High Voltage Research Articles

Machine learning assisted optical diagnostics on a cylindrical surface dielectric barrier discharge

Abstract The present study explores combining machine learning (ML) algorithms with standard optical diagnostics (such as time–integrated emission spectroscopy and imaging) to accurately predict operating conditions and assess the emission uniformity of a cylindrical surface Dielectric Barrier Discharge (SDBD). It is demonstrated that these optical diagnostics can provide the input data for ML which identifies peculiarities associated with the discharge emission pattern at different high voltage waveforms (AC and pulsed) and amplitudes. By employing unsupervised (Principal Component Analysis (PCA)) and supervised (Multilayer Perceptron (MLP) neural networks) algorithms, the applied voltage waveform and amplitude are categorised and predicted based on correlations/differences identified within large amounts of corresponding data. PCA allowed us to effectively visualise patterns related to the voltage waveforms and amplitudes applied to the SDBD through a transformation of the spectroscopic/imaging data into principal components (PCs) and their projection to a two-dimensional PCs vector space. Furthermore, an accurate prediction of the voltage amplitude is achieved using the MLP which is trained with PCs. A particularly interesting aspect of this concept involves examining the uniformity of the emission pattern of the discharge. This was achieved by analysing spectroscopic data recorded at four different regions around the SDBD surface using the two ML algorithms. These discoveries are instrumental in enhancing plasma–induced processes. They open up new avenues for real–time control, monitoring, and optimization of plasma–based applications across diverse fields such as flow control for the present SDBD.

An Improved Cascaded Boost Converter with an Ultra-High Voltage Gain Suitable for Dielectric Quality Tests

Dielectric quality tests require a high AC voltage with a frequency range of 0.0001 Hz to 1000 Hz. However, providing a high AC voltage with such a frequency variety is challenging. Providing a high DC voltage and then applying such a voltage to an inverter to adjust the frequency can be an acceptable solution for such a challenge. Notably, a high DC voltage is required for DC tests. This study proposes an improved form of the cascaded boost converter, whose merits are as follows: (i) the high voltage gain providing low duty cycles is possible; (ii) the input current is continuous, which decreases the current ripple of the input filter capacitor; (iii) the current stress of the semiconductors is less than the input current, and most of them have a large difference with it; (iv) the voltage stress of the semiconductors is less than the output voltage with a large difference; (v) only one switch with a simple drive circuit is used; (vi) the common ground of the load and input source decreases the EMI noise; (vii) besides the high voltage gain, the voltage density of the converter based on the number of inductors, capacitors, switches, diodes, and whole components is greater than that of the recently proposed converters; (viii) only two stacked connections of the proposed topology can provide a 2.6 kV voltage for a higher DC voltage test of dielectrics. The functional details of the converter are extracted in ideal and continuous conduction (CCM) modes. Moreover, the converter’s voltage gain and density are compared with the recently proposed converters to show the superiority of the proposed converter. Finally, the experimental results are presented to validate the theoretical relations in a 140 W output power.

Nonsolvating Fluoroaromatic Cosolvent Enabled Long-Term Cycling of High-Voltage Lithium-Ion Batteries with Organosulfur Electrolytes.

The structure-activity relationships of nonsolvating cosolvents for organosulfur-based electrolyte systems were revealed. The performance of nonsolvating dilutant fluorobenzene (FB) was compared to various fluorinated ether dilutants in high-voltage electrolytes containing a concentration of 1.2 M LiPF6 dissolved in fluoroethylene carbonate (FEC), ethyl methyl sulfone (EMS), and the dilutant. In a high-voltage and high-loading LiNi0.8Mn0.1Co0.1O2 (NMC811) full cell configuration, the organosulfur-based electrolyte containing FB dilutant enabled superior electrochemical performance compared to the electrolytes using other nonsolvating fluorinated ether formulations. Moreover, the FB-containing electrolyte exhibited the highest ionic conductivity and lowest viscosity among all organosulfur-based electrolytes containing nonsolvating dilutant. These improvements are attributed to the enhanced physical properties of electrolyte and lithium-ion mobility. Furthermore, by employing first-principles simulations, the observed suppression of side reactions at high voltage is linked to FB's lower reactivity toward singlet dioxygen, which is likely produced at the NMC interface. Overall, FB is considered an excellent diluent that does not impede cell operation by mass decomposition at the cathode.

