Electrolyte Interface Research Articles

Chemo-electro-mechanical phase-field simulation of interfacial nanodefects and nanovoids in solid-state batteries

Solid electrolytes encompass various types of nanodefects, including grain boundaries and nanovoids at the Li-metal/solid electrolyte interface, where lithium dendrite penetration has been extensively observed. Despite the importance of ion transport near grain boundaries with different anisotropy and the combinatorial effects with interfacial nanovoids, a comprehensive understanding of these phenomena has remains elusive. Here, we develop a chemo-electro-mechanical phase-field model to elucidate how Li penetrates Li7La3Zr2O12 in the co-presence of grain boundaries and interfacial nanovoids. The investigation unveils a grain-boundary-anisotropy-dependent behavior for Li-ion transport correlated with the presence of interfacial nanovoids. Notably, the Σ1 grain boundary exhibits faster Li dendrite growth, particularly in the co-presence of interfacial nanovoids. The model quantitatively reveals whether interfacial electronic properties dominate Li dendrite morphology and penetration, providing a strategy for designing stable Li/solid electrolyte interfaces. These findings help prioritize approaches for optimally tailoring nanodefects and exploiting synergetic effects at the interface to prevent dendrite formation.

Designing electrolytes for enhancing stability and performance of lithium-ion capacitors at large-scale cylindrical cells

This study investigates the impact of fluorinated ethylene carbonate (FEC) as a co-solvent in the electrolytes of large-scale lithium-ion capacitors (LICs), an area previously unexplored. Our comprehensive analysis integrates electrochemical analysis, gas detection, and surface chemical examination to assess the performance and stability of a 1.2 M LiPF6 electrolyte system. We explored various formulations, including a standard EC/EMC/DEC mixed solvent and newly designed electrolytes with FEC additions, such as EC/EMC/DEC/FEC and DMC/FEC blends. Our findings demonstrate that the DMC/FEC blend matches and even surpasses the capacity retention of traditional electrolytes, suggesting enhanced long-term stability. FEC's presence significantly reduces electrolyte decomposition, as confirmed by in situ Differential Electrochemical Mass Spectrometry and ex-situ gas chromatography. Further, surface chemical analysis highlighted the formation of a stable, LiF-rich solid electrolyte interface (SEI) when FEC is included, thereby improving the chemical stability of the system. These results underline FEC's crucial role in optimizing electrolyte compositions, thus advancing the development of more efficient and durable LIC systems. FEC's integration into LIC electrolytes represents a significant breakthrough, enhancing overall performance and longevity, with broad implications for the application of LICs in various technologies.

Electrochemical Performance of Deposited LiPON Film/Lithium Electrode in Lithium-Sulfur Batteries.

This paper presents a composed lithium phosphate (LiPON) solid electrolyte interface (SEI) film which was coated on a lithium electrode via an electrodeposit method in a lithium-sulfur battery, and the structure of the product was characterized through infrared spectrum (IR) analysis, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), environment scanning electron microscope (ESEM), etc. Meanwhile, the electrochemical impedance spectrum and the interface stability of the lithium electrode with the LiPON film was analyzed, while the coulomb efficiency and the cycle life of the lithium electrode with the LiPON film in the lithium-sulfur battery were also studied. It was found that this kind of film can effectively inhibit the charge from transferring at the interface between the electrode and the solution, which can produce a more stable interface impedance on the electrode, thereby improving the interface contact with the electrolyte, and effectively improve the discharge performance, cycle life, and the coulomb efficiency of the lithium-sulfur battery. This is of great significance for the further development of solid electrolyte facial mask technology for lithium-sulfur batteries.

Composition and Structure of the solid electrolyte interphase on Na-Ion Anodes Revealed by Exo- and Endogenous Dynamic Nuclear Polarization─NMR Spectroscopy.

