Performance Of Li-ion Batteries Research Articles

Preparation and Lithium Storage Properties of MOF‐Derived Bimetallic Sulfide ZnxInyS/MXene Composites

Nanostructured metal sulfides (MSs) are considered promising anode materials for Li‐ion batteries (LIBs) due to their high specific capacity and abundant raw material resources. However, the practical application of these materials faces challenges such as poor conductivity and volume expansion. To address these issues and enhance the performance of LIBs, it is crucial to tackle the structural design problem associated with ZnxInyS anode material. The utilization of metal sulfides derived from metal‐organic frameworks (MOFs) not only improves conductivity but also mitigates the issue of volume expansion in metal sulfides. Furthermore, connecting the metal sulfides derived from MOF to various conductive substrates can further enhance their conductivity. Two‐dimensional transition metal carbides and nitrides (MXenes), a novel type of 2D material with plentiful functional groups and chemical properties, offer great potential. In this study, we have strategically constructed ZnxInyS/MXene heterostructures by combining the advantages of 2D Ti3C2TX nanosheets and bimetallic MOF structures. The results demonstrate that due to the synergistic effect between MXene and heterostructure, a significant number of lattice defects and ample buffer space are provided, resulting in excellent lithium storage performance and fast ion diffusion kinetics for the electrode.

Construction of uniform MgO nanoshells for improved high-voltage performance of Li-ion batteries.

A conformal Mg(OH)2 nanoshell was constructed through a wet-chemical process, where a gradual release of OH- as the precipitating agent was designed to ensure the heterogeneous growth of the coating species. Such a coating treatment was found to be efficient in improving the structural stability and electrochemical stability of a 5 V LiNi0.5Mn1.5O4 cathode.

Toward Long-Life High-Voltage Aqueous Li-Ion Batteries: from Solvation Chemistry to Solid-Electrolyte-Interphase Layer Optimization Against Electron Tunneling Effect.

Water is pursued as an electrolyte solvent for its non-flammable nature compared to traditional organic solvents, yet its narrow electrochemical stability window (ESW) limits its performance. Solvation chemistry design is widely adopted as the key to suppress the reactivity of water, thereby expanding the ESW. In this study, an acetamide-based ternary eutectic electrolyte achieved an ESW ranging from 1.4 to 5.1V. The electrolyte confines water molecules within the primary solvation sheath of Li-ions, reducing the free water and breaking the hydrogen bond network. Despite this, initial capacity retention is suboptimal due to inadequate formation of solid-electrolyte-interphase (SEI) layers. To address this, additional hydrogen evolution reaction is induced by widening the operation voltage range, thereby optimizing the SEI layer to mitigate the electron tunneling effect. This approach resulted in a denser LiF-rich SEI layer, effectively preventing water decomposition and improving long-term cycle stability. The optimized SEI layer reduced the electron tunneling barrier, achieving a discharge capacity of 152 mAh g-1 at 1 C and maintaining 76% of its capacity (116 mAh g-1) after 1000 cycles. This study highlights the critical role of both solvation structure and SEI layer optimization in enhancing the performance of high-voltage aqueous Li-ion batteries.

Improving Li-ion Battery Performance with Internal Cooling

The use of Li-ion batteries has expanded fast in recent decades due to the rising use of electric vehicles, mobiles, laptop, robots’ drone, digital cameras etc., but there are numerous issues with batteries, including thermal runaway, cell rupture, decreased battery life, and an internal short circuit caused by overheating and overcharging. High-power draw systems tend to heat the battery beyond its safe operating temperature range, reducing the cell's lifespan. Researchers used a variety of battery heat management systems (internal/external) to tackle these issues. Most researchers, as well as commercial applications, have embraced external cooling systems employing air, PCM, or liquid cooling. There is a shortage of study on cell internal cooling. Internal cooling of Li-Ion prismatic cells and battery packs has been designed and analysed in this study (2S-2P). Under various C rates, we observed heat generation. Then we used rectangular flow channels inside the electrodes and de-ionized water as a coolant. CFD analysis were done for simulation. Without cooling, the maximum temperature of the battery pack was 338K, but after internal cooling, the maximum temperature of the battery pack was 306K, which is ideal for maintaining good battery health.

