Low Operation Research Articles

Effect of solids concentration and operational variables on the performance of a geometrically optimized concentrator hydrocyclone employing a pseudoplastic fluid

The employment of hydrocyclones in thickening operations is an attractive option when compared to centrifuges and filters due to their low operating, maintenance, and acquisition costs. However, the performance of hydrocyclone separation is impaired as the concentration of solids and the viscosity of the suspension increases. Using geometric optimization techniques, the Federal University of Uberlândia developed one concentrator hydrocyclone named HC. When working with diluted and Newtonian slurries, the HC could generate a stream 45 times more concentrated than the one fed into it. In this study, the HC performance was evaluated when operating pseudoplastic fluids containing up to 10% solids by volume. The combination of the underflow diameter and vortex finder length with an adequate supply of pressure energy maintained the thickening potential of the HC even when the rheology of the fluid was changed. For different working suspensions, the HC hydrocyclone achieved a minimum water split to underflow of 5%, a maximum concentration ratio of 7.0, and a maximum efficiency of 49%. The encouraging results obtained by the HC validated the benefits of the geometric optimization, as they point to a significant advance in the thickening operation of non–Newtonian sludges with a flow behavior index greater than 0.5.

Deep Autoencoder for Real-Time Single-Channel EEG Cleaning and Its Smartphone Implementation Using TensorFlow Lite With Hardware/Software Acceleration.

To remove signal contamination in electroencephalogram (EEG) traces coming from ocular, motion, and muscular artifacts which degrade signal quality. To do this in real-time, with low computational overhead, on a mobile platform in a channel count independent manner to enable portable Brain-Computer Interface (BCI) applications. We propose a Deep AutoEncoder (DAE) neural network for single-channel EEG artifact removal, and implement it on a smartphone via TensorFlow Lite. Delegate based acceleration is employed to allow real-time, low computational resource operation. Artifact removal performance is quantified by comparing corrupted and ground-truth clean EEG data from public datasets for a range of artifact types. The on-phone computational resources required are also measured when processing pre-saved data. DAE cleaned EEG shows high correlations with ground-truth clean EEG, with average Correlation Coefficients of 0.96, 0.85, 0.70 and 0.79 for clean EEG reconstruction, and EOG, motion, and EMG artifact removal respectively. On-smartphone tests show the model processes a 4 s EEG window within 5 ms, substantially outperforming a comparison FastICA artifact removal algorithm. The proposed DAE model shows effectiveness in single-channel EEG artifact removal. This is the first demonstration of a low-computational resource deep learning model for mobile EEG in smartphones with hardware/software acceleration. This work enables portable BCIs which require low latency real-time artifact removal, and potentially operation with a small number of EEG channels for wearability. It makes use of the artificial intelligence accelerators found in modern smartphones to improve computational performance compared to previous artifact removal approaches.

Research on Low Speed Operation of PMSM Based on Improved Non-Singular Fast Terminal SMC

Research on Low Speed Operation of PMSM Based on Improved Non-Singular Fast Terminal SMC

Liquid Water Transport and Distribution in the Gas Diffusion Layer of a Proton Exchange Membrane Fuel Cell Considering Interfacial Cracks

The proton exchange membrane fuel cell (PEMFC), with a high energy conversion efficiency, has become an important means of hydrogen energy utilization. However, water condensation is unavoidable in the PEMFC because of low operating temperatures. The impact of liquid water on PEMFC performance and stability is significant. The gas diffusion layer (GDL) provides a critical transport path for liquid water in the PEMFC. Liquid water saturation and distribution in the GDL determine water flooding and mass transfer efficiency in the PEMFC. In this study, focusing on the effects of the water introduction method, osmotic pressure, and contact angle, the liquid water transport in the GDL was numerically investigated based on a pore-scale model using the volume of fluid (VOF) method. The results showed that compared with the conventional water introduction method without cracks, the saturation and spatial distribution of water inside the GDL obtained in the simulation were more consistent with the experimental results when the water was introduced through the microporous layer (MPL) crack. It was found that increasing the osmotic pressure resulted in a faster rate of water penetration, faster approaching the steady-state performance, and higher saturation. The ultra-high osmotic pressure contributed to the secondary breakthrough with a significant increase in saturation. Increasing the contact angle caused higher capillary resistance, especially in the region with small pore sizes. At a constant osmotic pressure, as the contact angle increased, the liquid water gradually failed to penetrate into the small pores around the transport path, causing saturation reduction and an ultimate failure to break through the GDL. Increasing the contact angle contributed to a higher breakthrough pressure and secondary breakthrough pressure.

