Usable Capacity Research Articles

Practical Aspect of Electrophoretic Deposition to Produce Commercially Viable Activated Carbon Supercapacitor Electrode

Recent years are seeing many published evidences in the successful electrophoretic deposition (EPD) of energy storage electrodes (notably electrodes for lithium-ion battery [1], solid-state electrolyte [2] supercapacitor [3] and flow batteries [4,5]), but their advancement for industrialization are still far from actual adoption [6]. An obvious reason is because the deposited thickness of the coating’s layer in these studies are very thin (less than 1 mm), which give the extreme performance values that are attributed to a complete utilization of low-density active materials (< 1 mg cm-2) for fast accessibility of electrons and ions through the thin layer to the current collector surface. While these fundamental studies are useful for identifying the maximum achievable properties, they are absolutely impractical for any commercial applications which demand thick layers (50 to 80 µm) and high-density active materials (5 to 20 mg cm-2) to provide usable capacity at all power extraction capabilities.This is particularly true for a packed supercapacitor device whereby it is essential to account for the entire mass of the system, which include current collectors, separators, electrode films, binder, electrolyte, connectors and packing materials [7]. This applies even if the estimation is based upon industrial-level active material mass loadings of 10 mg cm-2 or beyond. In such circumstances, the active material mass is only about 30% of the total weight of the device [8]. This means that the system performance calculated from the electrode property has to be divided by 3 or 4 [9]. The divisor is raised to 30 if a thinner electrode having a mass loading of 1 mg cm-2 is employed [7]. Thus, sufficient mass loading of an electrode is required to lower overheads from inactive materials, which can ensure a decent electrochemical performance for a supercapacitor.In view of closing the knowledge gap between fundamental studies and commercial applications, this presentation will show the practical aspects of energy storage electrodes produced by EPD (Figure 1). Activated carbon (AC) particles are sourced from a commercial supplier, and used as an exemplary system of supercapacitor investigation. Practical supercapacitor electrodes with industrially relevant parameters are demonstrated, specifically high-density active material and thick coating layers. This presentation will discuss: (a) formulation of colloidal electrolyte containing activated carbon particles, (b) methodologies and processes of electrophoretic deposition, (c) use of 2D foil vs 3D microporous structure as deposition substrate, (d) impact of post-process calendaring on electrode properties, and (e) electrochemical cycling activities in coin cell assembly, in particular cyclic voltammogram, capacitance, current density, electrochemical impedance spectroscopy and cycle number in comparison to the performance of a scaled-up AC electrode in an A7 sized pouch cell. Overall, this presentation will emphasize the practical aspects of EPD for producing high-quality commercially viable supercapacitors.

Coordinated photovoltaic re-phasing: A novel method to maximize renewable energy integration in low voltage networks by mitigating network unbalances

As combating climate change has become a top priority and as many countries are taking steps to make their power generation sustainable, there is a marked increase in the use of renewable energy sources (RESs) for electricity generation. Among these RESs, solar photovoltaics (PV) is one of the most popular sources of energy connected to LV distribution networks. With the greater integration of solar PV into LV distribution networks, utility providers impose caps to solar penetration in order to operate their network safely and within acceptable norms. One parameter that restricts solar PV penetration is unbalances created by loads and single-phase rooftop schemes connected to LV distribution grids. In this paper, a novel method is proposed to mitigate voltage unbalance in LV distribution grids by optimally re-phasing grid-connected rooftop PV systems. A modified version of the discrete bacterial foraging optimization algorithm (DBFOA) is introduced as the optimization technique to minimize the overall voltage unbalance of the network as the objective function, subjected to various network and operating parameters. The impact of utilizing the proposed PV re-phasing technique as opposed to a fixed phase configuration are compared based on overall voltage unbalance, which was observed hourly throughout the day. The case studies show that the proposed approach can significantly mitigate the overall voltage unbalance during the daytime and can facilitate to increase the usable PV capacity of the considered network by 77%.