Tailoring Li4Ti5O12 Performance in Li-Ion Batteries with a Focus on Rate Capability: Recent Advances on Ion Doping, Morphology Control, and Composite Formation

Tailoring Li4Ti5O12 Performance in Li-Ion Batteries with a Focus on Rate Capability: Recent Advances on Ion Doping, Morphology Control, and Composite Formation

Li-ion batteries with poly[poly(ethylene glycol) methyl ether methacrylate]-grafted oxidized starch solid and gel polymer electrolytes

Polymer electrolytes are considered in lithium-ion batteries because of their high safety and properties such as flexibility, easy moldability, etc. Starch is one of these polymers from renewable resources. Considering the semi-crystal structure of starch and ion conduction in amorphous phase, herein starch is oxidized and then modified with poly[poly(ethylene glycol) methyl ether methacrylate]. Solid polymer electrolytes (SPEs) are prepared by dissolution of lithium salt within polymer while gel polymer electrolytes (GPEs) as crosslinked structures are swollen in lithium salt solution. After validation of successful syntheses, all SPEs and GPEs with different oxidation state and various PEGMA/oxidized starch are evaluated in Li-ion battery performance. The synthesized GPEs and SPEs show the highest ionic conductivity of 5.5 × 10−3 and 2.19 × 10⁻⁴ S cm⁻1, respectively at room temperature. Lithium ion transfer number (t+) of 0.6–0.9 and electrochemical stability window of 4.4–4.9 V are obtained for SPEs and GPEs. The discharge capacity is ∼180 mAh g−1 at 0.2 C with capacity retention of 75 % after 100 cycles.

The Effects of Low-Temperature Exposures on Li-Ion Battery Performance

Li-ion batteries (LIBs) are the foundation of modern-day electronics, electric vehicles, and renewable energy storage solutions due to their high energy density and Coulombic efficiency and long cycle life. However, using Li-ion batteries at low temperatures, such as in northern climates and space applications, results in drastically reduced performance due to, in part, lower diffusion properties [1,2]. Moreover, recent studies indicate that storing LIBs at low temperatures leads to electrode degradation, which further reduces their performance at normal temperatures [3]. While multiple studies demonstrate reduced LIB performance during operation at low temperatures [4–8], the mechanisms affecting the LIBs during low-temperature storage are not well understood. Therefore, identifying these mechanisms is crucial to developing low temperature-compatible Li-ion batteries. In this work, we study the effects of low-temperature exposures on the performance of Li-ion batteries when they are restored to normal temperature conditions. Single-layer pouch cells with NMC cathodes and graphite anodes are fabricated and thermally cycled between ambient temperature and -60 °C with controlled ramp rates. Electrochemical studies are then performed at ambient conditions, which reveal two performance deterioration contributions: electrolyte effects in the initial stages of low-temperature exposures and loss of active material associated with long-term thermal cycling. Post-mortem analysis was used to identify that cathode particle cracking is the primary electrode degradation mechanism. Acknowledgments The authors gratefully acknowledge the NASA Established Program to Stimulate Competitive Research (EPSCoR) Program for funding this research (NASA Grant Number 80NSSC23M0068). The authors also acknowledge Dr. William West and Dr. Marshall Smart (NASA Jet Propulsion Laboratory) for technical discussion of this work and Dr. Sara Nelson and Ms. Hailey Waller (Iowa NASA EPSCoR) for administrative services.

Thermal Stability and Performance of Li-Ion Batteries at Elevated Temperatures: Separator Effects

The performance and safety of lithium-ion batteries (LIBs) are significantly influenced by the stability and integrity of their components that have been optimized for a limited temperature range (ca. 0 to 40°C). At elevated temperatures, conventional LIBs exhibit issues such as rapid capacity fade, compromised electrolyte stability, and an increase in internal resistances. With the push towards net-zero emissions, it is imperative that suitable materials and cell designs be identified to allow rechargeable battery integration into operations with temperatures as high as 100°C for applications such as space exploration, drilling equipment, and automotive technologies.In our presentation, we will report that a design of experiment (DOE) study examining several independent variables and interactions of variables in the cell design revealed that the standard polyolefin separator is associated with both decreased Coulombic efficiency and increased variability in cycling performance at elevated temperatures relative to non-polyolefin (e.g. polyimide) separators. In a separate study, electrochemical data were obtained by cycling coin cells at 100oC, varying only the separator (Fig. 1). After the first 20 cycles, the polyimide cells maintained a higher specific capacity relative to the polyolefin cells. Figure 1. Specific capacity vs. cycle number for NMC111/graphite coin cells with Polyimide and Polyolefin separatorsThe nature of the separator alterations from a chemical and electrochemical perspective will be presented, which will provide valuable insight into the critical role of separators in battery design while simultaneously offering alternative materials for operations as high as 100°C. Figure 1