Sodium ion batteries (SIB) are among the most promising devices for large scale energy storage. Their stable and long-term performance depends on the formation of the solid electrolyte interphase (SEI), a nanosized, heterogeneous and disordered layer, formed due to degradation of the electrolyte at the anode surface. The chemical and structural properties of the SEI control the charge transfer process at the electrode-electrolyte interface, thus, there is great interest in determining these properties for understanding, and ultimately controlling, SEI functionality. However, the study of the SEI is notoriously challenging due to its heterogeneous nature and minute quantity. In this work, we present a powerful approach for probing the SEI based on solid state NMR spectroscopy with increased sensitivity from dynamic nuclear polarization (DNP). Utilizing exogenous (organic radicals) and endogenous (paramagnetic metal ion dopants) DNP sources, we obtain not only a detailed compositional map of the SEI but also, for the first time for the native SEI, determine the spatial distribution of its constituent phases. Using this approach, we perform a thorough investigation of the SEI formed on Li4Ti5O12 used as a SIB anode. We identify a compositional gradient, from organic phases at the electrolyte interface to inorganic phases toward the anode surface. We find that the use of fluoroethylene carbonate as an electrolyte additive leads to performance degradation which can be attributed to formation of a thicker SEI, rich in NaF and carbonates. We expect that this methodology can be extended to examine other titanate anodes and new electrolyte compositions, offering a unique tool for SEI investigations to enable the development of effective and long-lasting SIBs.

Introducing nanodiamond-modified electrolyte to realize high capacity and rate performance of sodium ion batteries

The solid electrolyte interface (SEI) acts as a channel for sodium ions from electrolyte to anode, its structure and chemical properties are crucial to the Coulombic efficiency, cycling stability, and even safety of rechargeable batteries. In this work, using bio-carbon as an anode, and nanodiamond (ND) as electrolyte additive, the relation between ND and SEI properties and sodium storage performance is explored. It is found that ND is transferred to the surface of bio-carbon anode and induces the formation of stable and inorganic-rich SEI (such as NaF and Na2O). Besides, the introduction of ND significantly increases the ionic conductivity. The sodium-ion batteries with ND-electrolyte exhibit a superior reversible capacity of 340 mA g−1 after 400 cycles at 0.5 A g−1, long-term cycling stability (183 mA g−1 over 1000 cycles at 5 A g−1), and remarkable rate performance (157 mA h g−1 at 10 A g−1), which is attributed to the fact that the presence of ND could provide additional storage sites and improve the stability of SEI. This study provides valuable guidance for improving the electrochemical performance of electrode materials by regulating the SEI in the optimal electrolyte.

Pristine NASICON Electrolyte: A High Ionic Conductivity and Enhanced Dendrite Resistance Through Zirconia (ZrO2) Impurity-free Solid-Electrolyte Design.

Sodium batteries are considered a promising candidate for large-scale grid storage at tropical climate zone, and solid-state sodium metal batteries have a strong proposition as high energy density battery. The main challenge is to develop ultra-pure solid-state ceramic electrolyte and compatible metal interface. Here, a scalable and energy-efficient synthesis strategy of sodium (Na) Super Ionic CONductor, Na1+xZr2SixP3-xO12(x = 2, NZSP) solid electrolyte, has been introduced with the complete removal of unreacted zirconium oxide (ZrO2) impurities. Additionally, the reaction mechanism for the formation of pure phase NZSP is reported for the first time. The NZSP prepared by utilizing the Zr precursor, i.e., tetragonal zirconium oxide (t-ZrO2) derived from the Zr(OH)4 gets quickly and completely consumed in the synthesis process leaving no unreacted monoclinic ZrO2 impurities. The synthesis process only needs a minimum stay of 4 h, which is three times less than the conventional synthesis method. The elimination of ZrO2 impurities results in a 2.5-fold reduction in grain boundary resistivity, showcasing a total ionic conductivity of 1.75 mS cm-1 at room temperature and a relative density of 98%. The prepared electrolyte demonstrates remarkable resistance to dendrite formation, as evidenced by a high critical current density value of 1.4mA cm-2.

