High Discharge Rates Research Articles

An experimental and comparative study on passive and active PCM cooling of a battery with/out copper mesh and investigation of PCM mixtures

The carbon emission contribution to global warming accelerated both research on and transition to electric vehicles (EVs). Drivers demand high power, fast acceleration and less charging times. All these demands require high C rate charging/discharging demands from batteries. The rate of heat generation is exponentially proportional to C rates which decreases battery lifetime and may lead to thermal runaway. However, a battery thermal management system decreases thermal runaway risk and decelerates battery degradation via controlling battery temperature. In this paper, we first document the thermal conductivity enhancement via copper foam into phase change material (PCM) domain to uncover their possible use in EV thermal management applications. Maximum 15.93 times increment is achieved with a specific copper foam. Then, physical properties and behaviors of distinct PCM mixtures are documented. Homogeneity of mixtures is associated with the chemistry of PCMs and the mixture melting point is proportional to the volume weighted average of melting temperatures. The results document that the PCM with relatively lower melting point is beneficial when end of discharge temperatures considered, except for high discharge rate of 2C. Temperature uniformity across the battery increases with relatively higher melting point PCM. Experiments also document that the amount of PCM volume lost via insertion of copper foam yields higher end of discharge temperatures. Overall, both PCM and copper foam enhances temperature homogeneity and their benefit becomes more sensible during drive cycles relative to continuous charge/discharge use cases.

Carotid artery stenting versus carotid endarterectomy for symptomatic or asymptomatic extracranial carotid stenosis: A national cohort study

IntroductionStroke is now the 5th leading cause of death in the United States, and carotid artery stenosis is the cause of about 20% to 25% of strokes. We hypothesized that CAS may be an alternative to CEA in both symptomatic and asymptomatic patients with carotid artery stenosis. MethodsWe evaluated the clinical characteristics, adverse events and mortality of patients with carotid artery stenosis comparing CEA vs. CAS using data from a national population-based cohort study from January 1, 2016, to December 30, 2020. ResultsWe evaluated 374,875 patients with carotid stenosis, of whom 344,020 had asymptomatic carotid stenosis and 30,855 had symptomatic carotid stenosis. CAS was associated with higher mortality in both symptomatic and asymptomatic carotid stenosis, compared to CEA, with the trend slightly decreasing for both interventions from the years 2018-2020. CEA was associated with lower adverse events in both symptomatic and asymptomatic carotid stenosis, compared to CAS. ConclusionsOur current data suggest a benefit of CEA over CAS for both symptomatic and asymptomatic carotid stenosis with lower complications, lower mortality and a higher rate of discharge. However, this is not a head-to-head comparison as it becomes selection bias for this procedure; therefore, further prospective head-to-head comparison between 2 groups in the same patient population is needed.

Numerical Investigation of Different Cooling Methods for Battery Packs

This paper contains the results of numerical investigations into two cooling system types for cells of three types. The galvanic cell geometries which were considered were pouches, cylinders and prisms. By design, the cooling system for a vehicle is specialised to prevent an uncontrolled temperature increase at higher discharge rates. Consideration was given to the question of which cooling method would be sufficient to reduce the temperature rise of battery cells. The first cooling method investigated is one that uses direct contact with the air flow to cool the cells, a method that is very commonly used in automotive engineering, as it is less complicated. This study employs a method that uses a fan to induce forced convection, increasing the airflow over cells housed within a thermoplastic composite container. Another method, fluid cooling, is notable for its greater efficiency due to the use of a non-conducting coolant, which has also better energy absorption properties. In this study, immersion cooling was employed, utilising oil circulation through cells contained within a thermoplastic composite container, which was facilitated by a pump system. This publication shows the influence of the cell’s geometry and the type of cooling system on the temperature rise of cells when they are discharging at the appropriate power rate. The results of this study highlight the differences in cooling performance between the two methods, providing a clear basis for selecting the most suitable solution for specific applications.

