High SOC Research Articles

Temporal and spatial dynamics of carbon and water use efficiency on the Qinghai-Tibet plateau and their ecosystem responses

Research on the carbon and water use efficiency (CUE, WUE) in the Qinghai-Tibet Plateau (QTP) holds significant importance due to its implications in understanding and addressing global environmental challenges, particularly climate change. This study comprehensively explored the spatiotemporal distribution patterns and trends of WUE and CUE on the plateau from 2001 to 2018 using linear regression analysis and geostatistical methods. The results revealed a gradual decrease in WUE from southeast to northwest, showing a non-linear variation trend during the study period. CUE exhibited relatively minor spatial variations but demonstrated a significant decrease trend in the eastern regions. The results from the Random Forest algorithm and path analysis indicated that ecosystem respiration (Re) was the predominant controlling factor for WUE and CUE in the cold alpine (PA) region. In the temperate, warm temperate (Te&WT) region, temperature emerged as the primary determinant for WUE, while Leaf Area Index (LAI) served as the absolute dominant factor for CUE. Additionally, LAI also played a crucial role in determining WUE and CUE in the tropical and subtropical (Tr&S) region. Partial correlation analysis highlighted the heterogeneity in the responses of WUE and CUE to environmental changes across different regional climates and vegetation types. The findings emphasized the significant impact of biological factors on terrestrial carbon and water cycling processes (WUE and CUE) within the context of global climate change. Furthermore, the study identified a potential linkage between WUE and CUE, with their relationship to vegetation dynamics showing significant variations across various ecosystems. WUE and CUE showed a positive correlation in the western regions, particularly in high-altitude areas, while a negative correlation was observed in eastern regions with high SOC. In the Te&WT and the Tr&S region, the increase of NDVI (Normalized difference vegetation index) suppressed the rise of both WUE and CUE, establishing a negative correlation between them. Conversely, in the PA region, a significant positive correlation trend between WUE and CUE was observed, indicating a positive response to the decrease in NDVI. These findings are of significant importance for advancing the understanding of and effectively addressing climate change, maintaining ecosystem stability, and promoting sustainable socio-economic development.

Influence of Cycling in Different State-of Charge Windows on Lifetime and Electrode Expansion of Microscale Silicon-Dominant Lithium-Ion Batteries

Silicon (Si) is a promising active anode material for next-generation lithium-ion batteries due to its high theoretical electrochemical capacity of 3579 mAh/gSi (Li15Si4) and low costs using microscale Si particles.1,2 However, the wide usage of Si as an active anode material is hindered due to its lower lifetime compared to graphite anodes. The degradation in silicon-containing batteries can be suppressed by partial lithiation strategies,2,3,4 with applications for automotive cells leading to improved lifetime.5 However, the lifetime problem still exists in partially lithiated microscale Si particles with lower volume expansion2,3 with ≈200 cycles for one-third silicon utilization, i.e., 1200 mAh/gSi 2. Moreover, we confirmed in our previous study6 as reported by Wetjen et al.4 and Haufe et al.2 that lower cell discharge cut-off voltages and thus higher silicon delithiation potentials versus Li+/Li led to accerlated aging and should be avoided.Thus, the motivation for this study is to avoid these high anode delithiation potentials by operating the cells in a high full cell state of charge (SoC) and to investigate the influence of different SoC windows on lifetime with laboratory 182.1 ± 0.7 mAh/gNCA Swagelok T-cells comprising a microscale silicon-dominant anode and a NCA cathode. The electrode-specific aging is monitored with the lithium metal reference electrode based on the anode and cathode potentials and pulse tests. To investigate the aging in different SOC regimes, three cycling conditions were chosen in the low (LV), middle (MV) and high voltage (HV) window and compared to cells cycled between 2.8 and 4.2 V as full voltage6. The voltage window of LV, MV and HV were chosen to represent cycling between 0-50%, 25-75%, and 50-100% SOC, respectively. Formation and checkups were the same for all cells with 2.80 V to 4.20 V. After reaching the end-of-life criterion of 55% state of health (SoH), the cells were disassembled and anode and cathodes were re-assembled in half-cells for a post-mortem analysis to reveal loss of lithium inventory (LLI) and loss of active material of the anode LAMAn, and the cathode LAMCat of the respective full-cells. Complementary to the electrochemical aging, dilatometer measurements7 were conducted to quantify the electrode expansion for the different silicon anode SoC windows since particle decoupling is expected to be one of the major aging mechanisms for microscale silicon2, which is expected for high electrode expansions.For the electrochemical results, the lifetime can be drastically increased from ≈230 to ≈560 equivalent full cycles (EFCs) for operating the full cell in the HV compared to the FV window, as shown in Fig. 1a. One EFCs is defined as the total charge throughput for charging and discharging one cycle normalized to the capacity of the initial checkup cycle. Over aging, the full cell degradation correlates very well with the end of discharge potential of the silicon anodes. Moreover, the electrode-specific pulse results show strong anode degradation while the cathode remains intact. The post-mortem results reveal LLI as most dominenat aging mode, which was very similar for all voltage windows. The HV cells showed both the highest LAMNE and LAMPE, whereas LAMNE was more dominant compared to LAMPE. The silicon amorphization was the lowest for the LV anodes and the highest for the HV anodes at the same SoH. The dilatometer results show that the silicon electrode expansion is the lowest for the low lithiation, i.e., LV, and the highest for the highest lithiation, i.e., HV. From the dilatometry results, we conclude that the mechanical electrode stability does not limit lifetime.Our results demonstrate that lifetime can be significantly improved by a factor of ≈2.4 based on the EFCs if operating cells with silicon dominant anodes in high SoCs and that low SoCs should be avoided. Acknowledgments: S. F. gratefully acknowledges the financial support from the BMBF (Federal Ministry of Education and Research, Germany) under the auspices of the ExZellTUM III project (grant number 03XP0255). The authors want to thank our student worker, Maximilian Reichl, for the fabrication of the NCA coatings. We also thank Wacker Chemie AG for kindly providing the microscale silicon material.