In Situ Self‐Polymerization of Thioctic Acid Enabled Interphase Engineering Towards High‐Performance Lithium–Sulfur Battery

AbstractLithium–sulfur (Li–S) batteries possess high theoretical energy density, whereas the shuttle effect of polysulfides and the uncontrollable lithium (Li) dendrites seriously reduce the reversible capacity and cycling lifespan. Constructing an interphase to address the issues in both the cathode and anode simultaneously is significant but still challenging. In this study, a strategy of functionalizing commercial polypropylene (PP) separators is proposed by in situ poly(thioctic acid) (PTA) polymerization. Compared with the conventional separator modifications, the ring‐opening polymerization methodology initiated by heat is more facile and environment‐friendly without changing the nanostructures among the porous separators. On the cathode side, the PTA‐coated separator (PTA‐PP) blocks the shuttle of polysulfides through the electrostatic interaction. On the anode side, the PTA‐coated generates a lithium fluoride (LiF)‐rich solid electrolyte interface (SEI), identified by cryo‐transmission electron microscopy (cryo‐TEM), to accelerate the Li+ diffusion and inhibit the growth of Li dendrites. Due to the interphases constructed by the PTA‐PP separator, the Li–S cells exhibit excellent long‐term cycling in which the capacity retention rate is more than 76% after 700 cycles at 0.5 C. The in situ elaborate modification strategy may provide insights into the high‐performance separator design to promote the potentially large‐scale applications of Li–S batteries.

Collagen‐Mediated Solvent Sheathing and Derived Interfacial Manipulation Toward Ultrahigh‐Rate Zn Anodes

AbstractThe zinc (Zn) anode in zinc‐ion batteries suffers from potential defects such as wild dendrite growth, severe Zn corrosion, and violent hydrogen evolution reaction, inducing erratic interfacial charge transfer kinetics, which eventually leads to electrochemical failure. Here, collagen, a biomacromolecule, is added to achieve the reconstruction of the electrolyte hydrogen‐bonding network and the modification of the derived Zn interface. Benefiting from the electronegativity advantage of amino groups (‐NH2) in collagen, the Zn (002) crystal plane is preferentially exposed and the solid electrolyte interface (SEI) rich in ZnF2 and Zn3N2 promotes the rapid charge transfer of Zn anode. Thence, an impressive cumulative capacity of 7,500 mAh cm−2 at 30 mA cm−2 is achieved and the assembled Zn|VO2 cell exhibited robust cycle reversibility even when subject to a maximum current of 100 A g−1 and an ultra‐long cycle life of 20,000 cycles at 50 A g−1, with a single‐cycle capacity loss as low as 0.0021%. Such a convenient strategy of solvent sheathing regulation and derived interfacial manipulation opening up a promising universal approach toward long‐life and high‐rate Zn anodes.

Multi boron-doping effects in hard carbon toward enhanced sodium ion storage

Hard carbon (HC) has been considered as promising anode material for sodium-ion batteries (SIBs). The optimization of hard carbon’s microstructure and solid electrolyte interface (SEI) property are demonstrated effective in enhancing the Na+ storage capability, however, a one-step regulation strategy to achieve simultaneous multi-scale structures optimization is highly desirable. Herein, we have systematically investigated the effects of boron doping on hard carbon’s microstructure and interface chemistry. A variety of structure characterizations show that appropriate amount of boron doping can increase the size of closed pores via rearrangement of carbon layers with improved graphitization degree, which provides more Na+ storage sites. In-situ Fourier transform infrared spectroscopy/electrochemical impedance spectroscopy (FTIR/EIS) and X-ray photoelectron spectroscopy (XPS) analysis demonstrate the presence of more BC3 and less B–C–O structures that result in enhanced ion diffusion kinetics and the formation of inorganic rich and robust SEI, which leads to facilitated charge transfer and excellent rate performance. As a result, the hard carbon anode with optimized boron doping content exhibits enhanced rate and cycling performance. In general, this work unravels the critical role of boron doping in optimizing the pore structure, interface chemistry and diffusion kinetics of hard carbon, which enables rational design of sodium-ion battery anode with enhanced Na+ storage performance.