Impact of short-term total dissolved gas supersaturation on cognitive function and swimming performance in medaka (Oryzias latipes)

During the flood season, high dam discharge rates result in total dissolved gas (TDG) supersaturation. This condition causes gas bubble trauma and can lead to fish mortality, which poses a significant threat to downstream river ecosystems. Assessing the ecological risks of TDG supersaturation is a challenge in waterpower-intensive river basins worldwide. Few studies have explored the impact of TDG supersaturation on fish behaviours, such as aggression and memory, which are crucial for feeding, reproduction, and predator avoidance. In this study, behavioural tests were conducted in a T-maze to investigate the effects of acute TDG supersaturation on swimming behaviour, aggression, and memory in medaka (Oryzias latipes). The results demonstrated that medaka exposed to TDG levels of 115% and 130% for 2 h had significantly reduced swimming performance.At TDG levels of 100%, 115% and 130%, medaka activity rates in the mirror arm of the maze in the mirror test were 44.34 ± 12.88%, 40.27 ± 15.44% and 35.35 ± 16.07%, respectively. Similarly, the activity rates of medaka in the active stimulus arm of the maze in the memory test were 50.35 ± 14.75%, 40.76 ± 12.51% and 35.35 ± 18.47%, respectively. The behaviour of medaka changed with increasing TDG supersaturation. These findings contribute to the development of an ecological risk assessment model for TDG supersaturation based on memory and aggression in fish and provide data for developing management strategies to mitigate the adverse effects of TDG supersaturation.

Study on the parameter identification of lithium-ion battery model under high-rate pulse discharge conditions

With the rapid development of the new energy sector and lithium-ion (Li-ion) battery technologies, using Li-ion batteries with high energy density and high discharge rate to form the primary energy subsystem can further improve the compactness and miniaturization level of pulsed power systems. In traditional electric power systems, Li-ion batteries normally operate under the discharge condition of low current and long time. However, as the main power source of pulsed power systems, it is required that Li-ion batteries should have the capability for high-rate pulse discharge. To ensure the safe and reliable operation of the battery energy storage system, it is necessary to conduct the parameter identification of the Li-ion battery model to establish an accurate pulse discharge model under such working conditions. This paper focuses on the discharge characteristics of a cylindrical high-rate single Li-ion battery with a capacity of 3 Ah. At a 20 C rate, the discharge data were obtained when the pulse repetition frequency was 10 Hz and the duty cycle was 90%. By using the mathematical expressions of the Thevenin equivalent circuit model, the recursive relationship of the circuit parameters was obtained, and the parameter identification of the battery model was conducted based on the experimental data by using the genetic algorithm. The results show that the fitting accuracy of the parameter identification reaches 0.9995, indicating the high precision of the model for the Li-ion battery. This work provides a significant reference for the modeling and parameter identification of Li-ion batteries under high-rate pulse discharge conditions.

Study on the impact of turbulent spatiotemporal propagation in the outlet passage on the performance of vertical axial flow pumps.

Abstract Pumping station engineering is crucial for our country’s national economy as a part of water conservancy infrastructure. The vertical axial flow pump commonly used in pumping station construction features a high flow rate and low discharge pressure. Understanding the impact of turbulence on the flow of water entering and leaving the pump unit is crucial for the efficient and reliable operation of a pumping station. This paper examines the internal flow and hydraulic characteristics of the device for vertical axial flow pump at a pumping station through numerical simulation technology and experimental validation. It is inferred that turbulent flow develops in the outlet flow passage while the pump device is currently functioning, impacting the impeller’s outlet bend and guide vane. This leads to the formation of vortices, backflow, and folding flow at the guide vane and outlet bend. As water flows out through the outlet passage, bias and backflow develop, causing erosion on both sides of the outlet pool and impacting the pump unit’s overall head and efficiency.