Construction of Sulfone‐Based Polymer Electrolyte Interface Enables the High Cyclic Stability of 4.6 V LiCoO2 Cathode by In Situ Polymerization

AbstractLithium cobalt oxide (LiCoO2) is considered an indispensable cathode material in the realm of consumer electronic batteries due to its high volumetric energy density. However, at a charging cut‐off voltage as high as 4.6 V, significant interfacial side reactions between LiCoO2 and the electrolyte occur, which adversely impact the battery's cycle performance. The surface‐related issues of LiCoO2 at high charge voltages not only constrain its utilization in conventional lithium‐ion batteries with liquid electrolytes but also limit its application in solid‐state batteries. Although traditional coating methods using inert inorganic compounds can partially alleviate this issue, their point‐like coatings fail to completely prevent the surface of LiCoO2 from direct contact with the electrolyte. The exploration of novel surface protection strategies for LiCoO2 remains imperative to address the associated challenges. Herein, introducing a sulfone‐based polymer electrolyte interface is proposed on the surface of LiCoO2 using methyl vinyl sulfone (MVS) through in situ polymerization. Remarkably, LiCoO2 with sulfone‐based polymer electrolyte interface exhibits a capacity retention rate of 83% after 500 cycles when employing a carbonate electrolyte without additives at a charge cut‐off voltage of 4.6 V. Furthermore, the LiCoO2 and polymer electrolyte interface exhibits exceptional cycle stability when paired with polyether solid electrolytes that do not possess high voltage tolerance. Moreover, the incorporation of a polymer electrolyte interface not only enhances the cycle stability of LiCoO2 but also improves its thermal stability. This work presents novel research perspectives for exploring high‐voltage stable LiCoO2.

Dehydration Achieving the Iron Spin State Regulation of Prussian Blue for Boosted Sodium-Ion Storage Performance.

Prussian blue analogs (PBAs) show promise as cathodes for sodium-ion batteries due to their notable cycle stability, cost-effectiveness, and eco-friendly nature, yet the presence of interstitial water limits the specific capacity and obstructs Na+ mobility within the material. Although considerable experimental efforts are focused on dehydrating water for capacity enhancement, there is still a deficiency of a comprehensive understanding of the low capacity of low-spin Fe resulting from interstitial water, which holds significance in Na+ storage. This study introduces a novel gas-assisted heat treatment method to efficiently remove interstitial water from Fe-based PBA (NaFeHCF) electrodes and combines experiments and theoretical calculations to reveal the iron spin state regulation that is related to the capacity enhancement mechanism. This dehydration strategy significantly enhances battery capacity, especially the portion at higher voltages (3.4-4.0V). The increase in capacity is attributed to the following factors: an enhanced proportion of Fe2+, reduced water content which facilitates faster charge transfer, and the activation of low spin Fe2+. The optimized NaFeHCF demonstrated impressive half-cell performance of retaining 87.3% capacity after 2000 cycles at a 5C rate and achieving 100mAhg-1 capacity over 200 cycles when being paired with hard carbon, exhibiting its practical potential.

The Behavior of High Scanning Electron Voltage Electron in SEM Due to Mirror Effect

To determine the factors influencing the electron scattering process in a scanning electron microscope caused by the electron mirror, a set of physical and mathematical ideas were used. These equations, which relate the scattering of the input electron with the surface potential energy of the dielectric material under examination using a matched beam ion microscope and scanning electrons, are based on simplified engineering mathematics. After five minutes of charging the insulator to saturation with an acceleration voltage of 30 kV, the accumulated charge was 0.3 nC, from which the surface voltage across the working distance (WD = 15 mm) was determined. The scattering angle (β) was found to be inversely proportional to the incidence angle (θ) in the second stage, when scanning voltages (Vsc=2, 4, and 6 kV) were employed. This was because the angle between the incident and scattered electron (2

Tailoring Co‐Free LiNi0.5Mn1.5O4 Material for High‐Voltage Lithium‐Ion Batteries: Particle Design & Grain Boundary Engineering