Mitigating Capacity Degradation and Surface Oxygen Loss of Single-Crystalline LiNiO2 Cathodes Via Al2O3 Surface Coating

The performance of next-generation Li-ion batteries (LIBs) for electric vehicle applications relies on energy-dense and low-cost lithium-ion chemistries. Single-crystalline LiNiO2 (SC-LNO) cathodes are regarded as promising materials for high-energy-density applications owing to their high practical capacity, resistance to particle cracking and competitive cost [1]. However, under high voltage operation (≥ 4.4 vs. graphite), they experience rapid capacity loss, owing to parasitic electrode-electrolyte reactions expedited by surface oxygen loss [2]. Overcoming this, stabilising the long-duration performance of SC-LNO cathodes to operate at high voltages while maintaining capacity retention is critical for their integration into commercial batteries. Surface engineering by coating could provide an effective approach to tune the electrochemistry of Ni-rich cathodes while inhibiting degradation pathways [3,4]. Aluminium oxide (Al2O3) coating is used as a barrier to eliminate highly reactive electrolyte species (HF) from the cathode surface, thereby enhancing long-term stability and improving high voltage performance [5,6]. It offers a viable strategy to control the surface of SC-LNO from O loss (O-n, n > 2) and protect it from electrolyte attack. In this study, we employ an ultrathin and conformal film of AlOx on SC-LNO powder via Powder Atomic Layer Deposition (P-ALD). To minimise moisture exposure, the slurry and casting processes were performed in a controlled dry room environment. Electrochemical testing was carried out in balanced coin cells (vs. commercial graphite) at 25 oC and cycled between a voltage range of 2.5–4.2 V and 2.5–4.4 V. Following two formation cycles performed at a C/20 rate, the cells were cycled 100 times at C/3 rate. Electrochemical impedance spectroscopy measurements were also performed before and after 100 cycles to assess any impedance changes.The electrochemical data revealed that AlOx coated SC-LNO cathodes provide significantly higher capacity retention (94.5%) than uncoated ones (66.3%) after 50 cycles at 4.4 V (vs. graphite). Regarding the rate capability test, the coated cathode delivers improved and stable capacities at faster rates compared with uncoated SC-LNO cathodes. Online electrochemical mass spectroscopy (OEMS) analysis of the AlOx coated cathodes indicates that the onset potential for oxygen loss related gas evolution is > 4.4 V vs. Li/Li+. In contrast, for the uncoated SC-LNO sample, this was found to be ~4.2 V. Hence, the AlOx coating serves as a protective layer, for the cathode against electrolyte-induced degradation and transition metal dissolution at high voltage by forming Al-O-F species at the surface [6]. This beneficial interaction enhances the electrochemical performance by effectively inhibiting impedance growth and improving the cycling life and stability of SC-LNO cathodes. This study highlights the crucial role of AlOx coatings in mitigating surface oxygen loss, which is a key factor contributing to the deterioration of cell performance and issues related to Li+ kinetics. Our findings significantly contribute to advancing the development of high-performance SC-LNO cathode materials, offering valuable insights into the application of ALD coatings for enhancing the performance of Li-ion battery cells.[1]. Lee, Dong-hee, Maxim Avdeev, Dong-il Kim, Weon Ho Shin, John Hong, and Minkyung Kim. "Regulating Single-Crystal LiNiO2 Size and Surface Coating toward a High-Capacity Cathode for Lithium-Ion Batteries." ACS Applied Energy Materials 6, no. 10 (2023): 5309-5317.[2]. Zhang, Hanlei, Hao Liu, Louis FJ Piper, M. Stanley Whittingham, and Guangwen Zhou. "Oxygen loss in layered oxide cathodes for Li-ion batteries: Mechanisms, effects, and mitigation." Chemical reviews 122, no. 6 (2022): 5641-5681.[3]. Shi, Yang, Yingjie Xing, Kitae Kim, Taehwan Yu, Albert L. Lipson, Arrelaine Dameron, and Justin G. Connell. "Communication—reduction of DC resistance of Ni-rich lithium transition metal oxide cathode by atomic layer deposition." Journal of the Electrochemical Society 168, no. 4 (2021): 040501.[4]. Haworth, Abby R., Beth IJ Johnston, Laura Wheatcroft, Sarah L. McKinney, Nuria Tapia-Ruiz, Sam G. Booth, Alisyn J. Nedoma, Serena A. Cussen, and John M. Griffin. "Structural Insight into Protective Alumina Coatings for Layered Li-Ion Cathode Materials by Solid-State NMR Spectroscopy." ACS Applied Materials & Interfaces (2024).[5]. Chen, Zonghai, Yan Qin, Khalil Amine, and Y-K. Sun. "Role of surface coating on cathode materials for lithium-ion batteries." Journal of materials chemistry 20, no. 36 (2010): 7606-7612.[6]. Lebens-Higgins, Zachary W., David M. Halat, Nicholas V. Faenza, Matthew J. Wahila, Manfred Mascheck, Tomas Wiell, Susanna K. Eriksson et al. "Surface Chemistry Dependence on Aluminum Doping in Ni-rich LiNi0. 8Co0. 2− y Al y O2 Cathodes." Scientific reports 9, no. 1 (2019): 17720. Figure 1

