Positioned at the forefront of energy storage technology, lithium-ion capacitors (LICs) offer a unique solution by bridging the performance gap between lithium-ion batteries (LIBs) and supercapacitors (SCs). Their operational principle rests on a hybrid architecture that integrates a Faradaic (battery-type) anode with a capacitive (non-Faradaic) cathode. Carbon-based materials have established a preeminent role as the cathode material of choice in commercial LICs, a status conferred by a compelling combination of properties: high electronic conductivity, a substantial specific surface area, extensive pore volume, robust chemical stability, and economic viability. The deliberate engineering of their porous architecture and surface chemical characteristics creates substantial opportunities for enhancing performance. Offering a critical assessment of advanced optimization strategies, this review delves into the diverse landscape of carbon materials, encompassing activated carbon (AC), porous carbon, graphene, carbon nanotubes, and their composites. Focus on the fundamental mechanisms by which pore structure engineering, surface functionalization, heteroatom doping, and multidimensional composite design augment charge storage and transport dynamics. Finally, summarizes the key challenges currently facing the field and offer perspectives on the future development of high-performance LIC cathode materials, which is anticipated to progress toward refined design principles, multifunctional integration, and sustainable development.

ABSTRACT High‐temperature superconducting coated conductors are pivotal for nuclear fusion and other transformative electrical applications. However, the current‐carrying capacity of these conductors remains insufficient to realize such large‐scale applications, as it is fundamentally constrained by the “thickness effect”, an intrinsic degradation of critical current density with increasing superconducting layer thickness. Here, we report a dual‐modulation strategy that overcomes this long‐standing hurdle in pulsed‐laser‐deposited (PLD) REBa 2 Cu 3 O x (REBCO, RE = rare earth) superconductors. By coupling dynamic thermal control with rare‐earth composition engineering, we effectively balance deposition flux and surface diffusion to maintain structural continuity, and suppress a ‐axis grain formation to obtain dense mixed‐dimensional artificial pinning centers. Our approach enables the growth of high‐quality REBCO layers up to 6 µm thick on technical substrates without a discernible “thickness effect”. The 6 µm‐thick coated conductors deliver unprecedented critical current of 2500 A/cm at 20 K and 10 T and 1446 A/cm at 50 K and 5 T, representing the highest values reported for all PLD‐grown REBCO conductors to date. Our results demonstrate significant performance enhancements by eliminating the “thickness effect” in REBCO films, providing a scalable route for high‐field and fusion for producing high‐temperature superconducting coated conductors that are favorable for large‐scale applications.

ABSTRACT Halide solid‐state electrolytes (HSEs) have recently emerged as a highly promising class of ionic conductors for all‐solid‐state lithium batteries, owing to their high ionic conductivity, favorable electrochemical stability, and superior compatibility with high‐voltage cathodes. Despite rapid progress, a fundamental understanding of the structure‐transport relationships and interfacial behaviors in halide systems remains incomplete, limiting their rational design and practical deployment. In this review, we systematically summarize the recent advances in halide electrolytes by correlating crystal chemistry, defect chemistry, and lattice dynamics with Li + transport properties. We critically compare trivalent, divalent, and mixed‐valence halide systems, highlighting the roles of structural disorder, anion framework flexibility, and cation substitution in governing ionic conductivity. Particular emphasis is placed on emerging strategies including aliovalent doping, amorphization, and lattice softening to achieve fast ion conduction. Furthermore, we analyze interfacial compatibility between halide electrolytes and electrodes, focusing on electrochemical stability, interphase formation, and chemo‐mechanical degradation mechanisms. Finally, we propose design principles and future directions toward scalable synthesis, moisture stability, and integration into practical solid‐state battery architectures. This work provides a comprehensive and critical perspective on HSEs and offers guidance for the rational design of next‐generation solid‐state ionic conductors.

