Ion Path Research Articles

Micro Reference Electrode with an Ultrathin Ionic Path.

Reference electrode (RE) plays the core role in accurate potential control in electrochemistry. However, nanoresolved electrochemical characterization techniques still suffer from unstable potential control of pseudo-REs, because the commercial RE is too large to be used in the tiny electrochemical cell, and thus only pseudo-RE can be used. Therefore, microsized RE with a stable potential is urgently required to push the nanoresolved electrochemical measurements to a new level of accuracy and precision, but it is quite challenging to reproducibly fabricate such a micro RE until now. Here, we revisited the working mechanism of the metal-junction RE and clearly revealed the role of the ionic path between the metal wire and the borosilicate glass capillary to maintain a stable potential of RE. Based on this understanding, we developed a method to fabricate micro ultrastable-RE, where a reproducible ultrathin ionic path can form by dissolving a sandwiched sacrificial layer between the Pt wire and the capillary for the ion transfer. The potential of this new micro RE was almost the same as that of the commercial Ag/AgCl electrode, while the size is much smaller. Different from commercial REs that must be stored in the inner electrolyte, the new RE could be directly stored in air for more than one year without potential drift. Eventually, we successfully applied the micro RE in the electrochemical tip-enhanced Raman spectroscopy (EC-TERS) measurement to precisely control the potential of the working electrode, which makes it possible to compare the results from different laboratories and techniques to better understand the electrochemical interface at the nanoscale.

Biomass-based three-dimensional network porous carbon anodes derived from discontinuous activation for high performance Li-ion batteries

An approach of discontinuous activation and frozon-dry pretreatment toward a three-dimensional network porous carbon was proposed by using apple as the carbon source. The porous carbon, characterized by its high surface area and abundant porosity, was optimized through the manipulation of temperature and activator quantities during the activation process. The sample obtained by first calcining at 500 °C and then at 800 °C shows ultra-high rate electrochemical performance of over 900 mA h g−1 after 100 cycles and over 500 mA h g−1 after 500 cycles under the condition of charging and discharging current density of 0.2 A g−1 due to the high porosity. It is ascribed to the unique porous structure that can make the electrolyte and lithium ion transport and path short on the surface and inside the electrode material, further enhance its fast transport ability. The described approach represents an innovative and potentially impactful method for producing porous carbon electrodes with excellent electrochemical performance, particularly in the context of high-rate capability lithium-ion batteries.

Creating ionic current pathways: A non-implantation approach to achieving cortical electrical signals for brain-computer interface

This study introduces a novel method for acquiring brain electrical signals comparable to intracranial recordings without the health risks associated with implanted electrodes. We developed a technique using ultrasonic tools to create micro-holes in the skull and insert hollow implants, preventing natural healing. This approach establishes an artificial ionic current path (AICP) using tissue fluid, facilitating signal transmission from the cortex to the scalp surface. Experiments were conducted on pigs to validate the method's effectiveness. We synchronized our recordings with perforated electrocorticography (ECoG) for comparison. The AICP method yielded signal quality comparable to implanted ECoG in the low-frequency range, with a significant improvement in signal-to-noise ratio for evoked potentials. Our results demonstrate that this non-invasive technique can acquire high-quality brain signals, offering potential applications in neurophysiology, clinical research, and brain-computer interfaces. This innovative approach of utilizing tissue fluid as a natural conduction path opens new avenues for brain signal acquisition and analysis.

Unveiling crystal orientation-dependent interface property in composite cathodes for solid-state batteries by in situ microscopic probe

A critical bottleneck toward all-solid-state batteries lies in how the solid(electrode)-solid(electrolyte) interface is fabricated and maintained over repeated cycles. Conventional composite cathodes, with crystallographically distinct electrode/electrolyte interfaces of random particles, create complexities with varying (electro)chemical compatibilities. To address this, we employ an epitaxial model system where the crystal orientations of cathode and solid electrolyte are precisely controlled, and probe the interfaces in real-time during co-sintering by in situ electron microscopy. The interfacial reaction is highly dependent on crystal orientation/alignment, especially the availability of open ion channels. Interfaces bearing open ion paths of NCM are more susceptible to interdiffusion, but stabilize with the early formed passivation layer. Conversely, interfaces with closed ion pathway exhibit stability at intermediate temperatures, but deteriorate rapidly at high temperature due to oxygen evolution, increasing interfacial resistance. The elucidation of these distinct interfacial behaviors emphasizes the need for decoupling collective interfacial properties to enable rational design in solid-state batteries.

