High Energy Density Lithium-ion Batteries Research Articles

Robust self-healing ion-conductive interlocking dual-network binder based on gradient dynamic bonding for advanced SiO anodes in Li-Ion batteries

Silicon-based (e.g., SiO) anodes have attracted much attention for their high specific capacity; however, poor conductivity and dramatic volume change during the charge/discharge cycling hinder their commercial application in high energy density lithium-ion batteries (LIBs). Ideal binders hold a decisive effect on inhibiting the volume effect of the silicon-based anode. Herein, inspired by the hierarchical structure of living organisms, we design a multifunctional self-healing interlocking dual-network binder based on gradient dynamic bonding and apply the binder to SiO anode toward high specific capacity and long-term cycle performance. Specifically, rigid polyacrylic acid (PAA) and flexible polylipoic acid (PTA) are interlocked by gradient dynamic bonding containing of disulfide linkage, metalcoordination and hydrogen bonding. The obtained binder has strong adhesion, high mechanical toughness, fast self-healing performance and high ionic conductivity, which enable the SiO anode effectively buffering the volume expansion and exhibiting excellent cycling stability. The SiO electrode with the new binder delivers a high capacity of 884.8 mAh/g at a current density of 0.5 A/g after 500 cycles and a high capacity of 765.2 mAh/g at a high mass loading of 3.0 mg cm−2 after 100 cycles. Moreover, the assembled SiO||NCM811 full cell achieves a reversible capacity of 169.75 mAh/g with capacity retention of 77.5 % after 100 cycles. This work offers a new method for the design of versatile self-healing binder adaptive to electrode volume change, so as to accelerate the application of the silicon-based anode.

Promoting nitrogen-doped porous phosphorus spheres for high-rate lithium storage

Phosphorus anode has shown great potential for the high-rate and high-energy–density lithium-ion batteries. Nevertheless, it still suffers from possible electrode cracking, ion-transport restrictions, and active-particle decomposition resulting from repeated alloying/de-alloying. To address the aforementioned issues, a nitrogen-doped flower-like porous phosphorus (f-P) sphere has been developed. The abundant micro-mesopores facilitate ion diffusion and enhance the internal bonding strength of the electrode. Concurrently, the doped nitrogen promotes the generation of a favorable solid electrolyte interphase constructed by fast-ion-conductors. As a result, the f-P exhibits a high-rate capacity of 735mAh g−1 at 20 A g−1 and maintains high Coulombic efficiencies over 900 cycles at 10 A g−1. Furthermore, coin full-cells comprising the f-P anode and lithium cobalt oxide cathode demonstrate stable operation at a high current density of 6 mA cm−2. The combination of a porous structure and doping strategy represents a viable approach for strengthening the durability of electrodes and optimizing the ion transport kinetics of advanced alloy anode materials.

The numerical and experimental investigation of the transient behaviours of a lithium-ion pouch battery cell under dynamic conditions

In this paper, the transient model of a high energy density Lithium-ion pouch battery cell is developed under dynamic conditions. The battery cell has a capacity of 73 Ah and volumetric energy density of 642 Wh L−1. This is one of the few studies included the electro-thermal behaviour of high energy density battery under transient conditions by using second ordered model. The transient model indicated that the state of charge (SOC) decreased by 7 % at the end of the WLTP driving cycle and this value is good agreement with the experimental data. Moreover, the developed model provides an accurate prediction of the terminal voltage with a R2 value of 0.99 and a maximum relative error of 2.0 %. Furthermore, the proposed model predicts the electro-thermal characteristics more precisely and the heat generation rate and the entropic term can also be determined without using measurement device. The calculated total heat emitted from battery is about 6W at 1 C-rate for constant current and the heat generation rate is a peak value of ±1.75 105 Wm−3 under dynamic conditions. By using the estimated heat generation rate, more effective cold plates will be designed for thermal management of high energy density battery cells.

Unraveling the impact of the design of current collector on dry-processed lithium-ion battery electrodes

Dry processing emerges as a cost-effective technique for achieving high material loading in the field of lithium-ion battery fabrication. Nevertheless, insight into the role of current collectors in this process is still scarce. Herein, a set of dry-processed electrodes with three different current collectors is accordingly prepared and comprehensively studied. This work novelly reveals that the current collectors exhibit significant influence on the interface adhesion strength and the electron conductivity, which leads to difference in the mechanical strength and electrochemical performance of dry-processed electrodes. Consequently, it is recommended that carbon-coated current collector is preferred for dry-processed high energy density lithium-ion battery electrodes.

