Nonporous Gel Electrolytes Enable Long Cycling at High Current Density for Lithium-Metal Anodes

Gel Polymer Electrolytes for Lithium Batteries: Advantages, Challenges, and Perspectives

The increasing demand for high-energy-density and safe lithium batteries has driven significant advancements in electrolyte technology. Among the various options, gel polymer electrolytes (GPEs) have emerged as a promising solution, combining the high ionic conductivity of liquid electrolytes with the structural integrity of solid-state (polymer) electrolytes. GPEs possess a hybrid structure composed of a polymer matrix, lithium salts, one or more solvents or plasticizers, and often functional additives, offering exceptional flexibility, adaptability, and performance for advanced energy storage systems. This review provides a comprehensive analysis of GPE technology for lithium batteries, covering fabrication methods, advantages, and challenges, while emphasizing potential application scenarios and the underlying mechanisms. Finally, future research directions are outlined to provide valuable insights and guidelines for advancing GPE technology.

Sb nanoparticles embedded uniformly on the surface of porous carbon fibres for high-efficiency sodium storage

Sb nanoparticles (∼50 nm) are embedded uniformly on the surface of carbon fibers (Sb NPs-SCFs) without scattered Sb NPs. The Sb NPs-CNFs anode exhibits excellent sodium storage, delivering a second cycle discharge capacity of 455.7 mA h g-1 at 1.0 A g-1 and a stable capacity of 381.9 mA h g-1 after 200 cycles, achieving a notable retention of 83.8%.

Recent Advances in Porous Carbon Materials as Electrodes for Supercapacitors

Porous carbon materials have demonstrated exceptional performance in various energy and environment-related applications. Recently, research on supercapacitors has been steadily increasing, and porous carbon materials have emerged as the most significant electrode material for supercapacitors. Nonetheless, the high cost and potential for environmental pollution associated with the preparation process of porous carbon materials remain significant issues. This paper presents an overview of common methods for preparing porous carbon materials, including the carbon-activation method, hard-templating method, soft-templating method, sacrificial-templating method, and self-templating method. Additionally, we also review several emerging methods for the preparation of porous carbon materials, such as copolymer pyrolysis, carbohydrate self-activation, and laser scribing. We then categorise porous carbons based on their pore sizes and the presence or absence of heteroatom doping. Finally, we provide an overview of recent applications of porous carbon materials as electrodes for supercapacitors.

Suppression of Dendrites by a Self-Healing Elastic Interface in a Sodium Metal Battery

The safety issues caused by sodium dendrites limit the widespread application of sodium metal batteries. Herein, a self-healing polymer electrolyte (SPE) is prepared by immersing the self-healing polymer in a liquid electrolyte. Benefiting from the self-healing properties, elastic interface, and dense nonporous structure of the SPE, the fabricated NaK|MC SPE|NaK symmetric battery presents a long battery life (∼590 h) and low polarization voltage (192 mV). Moreover, the PTCDA|MC SPE|NaK full cell also delivers stable long cycles and outstanding rate performance.

Ion Flux Self-Regulation Strategy with a Volume-Responsive Separator for Lithium Metal Batteries

Lithium metal batteries (LMBs) are regarded as one of the most promising next-generation energy storage devices due to their high energy density. However, the conversion of LMBs from laboratory to factory is hindered by the formation of lithium dendrites and volume change during lithium stripping and deposition processes. In this work, a volume-responsive separator with core/shell structure thermoplastic polyurethane (TPU)/polyvinylidene fluoride (PVDF) fibers and SiO₂ coating layers is designed to restrict dendrite growth. The TPU/PVDF-SiO₂ separator can accommodate the volume change like an artificial lung and keep intimate contact with the electrodes, which leads to the formation of a uniform and high-density solid-electrolyte interphase. Meanwhile, the separator can regulate the transport channels and diffusion coefficients (D) of lithium ions with the change of porosity from both experimental and ab initio molecular dynamic analysis. The Li symmetric cells assembled with the TPU/PVDF-SiO₂ can run for 1000 h at the current of 1.0 mA cm^-2 without a short circuit. Moreover, the low melting point of PVDF can shut the ionic conduction down at 170 °C, guaranteeing the thermal safety of the batteries. With the above advantages, the TPU/PVDF-SiO₂ separator presents great potential to promote the commercial and industrial application of LMBs.

