Ion Migration Research Articles

2‐Bromonaphthalene‐Induced Defect Passivation to Suppress Ion Migration in CsPbBr3 Wafer for X‐Ray Detector with Bias‐Resistant Stability

AbstractFeaturing exceptional photoelectronic properties and scalability, hot‐pressing processed all‐inorganic (i. e., CsPbBr3) perovskite wafers have emerged as promising candidates for direct X‐ray imaging. Nonetheless, severe ion migration in CsPbBr3 wafers results in a large and drifting dark current, thereby compromising the bias‐resistant stability of the X‐ray detector. Herein, a solvent‐free interfacial defect passivation strategy is proposed by introducing a passivator molecule, 2‐bromonaphthalene, to passivate interfacial defects and suppress ion migration in CsPbBr3 wafers. Implementing this strategy effectively inhibits ion migration in CsPbBr3 wafers, as evidenced by an enhanced ion migration activation energy of 0.56 eV and a negligible dark‐current drift of 4.01 × 10−8 µA cm−1 s−1 V−1, representing a 100 fold reduction in dark current drift compared to untreated CsPbBr3 wafers under a high electric field of 100 V mm−1, indicating a high bias‐resistant stability. Consequently, the CsPbBr3 wafer X‐ray detector achieves an impressively high sensitivity of 11090 µC Gyair−1 cm−2, a low detection limit of 9.41 nGyair s−1 under a 100 V mm−1 electric field, and high‐contrast X‐ray imaging capabilities, with performance comparable to that of CsPbBr3 single‐crystal‐based X‐ray detector, highlighting the potential of interfacial defect passivation strategy for high‐performance X‐ray detectors.

Ion Concentration Gradient Induced Efficient Ion Migration in Hydrogen-Bonded Organic Frameworks for High-Performance, Self-Powered Humidity Sensing.

As one of the driving forces of ion migration, ion concentration gradients have large untapped potential to improve the performance of humidity sensors. A self-powered flexible humidity sensor based on hydrogen-bonded organic framework electrolytes wherein Na+ concentration gradients induce efficient ion migration is presented that can be attributed to the reversible effect of ambient water molecules on the migration barrier of Na+. The sensor exhibits superior flexibility, rapid responsiveness, high sensitivity (0.17 µA/% relative humidity), rapid response time (1.06 s), and outstanding stability (>200 cycles). The humidity-responsive device based on the Na+ concentration gradient exhibited excellent self-powering capability, eliminating the need for an external power unit and demonstrating impressive humidity power generation potential, which achieves a high current density of up to 164 mAm-2 and power density of 5.625 mWm-2. This research presents a new paradigm for developing self-powered humidity sensors and demonstrates their exceptional performance in noncontact sensing applications.

Porosity and Conductivity Dual‐Gradient Design on Ultrathin 3D Nanofibrous Anode for Flexible Zn‐Ion Batteries

AbstractFlexible Zn‐ion batteries (ZIBs) have been regarded as a promising energy storage solution for flexible electronics. However, the challenges of dendrite growth due to uneven current density distribution and limited anode flexibility have impeded their practical application. Herein, a flexible 3D zinc anode with a dual gradient in porosity and conductivity is presented. This dual‐gradient nanofibrous anode exhibits exceptional flexibility and durability, showing less than a 10% change in resistance after 15 000 bending cycles. The vertical gradient distribution in conductivity promotes preferential zinc deposition at the bottom section, while the gradient in porosity facilitates Zn2⁺ ion migration and ensures timely replenishment of the inner space of the membrane. The combination of the 3D structure and dual‐gradient design fosters bottom‐up zinc deposition, effectively preventing dendrite formation. Symmetric cells with this dual‐gradient anode demonstrate outstanding cycling stability, maintaining more than 410 h of operation at a current density of 1 mA cm−2 for 1 mA h cm−2, surpassing reference samples and most previously reported 3D zinc anodes. The quasi‐solid‐state ZIBs assembled with this dual‐gradient anode exhibit excellent stability under various mechanical deformations. These 3D nanofibrous anodes with dual‐gradient designs hold great promise for advancing the practical application of flexible Zn‐ion batteries.