A Novel 4-Fluorophenyl Isocyanate Additive Constructing Solid Cathodes-Electrolyte Interface for High-Performance Lithium-Ion Batteries.

Building a stable cathode-electrolyte interface (CEI) is crucial for achieving high-performance layered metal oxide cathode materials LiNixCoyMn1-x-yO2 (NCM). In this work, a novel 4-fluorobenzene isocyanate (4-FBC) electrolyte additive that contains isocyanate and benzene ring functional groups is proposed, which can form robust and homogeneous N-rich and benzene ring skeleton CEI film on the cathode surface, leading to significant improvement in the electrochemical performance of lithium-ion batteries. Taking LiNi0.5Co0.2Mn0.3O2 (NCM523) as an example, the NCM523/SiO@Graphite pouch full cells with electrolytes containing a mass fraction of 1% 4-FBC additives demonstrate improved capacity retention after 200 cycles, retaining capacity retention rates of 81.3%, which is much higher than that of 39.1% without additive. The improvement can be ascribed to the mitigation of electrolyte decomposition and inhibition of transition metal ions the dissolution from the cathode material due to the stable CEI film. Moreover, the electrochemical performance enhancement can also be achieved in high voltage and Ni-rich cathode materials, indicating the universality and effectiveness of this strategy for the practical applications of high energy density lithium-ion batteries.

Surface phosphorylated Li5FeO4 prelithiation additive synergistically improves the air-stability and lithium-ion conductivity

Because of the higher delithiation capacity, Li5FeO4 (LFO) can be used as sacrificial prelithiation additive to compensate the initial capacity loss caused by the formation of solid electrolyte interphase in lithium-ion batteries (LIBs). However, the extremely poor air stability and severe phase transition after Li+ deintercalation make it difficult for LFO to be applied in prelithiation engineering practice. Herein, the residual alkali layer generated on the LFO due to air exposure is directly converted into a Li3PO4 layer by a one-pot solid–liquid reaction. The as-obtained surface phosphorylated LFO (LP-LFO) ensures high air stability and effective prelithiation capability. Introducing only 3 wt% LP-LFO to the LiFePO4/Li half-cell can maximally replenish the active Li+ loss and the initial coulombic efficiency, displaying a 9.9 % increase in the initial charge capacity. Moreover, the Li3PO4 coating enables LP-LFO to be a fast ionic conductor, not only inhibiting the phase transition of LFO, but also improving the electronic and ionic conductivity of the electrode, which is confirmed by the complementary tests of galvanostatic intermittent titration technique and electrochemical impedance spectroscopy, as well as the structure and morphology characterization. As a result, the LiFePO4/Li half-cell with LP-LFO additive exhibits a higher rate capability (144 mAh g−1 at 2 C) and cycle stability (157 mAh g−1 after 100 cycles at 0.1 C). And a 17.4 % increase in the discharge capacity and a 12.7 % increase in energy density after 200 cycles for the 3 wt% LP-LFO-added LiFePO4||graphite full cell is also achieved. This work provides a facile and efficient conversion strategy for the air-instable electrode additives, and furtherly broadens their industrial application prospect in high energy density LIBs.

Phase compatible surface engineering to boost the cycling stability of single-crystalline Ni-rich cathode for high energy density lithium-ion batteries

Nickel-rich layered oxide is a promising cathode material for the next generation lithium-ion batteries (LIBs) because of its high energy density and cost efficiency. Unfortunately, it suffers from unsatisfying electrochemical performance owing to intrinsic interfacial and structural instability, which limits its application at scale. In this work, a phase compatible TiBO3 coating layer on single crystalline LiNi0.83Co0.11Mn0.06O2 (TBO-SC-NCM) is constructed via modified solid-state chemical reaction. The coating layer serves as a protective screen to mitigate the erosion of organic electrolyte towards TBO-SC-NCM. Furthermore, both titanium ions and boron ions successfully diffuse into the TBO-SC-NCM bulk phase during the annealing process, with titanium ions being uniformly distributed while boron ions accumulating close to the surface. The formation of strong Ti-O bond effectively inhibits the bulk phase structure degradation of TBO-SC-NCM. The near-surface enriched B-O bond greatly stabilizes the surface lattice oxygen at the deeply delithiated state. Additionally, the spread of layer spacing due to the doping of heterogeneous ions ensures the rapid diffusion of Li+, thus improving the rate performance of TBO-SC-NCM. As a h cathode materials.