Combining Enhanced Resolving Power with Duty Cycle Improvements on a Multi-Reflecting Time-of-Flight Mass Spectrometer.

The combination of enhanced resolving power and improved duty cycle on a multireflecting time-of-flight mass spectrometer is described. Resolving power increases are achieved by extending the effective ion path length from 47 m to greater than 200 m. Path length increases are achieved through containment of ions within the analyzer for up to N = 5 passes using a pulsed deflection electrode. Resolving power was shown to increase from 220,000 to 402,000 (fwhm) at m/z 785 for N = 1 and N = 4 analyzer passes, respectively. Due to the timing of the pulsed deflection electrode, the approach is particularly suited to high resolution analysis over a targeted m/z range. Duty cycle enhancements are achieved for ions of the targeted m/z range via accumulation prior to orthogonal acceleration, providing signal improvements of 2 orders of magnitude. Achieving such high resolving powers at fast scan rates (30 Hz) can yield additional information such as fine isotope structure; when combined with ppb mass measurement accuracy, high confidence in analyte identification can be achieved. The technique is applied for N = 2 analyzer passes, demonstrating fine isotope structure for a typical UHPLC metabolite identification experiment at a 10 Hz acquisition rate. Additionally, mass spectrometry imaging data is acquired using DESI, demonstrating the improved image clarity achieved at >300,000 (fwhm).

Fluorinated Hollow Porous Carbon Spheres as High-Performance Cathode Material for Primary Battery

Fluorinated carbon cathode materials have extremely high theoretical specific energy among known cathode materials of lithium primary batteries. Nevertheless, current fluorinated carbon cannot meet the performance demands of future applications due to the rate performance. This work innovatively applies hollow carbon spheres with a porous structure as carbon sources to prepare fluorinated hollow porous carbon spheres (FHPCS) with high energy density and power density. The porous structure provides more reaction sites for the fluorination process and also shortens the diffusion path of lithium ions during the discharge. Additionally, the hollow porous structure offers more interfacial contact areas and reduces volumetric expansion during discharge reactions. The Li/CFx primary battery has a maximum specific energy of 2007 Wh kg−1 and a maximum power density of 30,400 W kg−1 and can have a capacity retention rate of 80.8% at a current density of 16 A g−1. In addition, FHPCS also has the highest specific energy of 1999 Wh kg−1 and 1711 Wh kg−1 in Na/CFx and K/CFx primary batteries, respectively. The diffusion efficiency of an alkali metal ion is analyzed by the different discharge depths with electrochemical impedance spectroscopy and galvanostatic intermittent titration technique. This effort introduces a new high-performance fluorinated carbon featuring a hollow porous structure and puts forward an innovative approach to designing fluorinated carbon materials.

Multifunctional organic-inorganic hybrid coating for enhanced bronze corrosion protection

Bronze relics with vital historical, artistic, and scientific value, are one of the significant symbolizations of human civilization. However, due to the long burial time and the change in storage conditions, an inevitable and thorny problem arises in preventing the ancient bronze relics from corrosion. Coatings have great potential for metal corrosion protection at present. This study prepared a multifunctional coating consisting of zinc oxide (ZnO), titanium dioxide (TiO2), and fluoroethylene vinyl ether (FEVE) polymer by an organic-inorganic hybrid, which was applied onto the surface of corroded bronze using a self-assembly method and spraying. The rough structure of composite coating resembling that of the mastoid structure found on lotus leaf, effectively prolongs the transmission path of corrosive ions while preventing bronze contact with the corrosive media. Additionally, this study mainly investigated the bronze anti-corrosion mechanism through an electrochemical analysis perspective. Electrochemical tests revealed the lower corrosion current density, and the positive corrosion potential of multifunctional FEVE@ZnO/TiO2 coating immersion in 3.5 wt% NaCl solution. The experimental results demonstrate that the synergistic effect of organic-inorganic significantly enhances corrosion resistance by retarding the corrosion process and providing active protection against corrosion. The multifunctional coating also exhibits exceptional self-cleaning properties and weatherability when without changing the bronze color and appearance. Consequently, this preparation strategy and research approach for constructing a multifunction coating has a great application prospect in the conservation of bronze relics and metal anti-corrosion.