In Situ Cross‐Linking and Interfacial Engineering via Multifunctional Diamine Additive for High‐Temperature Magnesium Metal Batteries

AbstractThe electrolyte and its interfacial chemistry are crucial for the development of high‐temperature magnesium metal batteries. Here, a robust in situ cross‐linked gel polymer electrolyte (MgB@CGPE) and its derived Mg3N2‐rich (Mg3N2 and related Mg─N─H complexes) interphase are obtained by a multifunctional diamine additive. The Mg3N2‐rich interphase exhibits low magnesium ion migration activation energy and can effectively inhibit the continuous decomposition of electrolyte at the interface under elevated temperatures. Moreover, the MgB@CGPE can enable reversible magnesium deposition and dissolution over a wide temperature range of 30–180 °C. The assembled Mo6S8//MgB@CGPE//Mg cells demonstrate stable cycling over 200 cycles at 150 °C with 80% capacity retention. Additionally, these cells also address crucial mechanical and thermal safety concerns, indicating their potential for use under extreme conditions. This work presents a universal and practical strategy for designing polymer electrolytes that operate at elevated temperatures.

Investigation of Potential‐Induced Degradation in Perovskite Solar Cells under Inert Conditions

Perovskite solar cells (PSCs) have emerged as a promising photovoltaic technology due to their remarkable efficiency advancements. However, their commercialization is hindered by stability challenges, including sensitivity to environmental conditions and a critical degradation mechanism known as potential‐induced degradation (PID). PID can significantly impair PSC performance within hours under operational conditions. This study investigates PID in 48 triple‐cation p‐i‐n PSCs over 313 h in an inert environment, excluding additional stressors like moisture and oxygen. The PID‐stressed devices degraded to 79% of their initial efficiency, primarily driven by losses in short‐circuit current density. Time‐of‐flight secondary ion mass spectroscopy revealed sodium ion migration from soda‐lime glass substrates into the perovskite layer. Interestingly, photoluminescence and X‐ray diffraction analyses detected no measurable differences between PID‐stressed and reference devices, contradicting prior literature that associates PID with perovskite segregation and decomposition. These findings challenge the conventional understanding of PID, suggesting that environmental factors such as oxygen and moisture might exacerbate degradation effects. This work provides critical insights into the intrinsic mechanisms of PID under controlled conditions and highlights the need for further research into the interplay between PID and environmental stressors to guide the development of more stable PSC technologies.

Multiple B-site doping suppresses ion migration in halide perovskites.

Lead halide perovskites hold great promise for photovoltaics and optoelectronics, yet ion migration continues to challenge their long-term stability. Here, combining first-principles calculations and machine learning molecular dynamics, we unravel the interplay between perovskite octahedral lattice dynamics and energy barrier associated with ion migration. Our results show that B-site substitution, particularly with alkaline-earth and lanthanide elements, notably strengthens lattice interactions, restrains octahedral oscillation, and increases iodine-migration barriers, outperforming the commonly used A-site and X-site substitutions and interstitial doping. Moreover, the enhanced barrier aligns with the geometric factor of μτ (tolerance-octahedral product), underlining the superior effectiveness of co- and multiple-element B-site doping in lattice stabilization and ion migration suppression. Experimental validation with exemplary hysteresis-free Eu-Ca-doped perovskite single crystals demonstrates remarkable improvements in ambient stability and transport properties. These findings highlight B-site engineering as an effective microstructural strategy for controlling ion migration, with important implications for stable and lead-reduced perovskite devices.

Restrain Phase Segregation by In Situ Buried Prenucleation for Efficient and Stable Wide-Band Gap Perovskite Cells.

The phase segregation of wide-band gap perovskite solar cells (PSCs) typically originates from defect centers and strain induced by nonstoichiometric compounds. In this study, we have discovered an excess of PbI2 at the buried interface in inverted wide-band gap PSCs. To address this issue, RbI is introduced to interact with the excessive PbI2, thereby in situ forming a layer of inorganic perovskite RbPbI3. The presence of RbPbI3 as prenucleation centers facilitates intimate contact and enhances crystallinity of the wide-band gap perovskite, thereby alleviating lattice strain and reducing nonradiative recombination centers. Consequently, ion migration is suppressed, and phase segregation at the buried interface is inhibited. After the addition of RbI, the power conversion efficiency (PCE) of the wide-band gap semitransparent device is increased from 17.96 to 19.5%, and the bifacial factor is 83.4%. Furthermore, after continuous illumination at an intensity equivalent to AM 1.5 G for 1000 h, the device based on RbI retains approximately 81.71% of its initial PCE.