Electrolyte Dependence of Li+ Transport Mechanisms in Small Molecule Solvents from Classical Molecular Dynamics

As demands on Li-ion battery performance increase, the need for electrolytes with high ionic conductivity and a high Li+ transference number (tLi) becomes crucial to boost power density. Unfortunately, tLi in liquid electrolytes is typically <0.5 due to Li+ migrating via a vehicular mechanism, whereby Li+ diffuses along with its solvation shell, making its diffusivity slower than the counteranion. Designing liquid electrolytes where the Li+ ion diffuses independently of its solvation shell is of significant interest to enhance the transference number. In this work, we elucidate how the properties of the solvent influence the Li+ transport mechanism. Using classical molecular dynamics simulations, we find that a vehicular mechanism can be increasingly preferred with a decreasing solvent viscosity and increasing interaction energy between the solvent and Li+. Thus, a weaker interaction energy can enhance tLi through a solvent-exchange mechanism, ultimately improving Li-ion battery performance. Finally, metadynamics simulations show that in electrolytes where a solvent-exchange mechanism is preferable, the energy barrier to changing the coordination environment of Li+ is much lower than in electrolytes where a vehicular mechanism dominates.

Non-Dendritic Lithium Plating Enabled By LiBF4 and Lidfob Salts Prevents Rollover Failiure in High-Voltage Li Ion Batteries

Increasing the upper cut-off voltage (UCV) offers a pragmatic way to enhance energy density of Li ion batteries (LIBs). Nevertheless, it is accompanied by rapid capacity fade, and in the worst case, by a rollover failure. Rollover failure originates from high surface area lithium (HSAL) formation and subsequently, active lithium losses (ALL), which is triggered by transition metal deposits (TM) on the negative electrode in the course of electrode crosstalk. The electrolyte is capable to alter this failure cascade, either via suppressing TM dissolution and/or scavenging dissolved TMs. While the effect of solvents, additives, and LiPF6 decomposition products have been investigated, the impact of lithium salts on the performance of high-voltage LIBs, parricularly in practical cell format, remains ambiguous.In this work, the performance of common lithium salts, particularly LiBF4 and lithium difluoro oxalatoborate (LiDFOB), in an ethylene carbonate (EC)/ethyl methyl carbonate (EMC) mixture, are investigated in NCM 622 || graphite wounded pouch cells. Though the lower oxidative stability of LiBF4 and lithium difluoro(oxalate)borate (LiDFOB) compared to LiPF6 increases TM dissolution, they enhance capacity retention compared to LiPF6. Capacity endpoint slippage, combined with scanning electron microscopy and nuclear magnetic resonsnce analyses reveals that these salts suppress ALL due to the formation of non-dendritic metallic lithium over the course of TM-induced lithium plating. Also, active lithium generation enabled by DFOB- anion oxidation on the positive electrode, can additionally compensate ALL until the DFOB- anion is fully consumed. Consequnetly, lithium morphology is suggested to be more decisive than dissolved TM amounts in causing rollover failure, pointing to the importance of Li salt design for optimizing high-voltage electrolytes.

