In Situ Polymerization Permeated Three-Dimensional Li+-Percolated Porous Oxide Ceramic Framework Boosting All Solid-State Lithium Metal Battery

Three-Dimensional Continuous Ion Transport Skeleton-Reinforced Composite Solid Electrolyte for High-Performance Solid-State Lithium Metal Batteries

The Li1.3Al0.3Ti1.7(PO4)3 (LATP) electrolyte is recognized as a highly promising solid-state electrolyte for next-generation solid-state lithium batteries due to its high ionic conductivity, low cost, and exceptional air stability. Unfortunately, its practical application is impeded by significant grain boundary impedance and interfacial instability with lithium metal. In this study, we introduced a cost-effective template method to fabricate a three-dimensional LATP (3D-LATP) skeleton featuring continuous porosity, which was combined with the polymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) to fabricate a three-dimensional composite solid electrolyte (3D-CSE) exhibiting enhanced flexibility and superior interfacial contact. The 3D-LATP skeleton acts as an active filler, establishing continuous transport pathways for lithium ions within the electrolyte and substantially increasing the room-temperature ionic conductivity to 6.89 × 10-4 S cm-1. Furthermore, the nonflammability of the 3D-LATP skeleton significantly enhances the thermal stability of the electrolyte. Additionally, the inclusion of the PVDF-HFP polymer improves interfacial contact between the LATP skeleton and the electrodes, thereby mitigating erosion of the LATP skeleton by the lithium metal anode in Li|Li symmetric batteries and LiFePO4|Li full batteries. Consequently, the Li|3D-CSE|Li symmetric battery demonstrated stable lithium plating-stripping cycles for over 4000 h at 0.1 mA cm-2. Moreover, the LiFePO4|3D-CSE|Li full battery exhibited reliable cycling performance over 500 cycles at 0.5C. This high-performance 3D composite electrolyte highlights the potential of LATP for high-energy-density solid-state lithium metal batteries.

In-situ covalently bridged ceramic-polymer electrolyte with fast, durable ions conductive channels for high-safety lithium batteries

To meet the requirements of high-energy-density lithium batteries, an urgent increasing demand exists for high-safety electrolyte compatibility with high-voltage cathodes. However, the safety issues of widely used ether-based liquid electrolytes and their low oxidation stability have not been effectively resolved. Herein, a covalently bridged electrolyte with ceramics as the crosslinking center is constructed in situ. The fabricated electrolyte combines the advantages of polymer (poly-1,3-dioxolane (PDOL)) and ceramic (mesoporous SiO2 (MS)) as well as its unique crosslinking structures, possessing high oxidation stability, safety, and mechanical strength. Consequently, the symmetrical Li cells present a stable overpotential of 21 and 32 mV for up to 1000 h at 0.25 mAh cm-2 and 3700 h at 0.5 mAh cm-2, respectively. The assembled LiFePO4 (LFP)/Li cell delivers a capacity retention of 87.6 % after 600 cycles at 1C and shows only a small voltage gap of approximately 0.07 V. Even at 2C, the LFP/Li cell still exhibits a low capacity decay of 0.024 % per cycle over 1000 cycles. Moreover, the LiNi0.8Mn0.1Co0.1O2 (NCM811)/Li cell maintains a high discharge capacity of 152.1 mAh/g and a capacity retention of 93.2 % after 300 cycles. Therefore, the invented electrolyte enables high-energy-density Li batteries with high safety and excellent electrochemical performance, blazing a trail for their rapid development.

Understanding the Electrochemical Window of Solid-State Electrolyte in Full Battery Application

In recent years, solid-state Li batteries (SSLBs) have emerged as a promising solution to address the safety concerns associated. However, the limited electrochemical window (ECW) of solid-state electrolytes (SEs) remains a critical constraint full battery application. Understanding the factors that influence the ECW is an essential step toward designing more robust and high-performance electrochemical systems. This review provides a detailed classification of the various "windows" of SEs and a comprehensive understanding of the associated interfacial stability of SEs in full battery application. The paper begins with a historical overview of SE development, followed by a detailed discussion of their structural characteristics. Next, examination of various methodologies used to calculate and measure the ECW is presented, culminating in the proposal of standardized testing procedures. Furthermore, a comprehensive analysis of the numerous parameters that influence the thermodynamic ECW of SEs is provided, along with a synthesis of strategies to address these challenges. At last, this review concludes with an in-depth exploration of the interfacial issues associated with SEs exhibiting narrow ECWs in full SSLBs.

Competitive Anion Anchoring and Hydrogen Bonding in Multiscale-Coupling Composite Quasi-Solid Electrolytes for Fire-Safety and Long-Life Lithium Metal Batteries

Composite solid-state electrolytes (CSEs) using Li1+xAlxTi2-x(PO4)3 (LATP) as active fillers offer promising prospects for large-scale lithium metal batteries (LMBs) applications due to their high environmental stability, cost-effectiveness, and improved safety. However, the challenges persist owing to high interfacial resistance with electrodes and instability with lithium metal. Herein, self-assembly nanofiber/polymers/LATP composite quasi-solid electrolytes (SL-CQSEs) are reported through in situ polymerization of precursor solution containing vinylene carbonate (VC), fluoroethylene carbonate (FEC), lithium bis(trifluoromethanesulfonic) imide (LiTFSI) in a porous and flexible self-supporting skeleton (SSK) consisting of 2-(3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-yl)ureido)ethyl methacrylate (UPyMA)'s self-assembly nanofiber (SAF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and LATP. Anion-anchoring/hydrogen-bonding competition and intercomponent multiscale-coupling effects on SL-CQSEs are found, which contribute to their incombustibility, excellent room-temperature ionic conductivity (1.03 mS cm-1), wide electrochemical window (5.1 V), good interfacial compatibility, and lasting inhibition of lithium dendrites. LiFePO4/Li cells with SL-CQSEs not only exhibit high-rate performance and long-term cycling stability, with a capacity retention of 90.4% at 1C and 87% even at 4C after 1000 cycles, but also can resist fire and mechanical abuse, highlighting the potential applications of SL-CQSEs for high-performance and safety LMBs.