A capacity-based equalization method for aged lithium-ion batteries in electric vehicles

A capacity-based equalization method for active balancing is proposed to increase the usable capacity of aged lithium-ion batteries within a minimum of balancing effort. The main goal of the presented algorithm is to predict the equalization charge for each cell, which is needed to fully charge and discharge every cell of the battery in the next cycle. For this, State-Of-Charge (SOC) and State-Of-Health (SOH) of each cell must be determined. The predicted energy is balanced at the beginning of the cycle and further balancing is performed only if the parameters of the cells change. This ensures that the minimum possible balancing effort is achieved. To validate the performance of the proposed method, a simulation is carried out. For this purpose, a battery model and Battery Management System (BMS) model are built in Matlab/Simulink. The parameters of the simulated cells differ in capacity and initial SOC to imitate an aged battery. The simulation results verify that the developed balancing method can improve the usage of aged batteries compared to conventional methods. This algorithm for active balancing can be used in second life cases of battery systems.

System Recovery Boost on IBM z15

System Recovery Boost on the IBM z15 server expedites planned operating system shutdown, either planned or unplanned operating system initial program load (IPL), middleware and workload restart and recovery, and the client workload execution that follows, to accelerate service restoration around downtime. It does this by providing limited-duration “boost periods” that deliver significant usable additional processor capacity and parallelism. On subcapacity machine models, it provides a boost in processor speed by running the general-purpose processors at full-capacity speed, for the boosting LPARs only, and only during the boost periods. It makes all available processing capacity defined to the boosting images available to process any kind of work, “blurring” general-purpose processor and specialty processor capacity together during the boost period. System Recovery Boost also expedites and parallelizes processor reconfiguration actions that may be part of the client's overall restart and recovery process, as orchestrated by Geographically Dispersed Parallel Sysplex (GDPS) automation. Optionally, System Recovery Boost provides the ability to add additional processor capacity from the client's unused “dark cores” via activation of a new type of temporary capacity record. All of this can be accomplished without increasing the client's IBM software billing costs or the processor consumption associated with the client's workload during these boost periods.

Simulations on Design and System Performance of Building Heating Boosted by Thermal Energy Storage (TES) with Magnesium Hydro Carbonates/Silica Gel

In this paper, a simulations model of a seasonal thermal energy storage (TES) reactor integrated into a house heating system is presented. The water vapour chemisorbing reactor contains a composite material composed of silica gel and hydrated magnesium carbonate (nesquehonite, MgCO3·3H2O) that can be produced by a carbon capture and storage by mineralisation process. The performance of the TES to supply winter heat instead of electrical resistance heat is analysed. Dividing the reactor into a few units (connected in series) for better heat output and storage capacity as developed by the authors is compared to one unit or parallel unit solutions. The heating system components are an exhaust air heat pump, solar collectors and a heat recovery ventilation unit (HRV). The TES is used as heat source during colder periods, which implies improved efficiency and coefficient of performance (COP). Around 70% of electrical resistance heat, assisting an exhaust air heat pump during cold periods, can be substituted with heat from the TES according to the simulation model. Connecting three units in series will increase the usable storage capacity possibilities with by a 49% higher heat output.

SVC device optimal location for voltage stability enhancement based on a combined particle swarm optimization-continuation power flow technique

The increased power system loading combined with the worldwide power industry deregulation requires more reliable and efficient control of the power flow and network stability. Flexible AC transmission systems (FACTS) devices give new opportunities for controlling power and enhancing the usable capacity of the existing transmission lines. This paper presents a combined application of the particle swarm optimization (PSO) and the continuation power flow (CPF) technique to determine the optimal placement of static var compensator (SVC) in order to achieve the static voltage stability margin. The PSO objective function to be maximized is the loading factor to modify the load powers. In this scope, two SVC constraints are considered: the reference voltage in the first case and the total reactance and SVC reactive power in the second case. To test the performance of the proposed method, several simulations were performed on IEEE 30-Bus test systems. The results obtained show the effectiveness of the proposed method to find the optimal placement of the static var compensator and the improvement of the voltage stability.