Si particle size blends to improve cycling performance as negative electrode for all-solid-state lithium-ion battery

Silicon negative electrodes dramatically increase the energy density of lithium-ion batteries (LIBs), but there are still many challenges in their practical application due to the limited cycle performance of conventional liquid electrolyte systems. In this study, we clarified that the use of an inorganic solid electrolyte improves the cycle performance of the LIB with the Si negative electrode and the size of Si particles influenced the properties of the all-solid-state LIB. The all-solid-state LIB using micro-sized silicon (mSi) particles as the negative electrode active material showed a large initial discharge capacity (2400 mAh g-1), but the discharge capacity decreased as charge/discharge cycles increased. In contrast, the all-solid-state LIB using nano-sized silicon (nSi) particles showed a low initial discharge capacity (1000 mAh g-1), but the discharge capacity increased for the initial 20 charge/discharge cycles. The cross-sectional images analyzed by scanning electron microscopy showed that for mSi particles, cracks and voids occurred due to volumetric changes during charging and discharging, interrupting the flow path of ions and electrons, whereas for nSi particles, the contact with the solid electrolyte and conductive material was improved. Moreover, the all-solid-state LIB using the negative electrode of nSi: mSi = 7: 3 (mass ratio) showed higher initial discharge capacity and longer cycle performance than that using mSi and nSi.

Fabrication of RuO2-graphene/graphene thick-and-dense micro-hole array material by femtosecond laser for high volumetric rate performance

Nanostructured materials have a great application prospect in the next generation of electrochemical energy storage devices. However, there is a great obstacle for thick and dense electrodes with large tortuosity to simultaneously attain high areal and rate performance at the same time to meet the practical requirements. Herein, a simple electrostatic self-assembly method is adopted to anchor RuO2 onto graphene nanoflakes, the thick and dense film of RuO2-Graphene/Graphene(RuO2-G G-1) are prepared by filtration and mechanical compression, and then the micro-hole array structure was fabricated by femtosecond laser drilling, which shortened the diffusion path of hydrogen ion (H+). After etching, the pore diameter is 7 μm; the pore spacing is 40 μm and the array was regular. The mass loss of the electrode caused by etching was only 3 %, and the relative density of the electrode reached 79 %. Under the same thickness of the electrode, the pore electrode obviously reduces the ion resistance. The micro-hole array not only improves the areal and volumetric capacity of the RuO2-G G-1 electrode, but also improves the rate performance of the electrode., the rate capability increased from 65.6 % to 87.7 % at 20 A g-1. The study provides a powerful technique for the fabrication of dense and thick electrode in energy storage system.

Synergistic effects of multi-dimensionality in an aerogel for lithium-ion battery anodes with an enhanced capacitive contribution

The rational design of anode materials is important when seeking to produce high-performance lithium-ion batteries (LIBs) that offer both a high-power density (P) and a high energy density (ε). In this study, a multi-dimensional aerogel composed of 1-dimensional (1D) and two-dimensional (2D) nanostructures was synthesized. To impart conductivity and dimensional diversity, reduced graphene oxide (rGO) nanoplates were introduced to a 1D Co-S aerogel using a metal coordination-assisted sol–gel method. As the anode material for an LIB, the resulting multi-dimensional rGO@Co-S aerogel with 1.4 wt% GO exhibited outstanding electrochemical performance, with a high specific capacity, high-rate capability, strong cycling stability (84 % at 0.5 A/g after 350 cycles), an excellent P (9,660 W/kg), and a high ε (1,566 Wh/kg). This was attributed to the shorter ion and electron diffusion paths arising from the multi-dimensional structure, coupled with the higher surface area and enhanced capacitive contribution due to the addition of the rGO nanoplates.