Comprehensive Review of Li-Rich Mn-Based Layered Oxide Cathode Materials for Lithium-Ion Batteries: Theories, Challenges, Strategies and Perspectives.

Lithium-rich manganese-based layered oxide cathode materials (LLOs) have always been considered as the most promising cathode materials for achieving high energy density lithium-ion batteries (LIBs). However, in practical applications, LLOs often face some key problems, such as low initial coulombic efficiency, capacity/voltage decay, poor rate performance and poor cycle stability. It seriously shortens the lifespan of lithium-ion batteries and hinder the large-scale commercial application of LLOs. Herein, firstly, the basic theories of LLOs were systematically reviewed, including the structural characteristics, the working mechanism of LLOs, the preparation methods of LLOs (liquid phase co-precipitate method, sol-gel method, hydrothermal synthesis method, solid phase method, low heat solid-phase method, high temperature solid-state method etc.), and electrochemical characteristics of LLOs (first charge discharge characteristics and reversible efficiency, cycling performance, high and low temperature performance and thermal stability etc.). Then, key challenges faced by LLOs were systematically discussed. Finally, the LLOs modification strategies used to address these challenges (element doping, surface modification, defect engineering, structural and morphological control etc.) were elaborated in detail. This important review provides potential insights and directions for further improving the electrochemical performance of LLOs, and provides a necessary theoretical basis for accelerating the large-scale commercial application of LLOs. It possesses important scientific research value and far-reaching social significance.

Scalable Synthesis of Single Crystal Ni-Rich Cathodes for Advanced Lithium-Ion Batteries

Long-range electrical vehicles require high energy density lithium-ion batteries that utilize stable, high-energy cathode materials. Among various cathodes, Ni-rich NMC cathodes with a layered structure, knows for their high capacity, high voltage, and cost-effectiveness, stand out as one of the most promising cathodes. Traditional polycrystalline Ni-rich NMC encounter issues such as pulverization, gas generation and moisture sensitivity, limiting their widespread use in EV batteries on large scale. The single crystal format of Ni-rich cathode can effectively eliminate and mitigate these issues. However, synthesizing of high-performance single crystal Ni rich NMC, especially when Ni ≥0.8, presents a significant challenge.We’ve explored an innovative phase separation approach for direct synthesis of high-performance single crystal NMC811. The comprehensive investigation into the reaction mechanism of single crystal growth was conducted to understand the relationship between synthesis, morphology, and performance in growing single crystal NMC811. The enhanced performance of these materials was realized through the precise morphological and structural control of precursors and has been confirmed in practical 2Ah pouch cells. The developed approach is readily adaptable to current industry manufacturing processes and provides valuable new insights that can be broadly applied to cost-efficient large-scale synthesis of single crystals and various advanced battery materials technologies.

(Battery Division Postdoctoral Associate Research Award Sponsored by MTI Corporation and the Jiang Family Foundation) Science of Multiphysics Behavior of Si/C Composite Anodes in High-Energy-Density Lithium-Ion Batteries