AbstractCobalt‐free LiNi0.5Mn1.5O4 (LNMO) is a promising cathode material for high‐energy and power‐density lithium‐ion batteries (LIBs). However, its commercial adoption is hindered by rapid capacity degradation due to the unstable LNMO/electrolyte interface caused by LNMO's high operating voltage. Structural degradation from Jahn–Teller distortion and metal‐ion dissolution also contributes to poor cycling stability. Additionally, producing industrial‐grade LNMO with high tap density, low surface area and reduced metal‐ion dissolution is challenging. This study addresses these challenges through a rational material design approach, synthesizing LNMO with large spherical secondary particles (>14.0 µm) and high tap density (>2.0 g cm−3). The primary particles (1.5–6.0 µm) exhibit a truncated‐octahedral shaped morphology that predominantly exposes (111) surface facets, with fewer (100) surfaces, stabilizing the LNMO/electrolyte interface, reducing metal dissolution, and enhancing lithium‐ion kinetics. Silicon infusion into grain boundaries further improves structural integrity by forming a silicon‐rich phase. The tailored LNMO demonstrates exceptional rate capability, cycling stability, and improved interfacial kinetics, significantly advancing the potential for cobalt‐free LNMO in high‐voltage LIBs. This work highlights the importance of tailored cathode material design for achieving the performance and stability required for emerging high‐voltage LIBs applications.

Low-Voltage Control Circuits of Formula Student Electric Racing Cars

Formula Student (FS) competitions aim to prepare and encourage engineering students to participate in the progression of automotive and motorsport industries. The built racing cars adhere to strict regulations set by competition guidelines to ensure the safety of both teams and spectators. For electric racing cars, the high-voltage (HV) battery system usually operates within a voltage range between 100 V to 600 V to supply the motor and its controller with the required electrical power. It is essential to ensure that these components are operating effectively to minimize battery and motor current as well as to ensure efficient and reliable performance throughout the race. A low-voltage control system (LVCS), usually operating at 12 V, is used to coordinate a wide array of critical operational and safety functions to control the HV system. These functions include: (1) turning on/off procedures, (2) monitoring speed, voltage, and current, (3) interfacing with pedals, (4) controlling dashboard features, (5) managing lighting, (6) facilitating data communication, and (7) implementing safety protocols. The design and operation of the LVCS are crucial for compliance with safety regulations and enhancing the FS electric racing car (FSERC) performance. This details and discusses the design procedures of the LVCS, using the Lancaster E-Racing (LER) FSERC as a case study. The LER car employs a 400 V battery system to power a 68-kW permanent manet synchronous motor (PMSM) using a three-phase voltage source inverter. Using mathematical analysis, SIMULINK/MATLAB® computer simulations, and the experimental real-data results provided by the LER FSERC, this study seeks to offer valuable insights regarding the LVCS practical implementation and optimization.

Antimony nanoparticles encapsulated in interconnected nitrogen-doped carbon nanospheres for high performances PIBs

Antimony (Sb) has attracted significant attention as an anode material for potassium-ion batteries (PIBs) due to its high theoretical capacity and suitable working voltage. However, the severe volume variations of Sb during potassiation/depotassiation process lead to sluggish kinetics and poor cyclic stability for PIBs. In this study, Sb nanoparticles are confined within interconnected N-doped carbon nanospheres (Sb@NC) through an effective carbothermal reduction process. The potassium storage performances and mechanism are elucidated through electrochemical tests combined with ex-XRD analysis. When used as an anode for PIBs, the optimized Sb@NC-2 anode exhibits excellent cycle stability of 463.0 mAh g−1 at 200 mA g−1 over 100 cycles and superior rate capability of 113.4 mAh g−1 at a high current density of 2 A g−1. Besides, a full cell comprising an Sb@NC-2 anode and a PTCDA cathode is also tested to validate the practical feasibility of the anode. Furthermore, Density Functional Theory (DFT) calculations demonstrate that N-doped carbon can enhance the adsorption of K+ and improve the kinetics of electrochemical reactions. Therefore, the unique yolk-shell structure in this study effectively restricts volume expansion and aggregation of Sb particles while facilitating rapid electron/ion transfer. These findings provide a potential alternative anode material for advanced PIBs.

Nonflammable All-Fluorinated Electrolyte Enabling High-Voltage and High-Safety Lithium-Ion Cells.

In this study, a nonflammable all-fluorinated electrolyte for lithium-ion cells with a Li(Ni0.8Mn0.1Co0.1)O2 cathode is investigated under high voltages. This electrolyte, named FT46, consists of fluoroethylene carbonate (FEC) and bis(2,2,2-trifluoroethyl) carbonate (TFEC) in a mass ratio of 4:6. Compared to a commercially available electrolyte and several other fluorinated electrolytes, cells containing FT46 demonstrate significantly better cycling performances under high voltage (3.0-4.5 V). This result may be ascribed to the generation of a stable, smooth, and thin passivation layer and the improved solvation structure formed by FT46. The LiF-rich passivation layer strengthens the electrode/electrolyte interface, inhibits the degradation of the electrode, and suppresses side reactions between the electrodes and electrolytes under high voltage. The solvation structure formed by FT46 is derived from anions, enabling an enhanced Li+ migration rate and inhibiting lithium plating generation. Additionally, due to the nonflammability of the electrolyte and the stable passivation layers, FT46 cells also demonstrate promising safety characteristics when exposed to typical abusive conditions, such as thermal abuse, mechanical abuse, and electrical abuse.