Ultra-high rate performance of single-crystalline NMC cathodes enabled by a TEP-based electrolyte

Harnessing the full potential of Ni-rich single-crystal cathodes (LiNixMnyCo1-x-yO2, NMC) for next-generation high-energy lithium batteries is hindered by their slow reaction kinetics and susceptibility to interfacial decay. Our research introduces a novel strategy utilizing triethyl phosphate (TEP) and fluoroethylene carbonate (FEC) to optimize the Li+ solvation environment, lowering the coordination number and diminishing the energy threshold for Li+ transport. Mechanistic studies indicate that this intervention not only accelerates the Li+ transfer at the electrode/electrolyte interface but also catalyzes the development of a robust LiF-rich CEI layer. As a result, the single-crystal NMC83 cathode exhibits remarkable high-rate discharge capacities of approximately 209 mAh g−1 at 0.1 C and 192 mAh g−1 at 0.5 C. The robust CEI layer also mitigates parasitic reactions, substantially improving the cycle life, with capacity retention increasing from 46.1 % to 88.2 % after 300 cycles at 1 C. This work underscores the transformative impact of solvation sheath engineering on the interfacial dynamics of single-crystal cathodes, paving the way for more durable and efficient energy storage solutions.

Constructing three-dimensional GO/CNT@NMP aerogels towards primary lithium metal batteries

Abstract Graphene oxide (GO) can serve as cathode material for a viable primary lithium metal battery due to its richness in oxygen-containing functional groups. However, its application is hindered by non-conductivity of GO. Herein, a proposed electrode structure design strategy is carried to regulate the electron and ion conductivity of the graphene oxide aerogel (GO/CNT@NMP) electrode while retaining the original energy density. GO/CNT@NMP exhibits a discharge specific capacity of 703 mAh g−1 and an ultra-high energy density of 1655.76 Wh kg−1 at a low rate of 0.02 A g−1. Additionally, it achieves a maximum discharge rate of 1.4 A g−1, five times higher than the initial maximum discharge rate of GO. Characterization and electrochemical tests reveal that the excellent performance of GO/CNT@NMP can be attributed to its porous structure, high electrical conductivity, and large layer spacing. This study presents a potent strategy for the advancement of ultra-fast primary batteries, aiming to integrate ultra-high energy density and high-rate discharge capabilities.

Effect of Cell-to-Cell Internal Resistance Variations on the Thermal Performance of Lithium-Ion Batteries for Urban Air Mobility

This study examines the thermal behavior of lithium-ion battery modules intended for Urban Air Mobility (UAM), a forthcoming urban transport system designed to facilitate efficient and secure passenger and cargo transport within city centers. UAM applications necessitate batteries with high energy densities capable of sustaining elevated discharge rates during critical phases such as takeoff and landing. The battery module evaluated in this study comprises four cells arranged in series and configured as a submodule for UAM applications. A three-dimensional thermal model was utilized to analyze the impact of external temperature fluctuations and high discharge rates on the performance of the battery module. The numerical findings indicated considerable variations in temperature and internal resistance among the cells, especially under high discharge rates at low temperatures, with a maximum temperature deviation of 32.952 °C observed at an 8 C discharge rate. These thermal non-uniformities were attributed to variations in cell capacity and internal resistance, which were amplified by manufacturing inconsistencies and operational conditions. The study underscores the necessity of robust thermal management strategies to mitigate the risk of thermal runaway and ensure the operational safety and reliability of UAM systems. The results emphasize the critical role of advanced Battery Management Systems (BMS) in monitoring and controlling cell voltage and temperature to achieve consistent performance across the battery module. This research contributes valuable insights into the design of more efficient and reliable battery modules for UAM, highlighting the importance of addressing cell-to-cell performance discrepancies to enhance overall module efficacy and durability.