Reversible redox chemistry in azobenzene-based organic molecules for high-capacity and long-life nonaqueous redox flow batteries

Redox-active organic molecules have drawn extensive interests in redox flow batteries (RFBs) as promising active materials, but employing them in nonaqueous systems is far limited in terms of useable capacity and cycling stability. Here we introduce azobenzene-based organic compounds as new active materials to realize high-performance nonaqueous RFBs with long cycling life and high capacity. It is capable to achieve a stable long cycling with a low capacity decay of 0.014% per cycle and 0.16% per day over 1000 cycles. The stable cycling under a high concentration of 1 M is also realized, delivering a high reversible capacity of ~46 Ah L−1. The unique lithium-coupled redox chemistry accompanied with a voltage increase is observed and revealed by experimental characterization and theoretical simulation. With the reversible redox activity of azo group in π-conjugated structures, azobenzene-based molecules represent a class of promising redox-active organics for potential grid-scale energy storage systems.

Conceptual model framework for demand response ancillary services deployed by inter-connected microgrids in West Africa – A Nigerian case study

As a result of the poor electrification rate in many Sub-Saharan countries, several researches have been geared towards the adoption of distributed generation resources (in micro-grids) as a means to ameliorate this menace. For substantial ancillary services rendered, multiple micro-grid operators need to participate in the capacity and energy market. A conceptual framework model is presented in this paper where four distinct microgrids within rural communities are inter-linked and provide ancillary services to one another in the case of a capacity outage in any one of the other microgrids. The Microgrid Ancillary Service Operator (MASO) is in charge of managing the ancillary service which will accept bids from demand response aggregators, and then perform an optimal power flow to allocate capacities (energy resources) to meet demands in a day-ahead or hour-ahead time frame. The techno-economic analysis and distribution network design for one of the micro-grids considered was performed for a typical rural community in a Nigeria which had a residential and commercial load of 551 kWh/day and 23 kW h/day respectively. Results from HOMER showed an optimal system combination of 350 kW solar PV, 150 kW diesel generator, 300 units of Surrette 4KS25 P battery (having a usable nominal capacity of 1368 kW h), and a 100-kW converter. Also, using voltage drop constraints, the analytical design for a 3-bus ring distribution network which comprised a main feeder, and two load buses produced appropriate wiring sizes alongside commensurate resistance and reactance parameters which were within the permissible voltage limits set.

State of charge estimation of lithium-ion batteries using hybrid autoencoder and Long Short Term Memory neural networks

The state of charge (SOC) of a battery indicates its useable capacity. In the case of lithium-ion batteries, an accurate estimate improves their performance. With the recent tendency in the increased use of lithium-ion batteries in electric vehicles, the estimation of SOC has become even a more critical issue than before. In this paper, the combination of an Autoencoder neural network and a Long Short-Term Memory (LSTM) neural network is proposed for the estimation of the SOC of a battery with high precision. The Dynamic Stress Test (DST) drive cycle and the Federal Urban Driving Schedule (FUDS) drive cycle datasets are used to test the proposed algorithm at three different temperatures. To reveal the performance of the proposed method, the results are compared with several other methods from the literature. It is observed that the SOC estimation by the proposed method yields to a significantly better accuracy at all three temperatures.

Phase-field modeling of chemo-mechanical relaxation effect on the fracture tolerance of a tin-based electrode

The fracture phenomenon of high-capacity electrode materials during electrochemical cycles poses a major limitation on further advancements in Li-ion batteries. In this paper, a diffusion-creep-stress-fracture coupling model using the phase-field method is established to explore the chemo-mechanical relaxation effect on the fracture tolerance in a tin-based cylindrical electrode during lithiation. The results show that the creep relaxation mechanisms have twofold influence on the evolution of the multi-field system by altering the distribution of stresses. On the one hand, the relaxation mechanism which is crack size-dependent can improve the mechanical stability and fracture resistance of a tin-based electrode; on the other hand, the Li distributions accounting for creep are more uneven than those without creep, which may result in a reduction in usable capacity. Furthermore, the critical state of charge and its improvement for safe state due to creep relaxation are found to be size-dependent with regard to crack size. It can be associated to the stress concentration effect of flaws which can result in the earlier crack propagation and insufficient creep accumulation for a sharper (or longer) crack with large stress concentration.