Role of AI and ML in Reducing Testing Costs and Improving Yield of High Density SoCs

Role of AI and ML in Reducing Testing Costs and Improving Yield of High Density SoCs

Dynamic thermal runaway evolution of Li-ion battery during nail penetration

The nail penetration test is widely adopted to evaluate the safety of lithium-ion batteries by triggering the internal short circuit. This work compares the phenomena, temperature rise rate, surface temperature, and mass loss under the penetration test for different nail materials, nail diameters, and cell SOCs. The thermal runaway behaviour and characteristics of these test cells are studied in depth. The results show that the maximum temperature and temperature rise rate of the cell increase with the increase of SOC. The maximum temperature and the temperature rise rate of the cell decrease with the increase of the nail diameter. Under high SOC conditions (greater than 75 % SOC), the more conductive nail increases the release of Joule heat generation inside the battery, which leads to a more intense thermal runaway behaviour. At low SOC (less than 50 % SOC), the more conductive nail promote cooling, which reduces the intensity of thermal runaway. However, non-conductive nails show the exact opposite effect. This dual effect of different nail materials was elucidated by a simplified heat transfer analysis. By calculating the heat production and heat dissipation during the thermal runaway process, the effects of the nail material and the cell SOCs on the thermal runaway behaviour of the battery can be summarized. This work deepens the understanding of the safety of batteries under external shocks and provides new scientific insights into battery design and its safety testing.

Self-Discharge and Calendar Aging Behavior of Li-Ion and Na-Ion Cells

The calendar aging and self-discharge behavior of Na-Ion cells containing a layered oxide NaNi1/3Fe1/3Mn1/3 (NFM) cathode were investigated and compared to two Li-Ion cell chemistries, G/LiFePO4 (LFP) and SiG/LiNi0.8Mn0.1Co0.1O2 (NMC811). The self-discharge measurements were performed via voltage hold experiments at different states of charge (10%, 40%, 50%, 70%, 90%, and 100%) and temperatures (25 °C, 40 °C and 55 °C). A high-precision coulometry analysis was conducted to investigate the coulombic efficiency (CE), differential voltage analysis (DVA), and end-point slippage. The results show that the Na-Ion cells present a similar self-discharge behavior to the NMC811 Li-Ion cells. In addition, via CE and end-point slippage analysis, strong reversible reactions were observed for the Na-Ion cells. Despite the poor CE values, the cells presented a low capacity loss. Post-mortem analysis showed sodium plating on the edges of all the SOCs investigated. The LFP results presented mainly calendar losses from lithium inventory loss with almost no cathode-related degradation. At high SOCs, both transition metal cathodes, NMC811 Li-Ion and NFM Na-Ion, exhibited more cathode-related processes dominating the self-discharge current and presumably improving the capacity retention due to electrolyte oxidation. Finally, the Na-Ion cells showed anode overhang equalization effects like Li-Ion cells.