Reaction Mechanisms of High-Rate Copper Electrochemical Machining in Nitrate Electrolytes.

The high-rate electrochemical dissolution of copper in nitrate electrolytes is investigated primarily via polarization curves, while varying parameters such as the electrolyte flow velocity, the electrolyte resistance, the anode geometry, and the temperature. This study focuses on the re-rise in current at high voltages after the limiting current plateau. As a result of the studies, a change in the complexation mechanism from hydration to "solvo-nitration" is proposed, which requires an additional potential drop within the electrochemical double layer.

Bottom Contact Engineering for Ambient Fabrication of >25% Durable Perovskite Solar Cells.

The bottom contact in perovskite solar cells (PSCs) is easy to cause deep trap states and severe instability issues, especially under maximum power point tracking (MPPT). In this study, sodium gluconate (SG) is employed to disperse tin oxide (SnO2) nanoparticles (NPs) and regulate the interface contact at the buried interface. The SG-SnO2 electron transfer layer (ETL) enabled the deposition of pinhole-free perovskite films in ambient air and improved interface contact by bridging effect. SG-SnO2 PSCs achieved an impressive power conversion efficiency (PCE) of 25.34% (certified as 25.17%) with a high open-circuit voltage (VOC) exceeding 1.19V. The VOC loss is less than 0.34V relative to the 1.53eV bandgap, and the fill factor (FF) loss is only 2.02% due to the improved contact. The SG-SnO2 PSCs retained around 90% of their initial PCEs after 1000h operation (T90 = 1000h), higher than T80 = 1000h for the control SnO2 PSC. Microstructure analysis revealed that light-induced degradation primarily occurred at the buried holes and grain boundaries and highlighted the importance of bottom-contact engineering.

How pulse electric field treatment affects anti-nutritional factors and plant protein digestibility: A concise review

Consumption of foods rich in anti-nutritional factors (ANFs) can lead to inadequate absorption of vitamins and minerals. Pulsed electric field (PEF) treatment is a non-thermal food processing technology that uses short bursts of high voltage electric fields to induce structural modifications in biomolecules, including proteins, through electrochemical reactions and polarization of structural moieties. PEF offers potential benefits in enhancing the nutritional quality of food products by altering the structure and function of ANFs. However, the effects of PEF on ANFs in food have not been well established. Additionally, PEF-treated samples may undergo protein structural orientation modification due to electroporation and free radical species, potentially unfolding the native structure and influencing protein digestibility. Moreover, by increasing the mass transfer rate, electroporation can enhance the extraction of the initially trapped fractions into the solvent medium, which may include target compounds that affect protein functionality and digestibility. However, the protein digestibility of PEF-treated food products is yet to be thoroughly explored. Therefore, this review objectively investigates the possible mechanisms involved and the effectiveness of PEF in reducing different ANFs and modifying plant protein digestibility. This review also provides in-depth information about the possible applications of PEF-treated food items in the food industry.

Bayesian-optimized LSTM-DWT approach for reliable fault detection in MMC-based HVDC systems

As Europe integrates more renewable energy resources, notably offshore wind power, into its super meshed grid, the demand for reliable long-distance High Voltage Direct Current (HVDC) transmission systems has surged. This paper addresses the intricacies of HVDC systems built upon Modular Multi-Level Converters (MMCs), especially concerning the rapid rise of DC fault currents. We propose a novel fault identification and classification for DC transmission lines only by employing Long Short-Term Memory (LSTM) networks integrated with Discrete Wavelet Transform (DWT) for feature extraction. Our LSTM-based algorithm operates effectively under challenging environmental conditions, ensuring high fault resistance detection. A unique three-level relay system with multiple time windows (1 ms, 1.5 ms, and 2 ms) ensures accurate fault detection over large distances. Bayesian Optimization is employed for hyperparameter tuning, streamlining the model’s training process. The study shows that our proposed framework exhibits 100% resilience against external faults and disturbances, achieving an average recognition accuracy rate of 99.04% in diverse testing scenarios. Unlike traditional schemes that rely on multiple manual thresholds, our approach utilizes a single intelligently tuned model to detect faults up to 480 ohms, enhancing the efficiency and robustness of DC grid protection.