High-Performance Organic Field-Effect Transistors and Inverters with Good Flexibility and Low Operating Voltage.

Organic field-effect transistors (OFETs) with good flexibility and low operating voltage, are of great meaning for the low power stretchable and wearable electronic devices. The operating voltage and flexibility are easily affected by the dielectric layers in the OFETs. Bilayer dielectrics comprising both high- and low-permittivity (k) insulating polymers, have been reported. The flexible bilayer dielectrics can combine the advantages of both insulating polymers, which are high charge carriers from low-k polymers and low operating voltage from high-k polymers. However, the effect of film thicknesses in the bilayer dielectrics on the OFET performance is seldom investigated. Here, bilayer dielectrics comprising high-k polyvinyl alcohol (PVA) and low-k polymethylmethacrylate (PMMA) were fabricated. And PVA/PMMA bilayers with three different PVA film thicknesses are carefully investigated. The 300 nm PVA/100 nm PMMA bilayer dielectric makes the pentacene OFETs show the highest hole mobility of 1.24 cm2V-1s-1 and the corresponding inverters give a high voltage gain of 40 and a noise margin of 2.3 V (77% of 1/2 VDD) at low operating voltage of 6 V. Both the pentacene transistors and the inverters still work properly under bending radium of 5.85 mm, proving the good prospects of the PVA/PMMA bilayer dielectric in practical applications.

Procedural Volume and Outcomes After Septal Reduction Therapies in Hypertrophic Obstructive Cardiomyopathy.

Septal myectomy and alcohol septal ablation (ASA) are septal reduction therapies for patients with symptomatic obstructive hypertrophic cardiomyopathy. Operator and hospital volume may influence outcomes, but contemporary data on this relationship are limited. This retrospective cohort study used data from the Vizient Clinical Data Base (2016-2022). Patients with undergoing septal myectomy and ASA were identified using International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) codes and stratified into low-, medium-, and high-volume groups based on annualized operator and hospital volumes. The outcomes were 30-day in-hospital mortality and 90-day readmission, analyzed using multivariable adjusted logistic and Cox models. Among 5725 patients with hypertrophic cardiomyopathy (3990 septal myectomy; 1735 ASA), most operators and hospitals performed <10 procedures annually. For septal myectomy, low-volume operators were associated with higher odds of 30-day mortality (adjusted odds ratio [aOR], 1.86 [95% CI, 1.11-3.15]) and greater risk for 90-day readmission (aOR, 1.51 [95% CI, 1.22-1.88]), and medium-volume operators had higher odds of 30-day mortality (aOR, 1.93 [95% CI, 1.05-3.55]). Medium-volume hospitals had higher 30-day mortality (aOR, 2.29 [95% CI, 1.32-3.99]), with low-volume hospitals showing greater risk for 90-day readmission (aOR, 1.60 [95% CI, 1.14-2.23]). For ASA, low- and medium-volume operators had increased 30-day mortality (aOR, 2.99 [95% CI, 1.15-7.75] and aOR, 3.86 [95% CI, 1.30-11.46]), but the risk of 90-day readmission was similar. Hospital volumes did not significantly impact outcomes for ASA. Low operator and hospital volumes were associated with worse outcomes for septal reduction therapies, emphasizing the need to refer patients with hypertrophic cardiomyopathy to high-volume centers with experienced operators.

Very High-Capacity Li/Na-Ion battery anodes Enabled by Blue phosphorene and boron phosphide vdW heterostructure