Fabrication of Conjugated Conducting Polymers by Chemical Vapor Deposition (CVD) Method

Chemical vapor deposition (CVD) is a highly adaptable manufacturing technique used to fabricate high-quality thin films, making it essential across numerous industries. As materials fabrication processes progress, CVD has advanced to enable the precise deposition of both inorganic 2D materials, such as graphene and transition metal dichalcogenides, and high-quality polymeric thin films, offering excellent conformality and precise nanostructure control on a wide range of substrates. Conjugated conducting polymers have emerged as promising materials for next-generation electronic, optoelectronic, and energy storage devices due to their unique combination of electrical conductivity, optical transparency, ionic transport, and mechanical flexibility. Oxidative CVD (oCVD) involves the spontaneous reaction of oxidant and monomer vapors upon their adsorption onto the substrate surface, resulting in step-growth polymerization that commonly produces conducting or semiconducting polymer thin films. oCVD has gained significant attention for its ability to fabricate conjugated conducting polymers under vacuum conditions, allowing precise control over film thickness, doping levels, and nanostructure engineering. The low to moderate deposition temperature in the oCVD method enables the direct integration of conducting and semiconducting polymer thin films onto thermally sensitive substrates, including plants, paper, textiles, membranes, carbon fibers, and graphene. This review explores the fundamentals of the CVD process and vacuum-based manufacturing, while also highlighting recent advancements in the oCVD method for the fabrication of conjugated conducting and semiconducting polymer thin films.

Beyond Polymerization: In Situ Coupled Fluorination Enables More Stable Interfaces for Solid-State Lithium Batteries

In situ polymerization strategies hold great promise for enhancing the physical interfacial stability in solid-state batteries, yet (electro)chemical degradation of polymerized interfaces, especially at high voltages, remains a critical challenge. Herein, we find interphase engineering is crucial for the polymerization process and polymer stability and pioneer an in situ polymerization-fluorination (Poly-FR) strategy to create durable interfaces with excellent physical and (electro)chemical stabilities, achieved by designing a bifunctional initiator for both polymerization and on-surface lithium donor reactions. The integrated in situ fluorination converts Li2CO3 impurities on LiNi0.8Co0.1Mn0.1O2 (NCM811) surfaces into LiF-rich interphases, effectively inhibiting the aggressive (de)lithiation intermediates and protecting the interface from underlying chemical degradation, thereby surpassing the stability limitations of polymerization alone. Furthermore, the Poly-FR mediated symmetric Li|Li cells achieve an impressive cycling stability of up to 12,000 h. Solid-state cells with NCM811 cathodes and Li metal anodes realize an ultrastable cycling performance of 400 cycles with 83.4% retention at a high voltage of 4.5 V. This work points toward advanced in situ polymerization and beyond.

Beneficial Effects of FEC on an In-Situ Polymerized Deep Eutectic Electrolyte for Solid-State Batteries

Eutectic-based polymer electrolytes have emerged as promising solid electrolytes because of their ionic liquid-like properties, while modifications are essential to further increase their ionic conductivity at room temperature and solve their compatibility with lithium anode. In this work, an in situ polymerized composite electrolyte is modified by the addition of fluoroethylene carbonate (FEC) whose beneficial effect is systematically investigated in different contents. Poly(ethylene glycol) diacrylate (PEGDA), deep eutectic solvent (LiTFSI:N-methylacetamide = 1:3), and alumina fiber work as the monomer, solvent, and three-dimensional skeleton, respectively. In adjusting FEC content, ionic conductivity at room temperature is dramatically raised by three times to 8.93 × 10-4 S cm-1, with a 4-fold increase in lithium-ion transference number to 0.405. Meanwhile, the electrochemical window is widened from 3.5 to 4.8 V. The FEC addition also helps in improving the stability with Li anode, which comes from LiF-rich interphases formed at interfaces. The dynamics of LiFePO4 is significantly enhanced with higher reversibility in full cells, so that fast capacity decay is inhibited with a specific capacity of 124.1 mAh g-1 obtained after 300 cycles at 1 C. These results provide an effective modification for the deep eutectic electrolyte, which will boost its development in solid-state batteries.

Self-Templated 3D Sulfide-Based Solid Composite Electrolyte for Solid-State Sodium Metal Batteries

Rechargeable solid-state sodium metal batteries (SSMBs) experience growing attention owing to the increased energy density (vs Na-ion batteries) and cost-effective materials. Inorganic sulfide-based Na-ion conductors also possess significant potential as promising solid electrolytes (SEs) in SSMBs. Nevertheless, due to the highly reactive Na metal, poor interface compatibility is the biggest obstacle for inorganic sulfide solid electrolytes such as Na3SbS4 to achieve high performance in SSMBs. To address such electrochemical instability at the interface, new design of sulfide SE nanostructures and interface engineering are highly essential. In this work, a facile and straightforward approach is reported to prepare 3D sulfide-based solid composite electrolytes (SCEs), which utilize porous Na3SbS4 (NSS) as a self-templated framework and fill with a phase transition polymer. The 3D structured SCEs display obviously improved interface stability toward Na metal than pristine sulfide. The assembled SSMBs (with TiS2 or FeS2 as cathodes) deliver outstanding electrochemical cycling performance. Moreover, the cycling of high-voltage oxide cathode Na0.67Ni0.33Mn0.67O2 (NNMO) is also demonstrated in SSMBs using 3D sulfide-based SCEs. This study presents a novel design on the self-templated nanostructure of SCEs, paving the way for the advancement of high-energy sodium metal batteries.

Highly Conductive and Stable Composite Polymer Electrolyte with Boron Nitride Nanotubes for All-Solid-State Lithium Metal Batteries

All-solid-state lithium metal batteries (ASSLMBs) have emerged as the most promising next-generation energy storage devices. However, the unsatisfactory ionic conductivity of solid electrolytes at room temperature has impeded the advancement of solid-state batteries. In this work, a multifunctional composite solid electrolyte (CSE) is developed by incorporating boron nitride nanotubes (BNNTs) into polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP). BNNTs, with a high aspect ratio, trigger the dissociation of Li salts, thus generating a greater population of mobile Li+, and establishing long-distance Li+ transport pathways. PVDF-HFP/BNNT exhibits a high ionic conductivity of 8.0 × 10-4 S cm-1 at room temperature and a Li+ transference number of 0.60. Moreover, a Li//Li symmetric cell based on PVDF-HFP/BNNT demonstrates robust cyclic performance for 3400 h at a current density of 0.2 mA cm-2. The ASSLMB formed from the assembly of PVDF-HFP/BNNT with LiFePO4 and Li exhibits a capacity retention of 93.2% after 850 cycles at 0.5C and 25 °C. The high-voltage all-solid-state LiCoO2/Li cell based on PVDF-HFP/BNNT also exhibits excellent cyclic performance, maintaining a capacity retention of 96.4% after 400 cycles at 1C and 25 °C. Furthermore, the introduction of BNNTs is shown to enhance the thermal conductivity and flame retardancy of the CSE.