Holistic calendar aging model parametrization concept for lifetime prediction of graphite/NMC lithium-ion cells

Aging and life time prediction is most important for any usage of Li-ion cells, especially for battery electric vehicles (BEV). One main focus is on the calendric aging, as a BEV will be used for many years, often in parking mode for most of the time. In this work a model approach is chosen based on a simplified physical description of the main aging mechanisms. The presented calendric aging model is based on the main aging mechanisms anodic side reaction (ASR), cathodic side reaction (CSR) and passive anode effect (PAE). Considering these three aging mechanisms, as well as the half and full-cell open circuit voltage (OCV) characteristics, an aging model with the ability for extrapolation and interpolation between operational conditions is achieved. It does not require many parameters that need to be determined specifically for the used materials such as particle sizes or diffusivity. For parametrization, several calendric storage tests are necessary, evaluating usable and mobile Li capacity, internal resistance and self-discharge at varying states of charge (SoC) and temperatures. With the chosen set of main aging mechanisms, the aging model test matrix and the parametrization procedure, we were able to model the capacity increase in the beginning of the tests due to the PAE. Moreover, by including CSR in the model, the maximum capacity fading at 70% compared to 100% SoC is represented.

Advances in Metal‐Organic Frameworks for Acetylene Storage

Acetylene is an important chemical raw material, but its flammability, explosiveness and incompressibility bring great challenges to its safe storage and transportation. The conventional storage method has high cost and affects the purity of acetylene. It is an efficient means to store acetylene by adsorption using porous materials. Metal‐organic frameworks (MOFs) are a new kind of porous materials with high specific surface area, adjustable and modifiable framework and pore, showing excellent performance in gas adsorption. Therefore, MOFs are expected to provide a way to solve the problem of acetylene storage. In this review, MOFs for acetylene storage are listed, and three strategies to improve the acetylene adsorption capacities of MOFs are concluded; the structure–property relationships of acetylene adsorption of MOFs were revealed, and the usable acetylene storage capacities of MOFs were analyzed. Finally, the issues and challenges of MOFs in acetylene storage were summarized and outlooked.

Hydrogen trapping potential of Ca decorated metal-graphyne framework

Hydrogen holds the promise for alternative clean energy carrier due to its renewable and pollution free nature. A metal-organic framework (MOF) is designed with graphyne linker. Each graphyne linker is decorated with two Ca atoms across the linker with average metal binding energy 3.0 eV. The structural, electronic and hydrogen storage properties of Ca decorated MOF have been explored by using first principle calculations. On full saturation with hydrogen, each Ca atom of MOF-Ca8 adsorbs a maximum of six H2 molecules and results in MOF-Ca8-48H2 structure. Further twelve more hydrogen molecules could be accommodated in the pore space of MOF resulting in the MOF-Ca8-60H2 structure having 7.9 hydrogen wt%. According to the simulations, the H2 molecules can be adsorbed on Ca by Kubas mechanism with elongation in H−H bond distance. The calculated hydrogen interaction energy is found in the range between 0.25 and 0.30 eV while desorption energy varies between 0.15 and 0.32 eV. The charge transfer during hydrogen adsorption is investigated by Hirshfeld charge analysis and electrostatic potential map. The molecular dynamics simulations revealed a high degree of reversibility in hydrogen adsorption of the system at ambient conditions. The usable capacity of H2 is explored by calculating occupation number at adsorption and desorption conditions. The energetics and storage capacity meets the US DOE target which makes the MOF-Ca8 as a potential hydrogen storage material.

The influence of the anode overhang effect on the capacity of lithium-ion cells – a 0D-modeling approach

Abstract In this work, the behavior of the anode overhang effect in lithium-ion cells is experimentally investigated and simulated for experimental three electrode cells. An empirical method is presented to transfer the simple 0D-model from the experimental cell level to pouch cells. An anode overhang model will help to correctly interpret cyclic and calendaric aging experiments e.g. in terms of a more reliable and detailed separation of reversible and irreversible capacity losses as well as evaluating the actual state of health of a lithium-ion battery. For the three electrode cells different cathode diameters are used to modulate different sized anode overhang areas. Moreover, the influence of different state of charges on the reversible capacity effect is investigated. To examine the influence of the separator on the evolution of usable cell capacity different separator thicknesses are applied. It is found that the properties of the separator significantly influence the rate at which balancing processes between overhang and active region take place. The results show good accordance of the experimental results to the simulation.

