Battery Longevity Research Articles

A V2G strategy to increase the cost–benefit of primary frequency regulation considering EV battery degradation

AbstractElectric vehicle (EV) will prevail in the near future and many EVs are expected to be parked all day or almost all day according to a survey in Japan. They can contribute as vehicle‐to‐grid (V2G) to primary frequency regulation in power systems. However, as lithium‐ion battery or EV battery is still expensive, it is economically important to evaluate V2G frequency regulation cost. This paper proposes the evaluation method of the frequency regulation cost. The proposed method is based on the EV battery cost and longevity, which is shortened by performing the frequency regulation. The battery degradation consists of calendar aging and cycle aging, and an empirical model is used in this paper. Simulation results are shown using the proposed method under the various conditions such as state of charge (SoC) of the EV battery. Those results indicate a V2G control strategy to increase the cost–benefit of primary frequency regulation.

Technical note: Random forests prediction of daily eating time of dairy cows from 3-dimensional accelerometer and radiofrequency identification

Feed intake and time spent eating at the feed bunk are important predictors of dairy cows' productivity and animal welfare, and deviations from normal eating behavior may indicate subclinical or clinical disease. In the current study, we developed a random forests algorithm to predict dairy cows' daily eating time (of a total mixed ration from a common feed bunk) using data from a 3-dimensional accelerometer and a radiofrequency identification (RFID) prototype device (logger) mounted on a neck collar. Models were trained on continuous focal animal observations from a total of 24 video recordings of 18 dairy cows at the Danish Cattle Research Centre (Foulum, Tjele, Denmark). Each session lasted from 21 to 48 h. The models included both the present time signal and observations several seconds back in time (lag window). These time-lagged signals were included with the purpose of capturing changes over time. Because of the high costs of installing an RFID antenna in the feed bunk, we also investigated a model based solely on 3-dimensional accelerometer data. Furthermore, to address the trade-off between prediction accuracy and reduced model complexity and its implications for battery longevity, we investigated the importance of including observations back in time using lag window sizes between 8 and 128 s. Performance was evaluated by internal leave-one-cow-out cross-validation. The results indicated that we obtained accurate predictions of daily eating time. For the most complex model (a lag window size of 128 s), the median of the balanced accuracy was 0.95 (interquartile interval: 0.93 to 0.96), and the median daily eating time deviation was 7 min 37 s (interquartile interval: -6 to 15 min). The median of the average daily eating time during sessions was 3 h 41 min with an interquartile interval of 2 h 56 min to 4 h 16 min. Exclusion of RFID data resulted in a considerable decrease in prediction accuracy, mainly due to a decreased sensitivity of locating the cow at the feed bunk (median balanced accuracy of 0.87 at a lag window size of 128 s). In contrast, prediction accuracy only slightly decreased with decreasing lag window size (median balanced accuracy of 0.94 at a lag window size of 8 s). We suggest a lag window size of 64 s for further development of the prototype logger. The methodology presented in this paper may be relevant for future automatic recordings of eating behavior in commercial dairy herds.

Single- and multi-site pacing strategies for optimal cardiac resynchronization therapy: impact on device longevity and therapy cost.

Multiple left ventricular pacing strategies have been suggested for improving response to cardiac resynchronization therapy (CRT). However, these programming strategies may sometimes entail accepting configurations with high pacing threshold and accelerated battery drain. We assessed the feasibility of predefined pacing programming protocols, and we evaluated their impact on device longevity and their cost-impact. We estimated battery longevity in 167 CRT-D patients based on measured pacing parameters according to multiple alternative programming strategies: single-site pacing associated with lowest threshold, non-apical location, longest interventricular delay, and pacing from two electrodes. To determine the economic impact of each programming strategy, we applied the results of a model-based cost analysis using a 15-year time horizon. Selecting the electrode with the lowest threshold resulted in a median device longevity of 11.5years. Non-apical pacing and interventricular delay maximization were feasible in most patients and were obtained at the price of a few months of battery life. Device longevity of > 10years was preserved in 87% of cases of non-apical pacing and in 77% on pacing at the longest interventricular delay. The mean reduction in battery life when the second electrode was activated was 1.5years. Single-site pacing strategies increased the therapy cost by 4-6%, and multi-site pacing by 12-13%, in comparison with the lowest-cost scenario. Modern CRT-D systems ensure effective pacing and allow multiple optimization strategies for maximizing service life or for enhancing effectiveness. Single- or multi-site pacing strategies can be implemented without compromising device service life and at an acceptable increase in therapy cost.