The fascinating features of van der Waals heterostructure (vdWH) based electrodes and their potential to overcome the limiting properties of single-material systems have sparked a great deal of scientific attention. In this study, we investigate the potential of a blue phosphorene/boron phosphide (Blue-P/BP) vdWH as an anode material for both lithium-ion (Li-ion) and sodium-ion (Na-ion) batteries using first-principles calculations. We suggest that this vdWH could act as an effective anode material for metal-ion batteries, due to their high theoretical capacity and strong binding strength. Intriguingly, the theoretical specific capacity exhibits remarkable values, notably reaching 4510 mAhg−1 for Li and 3849 mAhg−1 for Na, which surpasses all capacities reported in the existing literature. Additionally, electronic structure calculations reveal a significant charge transfer that enhances the metallic characteristics, thereby increasing electrical conductivity. As we delve deeper into the electronic structure and calculate diffusion barriers and pathways, we observe that ionic diffusion (∼0.12/0.11 eV) is notably rapid compared to graphitic anodes (∼0.2 eV). We also found that intercalating Li/Na atoms in the Blue-P/BP vdWH results in low operating potentials of 0.38 V for Li and 0.34 V for Na. This research highlights the substantial enhancement of electrochemical performance of Blue-P/BP vdWH and holds great promise as high-power-density anode materials for Li/Na-ion batteries, facilitating rapid charge and discharge rates.

Deciphering competing interactions of Kitaev–Heisenberg-Γ system in clusters: I. Static properties

Recently, the Kitaev-Heisenberg-Γ system has been used to explore various aspects of Kitaev spin liquid physics. Here, we consider a few small clusters of up to twelve sites and study them in detail to unravel many interesting findings due to the competition between all possible signs and various magnitudes of these interactions under the influence of an external magnetic field. When Heisenberg interaction is taken anti-ferromagnetic, one obtains plateaus in correlation functions where, surprisingly, the exact groundstate reduces to the eigenstate of Heisenberg interaction as well. On the other hand, for ferromagnetic Heisenberg interaction, its competition with Kitaev interaction results in non-monotonicity in the correlation functions. We discuss, in detail, the competing effects on low energy spectrum, flux operator, magnetization, susceptibility, and specific heat. Finally, we discuss how our findings could be helpful to explain some of the recent experimental and theoretical findings in materials with Kitaev interactions.

Performance prediction of IPMC modified with SiO2-SGO based on backpropagation neural network

Ionic polymer–metal composites (IPMCs) constitute a new type of artificial muscle material that is commonly used in bionic soft robots and medical devices because of its small driving voltage and considerable deformation. However, IPMCs are limited by performance issues such as low output force and small operating time away from water. Silicon dioxide sulfonated graphene (SiO2-SGO) particles are often used to improve the performance of polymer membranes because of their hydrophilicity and high chemical stability. Reported here is the addition of SiO2-SGO particles prepared by in situ hydrolysis to perfluorosulfonic acid in order to improve the IPMC properties. Also, a predictive model was constructed based on a backpropagation neural network, with the SiO2-SGO doping amount and the IPMC excitation voltage in the input layer and the driving displacement in the output layer. The results show that the IPMC prepared with 1.0 wt. % doping content performed the best, with a maximum output displacement of 47.7 mm. The correlation coefficient (R2) was 0.9842 and the mean square error was 0.000 370 73, which show that the predictive model has high predictive accuracy and is suitable for predicting the performance of the SiO2-SGO-modified IPMC.

Application of chaotic teaching-learning-based optimization technique for estimating unknown parameters of proton exchange membrane fuel cell model.

Proton exchange membrane fuel cells (PEMFC) possess features like high specific power density, low operating temperature, and low operating pressure and thus are most widely used. The performance of PEMFC highly depends on its output voltage which further affects its efficiency. This research paper aims to improve this output voltage by minimizing the losses through parameter estimation technique for three well-known commercial PEMFC stacks, namely, 250W, BCS 500W, and Ballard Mark V. The multiobjective function framed for optimization serves two goals. One is to extract the unknown parameters of FC, and second is to achieve the minimum sum of squared errors (SSE) that occur due to the difference between experimental voltage and estimated voltage. Chaotic teaching-learning-based optimization (CTLBO) algorithm is used for optimization process. SSE values obtained for three commercial PEMFC stacks 250W, BCS 500W, and Ballard Mark V are 7.02267, 4.00150, and 0.8100, respectively. The applicability of this technique is further checked for different operating conditions of each model. The I-P (current-power) curve and I-V (current-voltage) curve obtained using estimated data closely matched the experimental data that showed the practical relevance and efficacy of the algorithm. A comparison is done among the SSE results obtained using CTLBO to other competitive algorithms mentioned in the literature. CTLBO showed its superiority over other algorithms in estimating the unknown parameters of PEMFC stack parameters.