Investigation on the ion diffusion and migration transport mechanism in Polypyrrole tri-layers actuators conducting polymer

Investigation on the ion diffusion and migration transport mechanism in Polypyrrole tri-layers actuators conducting polymer

Layered Organic Molecular Crystal with One-Dimensional Ion Migration Channel for Durable Magnesium-Based Dual-Ion Batteries

Layered Organic Molecular Crystal with One-Dimensional Ion Migration Channel for Durable Magnesium-Based Dual-Ion Batteries

New fast ion conductors discovered through the structural characteristic involving isolated anions

One of the key materials in solid-state lithium batteries is fast ion conductors. However, Li+ ion transport in inorganic crystals involves complex factors, making it a mystery to find and design ion conductors with low migration barriers. In this work, a distinctive structural characteristic involving isolated anions has been discovered to enhance high ionic conductivity in crystals. It is an effective way to create a smooth energy potential landscape and construct local pathways for lithium ion migration. By adjusting the spacing and arrangement of the isolated anions, these local pathways can connect with each other, leading to high ion conductivity. By designing different space groups and local environments of the Se2− anions in the Li8SiSe6 composition, combined with the ion transport properties obtained from AIMD simulations, we define isolated anions and find that local environments with higher point group symmetry promotes the formation of cage-like local transport channels. Additionally, the appropriate distance between neighboring isolated anions can create coplanar connections between adjacent cage-like channels. Furthermore, different element types of isolated anions can be used to control the distribution of cage-like channels in the lattice. Based on the structural characteristic of isolated anions, we shortlisted compounds with isolated N3−, Cl−, I−, and S2− features from the crystal structure databases. The confirmation of ion transport in these structures validates the proposed design method of using isolated anions as structural features for fast ion conductors and leads to the discovery of several new fast ion conductor materials.

Synergistic Intercalation and Vacancy Engineering Boosting Superior Rate Performance for High-Performance Potassium Storage

Abstract In this work, a dual-strategy approach of Ti-intercalation and Mo vacancies was utilized to engineer VMo-Ti-MoSe2, aiming to enhance the electrochemical performance of potassium-ion batteries (PIBs). The intercalation strategy reduces the band gap and expands the layer spacing of MoSe2, which alleviates the volume expansion during potassiation/depotassiation processes and accelerates the rapid migration of potassium ions. Furthermore, the engineered Mo vacancies not only facilitate the excitation and conduction of electrons but also significantly accelerate carrier transfer, thereby enhancing the reaction kinetics during the charge/discharge process. Additionally, these vacancies provide abundant active sites that ensure a more stable and superior potassium ion adsorption capability. More importantly, in-situ X-ray diffraction and in-situ Raman spectroscopy, coupled with density functional theory calculations, elucidate the potassification/depotassification behaviors of VMo-Ti-MoSe2 anode during the cycling process. Consequently, VMo-Ti-MoSe2 anode demonstrates an outstanding cycling performance, retaining of 360.1 mAh g-1 after 100 cycles at 2 A g-1. It also delivers a high rate capability of 270.9 mAh g-1 at 5 A g-1. This study shows that vacancy and intercalation strategies significantly enhance the electrochemical performance of PIBs and may be applicable to other battery systems to achieve higher capacity and better cycling stability.

Suppressing Ion Migration through Dual Interface Engineering toward Efficient and Stable Perovskite Solar Modules

Suppressing Ion Migration through Dual Interface Engineering toward Efficient and Stable Perovskite Solar Modules

Fast Sodium Ion Conductivity in Pristine Na8SnP4 – Synthesis, Structure and Properties of the two Polymorphs LT‐ Na8SnP4 and HT‐Na8SnP4

Achieving high ionic conductivities in solid state electrolytes is crucial for the development of efficient all‐solid‐state‐batteries. Considering future availability and sustainability, sodium materials hold promises for an alternative for lithium materials in all‐solid‐state batteries, due to the higher abundance. Here we report on a sodium phosphide ion conductor Na8SnP4 with a conductivity of 0.53 mS cm‐1 at room temperature as pristine material. Due to the simple tetrahedral SnP4 structure units, Na8SnP4 has potential for optimization through aliovalent substitution as successfully applied in sulfide‐based materials. Na8SnP4 is easily accessible from exclusively abundant elements and forms a high‐ and low‐temperature polymorph, which further allows for a fundamental understanding of the structure‐property relationship. Both polymorphs are structurally characterized by synchrotron X‐ray powder diffraction and MAS‐NMR spectroscopy. Ion conductivity and activation energy for ion mobility was determined by temperature dependent impedance spectroscopy and static 23Na‐NMR measurements. Both MEM analysis of scattering densities as well as structure determination by Rietveld‐methods hint for ionic motion between special Na positions in the structure and that ion migration proceeds along pathways passing triangular faces of neighboring tetrahedral and octahedral voids. The specific voids filling in the disordered HT‐phase is found to be a crucial parameter for ion migration.