An improved vehicle to the grid method with battery longevity management in a microgrid application

This paper proposed an improved vehicle-to-grid (V2G) scheduling approach for the frequency control with the advantage of protecting the batteries hence saving the battery lifetime during grid connected service. The proposed methodology is improved in two ways. Firstly, to give a prediction of the available electric vehicle (EV) battery capacity in the control time-step for the V2G service, a deep learning based prediction is developed. Secondly, this study advances the previous V2G method by adding the quantitative analysis of the battery cycle life into the V2G optimization. The accurate prediction of the schedulable battery capacity based on the LSTM algorithm is shown very effective in the power system frequency control. Also, compared with the previous method that without battery lifetime control, the proposed method benefits in the reduction of charge/discharge cycles.

Extending multipoint pacing CRT battery longevity by swapping left ventricular pulse configurations

Cardiac resynchronization therapy (CRT) with left ventricular (LV) MultiPoint™ pacing (MPP) has been shown to improve CRT response by pacing two LV sites (LV1, LV2). While an additional LV pacing site reduces battery longevity, this cost can be minimized by leveraging an existing device-based capture management algorithm (LVCap™ Confirm). The purpose of this study was to evaluate the MPP battery longevity improvement achieved by configuring LV pacing sites to properly leverage LVCap Confirm. Patients previously enrolled in the MORE-CRT MPP trial with existing MPP-enabled CRT-D devices (Abbott Quadra Assura MP™ CD3371-40QC, Quartet™ LV lead) underwent device interrogation. Device electrical characteristics and estimated battery longevities were compared for various MPP settings. At 2.1 ± 1.1years post-implant, the estimated remaining battery longevity in 65 patients was 70 ± 14months with MPP Off (LV pacing from minimum capture threshold). Enabling MPP with maximal anatomical separation between LV1 and LV2 cathodes reduced longevity by 15 ± 14%. However, swapping the LV1 and LV2 cathodes, such that the LV1 threshold was the higher of the two, allowed the device to take full advantage of the LVCap™ Confirm capture management algorithm, resulting in significantly lower longevity reduction of 9 ± 11% (p < 0.001). Ultimately, a mean MPP battery longevity improvement of 7.7 ± 10.3% (p < 0.001) was achieved by simply swapping LV1/LV2 configurations. By properly leveraging device-based capture management features, the impact of MPP on battery longevity can be significantly reduced.

A review of vibrational energy harvesters underpinned by a flexible snap-through buckling beam

Energy Harvesting (EH) is becoming mandatory in autonoumus measurement systems. EH encompasses all of the technologies and processes aimed at scavenging energy from alternative sources and, in particular, unused energy dispersed in the environment. In particular, the application to power directly or prolong the battery longevity of electronic devices (e.g., sensor nodes in a wireless sensors network or wearable sensors) has come to be recognized as very promising, even more so when the devices are installed in hazardous zones, embedded in infrastructure, or where the mains power is unavailable. Recently, it has also been acknowledged that the lack of self-powered devices and the limited life time of batteries represent the main barriers to the diffusion of the Internet of Things (IoT) [1] and to other measurement related applications.

ENERGY FOCUS: Metal–organic-framework-derived “sandwiches” enhance longevity of Li-S batteries

ENERGY FOCUS: Metal–organic-framework-derived “sandwiches” enhance longevity of Li-S batteries

Aging-aware co-optimization of battery size, depth of discharge, and energy management for plug-in hybrid electric vehicles

Plug-in hybrid electric vehicles (PHEVs) have a large battery pack, and the depth of discharge (DOD) significantly affects the battery longevity. In this paper, the battery degradation is considered in the co-optimization of battery size and energy management for PHEVs using convex programming. The impact of DOD on battery degradation and energy management is also investigated. The cost function consists of fuel consumption, electrical energy consumption, and equivalent battery life loss. A real-world speed profile collected from the urban city bus route up to about 70 km is used as an input to evaluate the proposed method. The results suggest that, for both cases with and without battery degradation, the total cost curve with respect to the preset final state of charge (SOC) is an upward parabola, where the optimal DOD can be identified, and the optimal battery size and energy management can be determined. The results also show that, with an initial SOC of 0.9, the proposed method can reduce the total cost by 3.6 CNY compared to other existing studies with the fixed final SOC. Moreover, a sensitivity analysis is conducted to explore the effect of battery price and initial SOC on the optimal DOD and total cost.