The OrbiTOF mass analyzer: Time-of-flight analysis via an orbitrap quadro-logarithmic field with periodic drift focusing

Thermo Scientific™ Orbitrap™ analyzers represent a prominent class of high-resolution mass analyzer commonly used in life sciences, and for interrogation of complex samples. Injected ions, trapped within a quadro-logarithmic field, orbit a central electrode and oscillate up and down the axis. A new class of multi-reflection time-of-flight mass analyzer has been developed based on the Orbitrap field structure plus an additional series of periodic lenses wrapped around the central axis to constrain beam dispersion. The axial and angular velocity of the injected ions was balanced so that with each axial oscillation, the ions passed through the next lens in the series, to form a tightly folded 25-m long, 3-dimensional ion path, ending with ions striking a detector surface.Performance was interrogated via experiment and simulation. 70k resolving power was observed within the relatively compact analyzer, albeit at cost to transmission. A larger design with an integrated extraction trap and greater flight energy is discussed.

A High Dynamic Range Ion Detector for Multireflection Time-of-Flight Analyzers.

Reflectron-based time-of-flight analyzers rely on subnanosecond detector time response to achieve acceptable resolving power for low-mid-mass, multiple-ion peaks. With the adoption of multireflection analyzers, order of magnitude longer folded ion paths relax restrictions on detector response time, allowing implementation of new technologies that greatly improve dynamic range, detector lifetime, and ion detection efficiency. A detection system is presented, integrated into a multireflection analyzer, that combines 10 keV postacceleration and focal plane correction with a unique BxE focusing, optically coupled detector, preamplification, and dual-channel digitization. Calibration and peak-handling methods are also described. The instrument demonstrated >1 × 104 dynamic range in a single shot, > 100k resolving power, and a relative immunity to detector aging.

Energy-Resolving Time-of-Flight Mass Spectrometry for Bulk Plasma Analysis.

This work presents a newly designed energy-resolving time-of-flight mass spectrometer (E-TOFMS) for analysing the energy and mass of ions in bulk plasma. The system comprises an electrostatic sector analyser (ESA) for energy-to-charge (E/Q) ratio resolution and an orthogonal reflectron TOFMS for mass-to-charge (m/Q) ratio analysis. The design choices are explained, providing insight into electron and ion path simulations. The instrument was characterised using various ion generation sources, including an electron impact ion source, high power impulse magnetron sputtering, and microwave plasma electron cyclotron resonance sources. To validate its functionality, the energy-resolving data was compared with data obtained under the same conditions using a Langmuir probe and a retarding field energy analyser (RFEA). The benefits of the proposed E-TOFMS were demonstrated by sputtering highly alloyed steel with multiple isotope-rich elements, such as Mo or W. This technique offers an E/Q ratio resolution of up to 0.15 V for a range up to 125 V and a m/Q ratio resolution of at least 700 Th for a range up to 250 Th, with a temporal resolution of 10 μs.

Metal-Organic Framework-Derived Co9S8 Nanowall Array Embellished Polypropylene Separator for Dendrite-Free Lithium Metal Anodes.

Developing a reasonable design of a lithiophilic artificial solid electrolyte interphase (SEI) to induce the uniform deposition of Li+ ions and improve the Coulombic efficiency and energy density of batteries is a key task for the development of high-performance lithium metal anodes. Herein, a high-performance separator for lithium metal anodes was designed by the in situ growth of a metal-organic framework (MOF)-derived transition metal sulfide array as an artificial SEI on polypropylene separators (denoted as Co9S8-PP). The high ionic conductivity and excellent morphology provided a convenient transport path and fast charge transfer kinetics for lithium ions. The experimental data illustrate that, compared with commercial polypropylene separators, the Li//Cu half-cell with a Co9S8-PP separator can be cycled stably for 2000 h at 1 mA cm-2 and 1 mAh cm-2. Meanwhile, a Li//LiFePO4 full cell with a Co9S8-PP separator exhibits ultra-long cycle stability at 0.2 C with an initial capacity of 148 mAh g-1 and maintains 74% capacity after 1000 cycles. This work provides some new strategies for using transition metal sulfides to induce the uniform deposition of lithium ions to create high-performance lithium metal batteries.