The rapidly growing demands on energy storage technologies over the last decade have imposed further requirements for the high energy/power density, safety, and durability of lithium-ion batteries (LIBs). Si/C composite materials have attracted enormous research interest as the most promising candidates for the anodes of next-generation lithium-ion batteries, owing to their high energy density and mechanical buffering property. However, the major disadvantage of materials with ultra-high capacities, such as Si-based materials, is the significant volume change during cycling, which further leads to mechanical and electrochemical degradation. However, a sophisticated and quantitative understanding of the highly electrochemical-mechanical coupling behaviors is still lacking.A comprehensive computational model is indispensable in the developing process of the excellent performance of anode material due to the low-realizability, inconvenience, and high-cost of experiments, which also provides powerful tools for fabrication guidance of novel Si/C composites designs. Hence, a multiphysics modeling framework is established with a detailed geometric description to quantitatively reveal the underlying governing mechanisms of Si/C composite anode behaviors. We studied the effects of the Si weight percentage, the Si-related particle distribution, the Si-related particle size, the mechanical constraint, and the binder domain gradient on the battery performance regarding the potential behavior, capacity delivery, mechanical stress/strain, Li plating, and polarization evolution. In our study, we used silicon monoxide (SiO) as the Si element source and graphite (Gr) as the C element source. Results discover that an 8-10 wt% of SiO would be an optimal choice regarding capacity delivery and minimizing Li plating under 1C constant current charging condition. Positioning SiO particles near the separator and reducing the sizes of SiO particles are also demonstrated to be beneficial for electrochemical performance with trivial influence on mechanical mismatch. In addition, the mechanical constraint demonstrates a balanced effect on the overall performance of cells and the local behaviors of particles. Our findings also indicate that reducing the proportion of carbon-binder domain (CBD) in the upper domain (near the anode surface) compared to the lower domain (near the current collector) positively influences electrochemical performance, particularly in terms of capacity and Li plating. However, such an arrangement introduces potential risks of mechanical failures and we recommend to incorporate a higher proportion of CBD alongside the SiO particles. Finally, an anode design with a lower CBD proportion in the upper domain exhibits superior rate performance.This study explores the multiphysics behavior of Si/C anodes material using a comprehensive methodology combining experimental and FEA techniques, systematically revealing the coupling mechanism among various physical fields, as well as providing efficient and powerful tools in the design, development, and evaluation of high energy density lithium-ion batteries.

Impact of Pretension and Cycling Window on Degradation of Graphite/Silicon Composite Anodes

Challenges such as mechanical degradation and limited cycle life persist for high energy density lithium-ion batteries with silicon/graphite composite anodes. In this research work, the patterns of degradation of cells with silicon/graphite composite and NMC622 cathode are examined at varied cycling conditions and applied external pressure or pretension. The most notable outcome of this analysis is that cells cycled between 0 and 100 State-of-Charge (SoC) exhibit the most accelerated aging process. Increasing the pretension force effectively restrains the irreversible expansion of the cells, and has a positive effect on capacity retention.In this research, a comprehensive experiment was conducted involving 46 cells subjected to diverse cycling conditions, voltage windows, pretension forces, and temperatures. Reference performance tests (e.g. HPPC and 1/20 C-rate charge tests) are conducted regularly for analysis of degradation mechanisms. The capacity fade, resistance growth, and thickness increase are correspondingly shown in Figures 1, 2, and 3 with ampere hour throughput as the x-axis. The legend columns indicate test conditions, including C-rate, SoC window during cycling, temperature (in degrees Celsius), and pretension force (in psi). As is shown in all figures, there is a substantial dependence on the SoC window for cycling. To be specific, a rapid rate of capacity loss, resistance increase, and thickness increase occurs in the cell group cycled over the full SoC window (plotted in blue). Cells cycled under full SoC windows also exhibit an early accelerated fading (knee [1]) of capacity and accelerated increase (elbows [2]) of resistance and thickness. According to [3], this accelerated aging could be a consequence of side reactions and increased mechanical stress within the silicon particle when operating across a broad potential range.Meanwhile, for the cell group with restrained cycle windows (plotted in gray) the cells have not yet reached any knee, and have a relatively linear capacity loss. It should be noted that, within the range of partial cycling windows examined, cells subjected to a cycling range of 50-100 exhibit the most rapid degradation, which aligns with the conclusions presented in [4] due to the time at elevated potential. In Figure 2, the elevated temperature (depicted in red) exhibits a significant influence on the increase in resistance, potentially attributed to the growth of the solid electrolyte interface (SEI), but minimal impact on capacity loss. Maintaining other conditions constant and comparing cells under 25 psi and 15 psi (marked with hollow circles and filled circles, respectively), it is evident that a higher pretension force has a positive effect on cell capacity loss. Simultaneously, in Figure 3, the pretension force at 25 psi (marked with hollow circles) effectively restrains the irreversible expansion of the cells. The results are similar to the degradation pattern outlined in [5], it is observed that employing a high pretension force facilitates the mitigation of both degradation and expansion. As highlighted in [6], heightened temperatures lead to accelerated resistance growth. Nevertheless, the impact of various C-rates on degradation remains inconclusive [6].This research systematically analyzed cell-level degradation through an extensive array of experiments, providing valuable insights into the intricate dynamics of capacity fade, resistance increase, and thickness growth. The study's revelation that the cycle window exerts a pronounced impact on battery health could offer crucial guidance for the design of Battery Management Systems (BMS). Moreover, the work establishes a foundational basis for future research, particularly in exploring electrode-level degradation patterns. These contributions collectively enhance the understanding of energy storage systems, offering practical implications for optimizing battery performance and longevity in various applications.[1]Attia, Peter M., et al. "“Knees” in lithium-ion battery aging trajectories." Journal of The Electrochemical Society 169.6 (2022): 060517.[2] Strange, Calum, et al. "Elbows of internal resistance rise curves in Li-ion cells." Energies 14.4 (2021): 1206.[3] Verbrugge, Mark, et al. "Fabrication and characterization of lithium-silicon thick-film electrodes for high-energy-density batteries." Journal of The Electrochemical Society 164.2 (2016): A156.[4] Xu, Bolun, et al. "Modeling of lithium-ion battery degradation for cell life assessment." IEEE Transactions on Smart Grid 9.2 (2016): 1131-1140.[5] Mohtat, Peyman, et al. "Reversible and irreversible expansion of lithium-ion batteries under a wide range of stress factors." Journal of The Electrochemical Society 168.10 (2021): 100520.[6] Pannala, Sravan, et al. "An Experimental Correlation of Degradation with Cell Reversible and Irreversible Expansion Measurement in Pouch Cells." Electrochemical Society Meeting s 243. No. 2. The Electrochemical Society, Inc., 2023. Figure 1

