Electrode Alignment Research Articles

Growth of Ta-doped SnO2 on GaN as a UV-transparent conducting electrode and band alignment properties of the heterojunction

GaN-based ultraviolet light emitting diodes (UV LEDs) have attracted considerable attention in recent years and are required in various applications such as healthcare, light illumination, and optical communication. However, the limited UV transparency of the electrodes like indium-doped tin oxide has hindered the external quantum efficiency of current UV LEDs. In this work, we present the growth of UV-transparent Ta-doped SnO2 (TTO) thin films on GaN as a promising UV-transparent electrode for LEDs. TTO thin films with a thickness of 200 nm exhibit optical transmission exceeding 80% at the wavelength of 300 nm, with a low resistivity of 2.5 × 10−4 Ω·cm and a low contact resistance of 1.7 × 10−2 Ω cm2 to n-type GaN. High-resolution x-ray photoemission spectra were employed to reveal insight into the electronic structure of TTO and the interfacial band alignment of TTO/GaN heterojunction. The wide optical bandgap (∼4.6 eV) and high UV transparency of TTO films stem from a significant Burstein–Moss shift due to degenerate doping, giving rise to metal-like characteristics and a small barrier height at the interface of TTO/GaN. These findings imply the origin of low contact resistivity of TTO to n-type GaN and may be applicable to the development of UV-transparent electrodes of optoelectronic devices.

Spin Resolved Zero-Line Modes in Minimally Twisted Bilayer Graphene from Exchange Field and Gate Voltage

Abstract The reliance on spin-orbit coupling or strong magnetic fields has always posed significant challenges for the mass production and even laboratory realization of most topological materials. Valley-based topological zero-line modes have attracted widespread attention due to their substantial advantage of being initially realizable with just an external electric field. However, the uncontrollable nature of electrode alignment and precise fabrication has greatly hindered the advancement in this field. By utilizing minimally twisted bilayer graphene and introducing exchange fields from magnetic substrates, we successfully realize a spin-resolved, electrode-free topological zero-line mode. Further integration of electrodes that do not require alignment considerations significantly enhances the tunability of the system’s band structure. Our approach offers a promising new support for the dazzling potential of topological zero-line mode in the realm of low-energy-consumption electronics.

Robust photo-induced pure spin current in graphene–graphane superlattices

The photogalvanic effect has been demonstrated to be an effective method to generate pure spin current. However, obtaining robust pure spin current remains a big challenge as most of the photo-induced pure spin current is dependent on the light polarization/phase angle, photon energies, or the spin alignment of electrodes. In this paper, we present a scheme for obtaining robust pure spin current in zigzag graphene–graphane superlattices (ZGSLs). Through systemic first-principles calculations, we demonstrate that robust generation of pure spin current can occur in ZGSLs with varying widths due to the centrosymmetry of the system's geometric structure and the antiferromagnetic magnetic features. Moreover, the generation of pure spin current does not depend on the photon energy or the polarization/phase angles for both linearly and elliptically polarized light, exhibiting very strong robustness. Our study suggests that ZGSLs could be highly promising candidates for practically realizing pure spin current in spintronics experiments, which presents an avenue for using graphene and its derivatives in advanced electronic devices. Furthermore, considering the experimental advancements in graphene and graphene-like materials, our investigation presents a universally applicable methodology for the generation of robust pure spin currents within low-dimensional graphene-like systems.