Lateral 1200V SiC schottky barrier diode with single event burnout tolerance

For a power device to be used in space, it must be able to recover from a single event effect caused by heavy ion radiation. Conventional vertical silicon carbide (SiC) power devices such as automotive diodes and MOSFETs, can only meet this requirement if they are heavily derated, a 1200 V device typically unusable above 200 V. In this paper, a lateral RESURF Schottky diode has been designed in TCAD simulation using a radiation-hard (rad-hard) by design methodology. By preventing anode-to-cathode shorting that occurs in a vertical drift region, the lateral design is shown to recover after a heavy ion traverses the device with a linear energy transfer (LET) of 60 MeV·cm2/mg, while the device is blocking 1200 V. The design splits the drift region into a higher doping zone closer to the cathode (Zone 2) of 1.5×1017 cm−3 and a lower doping zone closer to the anode (Zone 1) of 1×1016 cm−3. The electric field spikes were reduced while the device was recovering. This design keeps the local temperature in the device to under 1000 K if the heavy ion penetrates the device in a direction perpendicular to the surface. Other entry positions and directions are also simulated and a maximum temperature of 1733 K occurs when the ion path is horizontal, entering at 1 μm below the surface. However, this temperature peak occurs at the cathode, which is not expected to lead to lasting leakage damage. A deep P+ pillar embedded into the anode acts as a collector for holes generated during the single event. Simulations show that a deeper P+ pillar, to a depth of up to 5 μm, reduces the hole density in the N-drift region and P-epi layer during recovery. This also allows the Zone 1 doping to be increased to as much as 5×1016 cm−3, thereby reducing on-state losses.

Plural molecular and cellular mechanisms of pore domain KCNQ2 encephalopathy.

KCNQ2 variants in children with neurodevelopmental impairment are difficult to assess due to their heterogeneity and unclear pathogenic mechanisms. We describe a child with neonatal-onset epilepsy, developmental impairment of intermediate severity, and KCNQ2 G256W heterozygosity. Analyzing prior KCNQ2 channel cryoelectron microscopy models revealed G256 as a node of an arch-shaped non-covalent bond network linking S5, the pore turret, and the ion path. Co-expression with G256W dominantly suppressed conduction by wild-type subunits in heterologous cells. Ezogabine partly reversed this suppression. G256W/+ mice have epilepsy leading to premature deaths. Hippocampal CA1 pyramidal cells from G256W/+ brain slices showed hyperexcitability. G256W/+ pyramidal cell KCNQ2 and KCNQ3 immunolabeling was significantly shifted from axon initial segments to neuronal somata. Despite normal mRNA levels, G256W/+ mouse KCNQ2 protein levels were reduced by about 50%. Our findings indicate that G256W pathogenicity results from multiplicative effects, including reductions in intrinsic conduction, subcellular targeting, and protein stability. These studies provide evidence for an unexpected and novel role for the KCNQ2 pore turret and introduce a valid animal model of KCNQ2 encephalopathy. Our results, spanning structure to behavior, may be broadly applicable because the majority of KCNQ2 encephalopathy patients share variants near the selectivity filter.

Synergistic enhancement of electric double layers and faradaic reactions in capacitive deionization: The role of NTP@C composite

Capacitive Deionization (CDI) has received attention for its energy efficiency and minimal environmental impact, but it faces practical limitations due to the constrained desalination capacity of conventional systems. Our study addresses this challenge by introducing a novel electrode material, NaTi2(PO4)3 (NTP) coated with interconnected mesoporous carbon (NTP@C). This innovative material leverages the synergistic effects of electric double layers and faradic reaction conversion faradic. Unlike traditional carbon coating, our new strategy significantly changes the shape of NTP from coral to ellipse, significantly shortening the diffusion path of sodium ions (Na+), thus accelerating the mass transfer kinetics. Comprehensive morphological, structural, and electrochemical analyses reveal that NTP@C outperforms traditional electrodes in terms of electrochemical stability, ion transmission rates, and desalination capacity. At 1.8 V and 3 g/L NaCl concentration, NTP@C achieves a remarkable salt adsorption capacity of 233.07 mg g−1, with a desalination capacity growth rate of 188 % between 1.4 V and 1.6 V—surpassing the 159 % growth rate of NTP. Additionally, NTP@C exhibits higher cycle performance, maintaining 89.42 % stability over 50 cycles compared to NTP’s 74.39 %. The innovative carbon coating technique prevents NTP particle agglomeration, enhances conductivity, and increases the specific surface area, culminating in a unique interconnected and wrapped carbon structure. This results in an exceptional synergy between the electric double layer and faradic reaction conversion faradic, propelling NTP@C to outstanding desalination performance and cycle stability.