Dry-process electrode technology represents a promising solvent-free manufacturing method, utilizing polytetrafluoroethylene (PTFE) as a fibrous binder. The active material film is bonded to current collectors via a priming conductive adhesive (PCA) to form electrodes. This study presents systematic investigation on the application of conductive adhesive as a conductive primer coating in dry-process electrodes. To evaluate the processing conditions, we investigated the influence of thermal treatment temperature on the flexibility of the PCA and determined that 60 degrees C is the optimal temperature for drying. Through comprehensive characterization, we definitively identified the conductive adhesive as having a phenolic resin matrix and incorporating conductive fillers of graphite and carbon black. Moving to performance analysis, the electrochemical evaluation of pouch cells with PCA-coated current collectors revealed that within the 0.01-3 V range, partial decomposition of the phenolic resin matrix is accompanied by lithium-ion intercalation into graphite, leading to particle dislodgment. Notably, the dry-process electrodes incorporating PCA demonstrate lower internal resistance and more stable capacity retention. The assembled all-dry-process pouch LIC delivers a specific capacity of 58 mAh g-1 and maintains 92.5% capacity retention after 5000 cycles at a 10C current rate. Overall, dry-process electrodes incorporating PCA demonstrate superior electrochemical stability. We fabricated high-performance all-dry-process lithium-ion capacitors, underscoring the crucial role of optimized interfacial design in advancing next-generation energy storage devices.

Iron-based superconductors (IBS) have emerged as a promising candidate for high-field magnets, owing to their extraordinarily high upper critical fields and the relatively simple fabrication processes. This study presents the design and numerical evaluation of a 5 T IBS insert coil, intended to operate within a 28 T background field, generating a total central field of 33 T. A genetic algorithm was employed to minimize the coil volume while ensuring the generation of a requisite central magnetic field. This volume-minimization strategy is pivotal for reducing conductor cost and conserving critical cryogenic space within the magnet bore, thereby enhancing the feasibility of high field magnet systems. Building upon this foundation, the mechanical structure for the IBS coil, including its support and suspension systems, was meticulously designed. A comprehensive analysis of the mechanical stability throughout the entire operational process of the iron-based superconducting insert coil was subsequently performed. This research primarily aims to explore the practical application of IBS coils under even higher magnetic fields, thereby accelerating the advancement of IBS technology towards practical.

Lithium-ion battery capacitor (LIBC) bridges the performance gap between lithium-ion battery (LIB) and supercapacitor, representing a novel hybrid energy storage device with great development potential. While overdischarge-induced failure in LIBs has been extensively studied, the overdischarge behavior and mechanisms of LIBCs remain unexplored. In this work, LIBCs with LiNi1/3Co1/3Mn1/3O2 (NCM)/activated carbon (AC) composite cathode and pre-lithiated soft carbon anode were fabricated, and then characterized by electrochemical tests and characterization techniques to systematically investigate their electrochemical behavior, kinetic characteristics, and failure mechanisms during overdischarge. Cycling tests and post-mortem analysis revealed that early-cycle performance decay mainly stems from irreversible phase transformation, transition metal dissolution and particle cracking of NCM caused by excessive lithium-ion intercalation. Subsequent anode solid electrolyte interphase (SEI) film decomposition/reconstruction and other side reactions further deteriorate device performance, with degradation severity depending on the depth of overdischarge. Notably, AC plays a critical buffering role: it withstands current impact under mild overdischarge to mitigate the damage to NCM caused by such abuse in practical applications and provides stable capacity during long-term abuse cycling, as evidenced by its capacity contribution increasing from 27% to 71% after 500 cycles at 4.0-0.5 V. Unlike LIBs, whose failure originates from hazardous anode copper dissolution, LIBCs shift primary degradation stress to the cathode via the pre-lithiated anode, effectively circumventing short-circuit risks from copper deposition. This study provides key mechanistic insights into the overdischarge failure mechanisms of LIBCs and offers important guidance for designing reliable and practical hybrid energy storage systems.