How Fast Charging Affects Manganese Spinel Structure

Lithium-ion batteries have transformed the market of portable electronics and electric vehicle due to their high energy density and efficiency. Positive electrode materials play a critical role in determining the performance and stability of Li-ion batteries. LiMn2O4 (LMO) and LiNi0.5Mn1.5O4 (LMNO) are important positive electrode materials known for their valuable electrochemical properties.1 LMO, a manganese-based spinel, exhibits low cost and high working potential, making it attractive material for consumer electronics.3 On the other hand, LMNO, which incorporates nickel into the manganese spinel structure, offers enhanced specific capacity and cycling stability, making it a potential candidate for high-energy applications such as electric vehicles.4,5 This study investigates the impact of fast charging on the structure of spinel-based positive electrode materials, focusing on LMO and LMNO representatives. Fast charging is achieved using the constant current constant voltage (CCCV) method, a common technique in Li-ion battery charging protocol characterized by an initial constant current phase followed by a constant voltage phase. We investigated samples charged at 2C, 5C and 10C-rate current as well as different voltage cut-off conditions. Ex situ Raman mapping, X-ray diffraction (XRD) and scanning electron microscopy (SEM) are employed to assess structural changes and possible impurity formation during the fast charging processes. Raman mapping is very sensitive on local structural changes and gives detailed insights into electrode composition with good statistics. By probing vibrational modes associated with spinel structures, the technique provides spatially resolved data on phase distribution and impurity formation. XRD complements this analysis by providing bulk structural information, including lattice parameters and crystallographic phase changes induced by fast charging. The combined application of these techniques allows a comprehensive understanding of the electrode's response to harsh charging conditions. This study underlines the importance of investigating structural stability and highlights the utility of readily available and very capable techniques, including Raman mapping and XRD, in explaining the mechanisms behind performance decline and capacity loss in Li-ion battery electrodes subjected to fast charging. An in-depth understanding of structural changes under fast charging conditions, especially in view of the growing fast charging infrastructure, is crucial for the advancement of battery technology.This work was funded by the National Center for Science in Poland through the Sonata BIS 11 programme (No. UMO-2021/42/E/ST5/00390). Marcus Fehse et al. Chem. Mater. 2022, 34, 14, 6529–6540Burak Aktekin et al. ACS Appl. Energy Mater. 2019, 2, 5, 3323–3335Francesco Paparoni et al. J. Phys. Chem. C 2023, 127, 18, 8649–8656Jinfeng Zeng et al. ACS Appl. Energy Mater. 2024, 7, 6, 2405–2415Nicholas P. W. Pieczonka et al. Phys. Chem. C 2013, 117, 31, 15947–15957

Estimating State of Charge and State of Health of Lithium-Ion Batteries in Japanese Satellite Reimei

In-orbit satellite REIMEI, developed by the Japan Aerospace Exploration Agency (JAXA), has been relying on off-the-shelf Li-ion batteries since its launch in 2005 [1]. The data from the batteries have been recorded and analyzed ever since. These comprise current and voltage measurements of several thousand cycles [2,3].The performance and durability of Li-ion batteries is impacted by various degradation mechanisms, one of which is the growth of the solid-electrolyte interphase (SEI). Long-term SEI growth is the greatest contributor to capacity fade in lithium-ion batteries. Physics-based models for long-term SEI growth have been developed [4,5]. To show the inhomogeneous growth of the SEI in 3D, we performed microstructure-resolved simulations [6].In this contribution, we will address several aspects of the analysis and simulation of the batteries of satellite REIMEI. We simulate long-term degradation under the generic LEO satellite cycling conditions in a P2D framework. The simulations are validated with terrestrial experiments and in-flight data provided by JAXA [1,6].These studies are the foundation for analyzing the states of the batteries, which cannot be measured directly. To estimate the state of charge and state of health, we make use of filter techniques and the in-flight data of the satellite batteries. Kalman filters are particularly suitable for the noisy data. Since the states change on different timescales, a multi-time-scale algorithm is developed, where two filters are combined to estimate the states simultaneously. With this approach, we aim to reliably predict the lifetime of satellite batteries in orbit [3].