Influence of soil pH and organic carbon content on the bioaccessibility of lead and copper in four spiked soils

Exploration of the association between heavy metal bioaccessibility (BAc) and soil properties is essential for rationalization of risk assessment and remediation of contaminated soil; however, the high complexity of soil systems often yield conflicting outcomes. To avoid erroneous conclusions, individual comparisons of soil properties is essential. Herein, we determined the changes in the BAc of Pb and Cu with the variation in soil pH and SOC content using Unified Bioaccessibility Research Group of Europe method, and validated these findings with in vivo mouse bioassays. Results indicated that the BAc of Pb and Cu in gastric and intestinal phases decreased by 1.76%–3.92% and 0.90%–3.27%, and by 0.41%–6.01% and 0.67%–1.59%, respectively, with every unit increase in soil pH. Furthermore, with every 1% increase in the absolute content of SOC, the BAc of Pb and Cu decreased by 4.04%–13.94% and 4.01%–34.7%, and by 8.98%–30.15% and 9.58%–20.03%, respectively. The in vivo bioassays results confirmed decrease in Pb concentrations in the liver, kidney, and blood of mice with the increase in Ferralosol pH and SOC content. These findings revealed that the health risks associated with accidental exposures to Pb- and Cu-contaminated soils with high pH and SOC level were relatively low, and the consistent in vivo and in vitro results for the BAc of Pb and Cu suggest the requirement for a swift and simple approach for assessing the risks of heavy metal contaminated soils. Thus, this study enhanced our understanding of the variations in risk assessments with soil properties of Pb- and Cu-contaminated soils, highlighting the role of soil characteristics in health risk assessment and remediation of contaminated soils.

An Aging-Optimized State-of-Charge-Controlled Multi-Stage Constant Current (MCC) Fast Charging Algorithm for Commercial Li-Ion Battery Based on Three-Electrode Measurements

This paper proposes a method that leads to a highly accurate state-of-charge dependent multi-stage constant current (MCC) charging algorithm for electric bicycle batteries to reduce the charging time without accelerating aging by avoiding Li-plating. First, the relation between the current rate, state-of-charge, and Li-plating is experimentally analyzed with the help of three-electrode measurements. Therefore, a SOC-dependent charging algorithm is proposed. Secondly, a SOC estimation algorithm based on an Extended Kalman Filter is developed in MATLAB/Simulink to conduct high accuracy SOC estimations and control precisely the charging algorithm. The results of the experiments showed that the Root Mean Square Error (RMSE) of SOC estimation is 1.08%, and the charging time from 0% to 80% SOC is reduced by 30%.

Core microbial taxonomies that maintain high organic carbon content in upland soil

The accumulation of soil carbon (C) is crucial for the productivity and ecological function of farmland ecosystems. The balance between microbial carbon dioxide (CO2) emission and fixation determines the sustained accumulation potential of C in soil. Microorganisms involved in this process are highly obscure, thus hindering identification and further application of microorganisms with fertile soil function. In this study, a series of typical upland farmland soils were collected from 29 regions and their microbial community structure and soil C fractions were analyzed. Additionally, the rates of CO2 emission and fixation in each soil were measured. The results showed that the correlation between soil CO2 emissions and the SOC concentration was logarithmic, while that between CO2 fixation and SOC was linear. Bacterial and fungal diversity showed an upward trend with increasing soil C, and their α diversity was significantly correlated with CO2 fixation, but not correlated with CO2 emission. Fungi were more associated with soil C than bacteria, and the strength of linkage with soil C varied among the different phyla of microorganisms. Furthermore, the core microbial taxa in soils with low, medium and high SOC levels were identified by discarding redundant amplicon sequence variants, and their community differentiation was significantly driven by soil CO2 emission and fixation based on Mantel analysis. The high abundance of Chloroflexi, Nitrospirota, Actinobacteria, and Mortierellomycota in core taxa might indicate a high level of SOC level. This study highlights that SOC fluctuations are mainly driven by the core microbial taxa, rather than all microbial taxa in the agricultural system. Our research sheds light on the targeted regulation of the soil microbial community structure in upland farmland for soil fertility enhancement.