Diethylenetriaminepentaacetic Acid-based Conducting Solid Polymer Electrolytes Impede Lithium Dendrites and Impart Antioxidant Capacity in Lithium-Ion Batteries.

In the development of lithium-ion batteries (LIBs), cheaper and safer solid polymer electrolytes are expected to replace combustible organic liquid electrolytes to meet the larger market demand. However, low ionic conductivity and inadequate cycling stability impede their commercial viability. Herein, a novel flexible conducting solid polymer electrolytes (CSPEs) based on polyvinyl alcohol (PVA) and ion-polarized diethylenetriaminepentaacetic acid (P-DETP) is developed for the first time and applied in LIBs. PVA and P-DETP form a compact polymer network through hydrogen bonding, enhancing the thermomechanical stability of CSPE while restricting the migration of larger anions. Furthermore, density functional theory calculations confirm that P-DETP can facilitate the dissociation of Li+-TFSI- via electrostatic attraction, resulting in increased mobility of lithium ions. Additionally, P-DETP contributes to the formation of a stable electrode-electrolyte interface layer, effectively suppressing the growth of lithium dendrites and improving antioxidant capacity. These synergistic effects enable CSPE to exhibit remarkable properties including high ionic conductivity (2.8 × 10-4 S cm-1), elevated electrochemical potential (5.1V), and excellent lithium transference number (0.869). Notably, the P-DETP/LiTFSI CSPE demonstrates stable performance not only in LiFePO4 batteries but also adapts to high-nickel ternary LiNi0.88Co0.06Mn0.06O2 cathode, highlighting its immense potential for application in high energy density LIBs.

