Understanding the separator pore size inhibition effect on lithium dendrite via phase-field simulations

Micro-Macro Hierarchical Hydrogel Architectures with Dual-Scale Polyanionic Networks for High Energy Density PBA||Zn Batteries

Hydrogel electrolytes are promising for aqueous zinc metal batteries but face challenges in suppressing Zn dendrites and cathode dissolution. This study develops a polyanionic hydrogel electrolyte, poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-acrylamide) (P(AMPS-co-AM)), featuring a dense porous structure that enables a higher Zn2+ transference number (tZn 2+ = 0.81) and homogeneous zinc deposition. Additionally, the dense porous structure further reduces the proportion of free water molecules, thereby suppressing side reactions. Based on the benefits of the hydrogel, the Zn||Zn symmetric cell demonstrates over 3000 h of continuous cycling, and the Zn||Cu asymmetric cell exhibits an exceptional Coulombic efficiency of 99.29% in the first cycle. Benefiting from the fixation of transition metals by polyanionic groups and the reduced content of free water molecules within a densely packed porous architecture, the PBA||Zn full cell achieves a high energy density of 267 Wh kg-1. This hydrogel electrolyte design strategy provides significant insights for achieving long cycle life through both the microscale and macroscale structure design to achieve low cost and high energy density of aqueous zinc-metal batteries (AZMBs).

Recent Advances in Polyphenylene Sulfide-Based Separators for Lithium-Ion Batteries

Polyphenylene sulfide (PPS)-based separators have garnered significant attention as high-performance components for next-generation lithium-ion batteries (LIBs), driven by their exceptional thermal stability (>260 °C), chemical inertness, and mechanical durability. This review comprehensively examines advances in PPS separator design, focusing on two structurally distinct categories: porous separators engineered via wet-chemical methods (e.g., melt-blown spinning, electrospinning, thermally induced phase separation) and nonporous solid-state separators fabricated through solvent-free dry-film processes. Porous variants, typified by submicron pore architectures (<1 μm), enable electrolyte-mediated ion transport with ionic conductivities up to >1 mS·cm-1 at >55% porosity, while their nonporous counterparts leverage crystalline sulfur-atom alignment and trace electrolyte infiltration to establish solid-liquid biphasic conduction pathways, achieving ion transference numbers >0.8 and homogenized lithium flux. Dry-processed solid-state PPS separators demonstrate unparalleled thermal dimensional stability (<2% shrinkage at 280 °C) and mitigate dendrite propagation through uniform electric field distribution, as evidenced by COMSOL simulations showing stable Li deposition under Cu particle contamination. Despite these advancements, challenges persist in reconciling thickness constraints (<25 μm) with mechanical robustness, scaling solvent-free manufacturing, and reducing costs. Innovations in ultra-thin formats (<20 μm) with self-healing polymer networks, coupled with compatibility extensions to sodium/zinc-ion systems, are identified as critical pathways for advancing PPS separators. By addressing these challenges, PPS-based architectures hold transformative potential for enabling high-energy-density (>500 Wh·kg-1), intrinsically safe energy storage systems, particularly in applications demanding extreme operational reliability such as electric vehicles and grid-scale storage.

Innovations Progress in Emerging Multifunctional Aramid Nanofiber Aerogels

Aerogels have attracted great attention in the academic and industrial fields due to their intrinsic low density, high porosity, and high specific surface area. As an ideal nanobuilding block for advanced aerogels, the research community has shown a strong interest in aramid nanofiber (ANF) aerogel materials and their applications in frontier fields. However, there is a lack of a comprehensive review of the basic development and practical applications of pure ANF aerogels regarding these latest achievements in the past decade. This review aims to fill this gap by comprehensively exploring the preparation, properties, application progress, challenges, and prospects of ANF aerogels. We begin with a summary of the rheological principles of ANF dispersions, different preparation strategies, and drying methods of ANF aerogels. Then, the unique properties of ANF aerogels of various morphologies and outstanding advantages based on these properties are critically reviewed. Besides, the progress of multifunctional applications in the fields of flexible thermal insulation, environmental protection, energy storage, and other fields is summarized. Finally, we explore the main challenges and prospects of ANF aerogels to give insights for further development promotion from lab-scale to industry-scale.

Covalent Organic Framework-Coated Polyimide Ion-Track-Etched Separator with High Thermal Stability for Developing Lithium-Ion Batteries with Long Lifespans

Separators play a crucial role in inhibiting thermal runaway in lithium-ion batteries (LIBs). In this study, the doctor blade coating method and heavy-ion track etching technology were used to prepare a polyimide-based covalent organic framework (PI_COF) separator with excellent thermal stability and a long cycle life. Specifically, COF300 was simply coated on the surface of a polyimide-based track-etched membrane (PI_TEM) with straight through holes, which provided a rigid framework and high-temperature stability at 300 °C. These features were conducive to inhibiting thermal runaway, while porous COF300 with large holes increased the wettability of the electrolyte, facilitating lithium-ion migration and suppression of lithium dendrite growth; consequently, LIBs with an excellent cycling performance and a high rate capacity were obtained. The cell with the PI_COF separator delivered a high capacity of 90.0 mA h g-1 after 1000 cycles. The PI_COF separator with high thermal stability exhibited a long cycle life in LIBs. These features are beneficial for improving the safety characteristics of LIBs as well as for accelerating the practical application process of the PI_COF separator.