Noncovalent Interactions-Driven Self-Assembly of Polyanionic Additive for Long Anti-Calendar Aging and High-Rate Zinc Metal Batteries.

Zinc anodes of zinc metal batteries suffer from unsatisfactory plating/striping reversibility due to interfacial parasitic reactions and poor Zn2+ mass transfer kinetics. Herein, methoxy polyethylene glycol-phosphate (mPEG-P) is introduced as an electrolyte additive to achieve long anti-calendar aging and high-rate capabilities. The polyanionic of mPEG-P self-assembles via noncovalent-interactions on electrode surface to form polyether-based cation channels and in situ organic-inorganic hybrid solid electrolyte interface layer, which ensure rapid Zn2+ mass transfer and suppresses interfacial parasitic reactions, realizing outstanding cycling/calendar aging stability. As a result, the Zn//Zn symmetric cells with mPEG-P present long lifespans over 9000 and 2500 cycles at ultrahigh current densities of 120 and 200mA cm-2, respectively. Besides, the coulombic efficiency (CE) of the Zn//Cu cell with mPEG-P additive (88.21%) is much higher than that of the cell (36.4%) at the initial cycle after the 15-day calendar aging treatment, presenting excellent anti-static corrosion performance. Furthermore, after 20-day aging, the Zn//MnO2 cell exhibits a superior capacity retention of 89% compared with that of the cell without mPEG-P (28%) after 150 cycles. This study provides a promising avenue for boosting the development of high efficiency and durable metallic zinc based stationary energy storage system.

In-situ construction of solid electrolyte interphase for stable zinc anode via synergy of electrochemical reduction and chemical precipitation

Aqueous zinc ion batteries (ZIBs) feature high theoretical capacity, low cost, and high safety, but they suffer from moderate reversibility arising from electrolyte decomposition, Zn corrosion/passivation, and dendrite growth. To address this issue, an effective strategy is to construct a functional solid electrolyte interface (SEI) in situ. However, this is substantially challenging owing to the severe hydrogen evolution reaction (HER) and a lack of substances that can be decomposed to form SEI in the aqueous electrolytes. Herein, we propose the fabrication of a stable SEI in situ via a synergistic electrochemical reduction-chemical precipitation approach. By chemically capturing the hydroxide ions (OH−) from HER, fatty acid methyl ester ethoxylate (FMEE), as an aqueous electrolyte additive, undergoes ester group hydrolysis following by a combination with Zn2+ to form insoluble fatty acid-zinc, enabling intelligent growth of a SEI on the Zn anode surface. As a result, the enhanced Zn anode exhibits a prolonged cycling life of up to 2700 h at 1 mA/cm2 and 1 mAh/cm2. The Zn-V2O5 full cell with the designed electrolyte demonstrates excellent rate capability and significantly improved cycling stability. This study presents a simple and practical strategy for in-situ formation of SEI in aqueous electrolytes, advancing the development of high-performance aqueous batteries.

Functional ternary salt construction enabling an in-situ Li3N/LiF-enriched interface for ultra-stable all-solid-state lithium metal batteries