Investigation of Vanadium-Based Oxide(L1+xV3O8) for Zn-Ion Batteries

Being a champion in the portable electronics world, high-energy density lithium-ion batteries(LIBs) are irreplaceable. Still, the scarcity of Li resources, high cost, and the inclusion of non-aqueous electrolytes make them relatively perilous and inefficient for grid-scale energy storage. Recently, the blooming aqueous Zn-ion batteries (ZIBs) have emerged as one of the pioneers featuring the inherently safe nature of metallic Zn anode and its unique properties.[1] Vanadium-based compounds show fast ion diffusion and excellent reversible capacity because of their rich valence state of V, facile distortion of V-O polyhedra, and tuneable composition, which offers an excellent treasure house. Moreover, the different oxidation states of vanadium allow a higher degree of structural change and greater functional flexibility while incorporating multivalent cations into vanadium-based compounds.[2] The present work focuses on a V-based oxide cathode, i.e., LixV3O8 (x = 1, 1.3, 1.5), named LVO (SG: P21/m, crystal: monoclinic). It was synthesized using V-pentoxide and LiOH precursors through a simple and economical sol-gel route. LVO was further chemically lithiated to the desired stoichiometries (1.3 and 1.5) using LiI in acetonitrile to get Li1.3V3O8 & Li1.5V3O8, to use them as a cathode material for ZIBs. The best-performing cathode, i.e., L1.5VO, showed the reversible capacity of ~150 mAhg-1 at a current rate of 5 Ag-1 for 3500 cycles in 2 M Zn(Otf)2. Moreover, at 1Ag-1, it showed a high capacity of 260 mAhg-1. In operando XRD suggests the overall phase evolution is highly reversible, as indicated by the reversible evolution of the LVO peaks, the underlying charge storage process can be distinguished into two halves. During discharge, those two halves are: 1.6V – 0.8V window representing Zn2+ intercalation and 0.8 – 0.2V window with predominant H+ intercalation. The latter process is evident from the appearance of the triflate based layered double hydroxide byproduct (triflate-LDH) diffraction peaks (marked with asterisk) [3] formed from the reaction of Zn2+, CF3SO2O- (triflate anion), and OH- left behind after H+ insertion. It is safe to say that the Zn2+ intercalation is the dominant process in the high voltage regime where the triflate-LDH peaks do not appear. Even though the transition from Zn2+ to H+ mediated charge storage coincides with a change in the shape of the voltage profile and its slope around 0.8 V, this is likely related to the puckering of the VOx layers as observed for Li+ intercalation in V2O5. In operando Raman suggested an evolution for the peaks which are associated with the V-O-V bending vibrations in the 200-600 cm-1 range. Overall, A detailed examination of this system using ex-situ, in-operando XRD, in-operando Raman spectroscopy, solid state 1H proton NMR, and ABF-STEM imaging will be discussed, which confirmed Zn-ion (de)intercalation in Li1.5VO with a reversible LDH formation. This vanadate can be proposed as a robust cathode for zinc-ion batteries. Reference s : [1] M. Song, et al., Adv. Funct. Mater. 2018, 28,1802564.[2] Y. Zhang et al., Chem. Front. 20 21, 5, 744-762.[3] P. Oberholzer et al., ACS Appl. Mater. Interfaces 2019, 11, 674−682

(Invited) Structured Electrode Manufacturing for Next-Generation Lithium-Ion Batteries

Achieving high-energy and high-power density Lithium-ion batteries (LIBs) with fast charging capabilities is critical to advancing electric vehicle (EV) and portable electronic technologies. Long-range, fast charge EVs and more compact portable electronics require significant advances in battery performance, lifetime, and cost. Conventional LIBs are composed of flat anode and cathode electrode stacks that can be optimized for energy or power, but not both concurrently. This is due to ion transport limitations that persist with increases in electrode thickness. Several research efforts have focused on optimizing LIB performance through material innovations with lithium metal and silicon anodes or new cathode materials, to name a few. Structured Electrode (SE) designs1 have been investigated over the last couple of decades as an alternate solution to address these challenges. SEs engineer electrode materials into different three-dimensional (3D) architectures on a scale ranging from tens to hundreds of microns to facilitate rapid ion-transport in thicker electrodes. While a promising concept, reliable and scalable manufacturing methods for fabricating SEs over the large and complex areas needed for EV and portable electronic applications remains limited.This talk covers manufacturing approaches investigated by our research group to fabricate SEs rapidly and efficiently. Both computational design and experimental approaches are employed to facilitate the development of new hardware, software, and processing techniques for SEs. Specifically, we highlight Additive Manufacturing (AM) tools for portable electronic applications and the use of acoustophoresis for manufacturing EV SEs. First, we have developed new computational fabrication tools2 and material formulations to push the bounds of AM for SE fabrication. Through this work, we investigate the impact of electrode design and fabrication on the rate capability and charge performance of Li4Ti5O12 and LiFePO4 cells. Next, taking AM towards larger area fabrication, we have combined acoustophoresis with AM principles to facilitate large-area printing and patterning of SEs for LIBs.3 Acoustophoresis utilizes acoustic standing wavesto drive particles into predefined patterns, with micron-scale control at time scales < 1 second. Our initial results with LiNi0.6Mn0.2Co0.2O2 and graphite have defined process conditions that enable acoustophoretic fabrication of SEs with improved rate capability over conventional, flat LIB electrodes. Our work highlights the material and processing considerations that must be given when developing new manufacturing processes for SEs. References C.-H. Hung, P. Huynh, K. Teo, and C.L. Cobb, “Are Three-dimensional Batteries Beneficial? Analyzing Historical Data to Elucidate Performance Advantages,” ACS Energy Letters, 8 (1), pp. 296–305, 2023.F. Fossdal, V. Nguyen, R. Heldal, C.L. Cobb, and N. Peek, “Vespidae: A Programming Framework for Developing Digital Fabrication Workflows,” In Proc. of 2023 Designing Interactive Systems Conference, ACM, New York, NY, USA.K.E. Johnson, D.S. Melchert, E.N. Armstrong, Daniel S. Gianola, C.L. Cobb, M.R. Begley, “A Simple, Validated Approach for Design of Two-dimensional Periodic Particle Patterns via Acoustophoresis,” Materials & Design, Vol. 232, 112165, 2023. Acknowledgements This material is based upon work supported in part by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Advanced Materials and Manufacturing Technologies Office (AMMTO) Award Numbers DE-EE0009112 and DE-EE0010226. The views expressed herein do not necessarily represent the views of the U.S. Department of Energy or the United States Government.This work was funded in part by a Defense Advanced Research Projects Agency (DARPA) Young Faculty Award and Director's Fellowship under grant number D19AP00038. The views, opinions, and findings expressed in this work are those of the authors and should not be interpreted as representing the official views or policies of the Department of Defense or the U.S. Government, and no official endorsement should be inferred. This is approved for public release and distribution is unlimited.