Sensory assessment of intramuscular quadratus lumborum block at the L2 level in open inguinal hernia repair patients

BackgroundThe effectiveness of the quadratus lumborum block (QLB) for postoperative pain management depends on the injection pathway used. There is limited research on the block area produced by intramuscular injection of local anesthesia in the quadratus lumborum muscle. This study aimed to determine the cutaneous sensory blockade area produced by an intramuscular quadratus lumborum block (QLBi) at the L2 level.MethodsTwenty patients aged 18–60 years with ASA grade I-II and a BMI of 18–30 kg/m2 who were scheduled for open inguinal hernia repair with mesh underwent ultrasound-guided QLBi injection of 20 ml of 0.5% ropivacaine. The cutaneous sensory blockade area was measured by applying a cold stimulus 1 h after the block and then measured every hour after surgery until the sensation returned to normal. The duration of a blockade is defined as the time it takes for all affected areas to fully regain normal sensation following a blockade. Pain scores (numeric rating scale, NRS) were recorded at 2, 4, 8, 12, and 24 h after surgery. Adverse reactions to QLBi were recorded 24 h after surgery.ResultsAll 20 patients had reduced or lost cold sensation areas. The greatest extent of cold sensation reduction occurred at T7 (10%), and the least amount of cold sensation reduction occurred at L3 (10%). The block level covered T8 (20%), T9 (30%), T10 (45%), T11 (90%), T12 (95%), L1 (100%), and L2 (15%). Eighteen patients experienced areas of sensory loss, with the highest range at T11 and the lowest at L2. The duration of the blockade was 8.9 ± 3.8 h, with a maximum of 24 h and a minimum of 5 h. One patient experienced quadriceps weakness after surgery.ConclusionQuadratus lumborum block of intramuscular pathway can produce effective cutaneous sensory blockade, which can be used for postoperative analgesia of indirect inguinal hernia operation, and may also be beneficial to analgesia of other lower abdominal operations. However, the best method needs further confirmation to determine specific anesthesia methods for various operations.Chinese clinical trial registryJune 2, 2018; ChiCTR1800016457.

High drain field impact ionization transistors as ideal switches

Impact ionization effect has been demonstrated in transistors to enable sub-60 mV dec−1 subthreshold swing. However, traditionally, impact ionization in silicon devices requires a high operation voltage due to limited electrical field near the device drain, contradicting the low energy operation purpose. Here, we report a vertical subthreshold swing device composed of a graphene/silicon heterojunction drain and a silicon channel. This structure creates a low voltage avalanche impact ionization phenomenon and leads to steep switching of the silicon-based device. Experimental measurements reveal a small average subthreshold swing of 16 µV dec−1 over 6 decades of drain current and nearly hysteresis-free, and the operating voltage at which a vertical subthreshold swing occurs can be as low as 0.4 V at room temperature. Furthermore, a complementary silicon-based logic inverter is experimentally demonstrated to reach a voltage gain of 311 at a supply voltage of 2 V.

Exploring the Potential of Cold Sintering for Proton-Conducting Ceramics: A Review.

Proton-conducting ceramic materials have emerged as effective candidates for improving the performance of solid oxide cells (SOCs) and electrolyzers (SOEs) at intermediate temperatures. BaCeO3 and BaZrO3 perovskites doped with rare-earth elements such as Y2O3 (BCZY) are well known for their high proton conductivity, low operating temperature, and chemical stability, which lead to SOCs' improved performance. However, the high sintering temperature and extended processing time needed to obtain dense BCZY-type electrolytes (typically > 1350 °C) to be used as SOC electrolytes can cause severe barium evaporation, altering the stoichiometry of the system and consequently reducing the performance of the final device. The cold sintering process (CSP) is a novel sintering technique that allows a drastic reduction in the sintering temperature needed to obtain dense ceramics. Using the CSP, materials can be sintered in a short time using an appropriate amount of a liquid phase at temperatures < 300 °C under a few hundred MPa of uniaxial pressure. For these reasons, cold sintering is considered one of the most promising ways to obtain ceramic proton conductors in mild conditions. This review aims to collect novel insights into the application of the CSP with a focus on BCZY-type materials, highlighting the opportunities and challenges and giving a vision of future trends and perspectives.