A gas spark switch electrode impact pressure test platform.

The discharge arc of a high-current gas spark switch has a strong mechanical effect on the electrode and adjacent objects. The measurement of this mechanical effect on the electrode plays a very important role in switch design and the theoretical study of spark discharge. However, in traditional stress measurement systems, the spatial electromagnetic interference caused by the discharge and the high electrode voltage affects the measurement accuracy and can even damage the experimental instrument. In this paper, an electrode impact stress measurement system based on PVDF piezoelectric film is designed to measure the electrode stress under a strong spatial electromagnetic field and high voltage. The experimental results show that the system can measure the impact pressure of high-voltage and high-current gas spark switch electrodes. The starting time of the stress measurement waveform shows that the shock to the electrode is formed in the initial stage of current buildup. The measured results clearly show the high magnetic field force component in the electrode impact pressure waveform. The shock waveforms induced by different pulse capacitor values, breakdown voltages, and loads are examined. It is found that the shock stress waveforms applied to the electrodes are affected by the peak value of the current, dI/dt, and the discharge duration.

Ribbon-Ordered Superlattice Enables Reversible Anion Redox and Stable High-Voltage Na-Ion Battery Cathodes.

High-voltage layered oxide cathodes attract great attention for sodium-ion batteries (SIBs) due to the potential high energy density, but high voltage usually leads to rapid capacity decay. Herein, a stable high-voltage NaLi0.1Ni0.35Mn0.3Ti0.25O2 cathode with a ribbon-ordered superlattice is reported, and the intrinsic coupling mechanism between structure evolution and the anion redox reaction (ARR) is revealed. Li introduction constructs a special Li-O-Na configuration activating reversible nonbonded O 2p (|O2p)-type ARR and regulates the structure evolution way, enabling the reversible Li ions out-of-layer migration instead of the irreversible transition metal ions out-of-layer migration. The reversible structure evolution enhances the reversibility of the bonded O 2p (O2p)-type ARR and inhibits the generation of oxygen dimers, thus suppressing the irreversible molecular oxygen (O2)-type ARR. After the structure regulation, the structure evolution becomes reversible, |O2p-type ARR is activated, O2p-type ARR becomes stable, and O2-type ARR is inhibited, which largely suppresses the capacity degradation and voltage decay. The discharge capacity is increased from 154 to 168 mA h g-1, the capacity retention after 200 cycles significantly increases from 35 to 84%, and the voltage retention increases from 78 to 93%. This study presents some guidance for the design of high-voltage, O3-type oxide cathodes for high-performance SIBs.

Unlocking the potential of cation vacancy-enriched ZnMn1.75O4 cathode for advanced aqueous aluminum-ion batteries

Manganese oxides are widely utilized in aqueous aluminum-ion batteries (AIBs) due to their high voltage and diverse crystal structures. However, the Jahn-Teller effect induced by Mn-O6 units results in irreversible structural damage. Here, we synthesized ZnMn1.75O4 (ZMO) cathodes loaded onto a carbon framework with manganese vacancies (VMn) for AIBs through ion substitution, manganese extraction, and carbonization on Mn-MIL. VMn stabilizes the ZMO structure by damping Mn-O bond vibrations and fosters Mn-O-C bonds between oxide particles and the carbon framework, effectively suppressing irreversible Mn2+ dissolution. Vacancy-modified cathodes provide more ion insertion sites, promoting ion diffusion. Ex-situ characterization revealed dominant H+ and Al3+ insertion behavior during different voltage regimes. Upon initial discharge, ion insertion into vacant lattice sites causes lattice distortions in adjacent unit cells, prompting ZMO to undergo a crystal structure transition and partial zinc deintercalation, resulting in a more stable cathode structure. Therefore, Al/ZMO batteries exhibit enhanced electrochemical performance.