Coupled Electrochemical-Thermal Runaway Model of Lithium-Ion Cells Operating Under High Ambient Temperatures

The risk of thermal runaway (TR) in high energy density Lithium-ion batteries (LIBs), which may initiate at around 90 °C, is a critical safety concern, particularly in regions where summer temperatures can reach nearly 50 °C. While multiple exothermic reactions that cause TR and modeled using Arrhenius equations lead to good predictions in controlled oven tests, their use in practical applications is questionable as these do not consider internal electrochemical processes that cause temperature rise and trigger exothermic reactions. Further, limited literature focuses on coupling electrochemical thermal models with exothermic reactions. This study demonstrates a method to couple the electrochemical and thermal runaway models for a commercial cylindrical Lithium-ion cell. The proposed model averages pseudo-2D electrochemical heat and couples it to a two-dimensional, axisymmetric heat transfer model of 18650-type Lithium-ion cell. The jellyroll structure is approximated as a homogeneous and anisotropic domain for electrochemical and exothermic heating. Simulations are performed through several, uninterrupted charge-discharge cycles at different ambient temperatures and C-rates. We show that while cycling rate is critical in instigating and accelerating TR, parameters like ambient temperature, particle radii and initial electrolyte concentration also play a role in determining the core temperature and its rate of growth in the cell.

Electrochemical properties of tungsten doped LiNi0.9Co0.1O2 lithium-ion battery cathode materials

High-nickel layered cathode materials for lithium-ion batteries have received widespread attention in new energy vehicles for their excellent specific energy and cost advantages, and are considered to be the most promising cathode materials for high-energy density lithium-ion batteries. Despite its many advantages, poor thermal stability and rapid capacity degradation have greatly limited its large-scale application. Ion doping is considered to be an effective way to improve its drawbacks, and in this paper, a series of W-doped LiNi0.9Co0.1O2 cathode materials were prepared using WO3 as a tungsten source. Among them, 1 mol% W doping was the most effective, and its reversible capacity of 204.44 mA g −1 still had 93.25 % capacity retention after 100 this cycles at 1C. Combined with DFT calculations, it is found that the introduction of W does not change the original layered structure and the material transitions from semi-metallic to metallic at lower doping concentrations, resulting in more electrons occupying the Fermi energy levels to enhance its electrical conductivity and leading to an elevated spin state and a lower oxidation state of Ni.