Facile synthesis of green graphite-based (Ni/Cu/N) MOF composite for a methanol oxidation reaction

Recently, direct methanol fuel cells (DMFCs) have been regarded as the greatest energy-producing owing to their low operating temperature, high production rate of methanol, and low greenhouse gas emission. However, the energy conversion efficiency of the DMFCs is still unsatisfactory due to the slow kinetics of the fuel oxidation reaction. So, an economic electrocatalyst with high efficiency and good stability is still needed. Herein, low-cost nanocomposites of (Ni/Cu/N) MOF and palm pollen-derived G-graphite were prepared with different ratios namely, (1:1), (1:2), and (2:1) through a solvothermal reaction. The nanocomposites were characterized via X-ray diffraction (XRD), Scanning electron Microscopy (SEM), Fourier transform infrared (FTIR), Thermal gravimetric analysis (TGA), and, (Brunauer–Emmett–Teller) technique (BET). Electrodes have been tested as electro-catalysts for methanol-oxidation reaction (MOR) in a basic medium. As revealed from the cyclic voltammetry measurements, all electrodes exhibit a good response to MOR, being the nanocomposite with the ratio between (Ni/Cu/N) MOF and G-graphite (2:1) is the best with an oxidation peak current density of 55 mA/cm2 at a scan rate of 50 mV/s, with an onset potential of 0.35 V, and stability reaches 96 %. The electrochemical impedance spectroscopy (EIS) test showed that the ratio (2:1) has the lowest charge transfer resistance, RCT, of 5.21 Ω which confirms its higher electrochemical activity. This superior performance of the (Ni/Cu/N) MOF and G-graphite (2:1) over other reported MOF-based electrocatalysts is attributed to the synergistic effect of the (Ni/Cu/N) MOF electrocatalyst, wherein Ni and Cu provide redox electrocatalytic active sites for MOR while the G-graphite contributes towards the chemical stability and electrical conductivity of the electrode, respectively. The good activity and stability of the prepared electrodes suggest the potential use of these electrodes as electrocatalysts for MOR in direct methanol fuel cells (DMFCs).This study opens the venue for valorizing the natural wastes derived graphitic material as stable supporting material in Mof based composites electrodes for MOR.

Resilience of DBI screened objects and their ladder symmetries

Scalar field theories with a shift symmetry come equipped with the K-mouflage (or kinetic screening) mechanism that suppresses the scalar interaction between massive objects below a certain distance, the screening radius. In this work, we study the linear response of the scalar field distribution around a screened (point-like) object subject to a long range external scalar field perturbation for the Dirac-Born-Infeld theory. We find that, for regular boundary conditions at the position of the particle, some multipoles have vanishing response for a lacunar series of the multipole order ℓ for any dimension. Some multipoles also exhibit a logarithmic running when the number of spatial dimensions is even. We construct a ladder operator structure, with its associated ladder symmetries, formed by two sets of ladders that are related to the properties of the linear response and the existence of conserved charges. Our results exhibit a remarkable resemblance with the Love numbers properties of black holes in General Relativity, although some intriguing differences subsist.

Conformal Li2O2 Growth and Decomposition Within 3D Lithiophilic Nanocages of Metal–Organic Frameworks for High‐Performance Li─O2 Batteries

AbstractLi─O2 batteries (LOBs) have the largest theoretical capacity among current batteries, but the irreversible growth and decomposition of Li2O2 products in positive electrodes cause dramatic degradation of their capacities over charging–discharging cycles. Herein, a metal–organic framework is reported with bipyridinic N linkers attached to graphene (bpyN‐MOF/g) as a positive electrode material to overcome the challenge. The bpyN‐MOF/g promotes conformal Li2O2 growth during discharging, while allowing Li2O2 decomposition at a low overpotential (0.487 V vs Li+/Li at 200 mA gc−1) during charging process, outperforming the Pt/C‐based electrode (0.857 V). Moreover, 3D‐tomography and density functional theory calculations consistently support the Li2O2 growth and decomposition mechanism inside bpyN‐MOF/g. Furthermore, bpyN‐MOF/g//Li LOBs achieve an exceptional discharge capacity (17 275 mAh gc−1 at 100 mA gc−1) and steady cycling for 270 cycles at 1000 mAh gc−1 under 2000 mA gc−1. Additionally, high gravimetric capacity at low mass loadings (0.27–0.44 mg cm−2) and stable cycle operation at a high areal current density (0.5 mA cm−2) open new opportunities for various practical applications.