Low-Strain Reticular Sodium Manganese Oxide as an Ultrastable Cathode for Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) are recognized as attractive alternatives for grid-scale electrochemical energy storage applications. Transition metal oxide cathodes represent one of the most dynamic materials for industrialization among the various cathodes for SIBs. Here, a cation-doped cathode Na0.44Mn0.89Ti0.11O2 with a tunnel structure is introduced, which undergoes a lowered volume change of only 5.26% during the Na+ insertion/extraction process. Moreover, the average Na+ diffusion coefficients are enhanced by more than 3-fold upon the doping of the Ti cation. The obtained cathode delivers a practically usable capacity of 119 mAh g-1 at 0.1 C as well as an enhanced discharge capacity of 96 mAh g-1 at 5 C. Durability is demonstrated by the retained 71 mAh g-1 after 1000 cycles, corresponding to a capacity retention of 74%. This work demonstrates that the reticular Na0.44Mn0.89Ti0.11O2 is a promising ultrastable cathode material for the development of long-life sodium-ion batteries.

Analysis of degradation in residential battery energy storage systems for rate-based use-cases

This article examines the impact of residential battery energy storage (BES) systems’ operational modes on the life (i.e. usable energy capacity) of the battery under several climatic conditions and battery chemistries. The sharp increase in residential BES installations has been a result of decreasing costs of batteries, increase in rate structures motivated applications such as solar self-consumption and time-of-use energy management, and customers purchasing these systems for backup power. While these different modes of operations provide a combination of increased bill savings, reliability of supply, and energy sustainability to the customer, their operational characteristics vary significantly between use-cases. Functional life of BES systems is known to be strongly dependent on their operating conditions. In this article, we analyze the operation of residential BES systems under different rate-based use-cases, for different battery chemistries and cell designs, and under different environmental conditions. This is conducted by simulating the control of BES operations using rate-based cycling algorithms and analyzing the prognosis of multiple battery lifetime models that consider complex nonlinear dependencies of operational stress factors such as state-of-charge, depth-of-discharge, and temperature on degradation. Significant variations in battery life are observed owing to the differences in characteristics of the uses-cases coupled with environmental conditions and battery chemistries. Such differences lead to the conclusion that choice of residential BES technologies and chemistries should account for their intended use-cases.

River Regulation Alleviates the Impacts of Climate Change on U.S. Thermoelectricity Production

AbstractClimate change is projected to elevate stream temperature and poses threats to thermoelectric power generation. Although two thirds of the global rivers are regulated by dams, the impacts of river regulation on stream temperature and thermoelectricity production have not been evaluated in previous studies. Using a state‐of‐the‐art integrated water cycle model and a power generation model, we quantify the impacts of river regulation on stream temperature and usable capacity of once‐through thermoelectric power in the United States. Our study demonstrates that by lowering stream temperature and increasing water availability during the low‐flow season, river regulation can curtail the loss of summer power plant usable capacity induced by climate change. The alleviation of power loss by water management is comparable to that resulting from emission mitigation that reduces warming in the future. Our new findings highlight the necessity of incorporating water management effects in thermoelectric power vulnerability assessment.

Lithium-Ion Polymer Battery for 12-Voltage Applications: Experiment, Modelling, and Validation

Modelling, simulation, and validation of the 12-volt battery pack using a 20 Ah lithium–nickel–manganese–cobalt–oxide cell is presented in this paper. The cell characteristics influenced by thermal effects are also considered in the modelling. The parameters normalized directly from a single cell experiment are foundations of the model. This approach provides a systematic integration of actual cell monitoring with a module model that contains four cells connected in series. The validated battery module model then is utilized to form a high fidelity 80 Ah 12-volt battery pack with 14.4 V nominal voltage. The battery cell thermal effectiveness and battery module management system functions are constructed in the MATLAB/Simulink platform. The experimental tests are carried out in an industry-scale setup with cycler unit, temperature control chamber, and computer-controlled software for battery testing. As the 12-volt lithium-ion battery packs might be ready for mainstream adoption in automotive starting–lighting–ignition (SLI), stop–start engine idling elimination, and stationary energy storage applications, this paper investigates the influence of ambient temperature and charging/discharging currents on the battery performance in terms of discharging voltage and usable capacity. The proposed simulation model provides design guidelines for lithium-ion polymer batteries in electrified vehicles and stationary electric energy storage applications.