Ba1-xKxFe2As2 (Ba-122) is a promising material for high-field applications due to its high upper critical magnetic field, low anisotropy, and minimal performance degradation under high fields. Recent advancements in both short and long Ba-122 tapes have brought practical applications within reach. Traditionally, high-pressure sintering via hot isostatic pressing (HIP) or hot pressing is utilized to densify the superconducting core and enhance critical current (Ic) performance. However, two major challenges hinder large-scale implementation: the high cost and technical complexity of large-scale HIP equipment, and the fact that Ba-122 becomes stress-sensitive after heat treatment, making the react-and-wind method impractical. To address these issues, we propose a two-step heat treatment method. In this process, the long tape is first coiled and subjected to a low-temperature pre-HIP stage in a compact HIP unit. Once the conductor or coil is formed, a subsequent atmospheric-pressure (AP) high-temperature sintering is performed. Experimental results show that this two-step process increases Ic by 33.3% compared to direct AP sintering-a gain comparable to the 30%-50% improvement typically achieved by direct HIP. Notably, the pre-HIP stage does not increase Ic degradation under stress; in fact, the tape's bending strain tolerance is slightly improved. This method was successfully applied to develop the first Ba-122 cable-in-conduit conductor, which fully retained the performance of the original tape. This confirms that the two-step heat treatment is a viable and cost-effective strategy for enhancing Ba-122 tape performance in large-scale applications.

MgB2 has more than 2 decades of development since the discovery of its superconductivity. Thanks to its high transition temperature (Tc), low anisotropy, and absence of weak links at grain boundaries, etc., MgB2 was considered as a promising material for superconducting applications at 20 K, low-field. This review gives a brief history of MgB2 wires and tapes, covering key advancements up to the latest progress. The fundamental properties of MgB2 are introduced at the beginning, including its crystal structure, superconducting characteristics, and notably its unique two-gap superconductivity. Then, an overview towards the development of high-performance MgB2 wires and tapes is provided. First, it includes an introduction to the 1st-generation powder-in-tube (PIT) method and the second-generation internal magnesium diffusion (IMD) method, highlighting their respective advantages and limitations. Second, various strategies are summarized, which are proposed by different research groups worldwide to enhance Jc and Je of MgB2 wires and tapes, such as chemical doping (e.g., C, SiC, or Dy2O3 doping) and process optimizations (e.g., ball milling, deformation, or heat treatment). Finally, the progress in long PIT and IMD wires, as well as the development of MgB2 superconducting joints, are being discussed. In terms of practical applications, numerous MgB2-based products developed by companies in the U.S., China, Europe, etc. have been introduced. These include high-current MgB2 cables (e.g., Superconducting Links - SC Links), or large-scale MgB2 magnets (e.g., Magnetic Resonance Imaging - MRI). We believe that, in the near future, MgB2 can partially replace NbTi wires in scalable applications, especially for helium-free superconducting magnets or cables.

Solvent-free dry electrode processing offers a promising route for lithium-ion capacitor (LIC) manufacturing, but the optimal design of polytetrafluoroethylene (PTFE)-fibrillated binder networks depends strongly on electrode material characteristics. Herein, dry-process soft carbon (SC), graphite, and activated carbon (AC) electrodes were fabricated through jet-milling-assisted PTFE fibrillation and roll pressing. The effects of PTFE content on film processability, electrochemical behavior, interfacial evolution, and full-cell performance were systematically investigated. For the battery-type anodes, 3wt% PTFE provided the most favorable balance between electrode cohesion and electrochemical accessibility. The optimized SC and graphite electrodes deliver specific capacities of 258 mAh g⁻¹ for SC and 370 mAh g⁻¹ for graphite at 0.05Ag⁻¹. The capacitive AC cathode with 5wt% PTFE delivered 58 mAh g⁻¹ and exhibited favorable rate behavior. Insufficient PTFE resulted in weak particle connection, whereas excessive PTFE was associated with reduced electrolyte accessibility and increased polarization. Although the graphite electrode provided a higher half-cell capacity, the AC-5%PTFE//SC-3%PTFE LIC exhibited better rate capability and retained 94.3% of its capacity after 2500 cycles at 5C. These results demonstrate that material-dependent PTFE-content optimization is essential for improving electrode compatibility and full-cell performance in LICs.