Li-Ga Alloy-Contained Hybrid Solid Electrolyte Interphase Induced by In Situ Polymerization for High-Performance Lithium Metal Batteries

Construction of quasi-solid-state lithium metal batteries (LMBs) by in situ polymerization is considered a key strategy for the next generation of energy storage systems with high specific energy and safety. Poly(1,3-dioxolane) (PDOL)-based electrolytes have attracted wide attention among researchers, benefiting from the low cost and high ionic conductivity. However, interfacial deterioration and uncontrollable growth of lithium dendrites easily appeared in LMBs due to the high reactivity of lithium metal, resulting in the failure of LMBs. In this work, a strategy is developed of using Ga(OTF)3 as the initiator to obtain a PDOL-based gel electrolyte (GaPD). In addition, a hybrid stable solid electrolyte interphase (SEI) of lithium fluoride/Li2O/Li-Ga alloys is observed on the surface of lithium metal. Combined with density functional theory calculations, the hybrid SEI shows high affinity toward Li+, indicating that a uniform deposition of Li+ could be achieved. Therefore, the Li/GaPD/Li cell operates stably for 1600 h at room temperature. In addition, the LiFePO4/GaPD/Li cell retains a capacity retention rate of 90.2% over 200 cycles at 1 C. This work provides a reference for the practical application of in situ polymerization technology in high-performance and safe LMBs.

Advancements and Challenges in Organic-Inorganic Composite Solid Electrolytes for All-Solid-State Lithium Batteries

To address the limitations of contemporary lithium-ion batteries, particularly their low energy density and safety concerns, all-solid-state lithium batteries equipped with solid-state electrolytes have been identified as an up-and-coming alternative. Among the various SEs, organic-inorganic composite solid electrolytes (OICSEs) that combine the advantages of both polymer and inorganic materials demonstrate promising potential for large-scale applications. However, OICSEs still face many challenges in practical applications, such as low ionic conductivity and poor interfacial stability, which severely limit their applications. This review provides a comprehensive overview of recent research advancements in OICSEs. Specifically, the influence of inorganic fillers on the main functional parameters of OICSEs, including ionic conductivity, Li+ transfer number, mechanical strength, electrochemical stability, electronic conductivity, and thermal stability are systematically discussed. The lithium-ion conduction mechanism of OICSE is thoroughly analyzed and concluded from the microscopic perspective. Besides, the classic inorganic filler types, including both inert and active fillers, are categorized with special emphasis on the relationship between inorganic filler structure design and the electrochemical performance of OICSEs. Finally, the advanced characterization techniques relevant to OICSEs are summarized, and the challenges and perspectives on the future development of OICSEs are also highlighted for constructing superior ASSLBs.

UV-Permeable 3D Li Anodes for In Situ Fabrication of Interface-Gapless Flexible Solid-State Lithium Metal Batteries

Flexible solid-state lithium metal batteries (SSLMBs) are highly desirable for future wearable electronics because of their high energy density and safety. However, flexible SSLMBs face serious challenges not only in regulating the Li plating/stripping behaviors but also in enabling the mechanical flexibility of the cell. Both challenges are largely associated with the interfacial gaps between the solid electrolytes and the electrodes. Here, a UV-permeable and flexible composited Li metal anode (UVp-Li), which possesses a unique light-penetrating interwoven structure similar to textiles is reported. UVp-Li allows one-step bonding of the cathode, anode, and solid electrolyte via an in situ UV-initiated polymerization method to achieve the gapless SSLMBs. The gapless structure not only effectively stabilizes the plating/stripping of Li metal during cycling, but also ensures the integrity of the cell during mechanical bending. UVp-Li symmetric cell presents a stable cycling over 1000 h at 0.5 mA cm-2. LiFePO4||UVp-Li full cells (areal capacity ranging from 0.5 to 3 mAh cm-2) show outstanding capacity retention of over 84% after 500 charge/discharge cycles at room temperature. Large pouch cells using high-loading cathodes maintain stable electrochemical performance during 1000 times of dynamic bending.

Small Additives Make Big Differences: A Review on Advanced Additives for High-Performance Solid-State Li Metal Batteries

Solid-state lithium (Li) metal batteries, represent a significant advancement in energy storage technology, offering higher energy densities and enhanced safety over traditional Li-ion batteries. However, solid-state electrolytes (SSEs) face critical challenges such as lower ionic conductivity, poor stability at the electrode-electrolyte interface, and dendrite formation, potentially leading to short circuits and battery failure. The introduction of additives into SSEs has emerged as a transformative approach to address these challenges. A small amount of additives, encompassing a range from inorganic and organic materials to nanostructures, effectively improve ionic conductivity, drawing it nearer to that of their liquid counterparts, and strengthen mechanical properties to prevent cracking of SSEs and maintain stable interfaces. Importantly, they also play a critical role in inhibiting the growth of dendritic Li, thereby enhancing the safety and extending the lifespan of the batteries. In this review, the wide variety of additives that have been investigated, is comprehensively explored, emphasizing how they can be effectively incorporated into SSEs. By dissecting the operational mechanisms of these additives, the review hopes to provide valuable insights that can help researchers in developing more effective SSEs, leading to the creation of more efficient and reliable solid-state Li metal batteries.

Ultralong Cycling and Interfacial Regulation of Bilayer Heterogeneous Composite Solid-State Electrolytes in Lithium Metal Batteries

Under the background of "carbon neutral", lithium-ion batteries (LIB) have been widely used in portable electronic devices and large-scale energy storage systems, but the current commercial electrolyte is mainly liquid organic compounds, which have serious safety risks. In this paper, a bilayer heterogeneous composite solid-state electrolyte (PLPE) was constructed with the 3D LiX zeolite nanofiber (LiX-NF) layer and in-situ interfacial layer, which greatly extends the life span of lithium metal batteries (LMB). LiX-NF not only offers a continuous fast path for Li+, but also zeolite's Lewis acid-base interaction can immobilize large anions, which significantly improves the electrochemical performance of the electrolyte. In addition, the in-situ interfacial layer at the electrode-electrolyte interface can effectively facilitate the uniform deposition of Li+ and inhibit the growth of lithium dendrites. As a result, the Li/Li battery assembled with PLPE can be stably cycled for more than 2500 h at 0.1 mA cm-2. Meanwhile, the initial discharge capacity of the LiFePO4/PLPE/Li battery can be 162.43 mAh g-1 at 0.5 C, and the capacity retention rate is 82.74% after 500 cycles. These results emphasize that this bilayer heterogeneous composite solid-state electrolyte has distinct properties and shows excellent potential for application in LMB.