(Invited) Tracking Lithiation with Advanced Transmission Electron Microscopy

The primary advantages of Li ion batteries (LIBs) over traditional energy storage devices include high voltage, large capacity and stable cycling ability [1]. Despite their tremendous success in the market of portable devices and electric vehicles, people are developing next generation of batteries for large-scale energy storage or severe working environment, which demands LIBs with better cycling stability, safety and higher energy-density. Investigations on how Li ions transport through the components in a battery, such as anode, cathode, and electrolyte, would be helpful to understand the performances of LIBs, and therefore to realize reversible lithiation/delithiation during cycling.Transmission electron microscopy (TEM) is an indispensable tool in probing real-space local structures at atomic resolution. Recently, advanced TEM techniques have been applied into tracking the transportation of lithium ions in battery materials [2]. Emerging methods like ABF, e-ABF, iDPC, EELS and ptychography offer possibilities to atomically observe Li ions' occupations, identify their chemical environment, and track the dynamics of their insertion and extraction [3-6]. At present, cryo-TEM technique is a hot spot to study the solid-electrolyte interphase where Li contained organic or inorganic compounds are very beam sensitive [7]. In-situ TEM techniques have unparallel merits to track the migration of lithium ions or see the phase transmission of electrode materials [8-9]. In this talk, we introduce the techniques for direct observation of Li species and their research advances in LIB materials. Perspectives for the current challenges and future development to investigate Li-containing materials are discussed.

Laser Ablation of High-Loading Electrodes to Improve Performance of Li-Ion Batteries in Behind-the-Meter Storage (BTMS) Applications

Behind-the-Meter Storage (BTMS) is a battery-based, stationary energy storage system that is connected to the residential or industrial customer’s side of the electrical grid utility service meter. BTMS systems enable consumers to (A) economically schedule charging and usage of stored energy, (B) store and use energy from on-site generation, especially from inconstant, renewable sources like solar and wind, and (C) avoid overworking the grid during peak hours via supplementation with stored energy. BTMS battery performance requirements and general priorities differentiate from other applications, like EVs, which has prompted the development of batteries with tailored electrode and electrolyte materials. These materials prioritize low cost, avoiding critical materials; high safety, mitigating thermal runaway; and longevity, achieving 8000 cycle and 20-year shelf lives.Lithium titanate (Li4Ti5O12, LTO) is a promising anode candidate for BTMS applications due to its high safety and stability, while maintaining an acceptable 160 mAhg-1 reversable capacity and composition of reasonably abundant materials.[1] Specifically, LTO has a high working voltage, which helps to prevent Li dendrite formation, improving safety. Furthermore, LTO, a “zero strain” material, has negligible lithiation-based volume change, leading to less active material loss upon cycling. Lithium manganese oxide (LiMn2O4, LMO) has been paired with LTO for BTMS applications in the past due to its safety, low cost (abundancy and critical material-free), and decently high operating voltage.[2-4] However, the low specific capacity of LMO limits energy density. While not the highest priority for BTMS applications, increasing energy density will enable BTMS deployment in space constrained applications as well as decrease total cost of the system. Therefore, improving volumetric energy density via the use of high-loading electrodes is of interest. A concern with the use of high-thickness, high-tortuosity, and low-porosity electrodes is that limitations arise with regard to electrode wettability, rate capability, and general performance, especially when paired with the high-stability, but also high-viscosity, ethylene carbonate-based electrolytes.[4] Previous studies have shown that limitations in electrode wettability and rate capability may be addressed by employing a scalable laser structuring technique on the electrodes prior to cell assembly.[5] Therefore, the study presented here focuses on the understanding of how structuring of high-loading LTO/LMO electrodes via laser ablation will impact cell performance. Specifically, a comparison is provided for cells with standard electrodes, a standard anode and ablated cathode, an ablated anode and standard cathode, and both electrodes ablated. Details of a novel laser structuring method will be provided in addition to material characterization as well as electrochemical characterization focused on rate capability and cycle life as they apply to BTMS requirements.This work was authored in part by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Funding was provided by the U.S. Department of Energy's Vehicle Technologies Office under the Behind-the-Meter Storage (BTMS) Consortium directed by Fernando Salcedo and managed by Anthony Burrell. The electrodes used in this manuscript are from Argonne's Cell Analysis, Modeling and Prototyping (CAMP) Facility, which is fully supported by the DOE Vehicle Technologies Office (VTO). The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes.