Proactive Power Management Scheme for Hybrid Electric Storage System in EVs: An MPC Method

Hybrid electric storage system (HESS) is a promising power supply for electric vehicles (EVs) to prolong battery cycling life. Battery longevity is affected by the magnitude and fluctuation of the charging/discharging power profiles. While vehicle driving, unexpected high power demand can cause battery degradation and should be supplied by the supercapacitor (SC) in the HESS. However, the limited capacity of SCs restricts the HESS benefit. Thus, one of the crucial while challenging issues for an HESS is how to effectively manage the power splitting between batteries and SCs to satisfy the vehicle’s driving demand as well as reducing battery degradation rate. In this paper, a proactive power management scheme is proposed to extend the EVs battery life with the HESS. First, we exploit a time-series forecasting method to predict the short-term vehicle velocity and calculate the future power demand based on prediction results. Next, due to the nonlinear dynamics of the HESS, the T-S fuzzy modeling method is adopted to approximate system nonlinearity and develop an empirical model. Finally, a model predictive control (MPC) based power management problem is formulated. Prediction errors are considered in MPC formulation to improve system robustness. Based on driving profile tests, simulation results demonstrate that the magnitude and fluctuation of battery current are both reduced and the battery life is prolonged by 17.81% compared with the existing methods.

P.657 Neurostimulators in vagus nerve stimulation for refractory depression: Battery longevity diagnostics and clinical considerations

P.657 Neurostimulators in vagus nerve stimulation for refractory depression: Battery longevity diagnostics and clinical considerations

Investigation, development and experimental analyses of a heat pipe based battery thermal management system

Abstract In this paper, the performance of a heat pipe based thermal management technique for batteries has been investigated experimentally. In this regard, a test rig was developed and used to demonstrate the effectiveness of flat heat pipe (heat mat) technology at controlling and maintaining the temperature of a prototype battery module, which consisted of sixteen prismatic lithium-titanate (LTO) cells. Test results were obtained which proved the ability of the technology to keep the battery cells at an optimal temperature, during cycling representative of real-world operation, from either a cold or hot start. The heat mat was shown to efficiently absorb the heat generated by the cells and transfer it effectively to an external cooling medium of either water or refrigerant. In conclusion, it was demonstrated that the maximum cell temperature is significantly reduced and the overall temperature uniformity of the module is greatly improved, when compared to a module with no thermal management. The maximum cell temperature was kept below 28 °C and the module temperature uniformity was maintained at +/−1 °C. By using test cycles that generated a quasi-steady-state heat load from the cells, it was shown that approximately 60% of the heat generated by the cells was removed by the heat mat. The results obtained from this work demonstrate that heat mat technology can improve battery performance and longevity by reducing the degradation and ageing process and cell imbalances, that result from high cell temperatures and module/pack-level temperature non-uniformity.

Finite-pulse waves for efficient suppression of evolving mesoscale dendrites in rechargeable batteries.

The ramified and stochastic evolution of dendritic microstructures has been a major issue on the safety and longevity of rechargeable batteries, particularly for the utilization of high-energy metallic electrodes. We analytically develop criteria for the pulse characteristics leading to the effective halting of the ramified electrodeposits grown during extensive timescales beyond inter-ionic collisions. Our framework is based on the competitive interplay between diffusion and electromigration and tracks the gradient of ionic concentration throughout the entire cycle of pulse-rest as a critical measure for heterogeneous evolution. In particular, the framework incorporates the Brownian motion of the ions and investigates the role of the geometry of the electrodeposition interface. Our experimental observations verify the analytical developments, where the dimension-free developments allows the application to the electrochemical systems of various scales.

Electrodeposition Technologies for Li-Based Batteries: New Frontiers of Energy Storage.