Electric double-layer capacitors (EDLCs) with a high energy density for ultralow-temperature use are crucial for polar and space explorations, but hindered by the lack of suitable electrolytes and electrodes. We proposed a strong-weak interaction strategy to precisely regulate the solvation structure of an ionic liquid-based electrolyte that is stable from 25 to -80 degrees C. Then, by using activated carbon with a mesopore-rich structure, we obtain an EDLC that can be used at -80 degrees C and 4.5 V and has a record energy density of 104.5 Wh kg-1 with an 89.5% capacitance retention after 10 000 cycles. Furthermore, a 300 F pouch-type EDLC was assembled and it can operate stably from 25 to -80 degrees C, demonstrating the practical applicability. This study provides strategic guidance for constructing EDLCs with a high energy density for use under extreme conditions.

Transition metal chalcogenides, such as cobalt selenide (CoSe2), have high lithium storage capacity. However, their practical application is hindered by severe volume expansion and the dissolution of intermediate polyselenides during repeated cycling. Here, we develop a hollow-embedded architecture in which monodisperse CoSe2 nanocrystals "sprout" from the walls of porous carbon nanoboxes (H-CoSe2/C) via tannic acid etching, low-temperature carbonization, and vacuum selenization. This "wall-growth" strategy combines confinement with continuity: the porous carbon walls guide uniform nucleation and provide electrical conductivity, while the internal cavity buffers expansion and relieves stress. The embedded geometry shortens Li+ diffusion pathways, suppresses particle aggregation, and establishes robust Co-C coupling to enhance charge transport. As a result, the H-CoSe2/C electrode delivers a high reversible capacity of nearly 950 mAh g-1, along with outstanding cycling stability. Remarkably, when paired with a LiCoO2 cathode in a quasi-solid-state battery, the device achieves an impressive energy density of 355 Wh kg-1 and a power density of 3074 W kg-1. This study effectively overcomes the inherent defects of CoSe2 based on the hollow structure and interface engineering of metal-organic frameworks, providing an effective design for anode materials of lithium-ion batteries. (c) 2025 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights are reserved, including those for text and data mining, AI

ABSTRACT Lithium‐ion capacitors (LICs) suffer from severely deteriorated energy output and sluggish kinetics under deep subzero conditions, primarily due to strong Li + ‐solvent shielding interactions and high desolvation barriers in conventional electrolytes. Herein, a solvation deshielding chemistry is proposed to reconstruct the solvation sheath using a moderately coordinating γ ‐valerolactone (GVL)‐based electrolyte system, which effectively weakens Li + ‐solvent interactions, enhances anion accessibility, and accelerates interfacial charge‐transfer kinetics. The engineered electrolyte maintains fast ion‐transport capability across a broad temperature window while inducing the formation of a robust inorganic‐dominated interphase that lowers Li + migration resistance at electrode interfaces. This enables the hard carbon anode to deliver a high capacity of 252 mAh g −1 at −20 °C, outperforming most reported carbon‐based LIC anodes under low‐temperature conditions. Meanwhile, the assembled all‐carbon LIC achieves a high energy density of 121 Wh kg −1 along with a maximum power density of 13.3 kW kg −1 at −20 °C, confirming the simultaneous realization of high energy and high power under subzero conditions. Even at −40 °C, it still delivers a remarkable energy density of 106.8 Wh kg −1 . This work demonstrates that rational deshielding of solvation structure provides a viable pathway to overcome the intrinsic kinetic limitations of LICs under extremely low‐temperature conditions.