Synergistic Enhancement of Efficient Perovskite/Quantum Dot Tandem Solar Cells Based on Transparent Electrode and Band Alignment Engineering

AbstractPerovskite‐based tandem solar cells have demonstrated high potential for overcoming the Shockley–Queisser limit. Routine bandgap (RBG, ≈1.55 eV) perovskites have achieved a perfect balance between efficiency and stability. The narrow bandgap (NBG) candidates for RBG perovskite‐based tandem devices are very limited. Lead sulfide (PbS) colloidal quantum dots (CQDs) are a promising partner due to their broad absorption spectra. However, the efficiency of RBG perovskite/QD tandem devices still lags behind. Herein, efficient RBG perovskite/QDs four‐terminal tandem photovoltaics are successfully implemented through synergistic enhancement from transparent electrode and band alignment Engineering. For tin doped indium oxide (ITO) electrodes, their conductivity and near‐infrared transparency are leveraged using magnetron sputtering and reactive plasma deposition (RPD) methods. Furthermore, instead of traditional zinc oxide, aluminum‐doped zinc oxide (AZO) is developed to enhance the carrier extraction capability of PbS QD bottom cells. Based on the above enhancements, ≈0.95 eV PbS solar cells achieve a record efficiency of 14.14%. Integrated with the front semi‐transparent perovskite solar cells, the four‐terminal perovskite/QD tandem device reaches a record efficiency of 26.12%. The synergistic combination of the RBG perovskite and NBG QD devices provides promising prospects for tandem photovoltaics.

Review of the Design and Operation Criteria of a DC Submerged Arc Discharge Carbon Nanostructure Synthesis Installation

The submerged arc discharge (SAD) allows the production of high-quality carbon nanostructures. The SAD method uses simple and inexpensive equipment. However, the carbon nanostructures obtained contain contaminants that are difficult to remove. The study of the published articles shows that reporting similar operating parameters informs quite different results. Reducing the generation of pollutants requires optimization of the design and the operation of installations. Nevertheless, the study of the state-of-the-art indicates that this aspect has been underestimated, which is manifested in the absence of publications on this subject. On the other hand, the increase in the production scale causes new problems that are not manifested in small-volume productions that are carried out in a research laboratory. The present work aims to analyze the SAD installation design and operation criteria to reduce the presence of contaminants. This study indicated that the key elements of the design and the operation are the electrodes alignment, feeding and attachment mechanisms, the electrode micropositioning system, the synthesis reactor design, the sensitive parameters control, the data acquisition system, and the selection of the liquid medium. Herein, these elements are analyzed and the best strategies for their design and operation are exposed. Those aspects relevant to scaling up of production are emphasized.

Measurement and analysis of arc pressure in two-TIG welding

The distributions of the arc pressure at the anode surface along the directions of the tungsten electrode alignment (x-axis) and that perpendicular to the x-axis (y-axis) in two-TIG welding were measured and analyzed with the aid of the numerical results. The influences of the electrode spacing, the proportion of the current through the electrodes with the same total current, the total current and the arc length on the arc pressure were investigated. The results showed that the two-TIG arc pressure is significantly lower than the single-TIG arc under the same conditions, and the distribution range is noticeably reduced. As the tungsten electrode spacing increases, the arc pressure decreases, and the direction in which the arc pressure distribution extends changes from the x-axis to the y-axis. When the currents through the two tungsten electrodes are different, the arc pressure distribution in the x-axis is not symmetrical but symmetrical in the y-axis. As the current ratio or the total current increases, the maximum arc pressure increases and the deviation of the maximum arc pressure from the central point becomes more pronounced. The arc pressure decreases as the arc length increases, and its distribution range extends more along the y-axis.

Numerical modeling of liquid metal embrittlement initiation during resistance spot welding of third generation advanced high strength steel – Effect of welding schedule and electrode alignment