Impact of Cobalt Addition on Single-Crystal Li1+x(Ni0.6Mn0.4)1−xO2 Cathode Material Performance

Nickel and manganese-based layered oxides with a nickel content ranging from 50% to 80% are promising cathode materials for high-energy density lithium-ion batteries. However, these materials face challenges such as poor rate capability and limited cycling stability. The addition of excess lithium can mitigate these issues to some extent. This study examines the impact of incorporating small amounts of cobalt (5% or 10%) into these materials through an “all-dry” synthesis approach in stoichiometric and excess lithium-containing compositions. Results indicate that adding even these small amounts of cobalt decreases the cation mixing, improves crystallinity, reduces electronic resistance, and influences the morphology depending on whether nickel or manganese is replaced. The materials can accommodate up to 15% excess lithium without significant surface impurities. The addition of cobalt further enhances the rate capability of the material in excess lithium materials, but increasing cobalt content tends to compromise cycling stability when the materials are cycled up to 4.4 V. Materials in which 5% cobalt replaces nickel still exhibit superior rate capability and cycling performance compared to materials without cobalt. Therefore, incorporating small amounts of cobalt can positively impact the performance of Li1+x(Ni0.6Mn0.4)1−xO2 materials, offering a balance between improved rate capability and cycling stability.

The Facile and Controllable Synthesis of Ultrafine Sn Nanocrystals Loaded on Carbon Black for High-Performance Lithium Storage.

Sn and C nanocomposites are ideal anode materials for high-energy and high-power density lithium ion batteries. However, their facile and controllable synthesis for practical applications is still a critical challenge. In this work, a facile one-step method is developed to controllably synthesize ultrafine Sn nanocrystals (< 5 nm) loaded on carbon black (Sn@C) through Na reducing SnCl4 by mechanical milling. Different from traditional up-down mechanical milling method, this method utilizes mechanical milling to trigger bottom-up reduction reaction of SnCl4. The in-situ formed Sn nanocrystals directly grow on carbon black, which results in the homogeneous composite and the size control of Sn nanocrystals. The obtained Sn@C electrode is revealed to possesses large lithium diffusion coefficient, low lithiation energy barrier and stable electrochemical property during cycle, thus showing excellent lithium storage performance with a high reversible capacity (942 mAh g-1 at a current density of 100 mA g-1), distinguished rate ability (480 mAh g-1 at 8000 mA g-1) and superb cycling performance (730 mAh g-1 at 1000 mA g-1 even after 1000 cycles).

Influence of the temperature-induced ordered-disordered phases for iron difluoride on the electrochemical performance

Iron difluoride (FeF2) is one of the promising cathodes to achieve high energy-density lithium-ion batteries (LIBs). However, the sluggish ion transportation kinetics in the FeF2 bulk phase may cause large voltage hysteresis and lower cell efficiency, which hinders its commercial adoption. Introducing a disordered phase into the ordered bulk FeF2 is proposed to promote ion transportation and increase ion diffusion channels. Here, varying ratios of the disordered phase are incorporated into the ordered matrix of FeF2 by adjusting the annealed temperatures. The ion transportation is improved due to the optimal ratio of the disordered to ordered (RDO) phase. Among four electrodes, the RDO25% electrode demonstrates the least electrochemical polarization of 1.22 V and the lowest voltage hysteresis of about 1.0 V, in addition to delivering a discharge capacity of 128 mAh g−1 after 100 cycles in the carbonate-type electrolyte. The introduction of the disordered phase enables FeF2 to exhibit a distinct intercalation and conversion dual-mechanism cathode. Additionally, appropriate ratios of the disordered-ordered phase can mitigate nanoparticle agglomeration, establish a conformal cathode electrolyte interface (CEI), reduce interfacial resistance, and thereby enhance ion transport.

Rigid-flexible mediated Co-polyimide enabling stable silicon anode in lithium-ion batteries

Silicon is considered as a promising electrode materials for the next generation of lithium-ion batteries. However, it’s commercial applications are hindered by significant volume changes. In this study, copolyimide binders with adjustable rigidity and flexibility were synthesized through simple copolymerization. The rigid segments containing adenine groups (p-APA) provide excellent mechanical strength and interface interaction, while flexible segments containing siloxane bonds and alkane chains (DS-NH2) can buffer volume changes through enhanced mobility and topological entanglement of molecular segments. Optimizing the copolymerization ratio helps minimize damage to the silicon electrode structure and stabilizes solid electrolyte interphase (SEI) growth. Compared to the rigid polyimide binders, rigid-flexible coupling strategy improves cycling stability, remaining a capacity of 2170 mAh/g at 2 A/g after 200 cycles and exhibiting stable cycling for over 750 cycles with a capacity limitation of 1500 mAh/g. The high mass loading silicon anodes, micron-sized silicon oxide electrodes and the full cells also exhibit favorable electrochemical performance. This research provides valuable insights for designing high-performance aromatic polymer binders for high energy density lithium-ion batteries.