Diversifying Ion-Transport Pathways of Composite Solid Electrolytes for High-Performance Solid-State Lithium-Metal Batteries

The application of composite solid electrolytes (CSEs) in solid-state lithium-metal batteries is limited by the unsatisfactory ionic conductivity underpinned by the low concentration of free lithium ions. Herein, we propose an interface design strategy where an amine silane linker is employed as a coupling agent to graft the Li7La3Zr2O12 (LLZO) ceramic nanofibers to the poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer matrix to enhance their interaction. The hydrogen bonding between amino-functionalized LLZO (NH2@LLZO) and PVDF-HFP not only effectively induces a uniform incorporation of high-content nanofibers (50 wt %) into the polymer matrix but also furnishes sufficient continuous surfaces to weaken the complexation between PVDF-HFP and Li-ion carriers. Additionally, introduction of the hydrogen bond and Lewis acid-base interplay strengthens the interfacial interactions between NH2@LLZO and lithium salts that release more free lithium ions for efficient interfacial transport. The impact of the linker's structure on the dissociation capacity of lithium salts is systematically studied from the steric effect perspective, which affords insights into interface design. Conclusively, the composite solid electrolyte achieves a high ionic conductivity (5.8 × 10-4 S cm-1) by synergy of multiple transport channels at ceramic, polymer, and their interface, which effectively regulates the lithium deposition behavior in symmetric cells. The excellent compatibility of the electrolyte with both LiFePO4 and LiNi0.8Co0.1Mn0.1O2 cathodes also results in a long lifetime and a high rate capability for full cells.

Lithium-Ion Transport and Exchange between Phases in a Concentrated Liquid Electrolyte Containing Lithium-Ion-Conducting Inorganic Particles

Understanding Li+ transport in organic-inorganic hybrid electrolytes, where Li+ has to lose its organic solvation shell to enter and transport through the inorganic phase, is crucial to the design of high-performance batteries. As a model system, we investigate a range of Li+-conducting particles suspended in a concentrated electrolyte. We show that large Li1.3Al0.3Ti1.7P3O12 and Li6PS5Cl particles can enhance the overall conductivity of the electrolyte. When studying impedance using a cell with a large cell constant, the Nyquist plot shows two semicircles: a high-frequency semicircle related to ion transport in the bulk of both phases and a medium-frequency semicircle attributed to Li+ transporting through the particle/liquid interfaces. Contrary to the high-frequency resistance, the medium-frequency resistance increases with particle content and shows a higher activation energy. Furthermore, we show that small particles, requiring Li+ to overcome particle/liquid interfaces more frequently, are less effective in facilitating Li+ transport. Overall, this study provides a straightforward approach to study the Li+ transport behavior in hybrid electrolytes.

PDOL-Based Solid Electrolyte Toward Practical Application: Opportunities and Challenges

Polymer solid-state lithium batteries (SSLB) are regarded as a promising energy storage technology to meet growing demand due to their high energy density and safety. Ion conductivity, interface stability and battery assembly process are still the main challenges to hurdle the commercialization of SSLB. As the main component of SSLB, poly(1,3-dioxolane) (PDOL)-based solid polymer electrolytes polymerized in-situ are becoming a promising candidate solid electrolyte, for their high ion conductivity at room temperature, good battery electrochemical performances, and simple assembly process. This review analyzes opportunities and challenges of PDOL electrolytes toward practical application for polymer SSLB. The focuses include exploring the polymerization mechanism of DOL, the performance of PDOL composite electrolytes, and the application of PDOL. Furthermore, we provide a perspective on future research directions that need to be emphasized for commercialization of PDOL-based electrolytes in SSLB. The exploration of these schemes facilitates a comprehensive and profound understanding of PDOL-based polymer electrolyte and provides new research ideas to boost them toward practical application in solid-state batteries.

An Ultrahigh Modulus Gel Electrolytes Reforming the Growing Pattern of Li Dendrites for Interfacially Stable Lithium-Metal Batteries

Gel polymer electrolytes (GPEs) have aroused intensive attention for their moderate comprehensive performances in lithium-metal batteries (LMBs). However, GPEs with low elastic moduli of MPa magnitude cannot mechanically regulate the Li deposition, leading to recalcitrant lithium dendrites. Herein, a porous Li7 La3 Zr2 O12 (LLZO) framework (PLF) is employed as an integrated solid filler to address the intrinsic drawback of GPEs. With the incorporation of PLF, the composite GPE exhibits an ultrahigh elastic modulus of GPa magnitude, confronting Li dendrites at a mechanical level and realizing steady polarization at high current densities in Li||Li cells. Benefiting from the compatible interface with anodes, the LFP|PLF@GPE|Li cells deliver excellent rate capability and cycling performance at room temperature. Theoretical models extracted from the topology of solid fillers reveal that the PLF with unique 3D structures can effectively reinforce the gel phase of GPEs at the nanoscale via providing sufficient mechanical support from the load-sensitive direction. Numerical models are further developed to reproduce the multiphysical procedure of dendrite propagation and give insights into predicting the failure modes of LMBs. This work quantitatively clarifies the relationship between the topology of solid fillers and the interface stability of GPEs, providing guidelines for designing mechanically reliable GPEs for LMBs.

Construction of a High-Performance Composite Solid Electrolyte Through In-Situ Polymerization within a Self-Supported Porous Garnet Framework

Composite solid electrolytes (CSEs) have emerged as promising candidates for safe and high-energy-density solid-state lithium metal batteries (SSLMBs). However, concurrently achieving exceptional ionic conductivity and interface compatibility between the electrolyte and electrode presents a significant challenge in the development of high-performance CSEs for SSLMBs. To overcome these challenges, we present a method involving the in-situ polymerization of a monomer within a self-supported porous Li6.4La3Zr1.4Ta0.6O12 (LLZT) to produce the CSE. The synergy of the continuous conductive LLZT network, well-organized polymer, and their interface can enhance the ionic conductivity of the CSE at room temperature. Furthermore, the in-situ polymerization process can also construct the integration and compatibility of the solid electrolyte-solid electrode interface. The synthesized CSE exhibited a high ionic conductivity of 1.117 mS cm-1, a significant lithium transference number of 0.627, and exhibited electrochemical stability up to 5.06 V vs. Li/Li+ at 30 °C. Moreover, the Li|CSE|LiNi0.8Co0.1Mn0.1O2 cell delivered a discharge capacity of 105.1 mAh g-1 after 400 cycles at 0.5 C and 30 °C, corresponding to a capacity retention of 61%. This methodology could be extended to a variety of ceramic, polymer electrolytes, or battery systems, thereby offering a viable strategy to improve the electrochemical properties of CSEs for high-energy-density SSLMBs.

Polydopamine-Induced Metal-Organic Framework Network-Enhanced High-Performance Composite Solid-State Electrolytes for Dendrite-Free Lithium Metal Batteries

Due to the high safety, flexibility, and excellent compatibility with lithium metals, composite solid-state electrolytes (CSEs) are the best candidates for next-generation lithium metal batteries, and the construction of fast and uniform Li+ transport is a critical part of the development of CSEs. In this paper, a stable three-dimensional metal-organic framework (MOF) network was obtained using polydopamine as a medium, and a high-performance CSE reinforced by the three-dimensional MOF network was constructed, which not only provides a continuous channel for Li+ transport but also restricts large anions and releases more mobile Li+ through a Lewis acid-base interaction. This strategy endows our CSEs with an ionic conductivity (7.1 × 10-4 S cm-1 at 60 °C), a wide electrochemical window (5.0 V), and a higher Li+ transfer number (0.54). At the same time, the lithium symmetric batteries can be stably cycled for 2000 h at 0.1 mA cm-2, exhibiting excellent electrochemical stability. The LiFePO4/Li cells have a high initial discharge specific capacity of 153.9 mAh g-1 at 1C, with a capacity retention of 80% after 915 cycles. This paper proposes an approach for constructing three-dimensional MOF network-enhanced CSEs, which provides insights into the design and development of MOFs for the positive effects of high-performance CSEs.