Paraffin/graphite/boron nitride composite as a novel phase change material for rapid heat absorption in battery thermal management technology

Phase change material (PCM) cooling is widely employed in the thermal management of compact battery packs. Thermal protection triggered by rapid temperature rise shortens the effective discharge time in high-rate discharge, making it essential to prepare PCM that rapidly absorbs heat at high temperatures. However, research on the thermal absorption performance and insulating properties of PCM at high-rate discharge remains limited. Herein, we innovatively propose a thermally conductive and insulating PCM with a wide phase transition temperature to address the overheating issue in batteries at 7 C, 8 C and 9 C discharge rates. The C236 consists of paraffin (PA236), graphite and boron nitride with a ratio of 6: 2: 2, which achieves outstanding thermal performance with a latent heat of up to 138.0 J/g and a high-volume resistivity of 1.6 × 108 Ω·m. It is found that at a discharge rate of 7 C, the C236 with a thickness of 3 mm effectively maintains the temperature below 80 °C. At discharge rates of 8 C and 9 C, the PCM significantly reduces the battery temperature by 26.9 % and 32.5 %, respectively, highlighting the rapid heat absorption capability at high temperatures. Furthermore, after four cycles at a 9 C discharge rate, the temperature differential of the battery remains below 5 °C. The low-cost PCM provides a new experimental reference for battery thermal management in high-rate discharge, with broad application prospects.

Comfort feeding in hospitalised people with dementia: a retrospective study of survival following comfort feeding recommendations

ObjectivesPersistent and significant swallowing impairment can occur in individuals with dementia. Determining prognosis and establishing realistic goals of care in this population is complex and comfort feeding may be recommended. This study aimed to establish evidence relating to patient outcomes following recommendation of comfort feeding to aid informed decision making. DesignA multi-centre, retrospective audit was conducted for a two-year period to establish the survival and readmission rates for hospitalised people with dementia, following recommendation of a comfort feeding plan. SettingThe study was conducted at three acute care hospitals in Adelaide, South Australia. ParticipantsA total of 163 participants were included, 90 male and 73 female, with a median age of 88 years. MeasurementsMortality within 30 and 90 days of admission and readmission rates within 30 days of discharge were calculated. ResultsForty-two percent of participants died during the admission during which a comfort feeding plan was recommended. Overall median survival time and one month survival was 13 days and 25%, respectively. Readmission rates were low (7.4% of those discharged). Comfort feeding recommendations aligned with dysphagia severity and those for whom Nil By Mouth (NBM) or ice chips only were recommended were at highest risk of dying in hospital, those recommended thickened fluids +/− ice chips were most likely to be alive 30 days after their original admission date. ConclusionDementia and comfort feeding were associated with high mortality rates, high rates of discharge to a supportive care facility and low readmission rates. Dysphagia severity associated with the consistency of fluids recommended.

Study on the influence of high rate charge and discharge on thermal runaway behavior of lithium-ion battery

With the development of the new energy industry, battery life and rapid charge-discharge capacity have attracted much attention. At the same time, the high temperature inside the cell during high-rate charging and discharging may increase the probability of the battery thermal runaway. This paper studied the thermal runaway reaction of Li-ion batteries under different state of charge (SOC) and charge rates using a self-made experimental platform. The experimental phenomena and the changes in the temperature field were recorded. The key parameters, such as trigger temperature (T1, Lithium battery back thermal runaway triggers temperature), maximum temperature (Tmax),voltage, and mass loss (ML) of thermal runaway, were measured. The morphology changes of electrode materials, the battery remains, and the dynamics of thermal runaway reaction after high rate charge and discharge were further analyzed. The results show that for the 4 C-100 % battery, the T1 and Ea are reduced by 22.6 ℃ and 82.2 %, and the Tmax and maximum mass loss rate (MLRmax) are increased by 218.14 ℃ and five times, compared with the 1 C-50 % battery. With the increase of charge-discharge rate, the thermal stability of the battery decreases, and the gravity degree of accident increases.