Lithium-ion capacitors (LICs) are emerging hybrid energy storage devices that combine the advantages of supercapacitors and lithium-ion batteries, offering both high energy density and high power density. In practical applications, cell over-discharge frequently occurs due to internal resistance mismatch within capacitor modules. The combination of internal short circuits induced by long-term cycling and high state of charge can lead to accelerated temperature rise in the module, thereby posing a serious threat to the thermal stability of LICs. In this work, a three-electrode configuration was embedded in LICs, and the over-discharge mechanisms under different cut-off voltages were systematically investigated by monitoring electrode potentials, temperature evolution, impedance characteristics, cyclic voltammetry behavior, and gas generation. The results indicate that the internal evolution of LICs under over-discharge can be divided into three distinct stages, with the cell voltages of 0.5 V and -0.5 V serving as critical boundary voltages. This study elucidates the evolution behavior of individual LIC cells at different depths of discharge and provides valuable insights into the abuse tolerance and overdischarge failure mechanisms of LICs.

Lithium-ion capacitors (LICs) require accurate cycle life prediction for reliable and safe operation. However, their complex, nonlinear degradation under real conditions, combined with limited and noisy operational data, makes precisely estimating key indicators like Remaining Useful Life (RUL) and State of Health (SOH) particularly challenging. To address these issues, we propose a LIC lifespan prediction framework combining deep feature learning and meta-heuristic hyper-parameter optimization. The framework employs convolutional mechanisms to automatically extract local temporal patterns and utilizes self-attention mechanisms to model long-range dependencies, enhancing the representation of short-term and global information. Additionally, key hyper-parameters are adjusted and optimized through an improved meta-heuristic bio-population search strategy, balancing parameter search efficiency and sample utilization efficiency. Systematic validation is conducted using laboratory data from pouch-type LICs composed of activated carbon cathodes and soft carbon anodes, and comparisons are made with mainstream time-series prediction models. Experimental results demonstrate the proposed method’s advantages in regression metrics such as MAE and RMSE, along with more robust performance in small-sample and noisy scenarios attributed to its enhanced feature extraction and optimized parameter search. Ablation experiments further validate the complementary effects of the model in local and global feature extraction. This study provides a practically viable solution for LICs online monitoring and predictive maintenance.

Achieving high critical current density in practical superconductors for high-field applications requires well-connected fine grains decorated with nano-scale crystalline defects to immobilize magnetic vortices. In compounds with rigid crystal lattices, however, grain refinement is usually accompanied by the release of stored strain energy rather than the retention of defects. Here, we demonstrate a scalable fluid-assisted milling strategy to produce high-purity Ba1–xKxFe2As2 precursor powders with uniform grains. Unlike dry milling that induces catastrophic fracture through breaking Fe–As covalent bonds, the liquid medium buffers impact energy and promotes shear-dominated deformation. This shear-dominated process selectively disrupts the weaker Ba–As ionic bonds, inducing a concerted lattice twist around the [001] axis and triggering the self-organization of interwoven screw dislocation networks. The dislocations with a density 2–4 orders of magnitude higher than those in conventional ceramics serve as strong pinning centers for magnetic vortices. Together with better grain connectivity and texture, the tapes fabricated from optimally milled powders exhibit a 50% enhancement in critical current density, reaching 1.45 × 105 A/cm2 at 4.2 K and 10 T. Our results establish fluid-assisted milling as a practical route to synergistically refine grains and construct strong pinning landscapes, offering a scalable pathway to high-performance iron-based superconductors.