Poly(ethylene oxide)-based polymer all-solid-state lithium metal batteries (ASSLBs) have received widespread attention due to their low cost, good process ability, and high energy density. Nevertheless, the growth of Li dendrites within polymer solid-state electrolytes damages the reversibility of Li anodes and still impedes their widespread application. One efficient strategy is to construct a superior solid electrolyte interface. Herein, a stable interface enriched with Li3N and LiF is in-situ formed between Li anode and a ternary salt electrolyte. This ternary salt electrolyte is innovatively designed by introducing lithium bis(trifluoromethane sulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and LiNO3 to poly(ethylene oxide) matrix. Surface characterization indicates that LiNO3 and LiFSI contribute to forming a Li3N-LiF-enriched interface and meanwhile LiTFSI ensures excellent conductivity. Theoretically, among various Li compound components, Li3N has high ionic conductivity, which is beneficial for reducing overpotential, while LiF has high interfacial energy which can enhance nucleation energy and suppress the formation of Li dendrites. The experimental results show that ASSLBs coupled with LiFePO4 cathode display extremely excellent cycle stability approximately 2200 cycles at 2 C, with a final and corresponding discharge specific capacity of 96.7 mA h g−1. Additionally, a schematic illustration of the working mechanism for the Li3N-LiF interface is proposed.

Selective detection of alpha synuclein amyloid fibrils by faradaic and non-faradaic electrochemical impedance spectroscopic approaches

This study utilized faradaic and non-faradaic electrochemical impedance spectroscopy to detect alpha synuclein amyloid fibrils on gold interdigitated tetraelectrodes (AuIDTE), providing valuable insights into electrochemical reactions for clinical use. AuIDE was purchased, modified with zinc oxide for increased hydrophobicity. Functionalization was conducted with hexacyanidoferrate and carbonyldiimidazole. Faradaic electrochemical impedance spectroscopy has been extensively explored in clinical diagnostics and biomedical research, providing information on the performance and stability of electrochemical biosensors. This understanding can help develop more sensitive, selective, and reliable biosensing platforms for the detection of clinically relevant analytes like biomarkers, proteins, and nucleic acids. Non-faradaic electrochemical impedance spectroscopy measures the interfacial capacitance at the electrode–electrolyte interface, eliminating the need for redox-active species and simplifying experimental setups. It has practical implications in clinical settings, like real-time detection and monitoring of biomolecules and biomarkers by tracking changes in interfacial capacitance. The limit of detection (LOD) for normal alpha synuclein in faradaic mode is 2.39-fM, The LOD for aggregated alpha synuclein detection is 1.82-fM. The LOD for non-faradaic detection of normal alpha synuclein is 2.22-fM, and the LOD for nonfaradaic detection of aggregated alpha synuclein is 2.40-fM. The proposed EIS-based AuIDTEs sensor detects alpha synuclein amyloid fibrils and it is highly sensitive.

Constructing a Li–Zn lithiophilic layer by a scalable method of magnetron sputtering for a high-quality Li–B alloy anode

Lithium metal anodes offer high theoretical capacity and low redox potential but face challenges like dendritic growth, fragile solid electrolyte interface (SEI), "dead lithium" formation, and volume expansion. Composite anodes or artificial SEIs can address these issues, but often suffer from poor lithiophilicity and mass burdens. This study presents a Li–Zn–B alloy anode combining a Li–Zn lithiophilic layer with a bulk Li–B alloy. The Li–Zn lithiophilic layer, formed by magnetron sputtering of Zinc oxide (ZnO), improves surface lithiophilicity. Symmetrical cells with this alloy cycled stably for 1300 (1 mA cm−2, 1 mAh cm−2) and 550 h (2 mA cm−2, 2 mAh cm−2) with minimal overpotentials. The LiBZn||NCM811 full cell showed a specific discharge capacity of 130.8 mAh/g and stable Coulombic efficiency of 98.9 % after 300 cycles.