Electrodeposition induces material syntheses on conductive surfaces, distinguishing it from the widely used solid-state technologies in Li-based batteries. Electrodeposition drives uphill reactions by applying electric energy instead of heating. These features may enable electrodeposition to meet some needs for battery fabrication that conventional technologies can rarely achieve. The latest progress of electrodeposition technologies in Li-based batteries is summarized. Each component of Li-based batteries can be electrodeposited or synthesized with multiple methods. The advantages of electrodeposition are the main focus, and they are discussed in comparison with traditional technologies with the expectation to inspire innovations to build better Li-based batteries. Electrodeposition coats conformal films on surfaces and can control the film thickness, providing an effective approach to enhancing battery performance. Engineering interfaces by electrodeposition can stabilize the solid electrolyte interphase (SEI) and strengthen the adhesion of active materials to substrates, thereby prolonging the battery longevity. Lastly, a perspective of future studies on electrodepositing batteries is provided. The significant merits of electrodeposition should greatly advance the development of Li-based batteries.

(Invited) Considerations of Ionic Charge Carriers for Aqueous Rechargeable Batteries

There is a pressing need for new battery technologies in two key areas: high-energy power batteries for electric vehicles, and large-scale storage batteries to buffer the output from the renewable-but-intermittent solar and wind power generation. For storage batteries, the goal is to minimize the levelized energy cost over the devices’ lifetime. This means that electrode materials containing rare and expensive elements should be avoided. Secondly, the cycle life of storage batteries must be excellent — ideally over 10,000 cycles. Thirdly, these batteries should be quickly rechargeable to store, for example, energy from wind farms. Most importantly, storage batteries should be intrinsically safe, i.e., nonflammable. To meet this list of requirements, batteries with aqueous electrolytes relish several distinct advantages. Aqueous electrolytes are cheaper and safer. The simplicity of an aqueous chemistry environment may facilitate long battery longevity, and its high conductivity brings an innate power advantage. In battery chemistry design, one of the most important considerations is the choice of working charge carriers. To date, a majority of battery technologies rely on metal-ion charge carriers. Surprisingly, non-metal cations, particularly proton-containing cations, i.e., H+, H3O+,1 and NH4 +,1,2, have received exceedingly little attention. The simplest form of hydrogen cation, a single proton, is nearly “invisible” with a measured radius of ~0.89 fm or ~2.1 fm, using muon or e- spectroscopy, respectively. Due to the negligible strain of hosting protons, the rate capability and cycle life of proton batteries have the potential to be far superior to those of existing batteries. In this talk, I will introduce some of our new results, experimental and computational, on the storage of new charge carriers in battery chemistry for grid-storage purposes, particularly related to the Grotthuss mechanism3 and the ion/electrode interactions. I will compare different charge carriers in terms of their correlations to electrochemical properties, such as capacity fading, polarization, and operation potentials.

Evaluation of an ultraviolet LED trap for catching Anopheles and Culex mosquitoes in south-eastern Tanzania

BackgroundImproved surveillance techniques are required to accelerate efforts against major arthropod-borne diseases such as malaria, dengue, filariasis, Zika and yellow-fever. Light-emitting diodes (LEDs) are increasingly used in mosquito traps because they improve energy efficiency and battery longevity relative to incandescent bulbs. This study evaluated the efficacy of a new ultraviolet LED trap (Mosclean) against standard mosquito collection methods.MethodsThe study was conducted in controlled semi-field settings and in field conditions in rural south-eastern Tanzania. The Mosclean trap was compared to commonly used techniques, namely CDC-light traps, human landing catches (HLCs), BG-Sentinel traps and Suna traps.ResultsWhen simultaneously placed inside the same semi-field chamber, the Mosclean trap caught twice as many Anopheles arabiensis as the CDC-light trap, and equal numbers to HLCs. Similar results were obtained when traps were tested individually in the chambers. Under field settings, Mosclean traps caught equal numbers of An. arabiensis and twice as many Culex mosquitoes as CDC-light traps. It was also better at trapping malaria vectors compared to both Suna and BG-Sentinel traps, and was more efficient in collecting mosquitoes indoors than outdoors. The majority of An. arabiensis females caught by Mosclean traps were parous (63.6%) and inseminated (89.8%). In comparison, the females caught by CDC-light traps were 43.9% parous and 92.8% inseminated.ConclusionsThe UV LED trap (Mosclean trap) was efficacious for sampling Anopheles and Culex mosquitoes. Its efficacy was comparable to and in some instances better than traps commonly used for vector surveillance. The Mosclean trap was more productive in sampling mosquitoes indoors compared to outdoors. The trap can be used indoors near human-occupied nets, or outdoors, in which case additional CO2 improves catches. We conclude that this trap may have potential for mosquito surveillance. However, we recommend additional field tests to validate these findings in multiple settings and to assess the potential of LEDs to attract non-target organisms, especially outdoors.