The solidification process is crucial for preparing high-performance ceramic super-conductor. The solidification process is strongly dependent on the characteristics of the starting powder, including particle size, morphology, and phase purity. This review concisely examines the study on four key ceramic superconductors: REBCO, Bi-2212, FeSeTe, and MgB2. In REBCO, additives such as CeO2, Pt, or BaO2 powder can refine the RE-211 phase. In Bi-2212, Pb or Nb powder additions stabilize the high-Tc phase. For FeSeTe, doping with F or Co modifies phase separation and introduces Δκ pinning. Meanwhile, in MgB2, the incorporation of SiC nanoparticles powder generates effective pinning centers. Concurrently, processing conditions exert a decisive influence on the final microstructure, as demonstrated by the TSMG/TSIG route in REBCO, partial melting parameters for Bi-2212, specific cooling protocols and thermal treatments for FeSeTe, and optimized sintering and post-annealing processes for MgB2. Future research directions should prioritize fundamental understanding of phase separation mechanisms during powder processing, development of multi-component doping strategies for powder modification, and advancement of scalable powder processing routes for practical conductor architectures.

Ba0.6K0.4Fe2As2 superconductors have been identified as potential candidates for magnet applications through their very high upper critical field, relatively high superconducting transition temperature and manufacturability through the powder-in-tube (PIT) route. Recent studies have reported that these conductors have a deep minimum critical current (Ic dip) near zero field, and this anomalous property exhibits hysteresis sometimes. However, little attention has been paid to AC loss in these conductors; a clear understanding of the loss behaviors is required for practical applications. In this work, preliminary AC loss simulations were performed at 15 K for stainless steel/silver double-sheathed nonfilamentary Ba0.6K0.4Fe2As2 tapes. A hypothetical tape without Ic dip was further used to investigate the influence of low-field Jc characteristics on the overall AC loss response. The simulation results indicate that the low-field anomaly causes a slight increase in magnetization loss at low fields and significantly impacts dynamic loss in the presentence of DC currents approaching Ic.

The solidification process is crucial for preparing high-performance superconductors and is strongly dependent on the characteristics of the starting powder, including particle size, morphology, and phase purity. This review concisely examines the study on four key superconductors: REBCO, Bi-2212, FeSeTe, and MgB2. In REBCO, additives such as CeO2, Pt, or BaO2 powder can refine the RE-211 phase. In Bi-2212, Pb doping stabilizes the high-Tc phase. For FeSeTe, doping with F or Co modifies phase separation and introduces Δκ pinning. Meanwhile, in MgB2, the incorporation of SiC nanoparticles powder generates effective pinning centers. Concurrently, processing conditions exert a decisive influence on the final microstructure, as demonstrated by the TSMG/TSIG route in REBCO, partial melting parameters for Bi-2212, specific cooling protocols and thermal treatments for FeSeTe, and optimized sintering and post-annealing processes for MgB2. Future research directions should prioritize fundamental understanding of phase separation mechanisms during powder processing, development of multi-component doping strategies for powder modification, and advancement of scalable powder processing routes for practical conductor architectures.

Transition metal phosphides (TMPs) are appealing anodes for lithium-ion capacitors because of their high theoretical capacities, but low conductivity and drastic volume changes remain critical barriers to practical use. Here we report a TMP heterostructure anode material featuring 10 nm CoP2 and GeP2 nanoclusters confined within N, P co-doped carbon polyhedra (CoP2-GeP2@NPC) via M-P-C (M = Co or Ge) bonding. The ultrasmall size of CoP2 and GeP2 nanoclusters provides more active reaction sites and shortens the electron/ion diffusion pathways. The M-P-C bonding bridges phosphide nanoclusters and carbon, changing the interface charge distribution between nanoclusters and carbon polyhedra to promote the reaction kinetics. Additionally, the N, P-doped carbon shells can not only increase the pseudocapacitance contribution by local charge change, but also physically restrain the volume expansion of transition metal phosphides, improving structural stability. The CoP2-GeP2@NPC heterostructure achieves an exceptional specific capacity exceeding 1600 mAh g−1 and sustain stable cycling for more than 1800 cycles. Notably, the YP80//CoP2-GeP2@NPC lithium-ion capacitor demonstrates an energy density of up to 124.09 Wh kg−1, power density of 11.26 kW kg−1, and cycle life exceeding 10000 cycles. This research provides a viable pathway for achieving rapid kinetic and structural stability in diverse metal phosphide anodes.