Interpreting CNN-RNN Hybrid Model-Based Ensemble Learning with Explainable Artificial Intelligence to Predict the Performance of Li-Ion Batteries in Drone Flights

Li-ion batteries are important in modern technology, especially for drones, due to their high energy density, long cycle life, and lightweight properties. Predicting their performance is crucial for enhancing drone flight safety, optimizing operations, and reducing costs. This involves using advanced techniques like machine learning (e.g., Convolutional Neural Network-CNNs, Recurrent Neural Network-RNNs), statistical modeling (e.g., Kalman Filtering), and explainable AI (e.g., SHAP, LIME, PDP) to forecast battery behavior, extend battery life, and improve drone efficiency. The study aims to develop a CNN-RNN-based ensemble model, enhanced with explainable AI, to predict key battery metrics during drone flights. The model’s predictions will aid in enhancing battery performance via continuous, data-driven monitoring, improve drone safety, optimize operations, and reduce greenhouse gas emissions through advanced recycling methods. In the present study, comparisons are made for the behaviors of two different drone Li-ion batteries, numbered 92 and 129. The ensemble model in Drone 92 showed the best performance with MAE (0.00032), RMSE (0.00067), and R2 (0.98665) scores. Similarly, the ensemble model in Drone 129 showed the best performance with MAE (0.00030), RMSE (0.00044), and R2 (0.98094) performance metrics. Similar performance results are obtained in the two predictions. However, drone 129 has a minimally lower error rate. When the Partial Dependence Plots results, which are one of the explainable AI (XAI) techniques, are interpreted with the decision tree algorithm, the effect of the Current (A) value on the model estimations in both drone flights is quite evident. When the current value is around −4, the model is more sensitive and shows more changes. This study will establish benchmarks for future research and foster advancements in drone and battery technologies through extensive testing.

Enhancing the Li-Ion Storage Capacity of Nitrogen-Doped Bilayer Graphdiyne in Li-Ion Battery: A First-Principles Study

Carbon-based materials are among the most important anode materials for Li-ion batteries (LIB). To improve the electrochemical performance of LIBs for large-scale manufacturing, advanced carbon allotropes are currently intensively evaluated. In this work, we applied density functional theory to investigate the atomistic and electronic structures as well as the maximum Li storage capacity of graphdiyne. The atomistic structures of monolayer graphdiyne (MGDY), bilayer AB(𝛽1)-stacking graphdiyne (AB(𝛽1)BGDY), and nitrogen-doped AB(𝛽1)BGDY (N-AB(𝛽1)BGDY) at different lithiation states were investigated. A detailed analysis of interlayer distance, Li adsorption energy, and voltage profile of MGDY, AB(𝛽1)BGDY, and N-AB(𝛽1)BGDY shows that the increased interlayer distance improves the theoretical capacity and open circuit voltage. Furthermore, our findings indicate that a small amount of N doping enhances the Li-ion storage for N-AB(𝛽1)BGDY. The superior capacity suggests the potential of N-doped bilayer AB(𝛽1) as a high-capacity anode material for LIBs. Thus, our study helps to discover novel anode materials for advancing LIB technology.