Challenges and Advances in Rechargeable Batteries for Extreme-Condition Applications

Rechargeable batteries are widely used as power sources for portable electronics, electric vehicles and smart grids. Their practical performances are, however, largely undermined under extreme conditions, such as in high-altitude drones, ocean exploration and polar expedition. These extreme environmental conditions not only bring new challenges for batteries but also incur unique battery failure mechanisms. To fill in the gap, it is of great importance to understand the battery failure mechanisms under different extreme conditions and figure out the key parameters that limit battery performances. In this review, the authors start by investigating the key challenges from the viewpoints of ionic/charge transfer, material/interface evolution and electrolyte degradation under different extreme conditions. This is followed by different engineering approaches through electrode materials design, electrolyte modification and battery component optimization to enhance practical battery performances. Finally, a short perspective is provided about the future development of rechargeable batteries under extreme conditions.

Contributing to the Revolution of Electrolyte Systems via In Situ Polymerization at Different Scales: A Review

Solid-state batteries have become the most anticipated option for compatibility with high-energy density and safety. In situ polymerization, a novel strategy for the construction of solid-state systems, has extended its application from solid polymer electrolyte systems to other solid-state systems. This review summarizes the application of in situ polymerization strategies in solid-state batteries, which covers the construction of polymer, the formation of the electrolyte system, and the design of the full cell. For the polymer skeleton, multiple components and structures are being chosen. In the construction of solid polymer electrolyte systems, the choice of initiator for in situ polymerization is the focus of this review. New initiators, represented by lithium salts and additives, are the preferred choice because of their ability to play more diverse roles, while the coordination with other components can also improve the electrical properties of the system and introduce functionalities. In the construction of entire solid-state battery systems, the application of in situ polymerization to structure construction, interface construction, and the use of separators with multiplex functions has brought more possibilities for the development of various solid-state systems and even the perpetuation of liquid electrolytes.

Enabling Scalable Polymer Electrolyte with Dual-Reinforced Stable Interface for 4.5 V Lithium-Metal Batteries

Hitherto, it remains a great challenge to stabilize electrolyte-electrode interfaces and impede lithium dendrite proliferation in lithium-metal batteries with high-capacity nickel-rich LiNx Coy Mn1- x-y O2 (NCM) layer cathodes. Herein, a special molecular-level-designed polymer electrolyte is prepared by the copolymerization of hexafluorobutyl acrylate and methylene bisacrylamide to construct dual-reinforced stable interfaces. Verified by X-ray photoelectron spectroscopy depth profiling, there are favorable solid electrolyte interphase (SEI) layers on Li metal anodes and robust cathode electrolyte interphase (CEI) on Ni-rich cathodes. The SEI enriched in lithiophilic N-(C)3 guides the homogenous distribution of Li+ and facilitates the transport of Li+ through LiF and Li3 N, promoting uniform Li+ plating and stripping. Moreover, the CEI with antioxidative amide groups can suppress the parasitic reactions between cathode and electrolyte and the structural degradation of cathode. Meanwhile, a unique two-stage rheology-tuning UV polymerization strategy is utilized, which is quite suited for continuous electrolyte fabrication with environmental friendliness. The fabricated polymer electrolyte exhibits a high ionic conductivity of 1.01 mS cm-1 at room temperature. 4.5 V NCM622//Li batteries achieve prolonged operation with a retention rate of 85.0% after 500 cycles at 0.5 C. This work provides new insights into molecular design and processibility design for polymer-based high-voltage batteries.

Eutectic-Based Polymer Electrolyte with the Enhanced Lithium Salt Dissociation for High-Performance Lithium Metal Batteries

The deployment of lithium metal anode in solid-state batteries with polymer electrolytes has been recognized as a promising approach to achieving high-energy-density technologies. However, the practical application of the polymer electrolytes is currently constrained by various challenges, including low ionic conductivity, inadequate electrochemical window, and poor interface stability. To address these issues, a novel eutectic-based polymer electrolyte consisting of succinonitrile (SN) and poly (ethylene glycol) methyl ether acrylate (PEGMEA) is developed. The research results demonstrate that the interactions between SN and PEGMEA promote the dissociation of the lithium difluoro(oxalato) borate (LiDFOB) salt and increase the concentration of free Li+ . The well-designed eutectic-based PAN1.2 -SPE (PEGMEA: SN=1: 1.2 mass ratio) exhibits high ionic conductivity of 1.30 mS cm-1 at 30 °C and superior interface stability with Li anode. The Li/Li symmetric cell based on PAN1.2 -SPE enables long-term plating/stripping at 0.3 and 0.5 mA cm-2 , and the Li/LiFePO4 cell achieves superior long-term cycling stability (capacity retention of 80.3 % after 1500 cycles). Moreover, Li/LiFePO4 and Li/LiNi0.6 Co0.2 Mn0.2 O2 pouch cells employing PAN1.2 -SPE demonstrate excellent cycling and safety characteristics. This study presents a new pathway for designing high-performance polymer electrolytes and promotes the practical application of high-stable lithium metal batteries.

Bilayer Zwitterionic Metal-Organic Framework for Selective All-Solid-State Superionic Conduction in Lithium Metal Batteries

Solid-state batteries (SSBs) hold immense potential for improved energy density and safety compared to traditional batteries. However, existing solid-state electrolytes (SSEs) face challenges in meeting the complex operational requirements of SSBs. This study introduces a novel approach to address this issue by developing a metal-organic framework (MOF) with customized bilayer zwitterionic nanochannels (MOF-BZN) as high-performance SSEs. The BZN consist of a rigid anionic MOF channel with chemically grafted soft multicationic oligomers (MCOs) on the pore wall. This design enables selective superionic conduction, with MCOs restricting the movement of anions while coulombic interaction between MCOs and anionic framework promoting the dissociation of Li+ . MOF-BZN exhibits remarkable Li+ conductivity (8.76 × 10-4 S cm-1 ), high Li+ transference number (0.75), and a wide electrochemical window of up to 4.9 V at 30 °C. Ultimately, the SSB utilizing flame retarded MOF-BZN achieves an impressive specific energy of 419.6 Wh kganode+cathode+electrolyte -1 under constrained conditions of high cathode loading (20.1 mg cm-2 ) and limited lithium metal source. The constructed bilayer zwitterionic MOFs present a pioneering strategy for developing advanced SSEs for highly efficient SSBs.