Spatiotemporal Quantification of Lithium both in Electrode and in Electrolyte with Atomic Precision via Operando Neutron Absorption.

The commercial uptake of lithium–sulfur (Li-S) batteries is undermined by their rapid performance decay and short cycle life. These problems originate from the dissolution of lithium polysulfide in liquid electrolytes, causing charge and active material to shuttle between electrodes. The dynamics of intractable polysulfide migration at different length scales often tend to escape the probing ability of many analytical techniques. Spatial and temporal visualization of Li in Li-S electrodes and direct mechanistic understanding of how polysulfides are regulated across Li-S batteries starting from current collector and active layer coating to electrode–electrolyte interface are still lacking. To address this we employ neutron depth profiling across Li-S electrodes using the naturally occurring isotope, 6Li, which yields direct spatial information on Li-S electrochemistry. Using three types of Li-S electrodes, namely, carbon–sulfur, carbon–sulfur with 10% lithium titanium oxide (LTO), and carbon–sulfur with LTO membrane, we provide direct evidence for the migration, adsorption, and confinement of polysulfides in Li-S cells at work. Our findings further provide insights into the dynamics of polysulfide dissolution and re-utilization in relation to Li-S battery capacity and longevity to aid rational electrode designs toward high-energy, safe, and low-cost batteries.

Economic Implications of Longer Battery Longevity of Cardiac Resynchronization Therapy Defibrillator Devices in the United States

Introduction The economic impact of generator longevity differs by indicated patient population, as the magnitude of Cardiac Resynchronization Therapy Defibrillator devices (CRT-Ds) survival benefit varies by indication and so does the expected survival of the patient. The objective of this study is to understand cost savings associated with incremental years of battery life from a U.S. payer perspective. Methods Patient data from 7 prospective trials were used to project expected patient survival. Weibull/Gompertz statistical models were fitted to data from: (a) InSync III Marquis, MIRACLE, MIRACLE ICD, PROSPECT and Adaptive CRT for Class III/IV patients, (b) REVERSE for Class II patients, and (c) BLOCK-HF for AV Block patients. Mean battery longevity scenarios used half-yearly increments. A payer perspective based on the 2018 U.S. Centers for Medicare and Medicaid Services (CMS) Medicare program was used. Results Testing mean battery scenarios from 5.5 to 8.5 years, 6 additional months of device longevity result in average Medicare savings of $2,692 for Class III/IV patients, $5,429 for Class II patients and $3,754 for AV Block patients. Additional economic benefits associated with avoiding changeout-related complications were not included in these device cost projections. Conclusions Increasing CRT-D battery life can result in reductions in device-related cost across all indicated patient groups, with economic benefits being maximized among NYHA Class II subjects. But the relative impact lessens as additional battery years are added.

Optimal Scheduling to Manage an Electric Bus Fleet Overnight Charging

Electro-mobility is increasing significantly in the urban public transport and continues to face important challenges. Electric bus fleets require high performance and extended longevity of lithium-ion battery at highly variable temperature and in different operating conditions. On the other hand, bus operators are more concerned about reducing operation and maintenance costs, which affects the battery aging cost and represents a significant economic parameter for the deployment of electric bus fleets. This paper introduces a methodological approach to manage overnight charging of an electric bus fleet. This approach identifies an optimal charging strategy that minimizes the battery aging cost (the cost of replacing the battery spread over the battery lifetime). The optimization constraints are related to the bus operating conditions, the electric vehicle supply equipment, and the power grid. The optimization evaluates the fitness function through the coupled modeling of electro-thermal and aging properties of lithium-ion batteries. Simulation results indicate a significant reduction in the battery capacity loss over 10 years of operation for the optimal charging strategy compared to three typical charging strategies.