Understanding Shelf Life of Electrolytes with LiPF6 Under Commercially Relevant Storage Conditions

Lithium hexafluorophosphate (LiPF6) salt is the most commonly used lithium salt in commercial Li-ion batteries due to its high conductivity, passivation of Al current collectors for positive electrodes, and participation in SEI layer formation at graphite anodes.1 However, LiPF6 suffers from poor thermal stability and poor stability toward protic species (like water) leading to decomposition that can significantly reduce Li-ion battery performance especially under the extreme conditions demanded by today’s industrial applications. Specifically, LiPF6 decomposition leads to HF generation, especially in the presence of water,2 which results in multiple negative outcomes in Li-ion cells including dissolution of cathode materials and gas generation.3 Conditions during electrolyte blending, transport, and/or storage often exacerbate LiPF6 instability and increase HF generation.To date, efforts to replace LiPF6 have not proven to be commercially successful, therefore strategies to improve the stability of LiPF6 electrolytes under relevant storage conditions are critical to support the deployment of Li-ion batteries. Orbia Fluor and Energy Materials has extensively characterized the degradation of LiPF6 as a function of multiple conditions, including temperature, water content, electrolyte composition, and container materials to inform the design of strategies to improve stability.This poster will illustrate the understanding of LiPF6 decomposition (and HF generation) under conditions relevant to the Li-ion electrolyte supply chain and will present data showing a series of fluorinated materials that improve the thermal stability of LiPF6 electrolyte through the elimination of existing HF and suppression of additional formation. In addition, Orbia Fluor and Energy Materials has launched a custom electrolyte blending business to provide high quality, domestically produced lithium-ion battery electrolytes to enable the clean energy transition.

Enabling Fast‐Charging and High Specific Capacity of Li‐Ion Batteries with Nitrogen‐Doped Bilayer Graphdiyne: A First‐Principles Study

AbstractCarbon‐based materials are the most important anode materials for Li‐ion batteries (LIBs). To improve the electrochemical performance of LIBs for high energy density and fast charging, advanced carbon allotropes are in the research focus. In this work, we applied the density functional theory to investigate the atomic and electronic structures as well as high Li‐ion specific capacity of graphdiyne (GDY). The atomic structures of monolayer graphdiyne (MGDY), bilayer AB(β1)‐stacking graphdiyne (AB(β1)BGDY) and nitrogen‐doped AB(β1)BGDY (N‐AB(β1)BGDY) at different lithiation states were thoroughly investigated. The AB(β1)BGDY and N‐AB(β1)BGDY exhibit promising characteristics in Li‐ion adsorption and intercalation, enhancing its specific capacity from 744 mAhg−1 in the monolayer GDY to 807 mAhg−1 in the bilayer. Besides increasing the capacity through a bilayer‐structure, it is possible to tailor its structural stability and band gap by doping. Especially shown for N‐AB(β1)BGDY (~1 %), an increased structural stability and a decreased band gap of 0.24 eV is found. While this means that N doping in AB(β1)BGDY can lead to longer‐lasting and more stable operatable high‐capacity anodes in LIBs, it increases the open‐circuit voltage (OCV).

Unraveling the Complex Temperature-Dependent Performance and Degradation of Li-Ion Batteries with Silicon-Graphite Composite Anodes

Competing effects of graphite and Si result in a complex temperature dependent performance and degradation of Li-ion batteries with Si-graphite composite anodes. This study examines the influence of varying the Si content (0 to 20.8 wt%) in Si-graphite composite anodes with consistent areal capacity and N/P ratio in full cells containing NMC622 cathodes. One hundred pilot-scale double-layer pouch cells were built and cycle aged in the temperature range from −10 to 55 °C. Electrochemical characterization demonstrated that increasing Si contents enhance capacity and mitigate internal resistance at low temperatures. On the other hand, high Si contents decrease charge-discharge energy efficiency and cycle life, particularly at elevated temperatures. Post-mortem analysis of aged electrodes, including physico-chemical characterization (scanning electron microscopy, energy-dispersive X-ray analysis, thickness measurements) and cell reconstruction revealed significant solid electrolyte interphase growth and increased loss of active material in anodes with high Si content. The optimum temperature for longest cycle life as derived from Arrhenius plots decreased from 30 °C for graphite anodes to 10 °C for cells with moderate Si content up to 5.8 wt%. These findings allow the design of optimized cells by balancing the Si content versus operating temperature in order to achieve lowest cell aging.