From science to practice: The AGSUS protocol for monitoring and certification of sustainable soil management and carbon sequestration

Sustainable soil management is indispensable for achieving the UN Sustainable Development goals and soil carbon sequestration for climate change mitigation has gained importance in recent years, yet there are few examples of projects carried out to this purpose, and protocols that facilitate this task. Here we present a monitoring system that relies on sampling soils in the field, as opposed to a modeling approach. The high spatial variability of SOC was addressed by requiring that the participating farms divide their land according to management zones, based on soil type, slope position and land use history, and the sampling density was established as one sampling point per one hundred hectares, while for environments smaller than 500 ha minimum of five points must be used. These points are georeferenced and will be revisited for annual monitoring of sustainable soil management, and every five years for soil sampling for SOC, texture, bulk density, pH, electric conductivity (if indicated), and available phosphorus determinations. The monitoring of sustainable soil management will be carried out through a visual evaluation of 12 soil quality parameters, as described in the handbook published by the AGSUS group. The data obtained from the visual evaluation and the soil analyses (bulk density, particle size fractions, C content, and pH) in the baseline monitoring of Argentinean and Brazilian farms during 2022 were analyzed for the relation between visual evaluation score and the means of these soil parameters. The organic matter indicator (OMI)was calculated by the formula OMI = OM/clay plus silt*100. The data base contained visual soil evaluation scores at 80 georeferenced sampling points, representing 12 farms located in different agroecological zones of the Argentinean Pampas, and 47 sampling points on two farms in Mato Grosso, Brazil. Our results showed a relationship between the VE (Visual Evaluation) score and SOC contents of the soils, especially when these were expressed in relation to their fine mineral particles as with the OMI for the soils of the Argentinean Pampa and the Brazilian Mato Grosso. The OMI showed differences between the three VE scores ranging from 4.7 to 6.7 and from 3.1 to 5.1 in the 0–0.1 m and 0.1–0.2 m depths, respectively. Relationships between the VE score and SOC, OMI, Sand, Silt and Clay plus Silt were only found for the 39 cases of VE “moderate” score in Pampas soils, whereas for the 39 cases of “good” scores no significant relations were encountered. These soils had high SOC and OMI, indicating that they are healthy soils, near saturation level, with low C sequestration potential.

Is the Comparator in Your Diagnostic Cost-Effectiveness Model “Standard of Care”? Recommendations from Literature Reviews and Expert Interviews on How to Identify and Operationalize It

ObjectivesThis research aimed to develop best-practice recommendations for identifying the “standard of care” (SoC) and integrate it when it is the comparator in diagnostic economic models (SoC comparator). MethodsA multi-methods approach comprising 2 pragmatic literature reviews and 9 expert interviews was used. Experts rated their agreement with draft recommendations based on the authors’ analysis of the reviews. These were refined iteratively to produce final recommendations. ResultsFourteen best-practice recommendations are provided. Care pathway mapping (using quantitative, qualitative, or mixed-methods approaches) should be used for identifying the SoC comparator. Guidelines analysis can be integrated with expert opinion to identify pathway variability and discrepancies from clinical practice. For integrating the SoC comparator into the model, recommendations around structure, input sourcing, data aggregation and reporting, input uncertainty, and model variability are presented. For example, modelers should consider that the reference standard is not synonymous with the SoC, and the SoC may not be the only comparator. The comparator limitations should be discussed with clinical experts, but elicitation of its diagnostic accuracy is not recommended. Probabilistic sensitivity analysis is recommended when evaluating the overall input uncertainty, and deterministic sensitivity analysis is useful when there is high model uncertainty or SoC variability. Consensus could not be reached for some topics (eg, the role of real-world data, model averaging, and alternative model structures), but the reported discussions provide points for consideration. ConclusionsTo our knowledge, this is the first guidance to support modelers when identifying and operationalizing the SoC comparator in diagnostic cost-effectiveness models.