Experimental and numerical studies on the chloride diffusion coefficient of calcium silicate hydrate gel

The chloride diffusivity of calcium silicate hydrate (C-S-H), as the main hydration product of cement paste, plays an important role for the durability of concrete structures, especially for low w/c ratio ones. In this paper, in order to measure the chloride diffusion coefficient of C-S-H, a diffusion path conversion method is proposed to convert the primary diffusion path of ions from capillary pores to gel pores. By combining diffusion path conversion method with steady-state migration test, the diffusion coefficients of C-S-H are obtained. Based on 3D nanostructure, which is generated by a hybrid scheme of Grand Canonical Monte Carlo and Molecular Dynamics, the chloride diffusion coefficient of C-S-H is predicted by a 3D diffusive lattice modelling. Results from the experiments and simulation are compared with the data in the literature. Our work contributes to the understanding of C-S-H diffusivity and is of great importance for predicting the long-term durability of concrete structure.

T‐Nb2O5 Surface Coating Enables a Stable Zinc Anode

The surface reactions of zinc anode, including dendrite formation, corrosion, and passivation, hinder the aqueous zinc‐ion batteries. Surface engineering is one effective strategy for zinc protection. Herein, a high dielectric constant and stable and easily prepared T‐Nb2O5 first demonstrate as the surface coating for zinc anode. The hydrophilic T‐Nb2O5 coating can restrict the migration path of zinc ions and induce the bottom‐up orderly deposition of zinc ions instead of disordered deposition. The T‐Nb2O5 coating zinc anode (T‐Nb2O5/Zn) shows improved electrochemical performance. The voltage of T‐Nb2O5/Zn symmetric cell is stable in the long cycle of 1600 h and about 50 mV in the first 20 h and 25 mV in the last 20 h. After 150 cycles, the discharge capacity of T‐Nb2O5/Zn || MnO2 full battery is 209 mAh g−1, showing a capacity retention rate of 94%. The design of T‐Nb2O5 coating provides an attractive strategy for stable and reversible aqueous zinc metal batteries.

Preparation and Evaluation of PVDF-HFP-Based Gel Electrolyte for Ge-Sensitized Thermal Cell.

The semiconductor-sensitized thermal cell (STC) is a new thermoelectric conversion technology. The development of nonliquid electrolytes is the top priority for the practical application of the STC. In this study, a novel gel polymer electrolyte (PH-based GPE) composed of poly(vinylidenefluoride-co-hexafluoropropylene) (PH), 1-Methyl-2-pyrrolidone (NMP), and Cu ions was synthesized and applied to the STC system. The PH-based GPE synthesized at 45 °C showed higher open-circuit voltage (-0.3 V), short-circuit current density (59 μA cm-2) and diffusion coefficient (7.82 × 10-12 m2 s-1), indicating that a well-balanced structure among the NMP molecules was formed to generate a high-efficiency conduction path of the Cu ions. Moreover, the ion diffusion lengths decreased with decreasing content rates of NMP for the PH-based GPEs, indicating that the NMP plays an important role in the diffusion of Cu ions. Furthermore, the activation energy was calculated to be 107 kJ mol-1, and that was smaller compared to 150 kJ mol-1 for the poly(ethylene glycol)-based liquid electrolyte. These results play an important reference role in the development of electrolytes for STC systems. At the same time, they also provide a new avenue and reference indicator for the synthesis of high-performance and safe GPEs.