A zincophilic separator with directional alignment and pore hydrophilicity towards stable aqueous zinc metal batteries

A zincophilic PAN@Zn(OTF)2 (PZO) separator with an extremely thin thickness of 65.6 μm is introduced. This separator with a low cost of 6.1 $ m-2, exhibiting excellent mechanical and wettability properties. The cell with the PZO separator exhibits impressive electrochemical performances both in symmetrical Zn||Zn cell and Zn||NVO full cell.

Dendrite-Free Lithium Metal Anodes Enabled by an Ordered Conductive Ni-Based Catecholate Interlayer for Solid-State Lithium Batteries

The large-scale commercial application of Li metal batteries is hindered by uncontrolled Li dendrite growth. Most of the present interfacial engineering strategies in lithium metal batteries can only prolong the nucleation time of lithium dendrites but cannot prevent the growth of lithium dendrites in three-dimensional space. In this work, a nickel-based catecholate (Ni-CAT) conductive interlayer that can guide the orderly migration of lithium ions and inhibit the disordered deposition of lithium dendrites is successfully constructed between the solid electrolyte and lithium metal through a reasonable design. The experimental analysis proves that the Ni-CAT nanorod arrays with unique vertical structures are closely connected to the solid electrolyte, which can reduce the charge-transfer resistance at the interface and guide lithium ions to be preferentially deposited on the surface of the Ni-CAT intermediate layer through the conduction gradient. Hence, this structure effectively avoids the phenomenon of apical growth during lithium deposition. In addition, the rich pores and inherent nanochannels of Ni-CAT itself act as an "ion sieve", successfully inducing the uniform deposition of lithium metal, which greatly reduces the occurrence of dead lithium due to the loss of electrical contact of lithium during cycling. This strategy holds promise for solving the lithium dendrite problem.

Advanced Composite Lithium Metal Anodes with 3D Frameworks: Preloading Strategies, Interfacial Optimization, and Perspectives

Lithium (Li) metal is regarded as the most promising anode candidate for next-generation rechargeable storage systems due to its impeccable capacity and the lowest electrochemical potential. Nevertheless, the irregular dendritic Li, unstable interface, and infinite volume change, which are the intrinsic drawbacks rooted in Li metal, give a seriously negative effect on the practical commercialization for Li metal batteries. Among the numerous optimization strategies, designing a 3D framework with high specific surface area and sufficient space is a convincing way out to ameliorate the above issues. Due to the Li-free property of the 3D framework, a Li preloading process is necessary before the 3D framework that matches with the electrolyte and cathode. How to achieve homogeneous integration with Li and 3D framework is essential to determine the electrochemical performance of Li metal anode. Herein, this review overviews the recent general fabrication methods of 3D framework-based composite Li metal anode, including electrodeposition, molten Li infusion, and pressure-derived fabrication, with the focus on the underlying mechanism, design criteria, and interfacial optimization. These results can give specific perspectives for future Li metal batteries with thin thickness, low N/P ratio, lean electrolyte, and high energy density (>350 Wh Kg^-1 ).

"Pore-Hopping" Ion Transport in Cellulose-Based Separator Towards High-Performance Sodium-Ion Batteries

Sodium-ion batteries (SIBs) have great potential for large-scale energy storage. Cellulose is an attractive material for sustainable separators, but some key issues still exist affecting its application. Herein, a cellulose-based composite separator (CP@PPC) was prepared by immersion curing of cellulose-based separators (CP) with poly(propylene carbonate) (PPC). With the assistance of PPC, the CP@PPC separator is able to operate the cell stably at high voltages (up to 4.95 V). The "pore-hopping" ion transport mechanism in CP@PPC opens up extra Na⁺ migration paths, resulting in a high Na⁺ transference number (0.613). The separator can also tolerate folding, bending and extreme temperature under certain circumstances. Full cells with CP@PPC reveal one-up capacity retention (96.97 %) at 2C after 500 cycles compared to cells with CP. The mechanism highlights the merits of electrolyte analogs in separator modification, making a rational design for durable devices in advanced energy storage systems.

Influences of Separator Thickness and Surface Coating on Lithium Dendrite Growth: A Phase-Field Study

Li dendrite growth, which causes potential internal short circuit and reduces battery cycle life, is the main hazard to lithium metal batteries. Separators have the potential to suppress dendrite growth by regulating Li⁺ distribution without increasing battery weight significantly. However, the underlying mechanism is still not fully understood. In this paper, we apply an electrochemical phase-field model to investigate the influences of separator thickness and surface coating on dendrite growth. It is found that dendrite growth under thicker separators is relatively uniform and the average dendrite length is shorter since the ion concentration within thicker separators is more uniform. Moreover, compared to single layer separators, the electrodeposition morphology under particle-coated separators is smoother since the particles can effectively regulate Li ionic flux and homogenize Li deposition. This study provides significant guidance for designing separators that inhibit dendrites effectively.