Calendar Aging of Lithium-Ion Batteries: Investigating the Influence of Electrolyte Additives in Open-Circuit and Floating State-of-Charge Conditions

Battery electrolytes play an important role in battery performance and safety. To improve the formation of a solid-electrolyte interface (SEI) and overall performance, additives such as vinylene carbonate (VC) and fluoroethylene carbonate (FEC) are added to the electrolyte. A thorough understanding of the aging process is critical to the safe operation of batteries. The reactions of the liquid electrolyte, its additives and the associated gas formation play a decisive role in cell aging and cell safety. Thus they are in the focus of the BatgasMod project (Modelling of battery gassing) funded by the German Federal Ministry of Education and Research (BMBF) in the framework of the competence cluster Battery usage concepts (BattUse). The aim of the BatgasMod project is the modeling of the gassing behavior of batteries over their lifespan and the combination of electrolyte aging models with battery models for an early prediction of cell behavior in the usage phase.In order to support the modeling with aging data, three different cell variants were produced, differing in terms of their electrolyte composition. The cells were assembled at the MEET by combining commercial LiNi0.6Mn0.2Co0.2O2 (NMC622) cathode and graphite anode material together with a ceramic coated separator. The electrolyte for all three cell types is a mixture of the organic solvents EC and EMC in a ratio of 3:7 with 1M LiPF6. This composition without additives represents the reference cell. To investigate the influence of the additives, cells were prepared with either5 wt.-% vinylene carbonate (VC) or 5 wt.-% fluoroethylene carbonate (FEC) as an additive.First, both at IAM-AWP and ISEA cell formation was performed to study the entire life of the cells, including the critical step of SEI formation in the first cycles. After degassing, the cells were subjected to 10 additional cycles to obtain a stable capacity for the start of the aging tests. The cells were stored in temperature chambers at 25°C with SOCs of 100%, 80%, 30% and 5%. At IAM-AWP measurements were performed under open circuit conditions to allow for self-discharge. For comparison, at ISEA the cells were aged under floating SOC conditions, i.e. the SOCs were kept constant throughout the entire measurement. At predetermined time intervals, the cells were checked for remaining capacity and pulse resistance. In both measurements the influence of the SOC is clearly visible and the high SOC leads to an increased aging. The electrolyte additives showed different results for the different aging tests. The cells without additives outperform the cells with additives under open circuit conditions. This unusual behavior was further investigated and was attributed to the high self-discharge of the cells without additives. As a result, the voltage drop leads to a lower storage SOC, which was beneficial for the aging of these cells. The electrolyte additives showed deviating results for the different aging tests. The floating SOC measurements revealed a superior performance of the cells with additives. In addition, it was found that cells containing VC have lower capacity loss but higher resistance increase than cells containing FEC. Differential voltage analysis and incremental capacity analysis were performed to better understand the dominant aging mechanisms. These methods suggest that a combination of loss of lithium inventory and impedance rise causes cell degradation.These results provide guidance for improving calendar aging by selecting the most appropriate electrolyte additive. Future work will focus on comparing the influence of additives on the safety of fresh and calendar aged cells.

Nano-enhanced phase change material using salt hydrate and cooper nanoparticles for battery thermal management system: Buoyancy-driven approach

Using computational fluid dynamic (CFD) simulation for battery thermal management system (BTMS) enables give a correct understanding of controlling battery temperature. The use of phase change material (PCM) is a popular option for managing the battery temperature in a certain range due to the solid-liquid transition, in which salt hydrate was used in this study. Also, adding nanoparticles with high thermal conductivity can compensate the low thermal conductivity of PCM, in which copper nanoparticles were used as PCM reinforcement in current work. In addition, the buoyancy force was considered in liquid phase, making the numerical results closer to physical ones. The present work focuses were on the effects of volume fraction of copper nanoparticle and discharge rate on battery temperature and melting fraction. Evidence indicated that the appropriate distance between the LIBs could set 0.1D, 0.2D, and 0.4D for C-rate of 2, 4, and 6, respectively. Additionally, most impacts of cooper nanoparticle with 3 % volume fraction was observed only in high SOC, e.g. 3 % volume fraction reduced the melting fraction from 38.5 % to 34.5 % in SOC = 100 %. Also, increase in C-rate from 2 to 6 warmed up LIB from 304 K to 319 K when zero volume fraction.