Versatile Asymmetric Separator with Dendrite-Free Alloy Anode Enables High-Performance Li-S Batteries

Lithium-sulfur batteries (LSBs) with extremely-high theoretical energy density (2600 Wh kg^-1 ) are deemed to be the most likely energy storage system to be commercialized. However, the polysulfides shuttling and lithium (Li) metal anode failure in LSBs limit its further commercialization. Herein, a versatile asymmetric separator and a Li-rich lithium-magnesium (Li-Mg) alloy anode are applied in LSBs. The asymmetric separator is consisted of lithiated-sulfonated porous organic polymer (SPOP-Li) and Li_6.75 La₃ Zr_1.75 Nb_0.25 O₁₂ (LLZNO) layers toward the cathode and anode, respectively. SPOP-Li serves as a polysulfides barrier and Li-ion conductor, while the LLZNO functions as an "ion redistributor". Combining with a stable Li-Mg alloy anode, the symmetric cell achieves 5300 h of Li stripping/plating and the modified LSBs exhibit a long lifespan with an ultralow fading rate of 0.03% per cycle for over 1000 cycles at 5 C. Impressively, even under a high-sulfur-loading (6.1 mg cm^-2 ), an area capacity of 4.34 mAh cm^-2 after 100 cycles can still be maintained, demonstrating high potential for practical application.

Boosting Polysulfide Catalytic Conversion and Facilitating Li+ Transportation by Ion-Selective COFs Composite Nanowire for LiS Batteries

The large-scale application of lithium-sulfur batteries (LSBs) has been impeded by the shuttle effect of lithium-polysulfides (LiPSs) and sluggish redox kinetics since which lead to irreversible capacity decay and low sulfur utilization. Herein, a hierarchical interlayer constructed by boroxine covalent organic frameworks (COFs) with high Li⁺ conductivity is fabricated via an in situ polymerization method on carbon nanotubes (CNTs) (C@COF). The as-prepared interlayer delivers a high Li⁺ ionic conductivity (1.85 mS cm^-1 ) and Li⁺ transference number (0.78), which not only acts as a physical barrier, but also a bidirectional catalyst for LiPSs redox process owing to the abundant heterointerfaces between the inner conductive CNTs and the outer COFs. After coupling such a catalytic interlayer with sulfur cathode, the LSBs exhibit a low decay rate of 0.07% per cycle over 500 cycles at 1 C, and long cycle life at 3 C (over 1000 cycles). More importantly, a remarkable areal capacity of around 4.69 mAh cm^-2 can still be maintained after 50 cycles even under a high sulfur loading condition (6.8 mg cm^-2 ). This work paves a new way for the design of the interlayer with bidirectional catalytic behavior in LSBs.

Guiding Uniformly Distributed Li-Ion Flux by Lithiophilic Covalent Organic Framework Interlayers for High-Performance Lithium Metal Anodes

Lithium (Li) metal anodes are regarded as prospective anode materials in next-generation secondary lithium batteries due to their ultrahigh theoretical capacities and ultralow potentials. However, inhomogeneous lithium deposition and uncontrollable growth of lithium dendrites always give rise to the low lithium utilization, rapid capacity fading, and poor cycling performance. Herein, we design the lithiophilic covalent organic frameworks (COFs) containing preorganized triazine rings and carbonyl groups as the multifunctional interlayer in lithium metal batteries (LMBs). Triazine rings rich in lone pair electrons can act as the donor attracting Li ions, and carbonyl groups serve as Li-anchoring sites effectively coordinating Li ions. These periodic arranged subunits significantly guide uniform Li ion flux distribution, guarantee smooth Li deposition and less lithium dendrite formation. Consequently, the symmetric batteries with COF interlayers exhibit an extraordinary cycling stability for more than 2450 and 1000 h with ultralow polarization voltage of about 12 and 14 mV at 0.5 and 1.0 mA cm^-1. Coupling with sulfur (S) cathodes and LiFePO₄ (LFP) cathodes, the full cells also demonstrate superb energy density achievement and rate performance. With introducing lithiophilic COFs interlayers, the Li-LFP batteries exhibit high capacity of 150 mAh g^-1 and 86% capacity retention after 450 cycles at 0.5 C.