Third generation (GEN3) advanced high-strength steels are increasingly used to reduce vehicle body structure weight for improved fuel economy. Zinc-induced liquid metal embrittlement (LME) has become a prevalent challenge when these steels are welded by resistance spot welding (RSW). In the literature, various numerical models have been developed to study LME during RSW of GEN3 steels. Those models tend to have a limited utility in predicting how various factors such as RSW parameters affect LME cracking. In this study, a novel LME calculation method has been developed by integrating an electro-thermo-mechanical finite element model of RSW process with an LME ratio for crack initiation established from hot tensile testing data. The onset of different types of LME cracking is tracked throughout the weld region over the entire course of RSW including the final cooling stage after electrode retraction. The model is validated using an existing set of literature data that involves different welding schedules, electrode geometries and electrode misalignments. The local temperature and stress conditions during RSW are calculated and used to understand how different welding parameters affect the severity of LME cracking. It is found that electrode misalignment exacerbates crack initiation on outer surfaces of the spot weld due to the tensile stress arisen from the off-centered squeeze force as well as the reduced surface cooling to electrodes. Initiation of cracks between the steel sheets, taking place mainly after electrode retraction, is not significantly affected by the welding schedule and the electrode tip diameter.

How to Make a Single-Layer Pouch Cell That Matches the Performance of a Commercial Li-Ion Cell

As lithium-ion batteries (LIBs) have exploded in popularity due to the consumer electronics and electric vehicle industries, many resources are poured into research. While the simplest cell format requiring the least amount of active material to make in a research laboratory to study various aspects of the cell is usually the coin cell, it is far from the most representative of commercial LIBs. Oftentimes, coin cells are made with a large negative electrode overhang to reduce the risk from positive/negative electrode misalignment, but the overhang region can cause Li+ to become effectively trapped at higher C-rates1. While this is a necessary trade-off in today’s commercial LIB manufacturing, the overhang area is normally a much smaller fraction of the total negative electrode area in a commercial cell than in a laboratory coin cell, which can lead to discrepancies in cycle testing. Moreover, during assembly of commercial stacked or wound cells, there is always a region in which one side of a double-sided coating, typically the negative, is not needed and thus a single-sided electrode should be used. However, not all manufacturers eliminate the outward-facing second side and elect to simply use double-sided coatings throughout. Therefore, studying the effects of excess electrode in single-layer pouch cells will be explored in this presentation. In this presentation, cells made in various formats (coin and stacked pouch) will be compared to single-layer pouch cells made with and without negative electrode overhang. Single-layer pouch cells are the easiest format for assembling full cells without overhang because they are neither too small nor too big for positive/negative electrode alignment to be difficult. Moreover, single-layer pouch cells made with double-sided coatings (without overhang) and cycled using Ultra-High Precision Coulometry (UHPC) will be shown to have poor cycling. This is for two reasons: 1) for a double-sided negative, the outward-facing coating of the electrode can trap Li+ just like the overhang on the inward-facing coating; and 2) the outward-facing positive can be deintercalated and provide more capacity than desired2, possibly even surpassing the negative/positive areal capacity ratio. Single-layer pouch cells with no overhang are shown in Figure 1a to outperform all other cell formats tested, retaining 90% of their original capacity after 500 cycles at C/3 and 40 °C, and have the lowest difference in capacity between typical C/3 and C/20 checkup cycles as shown in Figure 1b. The stacked pouch cells in Figure 1 are composed of 3 positive and 4 negative electrodes that are all double-sided, meaning there are two outward-facing negative electrode coatings that can trap Li+, possibly resulting in the much poorer capacity fade to 80% after 500 cycles illustrated in Figure 1a. Thus, single-layer pouch cells without overhang give the most realistic cycling results for the tested electrode materials. Figure 1. C/3 cycling of full cells of various formats denoted in the legend. Plotted in (a) is the normalized discharge capacity and (b) is the difference in areal discharge capacity between the C/20 checkup cycle and preceding C/3 cycle. REFERENCES Gyenes, B., Stevens, D.A., Chevrier, V.L., and Dahn, J.R. (2015). Understanding Anomalous Behavior in Coulombic Efficiency Measurements on Li-Ion Batteries. J Electrochem Soc 162, A278–A283. 10.1149/2.0191503jes.Smith, A., Stüble, P., Leuthner, L., Hofmann, A., Jeschull, F., and Mereacre, L. (2023). Potential and Limitations of Research Battery Cell Types for Electrochemical Data Acquisition. Batter Supercaps e202300080. doi.org/10.1002/batt.202300080. Figure 1

