm−1). In addition, the existence of LiF component builds a high-strength solid electrolyte interface to protect lithium metal, especially the Li-Al-O formed at the interface of Al2O3 fiber better guarantees the stability of lithium, and solves the problem of dendrite growth and interface compatibility.

Incombustible Polymer Electrolyte Boosting Safety of Solid‐State Lithium Batteries: A Review

AbstractLithium‐ion batteries with their portability, high energy density, and reusability are frequently used in today's world. Under extreme conditions, lithium‐ion batteries leak, burn, and even explode. Therefore, improving the safety of lithium‐ion batteries has become a focus of attention. Researchers believe using a solid electrolyte instead of a liquid one can solve the lithium battery safety issue. Due to the low price, good processability and high safety of the solid polymer electrolytes, increasing attention have been paid to them. However, polymer electrolytes can also decompose and burn under extreme conditions. Moreover, lithium dendrites are formed continuously due to the uneven charge distribution on the surface of the lithium metal anode. A short circuit caused by a lithium dendrite can cause the battery to thermal runaway. As a result, the safety of polymer solid‐state batteries remains a challenge. In this review, the thermal runaway mechanism of the batteries is summarized, and the batteries abuse test standard is introduced. In addition, the recent works on the high‐safety polymer electrolytes and the solution strategies of lithium anode problems in polymer batteries are reviewed. Finally, the development direction of safe polymer solid lithium batteries is prospected.

Advances in Ordered Architecture Design of Composite Solid Electrolytes for Solid-State Lithium Batteries.

Solid electrolyte lithium batteries are the next generation of advanced energy devices. The incorporation of solid electrolytes can significantly improve the safety issue of lithium-ion batteries. Organic-inorganic composite solid electrolytes (CSE) are promising candidates for solid-state batteries, but their application is mainly limited by low ionic conductivity. Many studies have shown that the architecture of ordered inorganic fillers in CSE can act as fast lithium-ion transfer channels by auxiliary means, thus significantly improving the ionic conductivities. This review summarises the recent advances in CSE with different dimensional inorganic fillers. Various effective strategies for the construction of ordered structures in CSE are then presented. The review concludes with an outlook on the future development of CSE. This review aims to provide researchers with an in-depth understanding of how to achieve ordered architectures in CSE for advanced solid state lithium batteries.

Molten lithium metal battery with Li4Ti5O12 cathode and solid electrolyte

Along with the rapid development of electric vehicles (EVs) and intermittent renewable energy, energy storage for EVs has received much attention over the past decade. Rechargeable batteries have been considered a feasible solution to utilize intermittent renewable energy with higher efficiency. Rechargeable batteries with promising safety, lifespan, low expenditure, durable components, or mature electric control systems are desired for energy storage systems. Recently, solid electrolyte-based liquid lithium (SELL) batteries have demonstrated excellent performances and great potential for energy storage applications by manipulating different cathode materials. Herein, a new type of SELL battery with Li4Ti5O12 cathode (SELL-LTO battery) is reported. Li4Ti5O12 is a distinctive electrode material with good rate performance, high-standard safety, moderate cost, and superior cycling stability at 280 °C, which make it an excellent cathode material for SELL batteries. The assembled SELL-LTO full cell has been cycled 100 times with an average energy efficiency of 92%. Moreover, the cell also exhibits good rate performance and can recover after being cooled and thawed.