Fast Sodium Ion Conductivity in Pristine Na8SnP4 - Synthesis, Structure and Properties of the two Polymorphs LT- Na8SnP4 and HT-Na8SnP4.

Achieving high ionic conductivities in solid state electrolytes is crucial for the development of efficient all-solid-state-batteries. Considering future availability and sustainability, sodium materials hold promises for an alternative for lithium materials in all-solid-state batteries, due to the higher abundance. Here we report on a sodium phosphide ion conductor Na8SnP4 with a conductivity of 0.53 mS cm-1at room temperatureas pristine material.Due to the simple tetrahedral SnP4 structure units, Na8SnP4 has potential for optimization through aliovalent substitution as successfully applied in sulfide-based materials. Na8SnP4 is easily accessible from exclusively abundant elements and forms a high- and low-temperature polymorph, which further allows for a fundamental understanding of the structure-property relationship. Both polymorphs are structurally characterized by synchrotron X-ray powder diffraction and MAS-NMR spectroscopy. Ion conductivity and activation energy for ion mobility was determined by temperature dependent impedance spectroscopy and static 23Na-NMR measurements. Both MEM analysis of scattering densities as well as structure determination by Rietveld-methods hint for ionic motion between special Na positions in the structure and that ion migration proceeds along pathways passing triangular faces of neighboring tetrahedral and octahedral voids. The specific voids filling in the disordered HT-phase is found to be a crucial parameter for ion migration.

Sustainable Release of Zincophilic Metal Ions from Separator Proactively Drives Interfacial Stabilization for Durable Zinc Anode

AbstractOne of the important challenges in advancing aqueous zinc‐ion batteries is the separator, which is crucial for promoting stable electrode‐electrolyte interface and energy density of the battery. Herein, this study introduces a metal ion‐activated air‐laid paper (ALP Act) as an alternative for traditional glass fiber separators with big thickness and weight. Notably, the sustainable release of metal ions facilitates in situ interface engineering, thus creating a surface layer with high zinc affinity to promote the uniform migration and deposition of zinc ions. By continuously adjusting the electrode‐electrolyte interface, the behaviors of dendrite growth and side reactions are effectively suppressed. Consequently, the ALP Act with continuous metal‐ion release function enables the zinc anode to attain a 21‐fold increase in running life beyond 3700 h compared with the conventional glass fiber separator at 1 mA cm−2 and l mAh cm−2. The Zn||Cu battery also achieves a remarkable Coulombic efficiency of 99.18% for 2000 h (1 mA cm−2/1 mAh cm−2). The assembled Zn||NVO battery exhibits a lifespan of 3000 cycles for the charge and discharge cycles at 3 A g−1. This research offers a new avenue for the separator to achieve low‐cost, long‐lasting, and energy‐dense aqueous zinc batteries.

Strategies for Stabilizing Metal Halide Perovskite Light-Emitting Diodes: Bulk and Surface Reconstruction of Perovskite Nanocrystals.

Light-emitting colloidal lead halide perovskite nanocrystals (PeNCs) are considered promising candidates for next-generation vivid displays. However, the operational stability of light-emitting diodes (LEDs) based on PeNCs is still lower than those based on polycrystalline perovskite films, which requires an understanding of defect formation in PeNCs, both inside the crystal lattice ("bulk") and at the surface. Meanwhile, uncontrollable ion redistribution and electrochemical reactions under LED operation can be severe, which is also related to the bulk and surface quality of PeNCs, and a well-designed device architecture can boost carrier injection and balance radiative recombination. In this review, we consider bulk and surface reconstruction of PeNCs by enhancing the crystal lattice rigidity and rationally selecting the surface ligands. Degradation pathways of PeNCs under applied voltage are discussed, and strategies are considered to avoid both undesirable ion migration and electrochemical reactions in the PeNC films. Subsequently, other critical issues hindering the commercial application of PeNC LEDs are discussed, including the toxicity of Pb in lead halide perovskites, scale-up deposition of PeNC films, and design of active-matrix prototypes for high-resolution LED modules.