Ultrathin, Large‐Area, and Multifunctional Polarizer Based on Highly Ordered Carbon Nanotubes Produced by Simple Shear Flow

AbstractAligning carbon nanotubes (CNTs) with high orientational ordering in a 2D array is essential for realizing optical polarizers with high polarization efficiency over a wide spectral range. Two methods are reported: dispersing CNTs in a polymer matrix followed by stretching, and mechanical stretching of a vertically grown CNT forest and then transferring it onto a substrate. However, neither can realize nanometer‐thin or large polarizers. Herein, a novel approach is demonstrated to construct a large and thin (150 nm) conductive CNT polarizer by achieving liquid crystal (LC) phase of size‐controlled CNTs in chlorosulfonic acid, unidirectional shearing, and then drying. The polarizer exhibits an excellent polarization efficiency of 98.4% for ultraviolet (365 nm) and 96.0% for visible light (550 nm). This performance is maintained even at 400 °C, while the conventional iodine‐type polarizer starts to lose efficiency over 100 °C. The CNT polarizer with high polarization efficiency for UV can replace the costly nano‐patterned wire‐grid polarizers currently used for photoaligning LCs and also its multifunction playing role of polarizer, electrode, and LC alignment is confirmed with switching of LC device. This study provides a new paradigm for realizing ultrathin and large CNT polarizers for broadband applications with outstanding heat resistance.

Real-Time, Non-Invasive Magnetic Field Imaging for Diagnosing Current Flow Patterns inside Fault-Simulated Li-Ion Batteries

With the growing popularity of Li-ion batteries in electric-powered mobility, securing battery safety has become a common goal of the battery community. Battery failures are commonly caused by small, undetectable defects that can form during manufacturing and operation, ranging from materials to the cell level. Although the small errors inside the cells trigger catastrophic failures, tracing them and distinguishing cell failure modes without cell anatomy remains challenging. Given that several defects within the cell could cause abnormal current flow compared to the normal cells, visualization of the current inside the battery is informative to find and trace the invisible defects that cannot be detected using imaging tools for the internal structure of fully packaged commercial cells.This study presents a real-time, non-invasive magnetic field imaging (MFI) method that can signal the magnetic field induced by battery current flow inside the Li-ion pouch cell during cycling (Figure 1). MFI can offer high-speed scanning in a few minutes (~100 mm/min) and spatially high resolution (0.161 mm2) and immediately measure the magnetic field with no need for shielding commonly required for MRI measurement. Based on the Biot-Savart law, we validated magnetic field-current correlation through the MFI of current-carrying 1D straight wires and 2D planes. Then, we found the optimal pouch cell structure for visualizing the current flow patterns using MFI and successfully converted the MFI contour map of the pouch cells into the normalized current distribution. To demonstrate the efficacy of current pattern analysis, we have collected MFI results of fault-simulated batteries (FSBs) to distinguish failure modes that intentionally possess cell manufacturing faults, such as lead-tab contact failure, electrode alignment, and stacking faults. Magnetic field offset using countercurrent-carrying, pouch cell-shaped 2D conductor underneath can selectively detect the failure spots where the current abnormally flows. It is believed that direct visualization of current distribution patterns and figuring out the pattern changes during operation can expedite the non-destructive, immediate diagnosis of commercial cells and troubleshoot safety-related challenges. Figure 1. Single-layer pouch cells and in operando MFI analysis during charging. (a) Scheme for internal structure of single-layer pouch cell (60 × 90 mm2) with counter-side, center-aligned tabs (CS-C cell). (b) Actual image of CS-C cell and MFI scan and applied current directions during the cell charging. MFI mapping images for (c) Bx , (d) By and (e) Bz vector fields at the cell. White arrows within each MFI contour map indicate the current flow prediction. Applying current density: 5.09 mA cm−2, the cell was situated 6 mm below the sensor (z-distance: 2.5 mm, scanned side: Cathode-side up). The total number of scanned data points are 1699 (11 cm) and 64 (16 cm) in y- and x-directions, respectively. Figure 1

Scalable Manufacturing of Large-Area Pressure Sensor Array for Sitting Posture Recognition in Real Time.