Perspectives on Effective Long-Term Management of Carbon Stocks in Chernozem under Future Climate Conditions

Arable Chernozems with high SOC contents have the potential to be significant sources of GHGs, and climate change is likely to increase SOC losses, making the issue of carbon sequestration in this region even more important. The prospect of maintaining SOC stock or increasing it by 4‰ annually under planned management practice modifications for the period up to 2090 was evaluated using a long-term experiment on Haplic Chernozem in the Rostov Region, Russia. In this study, we used the RothC model to evaluate SOC dynamics for three treatments with mineral and organic fertilization under two adaptation scenarios vs. business-as-usual scenarios, as well as under two climate change scenarios. The correction of crop rotation and the application of organic fertilizers at high rates are essential tools for maintaining and increasing SOC stocks. These methods can maintain SOC stock at the level of 84–87 Mg∙ha−1 until the middle of the 21st century, as the first half of the century is considered to be the most promising period for the introduction of adaptation measures for the additional accumulation of SOC on Chernozems. Part of the additional accumulated SOC is expected to be lost before 2090.

Depletion of Electrolyte Salt during Calendaric Aging at High State-of-Charge in Li-Ion Batteries

Batteries using Ni-rich cathode active materials are the most common cells in the automotive sector. They offer a high energy density at competitive prices which makes them attractive in a wide-range of applications.[1,2] However, a higher Ni-content results in more challenges for battery lifetime in comparison to low-Ni materials. These challenges are aggravated at elevated temperatures and high SOCs, stemming from detrimental side-reaction, such as parasitic heat and oxygen release.[3–6] In this study, we investigated an aging effect which is relevant in a wide-range of cell formats ranging from small single layer pouch cells to automotive cells. Upon storing cells at a high SOC at elevated temperatures (30 days, 45 °C) a significant drop in rate-performance was visible afterwards. At the same time, no active Li-loss and no significant increase in 10 second DCIR resistance at 50%SOC was seen. We propose a mechanism of LiPF6-loss during storage as the main reason for the worsened rate-performance.By conducting ion chromatography (IC) and NMR analysis of electrolytes from aged cells, it was found that cells stored at an upper cut-off potential of 4.2 to 4.4 V lose a significant fraction of LiPF6 after a 30-day storage at 45 °C. In addition to these storage experiments, cells with fresh electrolyte, but lower electrolyte salt concentrations (1 M LiPF6 to 0.2 M LiPF6) were built, with the goal of using them as a calibration curve to map the worsened rate performance after storage onto a corresponding electrolyte salt concentration without the need of a destructive analysis of the cells. As seen in Figure 1, the rate performance of freshly built single layer pouch cell is highly dependent on the electrolyte salt concentration. While all cells show good discharge capacities at C/10, at higher discharge rates the lower concentration cells show a worsened performance. 1 M LP572 cells show excellent rate-capabilities up to a rate of 2C and a 0.2 M cell already has a significant drop in discharge capacity at C/2. Using OEMS, electrochemical impedance measurements and theoretical models we further elucidate the mechanism of LiPF6-loss at elevated temperatures and high SOCs.

Comprehensive Approach about Time-Relevant Degradation of Ni-Rich Cathode Materials for Electric Vehicles

With the prevalence of electric vehicles, Ni-rich layered cathodes have been extensively developed to increase the energy density of Li-ion batteries (LIBs). However, cathodes with a high Ni content suffer from inherent structural and chemical instabilities, which lead to rapid capacity fading and thermal instability.1 In particular, the rapid capacity fading of Ni-rich layered cathodes is largely caused by microcracking and the resultant microstructural instability.2 In addition to microcracking, the time during which highly reactive Ni4+ ions are exposed to the electrolyte when the cathode is in a highly charged state also affects the deterioration of the cathode. Although the exposure time is not significant for cathodes with Ni contents of <60%, the calendar aging test of Ni-rich cathodes reveals that the exposure time, especially at high SoCs, critically affects the degradation of these high-Ni cathodes, as the internal surfaces of the particles are also exposed to the electrolyte via the microcracks.3 The exposure time is particularly pertinent for electric vehicle (EV) LIBs, as they remain stationary for long periods in the highly charged state and are operated intermittently. Consequently, the upper SoC limit of EV LIBs is commonly limited to ≈85%, but this limits the driving range and increases the cost of the batteries. Therefore, a holistic approach considering real-use behavior, as well as the properties of the material itself, is needed to overcome the limitations of Ni-rich cathodes.Here, 1 mol% B doping of a core–shell concentration gradient (CSG) Li[Ni0.88Co0.10Al0.02]O2 cathode (CSG-NCA88) is shown to dramatically alter the microstructure of the cathode and effectively protect the particle interior from parasitic electrolyte attack. The B-doped CSG-NCA88 cathode, CSG-NCAB87, maintains its original microstructure even after holding for 500 h in the fully charged state, whereas irreversible structural damage occurs in the pristine CSG-NCA88 cathode during the prolonged electrolyte exposure. The long-term cycling results confirm that the capacity retention of the cathodes is determined by the electrolyte exposure time at a high SoC and that microstructural modification can effectively suppress the time-dependent degradation from electrolyte attack. The proposed CSG-NCAB87 cathode can be utilized at full capacity without restricting the SoC, thus realizing the development of economical high-energy-density LIBs. Reference s : [1] H.-J. Noh, S. Youn, C. S. Yoon, Y.-K. Sun, J. Power Sources, 2013, 233, 121.[2] H.-H. Ryu, K.-J. Park, C. S. Yoon, Y.-K. Sun, Chem. Mater. 2018, 30, 1155.[3] H.-H. Ryu, G.-T. Park, C. S. Yoon, Y.-K. Sun, Small, 2018, 14, 1803179.