Garnet/polymer solid electrolytes for high-performance solid-state lithium metal batteries: The role of amorphous Li2O2

Solid-state electrolytes have been widely investigated for lithium batteries since they provide a high degree of safety. However, their low ionic conductivity and substantial growth of lithium dendrites hamper their commercial applications. Garnet-type Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) is one of the most promising active fillers to advance the performance of the solid polymer electrolyte. Nevertheless, their performance is still limited due to their large interfacial resistance. Herein, we embedded the amorphous Li₂O₂ (LO) into LLZTO particles via the quenching process and successfully achieved an interfacial layer of Li₂O₂ around LLZTO particles (LLZTO@LO). Amorphous Li₂O₂ acts as a binder and showed an excellent affinity for Li⁺ ions which promotes their fast transference. Moreover, the stable and dense interfacial Li₂O₂ layer enhances interfacial contact and suppresses the lithium dendrite growth during the long operation cycling process. The PEO/10LLZTO@2LO solid composite polymer electrolyte (SCPE) showed the highest ionic conductivity of 3.2 × 10^-4 S cm^-1 at 40 °C as compared to pristine LLZTO-based SCPE. Moreover, the Li│(PEO/10LLZTO@2LO) │Li symmetric cell showed a stable and smooth long lifespan up to 1100 h at 40 °C. Furthermore, the LiFePO₄//Li full battery with PEO/10LLZTO@2LO SCPE demonstrated stable cycling performance for 400 cycles. These results constitute a significant step toward the practical application of solid-state lithium metal batteries (SS-LMBs).

Rational Design of High-Performance PEO/Ceramic Composite Solid Electrolytes for Lithium Metal Batteries

Composite solid electrolytes (CSEs) with poly(ethylene oxide) (PEO) have become fairly prevalent for fabricating high-performance solid-state lithium metal batteries due to their high Li+ solvating capability, flexible processability and low cost. However, unsatisfactory room-temperature ionic conductivity, weak interfacial compatibility and uncontrollable Li dendrite growth seriously hinder their progress. Enormous efforts have been devoted to combining PEO with ceramics either as fillers or major matrix with the rational design of two-phase architecture, spatial distribution and content, which is anticipated to hold the key to increasing ionic conductivity and resolving interfacial compatibility within CSEs and between CSEs/electrodes. Unfortunately, a comprehensive review exclusively discussing the design, preparation and application of PEO/ceramic-based CSEs is largely lacking, in spite of tremendous reviews dealing with a broad spectrum of polymers and ceramics. Consequently, this review targets recent advances in PEO/ceramic-based CSEs, starting with a brief introduction, followed by their ionic conduction mechanism, preparation methods, and then an emphasis on resolving ionic conductivity and interfacial compatibility. Afterward, their applications in solid-state lithium metal batteries with transition metal oxides and sulfur cathodes are summarized. Finally, a summary and outlook on existing challenges and future research directions are proposed.

Effect of Nanoparticles in LiFePO4 Cathode Material Using Organic/Inorganic Composite Solid Electrolyte for All-Solid-State Batteries

Herein, we report the effect of using nanoparticles of LiFePO₄ on the electrochemical properties of all-solid-state batteries (ASSBs) with a solid electrolyte. LiFePO₄ (LFP) cathode materials are promising cathode materials in polymer-based composite solid electrolytes because of their limited electrochemical window range. However, LFP cathodes exhibit poor electric conductivity and sluggish lithium ion diffusion. In addition, there is a disadvantage in that the interfacial resistance increases due to poor contact between the LFP cathode material and the solid electrolyte when composing the composite cathode. The nano-sized LFP cathode material increases the contact area between solid electrolyte in the positive electrode and enhances lithium ion diffusion. Therefore, the structural differences and electrochemical performance of these nanoscale LFP cathode materials in the ASSB were studied by X-ray diffraction, scanning electron microscopy, and electrochemical analysis.

Distributed Li-Ion Flux Enabled by Sulfonated Covalent Organic Frameworks for High-Performance Lithium Metal Anodes

Metallic Li is considered the most promising anode material for high-energy-density batteries owing to its high theoretical capacity and low electrochemical potential. However, inhomogeneous lithium deposition and uncontrollable growth of lithium dendrites result in low lithium utilization, rapid capacity fading, and poor cycling performance. Herein, two sulfonated covalent organic frameworks (COFs) with different sulfonated group contents are synthesized as the multifunctional interlayers in lithium metal batteries. The sulfonic acid groups in the pore channels can serve as Li-anchoring sites that effectively coordinate Li ions. These periodically arranged subunits significantly guide uniform Li-ion flux distribution, guarantee smooth Li deposition, and reduce lithium dendrite formation. Consequently, these characteristics afford an excellent quasi-solid-state electrolyte with a high ionic conductivity of 1.9 × 10^-3  S  cm^-1 at room temperature and a superior Li⁺⁺ transference number of 0.91. A Li/LiFePO₄ battery with the COF-based electrolyte exhibited dendrite-free Li deposition during the charge process, accompanied by no capacity decay after 100 cycles at 0.1 C.

Quasi-Solid-State Ion-Conducting Arrays Composite Electrolytes with Fast Ion Transport Vertical-Aligned Interfaces for All-Weather Practical Lithium-Metal Batteries

The rapid improvement in the gel polymer electrolytes (GPEs) with high ionic conductivity brought it closer to practical applications in solid-state Li-metal batteries. The combination of solvent and polymer enables quasi-liquid fast ion transport in the GPEs. However, different ion transport capacity between solvent and polymer will cause local nonuniform Li⁺ distribution, leading to severe dendrite growth. In addition, the poor thermal stability of the solvent also limits the operating-temperature window of the electrolytes. Optimizing the ion transport environment and enhancing the thermal stability are two major challenges that hinder the application of GPEs. Here, a strategy by introducing ion-conducting arrays (ICA) is created by vertical-aligned montmorillonite into GPE. Rapid ion transport on the ICA was demonstrated by ⁶Li solid-state nuclear magnetic resonance and synchrotron X-ray diffraction, combined with computer simulations to visualize the transport process. Compared with conventional randomly dispersed fillers, ICA provides continuous interfaces to regulate the ion transport environment and enhances the tolerance of GPEs to extreme temperatures. Therefore, GPE/ICA exhibits high room-temperature ionic conductivity (1.08 mS cm^-1) and long-term stable Li deposition/stripping cycles (> 1000 h). As a final proof, Li||GPE/ICA||LiFePO₄ cells exhibit excellent cycle performance at wide temperature range (from 0 to 60 °C), which shows a promising path toward all-weather practical solid-state batteries.