Design of alveolar biomimetic enhanced heat transfer structure for cylindrical lithium battery pack

Aiming to address the issue of thermal runaway in high energy density batteries during high charge and discharge rates, a heat management system for an alveolar-like honeycomb liquid-cooled power battery was designed. This system is inspired by the bionic concept of cell cooling in biological tissues, with cylindrical batteries serving as cells and cooling channels resembling blood vessels. The cooling system for a battery pack consisting of 24 cylindrical cells was designed and implemented. Numerical simulations were conducted to optimize and study the effects of inlet diameter, branch angle, flow rate, and spiral baffle on coolant flow uniformity and temperature distribution within the battery pack. The results indicate that as the inlet diameter of the fractal channel increases from 2 mm to 20 mm, the coolant flow uniformity improves and the pressure drop decreases. However, the influence of inlet diameter diminishes after reaching a certain limit. When the inlet diameter increases from 10 mm to 20 mm, the relative standard deviation of the velocity at the branch outlet decreases only slightly, from 0.9 % to 0.8 %. Increasing the branch angle from 30° to 75° leads to an increase in the relative standard deviation of velocity, from 0.79 % to 1.24 %. Incorporating a spiral baffle into the internal flow channel of honeycomb cooling significantly enhances temperature uniformity within the battery pack while reducing maximum temperature levels considerably. Furthermore, a smaller pitch for the spiral baffle yields better cooling performance for the immersed liquid cooling thermal management system. After optimization, the maximum temperature difference is only 1.27 °C across the surface of the battery pack, achieving a remarkable temperature uniformity level of just 0.11 %.

Extended scope audiology clinic – a review of its outcomes and re-presentation to the ear nose and throat service

Objective To evaluate the role of Extended Scope (ES) audiologists in managing adult Ear Nose and Throat (ENT)/Otology waitlists and analyse patient re-presentation rate to the ENT service within 12 months of being discharged from the clinic. Design A retrospective cohort study assessing the efficacy of ES audiologists, measuring the discharge rate from ENT waitlists, the rate of escalation to ENT care, and the rate and reasons for any re-presentations to care. Study sample 394 adult patients. Results Of the referred patients, 95% (n = 374) were deemed suitable for ES care. Of these, 75% were discharged without further ENT intervention, 20% required escalation to ENT, and 5% were returned to the waitlist. Only one patient re-presented for care within 12 months. The inclusion of patients with CHL/MHL and vestibular symptoms marked an expansion from our previous work. The re-presentation rate was notably lower compared to other allied health ES clinics. Conclusion The ES Audiology clinic demonstrates a high discharge rate with a low incidence of patient re-presentation, highlighting the ES audiologists’ efficiency in managing non-urgent ENT cases. The study supports the continued use and expansion of ES roles to ensuring timely and quality care for patients on ENT waitlists.

Weakening the Space Charge Layer Effect Through Tethered Anion Electrolyte and Piezoelectric Effect Toward Ultra-Stable Zinc Anode.

The space charge layer (SCL) dilemma, caused by mobile anion concentration gradient and the rapid consumption of cations, is the fundamental reason for the generation of zinc dendrites, especially under high-rate discharge conditions. To address the issue, a physical (PbTiO3)/chemical (AMPS-Zn) barrier is designed to construct stable zinc ion flow and disrupt the gradient of anion concentration by coupling the ferroelectric effect with tethered anion electrolyte. The ferroelectric materials PbTiO3 with extreme-high piezoelectric constant can spontaneously generate an internal electric field to accelerate the movement of zinc ions, and the polyanionic polymer AMPS-Zn can repel mobile anions and disrupt the anions concentration gradient by tethering anions. Through numerical simulations and analyses, it is discovered that a high Zn2+ transference number can effectively weaken the SCL, thus suppressing the occurrence of zinc dendrites and parasitic side reactions. Consequently, an asymmetric cell using the PbTiO3@Zn demonstrates a reversible plating/stripping performance for 2900h, and an asymmetric cell reaches a state-of-the-art runtime of 3450h with a high average Coulombic efficiency of 99.98%. Furthermore, the PbTiO3@Zn/I2 battery demonstrated an impressive capacity retention rate of 84.0% over 65000 cycles by employing a slender Zn anode.