Multisite Cross‐Linked Ligand Suppressing Ion Migration for Efficient and Stable CsPbBr3 Perovskite Quantum Dot‐Based Light‐Emitting Diodes

AbstractPerovskite quantum dots (QDs), as promisingly solution‐processed emitters, have produced impressive external quantum efficiencies (EQEs) in light‐emitting diodes (LEDs). However, the operational stability of perovskite QD‐based LEDs (QLEDs) is still limited by severe ion migration. Here, we propose a multisite cross‐linked ligand strategy using α‐lipoic acid (LA) molecules to simultaneously reduce non‐radiative recombination and suppress ion migration in QLEDs. Meanwhile, the introduction of cross‐linked LA ligands can reduce the roughness and contact potential difference variation of QD films, which facilitates the injection and recombination of carriers in devices. As a result, the colour‐saturated green CsPbBr3‐based QLED deliver a maximum EQE of 25.6 % together with an operational lifetime of 1340 h at an initial luminance of 100 cd m−2, representing the most efficient and stable perovskite LEDs based on cross‐linked QDs. The improvement in device stability is attributed to the reduced ion migration, which is confirmed by analyzing the current behavior of QLEDs and time‐of‐flight secondary‐ion mass spectrometry. This study provides a facile strategy for mitigating halide ion migration in perovskite fields toward more efficient and stable perovskite QLEDs.

Inorganic Halide Perovskite Quantum Dots for Memristors

Abstract Memristor, a combination of memory and resistor, was first proposed as the fourth fundamental passive circuit element. While halide perovskites have emerged as promising materials for memristor devices, organic-inorganic hybrid perovskites face challenges such as hygroscopicity and thermal instability, limiting their long-term applicability. This paper focuses on inorganic halide perovskite quantum dots (IHPQDs), which offer enhanced environmental stability and unique properties, including high tolerance to native defects and ion migration capability. This paper provides a comprehensive review of recent advancements in IHPQDs, covering their crystal structures, synthesis techniques, and operational mechanisms in memristor devices. Unlike previous studies that predominantly explored bulk halide perovskites, we emphasize the role of IHPQDs in resistive switching memory and neuromorphic computing, highlighting their potential for multilevel resistance states and low-power operation. Additionally, this review addresses practical challenges, including thin-film uniformity, charge transport layer integration, and lead-free alternatives, which are critical for the commercialization of IHPQDs-based memristors. By proposing actionable strategies and future research directions, we aim to bridge the gap between fundamental research and real-world applications, positioning IHPQDs as key materials for next-generation electronic devices. Graphical Abstract

Cellulose-based organohydrogels for energy storage achieving high conductivity and wide temperature tolerance from -40°C to 100°C.

Cellulose-based organohydrogels for energy storage achieving high conductivity and wide temperature tolerance from -40°C to 100°C.

High‐ Density Post‐Perovskite for Ultra‐Sensitive Hard X‐ray Detection

The density properties of semiconductors play a crucial role in applications such as radiation detection, electronic devices, and aerospace technologies. However, controlling the density of semiconductors often leads to significant alterations in their electronic structure, which can result in the loss of their original semiconductor properties. Perovskite semiconductors, known for their excellent carrier transport properties, face limitations in hard X‐ray detection due to their relatively low density and loos atomic packing. This study explores a series of post‐perovskite semiconductors with densities exceeding 5 g cm−3, achieved through edge‐ and face‐sharing connectivity of octahedra and strong polarization between metal and chalcogenide ions. These dense materials retain semiconductor properties while exhibiting superior electrical transport characteristics. When applied to hard X‐ray detection, the post‐perovskite materials demonstrated superior attenuation cross‐sections compared to the heaviest 3D CsPbI3 perovskite and 0D Cs3Bi2I9 perovskite. Specifically, the BiCuSCl2 post‐perovskite detector exhibited a high sensitivity of 4126 μC Gyair‐1 cm‐2 and a minimum detection limit of 4.3 nGyair s‐1. The enhanced density also mitigates ionic migration, ensuring excellent electrical stability. These findings underscore the potential of post‐perovskite semiconductors for advanced optoelectronic and radiation detection applications.