Tetraethylphosphonium tetrafluoroborate electrolyte for paving the way to construct high-power and high-voltage supercapacitors

Phosphonium-containing electrolytes offer a new avenue for advancing high-performance supercapacitors. In this study, for the first time, we investigated the physical and electrochemical characteristics of a new phosphonium salt—tetraethylphosphonium tetrafluoroborate (TEPBF4) in various solvents including acetonitrile (AN), propionitrile (PN), propylene carbonate (PC), and trimethyl phosphate (TMP). Our investigations revealed that TEPBF4/AN electrolytes demonstrated high solubility (2.15 M), high ionic conductivity (52.2 mS cm−1), and wide electrochemical stability windows (≥4.7 V), suggesting that TEPBF4/AN emerges as a compelling alternative to conventional ammonium salts in AN for developing high-power and high-voltage supercapacitors. Our results also showed that supercapacitors based on 1 M TEPBF4/AN achieved the highest capacitance (24.7 F g−1), superior rate performance, highest energy (24.9 Wh kg−1) and power densities (6752 W kg−1) among the investigated electrolytes. Furthermore, it retained 75 % of its capacitance after 1000 h float test at a high working voltage of 3.2 V, which significantly outperformed other supercapacitors using conventional ammonium salts in AN.

Analyzing the Consequences of Power Factor Degradation in Grid-connected Solar Photovoltaic Systems

This study examines the impact of integrating solar photovoltaic (PV) systems on power factor (PF) within low-voltage radial distribution networks, using empirical data from the Energy Self-Sufficiency for Health Facilities in Ghana (EnerSHelF) project sites in Ghana. The research included simulations focusing on optimal PV integration, with and without PF considerations, and the strategic placement of PV and shunt capacitors (SC). Three scenarios evaluated PV injection at high-load demand nodes, achieving penetration levels of 85.00 percent, 82.88 percent with high voltage drop, and 100.00 percent with high loss nodes. Additionally, three scenarios assessed SC allocation methods: proportional to the node's reactive power demand (Scenario I), even distribution (Scenario II), and proportional to installed PV capacity at PV nodes (Scenario III).The analysis used a twin-objective index (TOI), combining voltage deviations and power factor degradation. Results showed significant PV curtailment was necessary to achieve standard PF. Optimal penetration levels, considering TOI, reduced PV penetration from 85.00 percent to 63.75 percent, 82.88 percent to 57.38 percent, and 100.00 percent to 72.50 percent for high load, high voltage drops, and high loss nodes, respectively. Notably, all scenarios showed a concerning PF of 0.00 at dead-end nodes (P20, P21, P22).Scenario I achieved PF ranges of -0.26 to 1.00 with PV at high load, -0.69 to 1.00 with PV at high voltage drop, and 0.95 to 1.00 with PV at high loss nodes. Scenario II produced similar ranges, -0.48 to 1.00, -1.00 to 0.99, and 0.30 to 0.96, with PV placement at high load, voltage drops, and loss nodes, respectively. Scenario III yielded ranges of -0.19 to 0.97 (high load), -0.23 to 1.00 (high voltage drop), and 0.86 to 0.96 (high losses).The study concluded that the most effective strategy involves installing PVs at high-loss nodes and distributing SCs proportionally to the node's reactive power demand (Scenario I). This approach achieved a more uniform PF pattern throughout the network, highlighting the practical implications of strategic PV placement and targeted reactive power compensation for maintaining a healthy and efficient distribution system with solar PV integration.

New insights into aluminium anodizing in phosphonic acid

Aluminium anodizing in phosphonic acid is known to produce anodic aluminium oxide (AAO) honeycomb structures with large interpore distances. However, detailed information on two-stage anodizing in phosphonic acid and annealing conditions required for the crystallization of AAO cell walls have not been reported yet. Here, the kinetics of aluminium anodizing in 1 M phosphonic acid and the thermal behaviour of the resulting AAO have been studied in detail. The apparent activation energy of aluminium anodizing is 65 kJ mol–1 and the AAO growth rate reaches 15 µm h–1 before oxide burning. A universal approach for stable two-stage anodizing at high voltages allowing to prevent porous structure rearrangement in the upper part of AAO is proposed. It involves the preliminary formation of a dense barrier alumina layer by anodizing in a weak acid electrolyte before the second anodizing step in phosphonic acid. The crystallization pathways of AAO obtained in phosphonic acid electrolyte are revealed based on differential scanning calorimetry, X-ray diffraction, and solid-state nuclear magnetic resonance techniques. The designed annealing program allows one to preserve the honeycomb porous structure after the crystallization of AAO in corundum at 1310°C for 60 h. AAO obtained in phosphonic acid possesses high thermal stability and, thus, is promising as a support for gas sensors and fuel cells.