Exploring the role of trace Indium in enhancing the cyclic stability and initial capacity of Lithium–ion cathodes

Developing Ni content over 80 % in Li–ion cathodes for batteries is crucial for achieving higher energy density. However, these materials suffer from instability and rapid capacity loss during repeated charging and discharging cycles. This is primarily due to unwanted structural changes caused by Ni2+ and Li+ ions mixture within the material. This study presents a novel approach using trace amounts of indium (In) doping to significantly improve the lifespan and capacity retention of high–nickel cathodes, even at high discharge rates. Additionally, our fabrication method is simple and scalable, utilizing calcination at a moderate temperature of 720 °C. The In-doped cathode exhibited impressive performance. For a cathode with 82 % nickel content with 0.1 mol% In dopant, the battery delivers a discharge capacity of 231 mAh g-1 at a low discharge rate (0.1 C) and maintains a remarkable capacity retention of 95.1 % even after 50 cycles. This enhanced performance can be ascribed to two key factors: the formation of radially oriented nanorods and a reduction in the overall pore volume within the material. These features contribute to improved stability and reduced cation mixing, leading to a longer–lasting and more efficient battery.

Tranq Dope: Characterization of an ED cohort treated with a novel opioid withdrawal protocol in the era of fentanyl/xylazine

BackgroundTreating opioid use disorder has reached a new level of challenge. Synthetic opioids and xylazine have joined the non-medical opioid supply, multiplying the complexities of caring for individuals in emergency departments (ED). This combination, known as ‘tranq dope,’ is poorly described in literature. Inadequate withdrawal treatment results in a disproportionately high rate of patient-directed discharges (also known as against medical advice dispositions, or AMA). This study aimed to describe a cohort of individuals who received a novel order set for suspected fentanyl and xylazine withdrawal in the ED. MethodsThis is a descriptive study evaluating a cohort of ED patients who received withdrawal medications from a novel protocol and electronic health record order set. Individuals being assessed in the ED while suffering from withdrawal were eligible. Individuals under age 18, on stable outpatient MOUD or who were pregnant were excluded. Treatment strategies included micro-induction buprenorphine, short acting opioids, non-opioid analgesics, and other adjunctive medications. Data collected included: demographics including zip code, urine toxicology screening, order set utilization and disposition data. Clinical Opiate Withdrawal Scale (COWS) scores were recorded, where available, before and following exposure to the medications. ResultsThere were 270 patient encounters that occurred between September 14, 2022, and March 9, 2023 included in the total study cohort. Of those, 66 % were male, mean age 37 with 71 % residing within Philadelphia zip codes. 100 % of urine toxicology screenings were positive for fentanyl. Of the 177 patients with both pre- and post-exposure COWS scores documented, constituting the final cohort, patients receiving medications had their COWS score decrease from a median of 12 to a median of 4 (p < 0.001). The AMA rate for this cohort was 3.9 %, whereas the baseline for the population with OUD was 10.7 %. Recorded adverse effects were few and resolved without complication. ConclusionsFentanyl and xylazine withdrawal are challenging for patients and providers. A novel tranq dope withdrawal order set may reduce both COWS scores and rate of patient-directed discharge in this cohort of patients, though further investigation is needed to confirm findings.

Passive battery thermal management and thermal safety protection based on hydrated salt composite phase change materials