Induction/Inhibition Effect on Lithium Dendrite Growth by a Binary Modification Layer on a Separator

In lithium metal batteries (LMB), unrestricted growth of lithium dendrites will pierce the separator and cause an internal short circuit. Therefore, we designed modified separator with an InN thin layer, which could be in situ converted into a binary mixed-modified layer of Li-In alloy and Li₃N during the lithium plating/stripping process. Among them, Li-In alloy induces the lateral growth of lithium dendrites and prevents the separator from being pierced; Li₃N balances ion distribution at the lithium anode/separator interface, which is beneficial to inhibit the growth of lithium dendrites. Under the synergistic effect of the two phases, the performance of LMBs was obviously improved. In addition, the separator modification does not need to be carried out in a protective atmosphere and is suitable for large-scale roll-to-roll processing.

Stabilizing the Halide Solid Electrolyte to Lithium by a β-Li3N Interfacial Layer

As a new class of solid electrolytes, halide solid electrolytes have the advantages of high ionic conductivity at room temperature, stability to high-voltage cathodes, and good deformability, but they generally show a problem of being unstable to a lithium anode. Here, we report the use of Li₃N as an interface modification layer to improve the interfacial stability of Li₂ZrCl₆ to the Li anode. We found that commercial Li₃N can be easily transformed into an α-phase and a β-phase by ball-milling and annealing, respectively, in which β-phase Li₃N simultaneously has high room-temperature ionic conductivity and good stability to both Li and Li₂ZrCl₆, making it a good choice for an artificial interface layer material. After the modification of the β-Li₃N interfacial layer, the interfacial impedance between Li₂ZrCl₆ and the Li anode decreased from 1929 to ∼400 Ω. At a current density of 0.1 mA cm^-2, the overpotential of the Li symmetric cell decreased from 250 to ∼50 mV, which did not show an obvious increase for at least 300 h, indicating that the β-Li₃N interface layer effectively improves the interfacial stability between Li₂ZrCl₆ and Li.

Self-Healing Polymer Electrolyte for Dendrite-Free Li Metal Batteries with Ultra-High-Voltage Ni-Rich Layered Cathodes

Practical applications of polymer electrolytes in lithium (Li) metal batteries with high-voltage Ni-rich cathodes have been hindered by the dendrite growth and poor oxidative stability of electrolytes. Herein, a self-healing polymer electrolyte is developed by in situ copolymerization of 2-(3-(6-methyl4-oxo-1,4-dihydropyrimidin-2-yl)ureido)ethyl methacrylate (UPyMA) and ethylene glycol methyl ether acrylate (EGMEA) monomers. With the electrolyte, the dendrite growth is inhibited by spontaneously repairing dendrite-induced defects, cracks, and voids at the Li/electrolyte interface; the suppressed dendrite growth and associated electro-chemo behaviors are visualized by the kinetic Mont-Carlo simulation. Benefitting from the high ionic conductivity, wide electrochemical window and good interfacial stability, the self-healing polymer electrolyte enables stable cycling of the LiNi_0.8 Mn_0.1 Co_0.1 O₂ (NMC811) cathode under 4.7 V, achieving a high specific capacity of ≈228.8 mAh g^-1 and capacity retention of 80.4% over 500 cycles. The new electrolyte is very promising for developing highly safe and dendrite-free Li metal batteries with high energy density.

Coupling Water-Proof Li Anodes with LiOH-Based Cathodes Enables Highly Rechargeable Lithium-Air Batteries Operating in Ambient Air

Realizing an energy-dense, highly rechargeable nonaqueous lithium-oxygen battery in ambient air remains a big challenge because the active materials of the typical high-capacity cathode (Li2 O2 ) and anode (Li metal) are unstable in air. Herein, a novel lithium-oxygen full cell coupling a lithium anode protected by a composite layer of polyethylene oxide (PEO)/lithium aluminum titanium phosphate (LATP)/wax to a LiOH-based cathode is constructed. The protected lithium is stable in air and water, and permits reversible, dendrite-free lithium stripping/plating in a wet nonaqueous electrolyte under ambient air. The LiOH-based full cell reaction is immune to moisture (up to 99% humidity) in air and exhibits a much better resistance to CO2 contamination than Li2 O2 , resulting in a more consistent electrochemistry in the long term. The current approach of coupling a protected lithium anode with a LiOH-based cathode holds promise for developing a long-life, high-energy lithium-air battery capable of operating in the ambient atmosphere.

Homogeneous and Fast Li-Ion Transport Enabled by a Novel Metal-Organic-Framework-Based Succinonitrile Electrolyte for Dendrite-Free Li Deposition

Lithium (Li) metal has emerged as a promising electrode material for high-energy-density batteries. However, serious Li dendrite issues during cycling have plagued the safety and cyclability of the batteries, thus limiting the practical application of Li metal batteries. Herein, we prepare a novel metal-organic-framework-based (MOF-based) succinonitrile electrolyte, which enables homogeneous and fast Li-ion (Li+) transport for dendrite-free Li deposition. Given the appropriate aperture size of the MOF skeleton, the targeted electrolyte can allow only small-size Li+ to pass through its pores, which effectively guides uniform Li+ transport. Specially, Li ions are coordinated by the C═N of the MOF framework and the C≡N of succinonitrile, which could accelerate Li+ migration jointly. These characteristics afford an excellent quasi-solid-state electrolyte with a high ionic conductivity of 7.04 × 10-4 S cm-1 at room temperature and a superior Li+ transference number of 0.68. The Li/LiFePO4 battery with the MOF-based succinonitrile electrolyte exhibits dendrite-free Li deposition during the charge process, accompanied by a high capacity retention of 98.9% after 100 cycles at 0.1C.

A novel polymer electrolyte with high elasticity and high performance for lithium metal batteries

A polymer electrolyte with high elasticity and high performance is prepared by IN SITU polymerization. The polymer electrolyte is amorphous and has a high ionic conductivity of 7.9 × 10^-4 S cm^-1 and good elasticity. The discharge capacity of Li/LiFePO₄ in the 100th cycle is 133.90 mA h g^-1 (0.5C, 25 °C).

Application of a Modified Porphyrin in a Polymer Electrolyte with Superior Properties for All-Solid-State Lithium Batteries

Porphyrins and their derivatives are a unique class of multifunctional and modifiable π-conjugated heterocyclic organic molecules, which have been widely applied in the fields of optoelectronic devices and catalysis. However, the application of porphyrins in polymer electrolytes for all-solid-state lithium-ion batteries (ASSLIBs) has rarely been reported. Herein, porphyrin molecules modified by polyether chains are used for composite solid-state polymer electrolytes (CSPEs) for the first time. The introduction of a modified porphyrin in an electrolyte can not only promote the electrochemical properties by constructing ordered ion channels via the intermolecular interaction between π-conjugated heterocyclic porphyrins, but also significantly improve the mechanical strength and interface contact between the electrolyte membrane and the lithium metal anode. Consequently, the all-solid-state batteries assembled by the modified porphyrin composite polymer electrolyte, LiFePO₄ cathodes, and Li anodes deliver a higher discharge capacity of 158.2 mA h g^-1 at 60 °C, 0.2 C, which remains at 153.6 mA h g^-1 after 120 cycles with an average coulombic efficiency of ∼99.60%. Furthermore, the flexible porphyrin-based composite polymer electrolyte can also enable a Li || LiCoO₂ battery to exhibit a maximum discharge capacity of 108.6 mA h g^-1 at 60 °C, 0.1 C with an active material loading of 2-3 mg cm^-2, which is unable to realize for the corresponding batteries with a pure PEO-based polymer electrolyte. This work not only broadens the application scope of porphyrins, but also proposes a novel method to fabricate CSPEs with improved electrochemical and mechanical properties, which may shed new light on the development of CSPEs for next-generation high-energy-density lithium-ion batteries.