Surface Energy and Reconstruction of Li and Na Based Transition Metal Oxides: A Computational Study

Interfaces between cathode particles and electrolyte have significant influence on performance and longevity of Li-ion batteries. Therefore, for further battery improvement deep understanding of cathode-electrolyte interface structure and its relationship with electrochemical processes inside the battery is strongly required. During the last few years, more and more studies are focused on the interfaces and surfaces of cathode particles, especially for layered transition metal oxides (TMO). For example, it was established that TMO surfaces experience reconstruction from layered to spinel and cubic structures, considerably affecting charge transfer through cathode/electrolyte interface and electrolyte and cathode stability [1]. Though initially reconstruction was considered mostly as a detrimental effect, resulting in increased barriers for Li insertion and cathode degradation, new studies show that reconstructed layer can serve as a natural protection from oxygen loss, preventing decomposition of electrolyte and insertion of water in cathode structure [2]. Though it is evident from experimental studies that the reconstructed layer resembles spinel and rock-salt structures, the exact ordering of atoms is controversial. More importantly, the governing factors for reconstruction are still not fully clear: in some cases, reconstruction occurs during synthesis and in others it proceeds under exposure to electrolyte and/or during cycling. Finally, surface reconstruction remains almost unexplored in promising Na-based TMO cathodes, where its role can be highly important, serving as a protective layer from water insertion [2]. In this work, we develop an algorithm for finding reconstructed structures of surface for transition metal oxides. The algorithm is based on the Monte-Carlo method used for a random swap of alkali atoms, transition atoms, and vacancies, while the density functional theory is used for atomic optimization after each Monte-Carlo step and accurate calculation of energies. The Metropolis method allows to take into account the influence of temperature and predict kinetically controlled surface structures. The algorithm is implemented in our SIMAN package for high-throughput materials modelling and available for free use [3]. Employing the developed algorithm, we consider several oxide compounds, such as LiNiO2, NaNiO2 and NaMnO2 used for pragmatic applications for rechargeable Li-ion and Na-ion batteries. We found that in LiNiO2 and NaNiO2 the formation of surface and subsurface anti-site defects is much easier than that in the bulk region. By making simulation at real synthesis temperatures, we observed kinetically controlled formation of spinel layers for both LiNiO2 and NaNiO2. Under oxidative conditions the transformation of the LiNiO2 surface to a rock-salt structure is thermodynamically favorable. The obtained results explain experimentally observed surface reconstruction to spinel and rock-salt structures in layered oxides. The undergoing study will identify the reasons that control the type of reconstruction depending on the chemical composition and synthesis conditions, providing useful guidelines for improving cathode materials.

His bundle has a shorter chronaxie than does the adjacent ventricular myocardium: Implications for pacemaker programming

Strength-duration curves for permanent His bundle (HB) pacing are potentially important for pacemaker programming. We aimed to calculate strength-duration curves and chronaxies of the HB and of the adjacent right ventricular (RV) working myocardium and to analyze zones of selective HB capture and battery current drain when pacing at different pulse durations (PDs). Consecutive patients with permanent HB pacing were studied. The RV and HB capture thresholds were assessed at several PDs. Battery current drain and zones of selective HB capture at PDs of 0.1, 0.2, 0.4, and 1.0 ms were determined. In the whole group (N = 127), the HB chronaxie was shorter than the RV chronaxie. This difference was driven by patients with selective HB pacing (HB chronaxie 0.47 ms vs RV chronaxie 0.79 ms). The strength-duration curve for the HB had a lower rheobase and its steep portion started at shorter PDs, thus creating wider distance-zone of programmable selective HB pacing-between the HB and RV strength-duration curves at shorter PDs. The battery current drain was lower with pacing at PDs of 0.1-0.4 ms vs 1.0 ms. Chronaxie-adjusted PDs offered the lowest current drain. For the first time, the strength-duration curves for permanent selective and nonselective HB pacing were determined. Selective HB capture and battery longevity can be promoted by shorter PDs (0.2 ms). Longer PDs (1.0 ms) offer greater safety margin for RV capture and may be preferable if simultaneous RV capture during HB pacing is desired.