Lithium-ion batteries (LIBs) are progressing towards higher energy densities, extended lifespans, and improved safety. However, battery thermal management systems are facing increased demand owing to high-rate charging and discharging, dynamic operating conditions, and heightened thermal safety concerns. Therefore, this paper proposes a novel composite phase change material (CPCM) comprising Na2SO4-10H2O as the core phase change material (PCM) and expanded graphite as the thermal conductivity enhancer. The CPCM offers high latent heat, superior thermal conductivity, and a two-stage temperature control function for battery thermal management and safety. The optimal mass CPCM ratio, determined through comprehensive characterization and thermal property tests, resulted in a melting point of 29.05°C, latent heat of 183.7 J.g−1, and high thermal conductivity of 3.926 W.m−1.K−1. During normal LIB operations, the CPCM efficiently absorbs and transfers heat, reducing the peak LIB temperature from 66 to 34°C at 15°C ambient temperature during a 3.7C high-rate discharge. Under dynamic conditions, the peak temperatures across the three cycles were consistently controlled at 36.7, 36.4, and 35.8°C, respectively. In a thermal runaway state, the thermochemical heat storage of hydrated salt dehydration effectively slowed LIB temperature increase, delaying the time to reach 130°C by 187 s. Suppression of the temperature rise outside the CPCM, combined with an extended dehydration plateau of up to 320 s, prevented the occurrence and propagation of thermal runaway in the battery.

High-performance single crystal Ni-rich cathode with regulated lattice and interface constructed by separated lithiation and crystallization calcination

Incorporating high valence dopants, such as W6+ and Mo6+ has been verified to be effective for tuning the microstructure and grain boundary of polycrystal Ni-rich cathode. However, the hindered consolidation of primary particles induced by dopants during lithiation calcination limits the utilization of those dopants to crystalize single-crystal Ni-rich cathodes with stabilized lattice and surface. Herein, high performance single crystal LiNi0.84Co0.11Mn0.05O2 cathode with Al3+ and W6+ regulated lattice and boundary phase was construed based on commercial process with two-step calcination process containing separated lithiation and crystallization. The introduction of appropriate amount of Al3+ in the first lithiation calcination of 6 h endows the bulk of crystalline with enhanced lattice stability, while the incorporation of W6+ with stoichiometrical LiOH in the secondary crystallization calcination of 6 h renders uniformly distributed surface layer without hampering the growth of single-crystal. With the Al3+ doped bulk lattice, W6+ doped subsurface region and hetero-epitaxially grown Li2WO4, the cathode infused by two-step calcination exhibits high discharge capacity, rate performance, and cycling stability. Specifically, the modified LiNi0.84Co0.11Mn0.05O2 exhibits exceptional capacity retention, maintaining 88.98% of its initial capacity after 200 cycles at a rate of 1 C within a voltage window of 2.7–4.3 V at a temperature of 25 °C in half-cell. This performance is markedly superior to the capacity retention of 72.96% observed for pristine cathode. Even when subjected to a stringent test after 200 cycles at the same rate, the modified cathode sustains an impressive capacity retention of 82.41% at an elevated cut-off voltage of 4.5 V and a temperature of 30 °C.

Crystal structure and hydrogen sorption properties of Nd0.5Y0.5MgNi4-xCox alloys (x = 0–3)

The gas-phase and electrochemical hydrogenation properties of Nd0.5Y0.5MgNi4-xCox (where x varies from 0 to 3) were studied. Samples were prepared using sintering and annealing procedures. X-ray diffraction analysis indicated that all the alloys were single-phase. The alloys readily absorbed hydrogen, and the crystal structures of the resulting saturated hydrides were refined. Nd0.5Y0.5MgNi4H4.2 and Nd0.5Y0.5MgNi3CoH4.4 belong to the NdMgNi4H3.6 structural type, while Nd0.5Y0.5MgNi2Co2H5.5 and Nd0.5Y0.5MgNiCo3H6.0 belong to the LaMgNi4H4.85 structural type. Electrochemical studies revealed that the maximum discharge capacity of Nd0.5Y0.5MgNi4-xCox electrodes increased from 236 mAh/g to 328 mAh/g as the cobalt content increased. The high-rate dischargeability (HRD1000) initially decreased from 48 % to 7 % with increasing cobalt content, but then increased to 32 % at the highest cobalt concentration. Additionally, the electrochemical kinetic properties were determined and compared for these electrodes, including the charge-transfer resistance (Rct), polarization resistance (Rp), exchange current density (I0), limiting current density (IL), and hydrogen diffusion coefficient (DH).