Pressure sensors are considered the key technology for potential applications in real-time health monitoring, artificial electronic skins, and human-machine interfaces. Despite the significant progress in developing novel sensitive materials and constructing unique sensor structures, it remains challenging to fabricate large-area pressure sensor arrays due to the involvement of complex procedures including photolithography, laser writing, or coating. Herein, a scalable manufacturing approach for the realization of pressure sensor arrays with substantially enlarged sensitive areas is proposed using a versatile screen-printing technique. A compensation mechanism is introduced into the printing process to ensure the precise alignment of conductive electrodes, insulation layers, and sensitive microstructures with an alignment error of less than 4 μm. The fully screen-printed sensors exhibit excellent collective sensing performance, such as a reasonable pressure sensitivity of -2.2 kPa-1, a fast response time of 40 ms, and superior durability over 3000 consecutive pressures. Additionally, an integrated 16 × 32 pressure sensor array with a sensing area of 190 × 380 mm2 is demonstrated to precisely recognize the sitting postures and the body weights, showing great potential in continuous and real-time health status monitoring.

A Guide to Making Highly Reproducible Li-Ion Single-Layer Pouch Cells for Academic Researchers

With the growing number of academic researchers focused on lithium-ion batteries, the cell format of choice is often overlooked. Coin cells that utilize either a lithium metal or greatly oversized graphite negative electrode are common but can provide unrealistic testing results when compared to commercial pouch-type cells. Instead, single-layer pouch cells provide a more similar format to those used in industry while not requiring large amounts of active material. Moreover, their assembly process allows for better positive/negative electrode alignment, allowing for assembly of single-layer pouch cells without negative electrode overhang. This work presents a comparison between coin, single-layer pouch, and stacked pouch cells, and shows that single-layer pouch cells without overhang perform best. As well, an Ultra-High Precision Coulometry experiment is performed to show that excess negative or positive electrode coating is detrimental to cell performance. Finally, a guide to assembling reproducible single-layer pouch cells without overhang is presented.

Magnetic field considerations for a multi-cell Penning–Malmberg trap for positrons

Multi-cell positron traps have been proposed to accumulate and store large numbers of positrons (e.g. ${\ge }10^{10}$ ). This design arranges lines of Penning–Malmberg traps (‘cells’) on and off the magnetic axis in a vacuum chamber in a common, uniform magnetic field. Confinement considerations impose additional constraints on the magnetic field beyond the usual on-axis homogeneity requirements. These requirements are discussed. A prototype magnetic field and associated coil geometry is suggested to achieve good single-component plasma confinement in all cells. Experimental confinement data as a function of electrode alignment with respect to a nominally uniform magnetic field are also presented. These results are related to the field-alignment considerations of the magnet design study.

Formation of Single‐Chain Anionic Bolaamphiphiles on Indium Tin Oxide Surfaces through Self‐Assembly To Improve Optoelectronic Device Performance

AbstractThe surface of indium tin oxide (ITO) was modified with bolaamphiphilic (BA) materials to tune the energy‐level alignment of electrodes in optoelectronic devices (OEDs). Tuning the energy‐level alignment of the electrode is crucial for enhancing OED efficiency by improving carrier injection. Although the dielectric properties of organic solvents influence the formation of BA self‐assembled monolayers (SAMs), our study found that the intermolecular forces of the dissolved BA materials and the solution medium are more important for the formation of a well‐ordered film on the electrode. Our results also showed efficient tunneling phenomenon between the electrode and the hole transport layer (HTL) using BA material. The holes were transported to the tunnel junctions where the Fermi energy was sufficiently close to the HOMO band of the BA. Therefore, the tunnel barrier height of the ITO/HTL of the OED was reduced, and favorable conditions for hole injection was created, resulting in a 2–3 times increase in luminance and current density. It is believed that the larger area of interface contact between electrode/BA/HTL and the formation of well‐ordered BA layers are responsible for the improved performance of the BA‐modified electrode surface and OED.