Understanding of Stress-Driven Internal Short Circuit Mechanisms in Lithium-Ion Batteries with High SOCs.

The characteristics of internal short circuits (ISC) play a critical role in determining the thermal runaway behaviors and associated hazards of lithium-ion batteries (LIBs). However, due to safety concerns and limitations in operando characterization at high state-of-charges (SoCs), the fundamental understanding of stress-driven ISCs under high SOC situations (above 30%) is still lacking. In this study, combined post-mortem characterization and multiphysics modeling is employed to clarify the evolution of ISC modes in LIBs with high SOCs. These findings reveal that the triggered ISC mode is SOC-dependent, with the Al current collector (Al)-Anode coating (An) mode dominant in high SOC situations. Experimentally obtained ISC resistance for the specified ISC mode is then assigned to the corresponding ISC region in the established multiphysics model, allowing for accurate coupling of the electromechanical relationship and prediction of mechanical-electrical-thermal responses of the LIB. Finally, a simple yet effective approach is proposed for avoiding the Al-An mode after battery fractures, achieved through surface notches on electrodes. Results discover novel phenomena for ISC in high SOC cells and reveal the underlying mechanisms, highlighting the importance and potential of battery structural design for developing next-generation robust batteries.

A dual-layer cooperative control strategy of battery energy storage units for smoothing wind power fluctuations

The large-scale integration of wind power with intermittent characteristics into grids brings a challenge to the power system. Installation of the battery storage energy system (BESS) in a wind farm (WF) can effectively smooth wind power fluctuation. However, the BESS units may face the problem of over-charge/over-discharge if the power dispatch strategy for multiple units of BESS is improper, which results in lifetime degradation. In this paper, a dual-layer cooperative control strategy of multiple BESS units is proposed. In the first layer, the time-varying characteristics of wind power are introduced to define a power fluctuation coefficient. The coefficient can adjust the time constant of the first-order low pass filter (FLF) to avoid the deep energy utilization of BESS and decrease the over-charge/over-discharge possibility. To facilitate more power output for units with high SOC and absorb more energy for units with low SOC, the second layer calculates a SOC distribution factor by a function of the SOC of each unit to allocate the power command. The two layers of control operate cooperatively to reduce the SOC variation and unbalance degrees, thus the over-charge/over-discharge can be avoided, which is good for prolonging the lifetime of BESS with multiple units. Taking an actual WF in the Hunan province of China as the research object, the effectiveness of the proposed strategy is verified by the co-simulation of DIgSILENT/PowerFactory and Matlab/Simulink.

Online parameters identification and state of charge estimation for lithium-ion batteries based on improved central difference particle filter

Accurate SOC is of great significance to alleviate the endurance anxiety of electric vehicle drivers. To improve the accuracy of SOC estimation, a method of combining FFRLS and GPR for parameter identification and an improved particle filter for lithium battery SOC estimation are proposed. The proposed collaborative parameter identification method uses the forgetting factor recursive least squares (FFRLS) to identify the parameters in the middle and high SOC region. In the low SOC region, the parameters identified by the FFRLS are used as the training data of Gaussian process regression (GPR) for model parameter prediction to improve the parameter identification accuracy in the low SOC region; in the SOC estimation stage, the central difference Kalman filter is used to generate the importance density function to overcome the particle degradation, and the step size h of the central difference is calculated suboptimal to further improve the prediction accuracy. Finally, the proposed method is compared with other methods under different working conditions and different temperatures, and the effectiveness and adaptability of the proposed method are verified.