Microbial inoculants: potential tool for sustainability of agricultural production systems.

Microbial inoculants are gaining importance for attaining sustainable agricultural production systems. Nutrient supply capacity of soil is diminishing continuously owing to soil erosions, degradation, deposition of salts, undesirable elements and metals, water scarcity or excess and imbalanced nutrient supply system. Numerous complementary microbial inoculation combinations are contributing immensely in the management of plant nutrients by way of fixation, solubilization or transformation in soil. Thus, biological wastes and microbial inoculants are alternatives for nutrient demands to bridge future gaps in. A consortium of microorganisms provides enabling and congenial option to maintain their usable capacity for sufficient durations that heads to the positive impact on the microbial activity of soil for desired activities at the target sites. Increased application of agro-chemicals results in deleterious effect on biological system and dependence of future agriculture on these will lead to deterioration in soil health, threats of pollution of water bodies and cumulative effect of these is making production system highly vulnerable and unstable consequently leading to heavy load on the fiscal system. To ameliorate negative impacts, microorganisms are strongly emerging as alternatives for conserving productive capacity for sustainable productions and financial balance of economies. Microbial inoculants that have assumed definite and significant roles for their specificity and necessity and their use in various combinations have emerged as viable and sustainable options to maintain and even enrich the soil health. Since these microbial inoculants are used under varied farming situations and diverse climates with heterogeneous management skills, their efficacies under field conditions remain variable. Thus, it is never-ending process to identify solutions for constraints and application difficulties and further identify newer microbial inoculants for unexplored areas. Adequate timely and quality access of these inoculants to end users is equally important along with developing their skills to utilize these for witnessing desirable and visible impacts.

Lung Damage Mechanisms For COVID-19 and Other Lung Infections, and Driving Force in Leukecyte Recruitment and Migration

To understand lung damage caused by COVID-19, we deduced two-phase lung damage mechanisms. After the lungs are infected with SARS-CoV-2 virus, the affected lung tissue swells and surface properties of pulmonary capillaries change, resulting in an increased flow resistance of affected capillaries. If a sufficient number of capillaries are affected by the infection, the swelling and increased cell wall adhesion collectively raise pulmonary vascular resistance. The increased vascular resistance further increases the dwell times of WBCs in affected capillaries and nearly capillaries. When pulmonary pressure is sufficiently higher, WBCs are forced to squeeze into interstitial spaces or alveolar spaces when local pressures are higher than what the capillaries can withstand. When more and more WBCs are dynamically retained, the flow resistance of more capillaries rises, pulmonary vascular resistance rises, and pulmonary pressure rises. The rise in the pulmonary pressure in turn results in elevated capillary pressures. When capillary pressures around the alveoli are sufficiently high, they cause interstitial pressures to change from normally negative values to positive values. The positive pressures cause fluid leakage to the alveolar space and thus degrade lung function. Tissue swelling, and occupation of WBCs in interstitial spaces and alveolar spaces further reduce compressible volume, and thus cause further rise in the pulmonary vascular resistance and pulmonary pressure. When the pulmonary pressure has reached a critical point as in the second phase, the blood breaks capillary walls and squeezes through interstitial spaces to reach alveolar spaces, resulting in irreversible lung damages. The available free volume in the thorax cage, organ usable capacities, temperature and humid are expected to have great impacts on degree of lung damages. The free volume in the thorax cage, lung usable surplus capacity, and other organ usable capacities determine the arrival time of last-phase irreversible damage. The mechanisms imply that the top priority for protecting lungs is maintaining pulmonary micro-circulation and preserving organ functions in the entire disease course while controlling viral reproduction should be stressed in the earliest time possible. The mechanisms also explain leukecytes are recruited and migrated into inflamed tissues by increasing their dwell times caused by increased local flow resistance.