Real-Time Condition Monitoring System for Electrode Alignment in Resistance Welding Electrodes.

Electrode misalignment, produced by mechanical fatigue or bad adjustments of the welding gun, leads to an increase in expulsions, deformations and quality problems of the welding joints. Different studies have focused on evaluations of the influence of a misalignment of the electrodes and the final quality of the weld nugget. However, few studies have focused on determining a misalignment of the electrodes to avoid problems caused by this defect, especially in industrial environments. In this paper, a method for performing the condition monitoring of electrode alignment degradation was developed following previous research, which has shown the relationship between the misalignment of short-circuited electrodes and the magnetic field generated by them. This method was carried out by means of a device capable of measuring the magnetic field. Finally, an integral system for the detection of misalignments in real production lines is presented. This system set behavior thresholds based on the experimentation, allowing the condition monitoring of the alignment after each welding cycle.

Electrode Alignment: Ignored but Important Design Parameter in Assembling Coin-Type Full Lithium-Ion Cells

Electrode alignment is one of design parameters that must be carefully controlled for reliable full cells with limited lithium ion inventory. Especially, since punched disk-type cathodes and anodes are movable during assembling coin-type cells, the misalignment of electrodes cannot be completely prevented. Furthermore, this misalignment is not only mixed with other defects but also sometimes leads to better electrochemical characteristics. To systematically unveil this ignored but important parameter, herein, we fabricate coin-type LiNi0.6Mn0.2Co0.2O2/graphite full cells with different electrode alignments and evaluate them to figure out any noticeable changes in their electrochemical properties. As frequently reported, the misaligned cell shows lower specific discharge capacity and initial coulombic efficiency than the well-aligned one due to an irreversible Li plating on the coin cell bottom during the first charging process. However, we have not recognized the misaligned cell can exhibit a smaller low-frequency semicircle in the AC impedance spectra and lower DC-IRs at lowly charged states than those of the well-aligned cell because of the less lithiated state of the misaligned cathode. Thus, to exclude data from misaligned full cells, it is necessary to verify the electrode alignment even after the cell evaluation process.

Spatially Resolved Operando Synchrotron-Based X-Ray Diffraction Measurements of Ni-Rich Cathodes for Li-Ion Batteries

Understanding the performance of commercially relevant cathode materials for lithium-ion (Li-ion) batteries is vital to realize the potential of high-capacity materials for automotive applications. Of particular interest is the spatial variation of crystallographic behavior across (what can be) highly inhomogeneous electrodes. In this work, a high-resolution X-ray diffraction technique was used to obtain operando transmission measurements of Li-ion pouch cells to measure the spatial variances in the cell during electrochemical cycling. Through spatially resolved investigations of the crystallographic structures, the distribution of states of charge has been elucidated. A larger portion of the charging is accounted for by the central parts, with the edges and corners delithiating to a lesser extent for a given average electrode voltage. The cells were cycled to different upper cutoff voltages (4.2 and 4.3 V vs. graphite) and C-rates (0.5, 1, and 3C) to study the effect on the structure of the NMC811 cathode. By combining this rapid data collection method with a detailed Rietveld refinement of degraded NMC811, the spatial dependence of the degradation caused by long-term cycling (900 cycles) has also been shown. The variance shown in the pristine measurements is exaggerated in the aged cells with the edges and corners offering an even lower percentage of the charge. Measurements collected at the very edge of the cell have also highlighted the importance of electrode alignment, with a misalignment of less than 0.5 mm leading to significantly reduced electrochemical activity in that area.