High-Voltage and Wide-Temperature Lithium Metal Batteries Enabled by Ultrathin MOF-Derived Solid Polymer Electrolytes with Modulated Ion Transport

Solid polymer electrolytes (SPEs) of superior ionic conductivity, long-term cycling stability, and good interface compatibility are regarded as promising candidates to enable the practical applications of solid lithium metal batteries (SLMBs). Here, a mixed-matrix SPE (MMSE) with incorporated metal-organic frameworks (MOFs) and ionic liquid is prepared. The dissociation of Li salt in MMSE can be promoted effectively due to the introduction of MOF via the Fourier-transform infrared spectroscopy (FT-IR) analysis, density functional theory calculation, and molecular dynamics simulation. The as-formed MMSE exhibits an ultralow thickness of 20 μm with a satisfactory ionic conductivity and lithium-ion transference number (1.1 mS cm^-1 at 30 °C, 0.72). The optimized SLMBs with high-voltage LiMn_0.75Fe_0.25PO₄ (LMFP) exhibit an excellent cyclability at 4.2 V under room temperature. Moreover, Li/MMSE/LiFePO₄ cells have desirable cycle performance from -20 to 100 °C, and their capacity remains 143.3 mA h g^-1 after being cycled 300 times at 10 C at 100 °C. The Li/LiFePO₄ pouch cells also show excellent safety under extreme conditions. The Li symmetric cells can work steadily even at a supreme current density of 4 mA cm^-2 at 100 °C. From the above analysis, these MMSEs present new opportunities for the development of SLMBs with good electrochemical properties.

Uniform and Anisotropic Solid Electrolyte Membrane Enables Superior Solid-State Li Metal Batteries

Rational structure design is a successful approach to develop high-performance composite solid electrolytes (CSEs) for solid-state Li metal batteries. Herein, a novel CSE membrane is proposed, that consists of interwoven garnet/polyethylene oxide-Li bis(trifluoromethylsulphonyl)imide (LLZO/PEO-LiTFSI) microfibers. This CSE exhibits high Li-ion conductivity and exceptional Li dendrite suppression capability, which can be attributed to the uniform LLZO dispersion in PEO-LiTFSI and the vertical/horizontal anisotropic Li-ion conduction in the CSE. The uniform LLZO particles can generate large interaction regions between LLZO and PEO-LiTFSI, which thus form continuous Li-ion transfer pathways, retard the interfacial side reactions and strengthen the deformation resistance. More importantly, the anisotropic Li-ion conduction, that is, Li-ion transfers much faster along the microfibers than across the microfibers, can effectively homogenize the electric field distribution in the CSE during cycling, which thus prevents the excessive concentration of Li-ion flux. Finally, solid-state Li||LiFePO₄ cells based on this CSE show excellent electrochemical performances. This work enriches the structure design strategy of high-performance CSEs and may be helpful for further pushing the solid-state Li metal batteries towards practical applications.

Unveiling Interfacial Li-Ion Dynamics in Li7La3Zr2O12/PEO(LiTFSI) Composite Polymer-Ceramic Solid Electrolytes for All-Solid-State Lithium Batteries

Unlocking the full potential of solid-state electrolytes (SSEs) is key to enabling safer and more-energy dense technologies than today's Li-ion batteries. In particular, composite materials comprising a conductive, flexible polymer matrix embedding ceramic filler particles are emerging as a good strategy to provide the combination of conductivity and mechanical and chemical stability demanded from SSEs. However, the electrochemical activity of these materials strongly depends on their polymer/ceramic interfacial Li-ion dynamics at the molecular scale, whose fundamental understanding remains elusive. While this interface has been explored for nonconductive ceramic fillers, atomistic modeling of interfaces involving a potentially more promising conductive ceramic filler is still lacking. We address this shortfall by employing molecular dynamics and enhanced Monte Carlo techniques to gain unprecedented insights into the interfacial Li-ion dynamics in a composite polymer-ceramic electrolyte, which integrates polyethylene oxide plus LiN(CF₃SO₂)₂ lithium imide salt (LiTFSI), and Li-ion conductive cubic Li₇La₃Zr₂O₁₂ (LLZO) inclusions. Our simulations automatically produce the interfacial Li-ion distribution assumed in space-charge models and, for the first time, a long-range impact of the garnet surface on the Li-ion diffusivity is unveiled. Based on our calculations and experimental measurements of tensile strength and ionic conductivity, we are able to explain a previously reported drop in conductivity at a critical filler fraction well below the theoretical percolation threshold. Our results pave the way for the computational modeling of other conductive filler/polymer combinations and the rational design of composite SSEs.

Dendrite-Suppressing Polymer Materials for Safe Rechargeable Metal Battery Applications: From the Electro-Chemo-Mechanical Viewpoint of Macromolecular Design

Metal batteries have been emerging as next-generation battery systems by virtue of ultrahigh theoretical specific capacities and low reduction potentials of metallic anodes. However, significant concerns regarding the uncontrolled metallic dendrite growth accompanied by safety hazards and short lifespan have impeded practical applications of metal batteries. Although a great deal of effort has been pursued to highlight the thermodynamic origin of dendrite growth and a variety of experimental methodologies for dendrite suppression, the roles of polymer materials in suppressing the dendrite growth have been underestimated. This review aims to give a state-of-the-art overview of contemporary dendrite-suppressing polymer materials from the electro-chemo-mechanical viewpoint of macromolecular design, including i) homogeneous distribution of metal ion flux, ii) mechanical blocking of metal dendrites, iii) tailoring polymer structures, and iv) modulating the physical configuration of polymer membranes. Judiciously tailoring electro-chemo-mechanical properties of polymer materials provides virtually unlimited opportunities to afford safe and high-performance metal battery systems by resolving problematic dendrite issues. Transforming these rational design strategies into building dendrite-suppressing polymer materials and exploiting them towards polymer electrolytes, separators, and coating materials hold the key to realizing safe, dendrite-free, and long-lasting metal battery systems.