Phenotypic diversity of bamboo Schizostachyum lima (Blanco) Merr. population grown in several critical habitats on Lombok Island, Indonesia

Abstract. Aryanti E, Arumingtyas EL, Azrianingsih R, Arisoesilaningsih E. 2023. Phenotypic diversity of bamboo Schizostachyum lima (Blanco) Merr. population grown in several critical habitats on Lombok Island, Indonesia. Biodiversitas 24: 2788-2796. This study aims to analyze the phenotypic diversity among populations of Schizostachyum lima (Blanco) Merr. grown in several critical habitats on Lombok Island. Sampling was conducted to record clump growth and habitat properties of 38 sites grouped based on the clump density using PAST 4.11 and ArcGIS 10.8.2 software. Sampling was conducted to record clump growth and habitat properties of 38 sites grouped based on the clump density using PAST 4.11 and ArcGIS 10.8.2 software. The results showed that habitat 1 was the most critical land and had the lowest fertility, but it provided a qualified bamboo as a raw material for the artisanal straw industry. The results showed that habitat 1 was the most critical land and had the lowest fertility, but it provided a qualified bamboo as a raw material for the artisanal straw industry. Bamboo density reached 46 culms per clump and had the smallest culms diameter of 13 mm. Bamboo density reached 46 culms per clump and had the smallest culms diameter of 13 mm. The soil comprised 90% sand, with SOC 0.9 g.kg-1, total N 0.08 g.kg-1, and CEC 8.3 me.100 g-1. The soil comprised 90% sand, with SOC 0.9 g.kg-1, total N 0.08 g.kg-1, and CEC 8.3 me.100 g-1. Meanwhile, habitat 6 and habitat 7 were lesser critical, consisted of 66% of sand, showed the best soil fertility, and mean SOC 4.98 g.kg-1, total N 0.30 g.kg-1, CEC 27.23 me.100 g-1, density 151 culms, and biggest culms diameter 33 mm. Meanwhile, habitat 6 and habitat 7 were lesser critical, consisted of 66% of sand, showed the best soil fertility, and mean SOC 4.98 g.kg-1, total N 0.30 g.kg-1, CEC 27.23 me.100 g-1, density 151 culms per clump, and biggest culms diameter 33 mm. The other habitats varied in soil quality and bamboo growth properties. It was revealed that the high culms density, diameter, height, and internodal length were significantly increased in the high soil CEC, SOC, and total N. Furthermore, the SOC and total N content significantly correlated with the wall thickness.

Predicting soil organic carbon stocks in different layers of forest soils in the Czech Republic

Carbon dioxide, the most produced anthropogenic greenhouse gas, could be moderated by sequestering carbon in forest soils. Forest soils store more carbon than there is in the atmosphere. Thus, the smallest variation in soil carbon levels could trigger a significant change in atmospheric carbon. This study focused on predicting the spatial distribution of carbon stocks within surface organic and mineral topsoil and subsoil layers of the forty-one natural forest areas of the Czech Republic. Cubist and Random Forests machine learning algorithms were employed with a grid search hyper tuning to improve prediction accuracy. We used the five-fold cross-validation to verify the model accuracy using Root Mean Square Error (RMSE), coefficient of determination (R2), and Mean Absolute Error (MAE). Random Forests yielded lower RMSE of 1.10 kg/m2, 3.85 kg/m2, and 4.77 kg/m2 in the surface organic horizon (F + H layer), mineral topsoil (0–30 cm layers) and subsoil horizons (30–80 cm layers), respectively, compared to the RMSE values of Cubist, which were 1.14 kg/m2, 3.90 kg/m2, and 4.91 kg/m2 in the surface organic, mineral topsoil and subsoil horizons, respectively. R2 values of both models were low for all three horizons considered. Random Forests were the preferred algorithm for SOC stock prediction in all layers of the forest soils. Cubist predicted the spatial distribution of SOC stocks with more covariates than Random Forests. Altitude was the most important covariate for the spatial distribution of SOC stocks for both Random Forests and Cubist in all soil horizons considered. High SOC stocks for all soil horizons are spatially concentrated in soil horizons along the country borders in the mountaineous natural forest areas.