Integrated Electro-Optic Modulator in Z-Cut Lithium Niobate Thin Film With Vertical Structure

We propose and demonstrate a Mach-Zehnder modulator in Z-cut lithium niobate thin film (LNTF) with a vertical electric field structure. By placing the metal electrodes on top and bottom of the waveguide rather than the usual lateral configuration, the electric field is fully overlapping the optical field. Such a configuration reduces the critical requirement of electrode alignment as needed in X/Y-cut LN based devices. Both the simulation and process details to realize the proposed device are demonstrated. The measured static performance accords well with the simulations. Additionally, we developed a new method to accurately characterize the dynamic performance of the Z-cut LNTF modulator, and the measured tuning efficiency is around 8.84 pm/V. Our proposed device validates the feasibility of integrated Z-cut LNTF based modulators, and will likely extend the research area of integrated lithium niobate photonics.

Cell Design Consideration Concerning Cell Failure Mechanism

Thermal swelling and dimension-changing properties of the LiB (Lithium-ion battery) cell during the cycle (charging/discharging) and aging are well-known LiB's intrinsic characteristics. These inherent properties are caused by expansion/contraction of electrode materials due to lithium-ion intercalation, irreversible reaction deposits changing/increasing the volume, and the cell internal pressure changes by decomposition and gas generation. The cell designer's fundamental phenomena should be fully understood and implicated in the cell design and manufacturing process. As the LiB energy density increases, the safety zone/concept of a cell model considering LiB's natural phenomena is getting diminished and minimized.This paper analyzed the effect of the thermal swelling and dimension-changing properties of LiB cell on cell safety and studied the cell safety mechanism related to the cell design, considering the thermal swelling and dimension-changing properties of LiB cell. We used the electrode alignment and overhang of the electrode assembly (the gaps between the end of the separator and the end of the anode, and between the end of the anode and end of the cathode). Some cell models increased their energy density by sacrificing their safety zone, minimizing the gaps among separator – anode - cathode.We analyzed the relationship between the electrode alignment and overhang of the electrode assembly and the battery safety. We measured the electrode alignment and gaps among separator-anode-cathode with the microscope measurement technology and applied the electrical, thermal, and mechanical trigger factors to the cell models.Experimental results identified that the status of the electrode alignment and gaps among separator-anode-cathode effect to the cell safety for all the tests of the electrical, thermal, and mechanical trigger factors. We develop and propose a cell safety mechanism from the relationship between the electrode alignment and gaps among separator-anode-cathode and the cell safety. Figure 1

Cell Supply Chain Management with Approval and Surveillance Program

Although many battery safety standards and certifications are in place to minimize hazards or prevent safety-related incidents in the field, many publicized field incidents have increased public concerns about LiB safety. Most battery field incidents reported that the cell internal short circuit initiated the causes, and many experts blamed battery industries do not have the test system that can predict the field incident nor reflect how the incidents occur. The certification is required when a cell model is developed and just before that goes into the market.Some intended or unintended modifications are in the cell model after the model is certified, and some failure analysis reports blame unknown and unproven changes on the cell model were the root causes of the incidents.To eliminate and prevent the root causes of battery field incidents by unknown and unproven changes on the cell model, we developed a verification process named cell supply chain management with approval and surveillance program. The verification process makes a technical database of all the analysis and test results of each step of a cell model as its fingerprint. The database enables the process can identify and prevent any unknown and unproven changes in the cell model through its life span.The verification process has: 1) Cell electrical properties, 2) X-ray investigation and Destructive Physical Analysis with -electrode alignment check with overhang gap, - electrode assembly (Jelly roll) function and dimension measurement, - insulation mechanism check and measurement, 3) Electrode dimension measurement and composition and materials analysis, and 4) Electrolyte composition analysis.This paper explains and proposes the concept and analysis method of each verification process and validates the cell model verification process by comparing the analysis results of each step of a cell model manufacturing. Figure 1