Sol-Gel Pt-VO2 Films as Selective Chemoresistive and Optical H2 Gas Sensors.

In this work, VO2 (M1/R) thin films were exploited as H2 gas sensors. A flat film morphology, obtained by furnace annealing, was compared with a laser-induced nanostructured one. The combination of the environmentally friendly sol-gel approach with the ultrafast laser crystallization allows for significant reductions in energy consumption and related emissions during the fabrication of VO2 sensors. By decorating the sensors' surface with Pt nanoparticles (NPs), the sensor response was enhanced exploiting the hydrogen spillover effect. The Pt/VO2 sensors, tested at operating temperatures between 20 and 200 °C and for concentration of H2 from few ppm to 50000 ppm, offered a dual chemoresistive and optical sensing mode. Low operating temperatures of 150 °C were achieved, along with a detection limit as low as 2 ppm and a perfect baseline recovery. Both sensors guaranteed specific selectivity toward H2, without response to NO2 or humidity, and long-term stability over 500 h. The H2 sensing mechanism, for both the monoclinic and rutile VO2 phases, was investigated through in operando X-ray Diffraction and in situ X-ray Photoelectron Spectroscopy tests. The interaction was found to be based on the reversible formation of HxVO2 bronze, along with the reversible variations in the oxidation state of V.

LARGE INFERIOR RECTUS RECESSION WITHOUT LOWER LID RETRACTION: TWO INCREDIBLE TECHNIQUES

Relevance. Lower lid retraction is a frequent undesirable result following inferior rectus recession operations. Especially in relatively larger amounts of recession, a special and close relationship between lower lid retractors and muscular fascia makes the complication more severe. Purpose of the study. To introduce two methods that allow wide inferior rectus recession without causing lower eyelid retraction and to evaluate the long-term results. Material and methods. There were 25 cases and 18 control group cases in first operation technique named ‘ninety percent of posterior fibers recession of inferior rectus’ which can be perform for any vertical deviation without muscle fibrosis; and 8 cases were in second operation technique which named ‘muscle elongation with both organic tissue and non-absorbable suture’. Results and conclusion. In both technique patients’ deviation corrected and all ocular movement was free. Both operation techniques, which introduces by us, does not affected lower lid retractor and operations has both effective results and no lid problem.

Digital transformation whitewashing and financing constraints

This study investigates the drivers and consequences of digital transformation whitewashing (DTW) among Chinese manufacturing firms from 2010 to 2021. We find that financing constraints have a robust and significant positive impact on DTW, an effect that is more pronounced for firms located in provinces with lower marketization or operating in industries with lower levels of monopoly. Regarding economic consequences, our results indicate that DTW fails to alleviate external financing constraints, instead causing firms to increasingly rely on internal financing.

Enable Rechargeable Carbon Fluoride Batteries with Unprecedented High Rate and Long Life by Oxygen Doping and Electrolyte Formulation.

Here, a rechargeable carbon fluoride battery is demonstrated with unprecedented high rate and long life by oxygen doping and electrolyte formulation. The introductions of Mn2+-O catalyst and porous structure during the oxidation process of CFx cathode can promote the splitting of Li-F during charging. By further modulating the electrolyte with triphenylantimony chloride (TSbCl) as anion acceptor and CsF as product modulator, the more readily dissociable CsLiF2 product instead of LiF is preferentially formed, and the TSbCl-salt protection interface is constructed to confine Li-F based products and reduce fluoride loss at cathode side. These effects endow Li-CFx batteries with durable reversible conversion reaction (for at least 600 cycles), ultrahigh rate performance (e.g., 364 mAhg-1 at 20 Ag-1) and low charging plateau voltage down to 3.2V. The cathode exhibits the maximum power density of 38342Wkg-1 and energy density of 1012Whkg-1. Furthermore, this Li-CFx system demonstrates the promising prospects for applications in view of its low temperature operation (e.g., 280 mAhg-1 at -20°C), low self-discharge ability, large-scale pouch cell fabrication and high cathode loading (5-6mgcm-2), enabling it to move beyond previous role as primary battery and into new role as fast-charging rechargeable battery with high energy density.