Rolling strategy for highly efficient preparation of phosphating interface enabled the stable lithium anode

Lithium metal anode has an ultra-high theoretical specific capacity and the lowest reduction potential, regarded as the next-generation anode material for high-energy-density batteries. However, the lithium metal anode suffers from the severe side reaction and Li dendrite growth caused by the inhomogeneous deposition of Li+ on the anode during the electrochemical cycling. Herein, a strategy is proposed to design an artificial solid electrolyte interface (SEI) by rolling with the organic phosphating lubricant. The obtained phosphating interface with high surface energy and surface Young’s modulus significantly induces the dense deposition of Li+ and results in a stable cycling. The phosphating interface enables the symmetric cells to cycle stably for 750 h at 1 mA cm−2 with 1 mA h cm−2 and for 450 h at 3 mA cm−2 with 3 mA h cm−2 using ester-based electrolyte. The full cell with high single-side mass loading (10 mg cm−2) of LiCoO2 achieves a capacity retention rate of 77.7 % after 165 cycles at 1 C and 75.6 % after 120 cycles at 2 C. This work paves a path to construct a green fluorine-free interface and provide a large-scale modification for practical lithium strips.

Improving Lithium-Ion Battery Performance: Nano Al2O3 Coatings on High-Mass Loading LiFePO4 Cathodes via Atomic Layer Deposition

Lithium iron phosphate (LiFePO4 or LFP) is a promising cathode material for lithium-ion batteries (LIBs), but side reactions between the electrolyte and the LFP electrode can degrade battery performance. This study introduces an innovative coating strategy, using atomic layer deposition (ALD) to apply a thin (5 nm and 10 nm) Al2O3 layer onto high-mass loading LFP electrodes. Galvanostatic charge–discharge cycling and electrochemical impedance spectroscopy (EIS) were used to assess the electrochemical performance of coated and uncoated LFP electrodes. The results show that Al2O3 coatings enhance the cycling performance at room temperature (RT) and 40 °C by suppressing side reactions and stabilizing the cathode–electrolyte interface (CEI). The coated LFP retained 67% of its capacity after 100 cycles at 1C and RT, compared to 57% for the uncoated sample. Post-mortem analyses, including scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), were conducted to investigate the mechanisms behind the improved performance. These analyses reveal that Al2O3 coatings are highly effective in reducing LFP electrode degradation during cycling, demonstrating the potential of ALD Al2O3 coatings to enhance the durability and performance of LFP electrodes in LIBs.

Inhibited Passivation by Bioinspired Cell Membrane Zn Interface for Zn-Air Batteries with Extended Temperature Adaptability.

Due to the slow dynamics of mass and charge transfer at Zn|electrolyte interface, the stable operation of Zn-air batteries (ZABs) is challenging, especially at low temperature. Herein, inspired by cell membrane, a hydrophilic-hydrophobic dual modulated Zn|electrolyte interface is constructed. This amphiphilic design enables the quasi-solid-state (QSS) ZABs to display a long-term cyclability of 180 h@50mAcm-2 at 25°C. Moreover, a record-long time of 173 h@4mAcm-2 at -60°C is also achieved, which is almost threefolds of untreated QSS ZABs. Control experiments and (in situ) characterization reveal that the growth of insulating ZnO passivation layers is largely inhibited by tuned hydrophilic-hydrophobic behavior. Thus, the enhanced transfer dynamic of Zn2+ at Zn|electrolyte interface from 25 to -60°C is attained. As an extension, the QSS Al-air batteries (AABs) with bioinspired interface also show unprecedented discharge stability of 420 h@1mAcm-2 at -40°C, which is about two times of untreated QSS AABs. This bioinspired-hydrophilic-hydrophobic dual modulation strategy may provide a reference for energy transform and storage devices with broad temperature adaptability.

Maximizing interface stability in all-solid-state lithium batteries through entropy stabilization and fast kinetics

The positive electrode|electrolyte interface plays an important role in all-solid-state Li batteries (ASSLBs) based on garnet-type solid-state electrolytes (SSEs) like Li6.4La3Zr1.4Ta0.6O12 (LLZTO). However, the trade-off between solid-solid contact and chemical stability leads to a poor positive electrode|electrolyte interface and cycle performance. In this study, we achieve thermodynamic compatibility and adequate physical contact between high-entropy cationic disordered rock salt positive electrodes (HE-DRXs) and LLZTO through ultrafast high-temperature sintering (UHS). This approach constructs a highly stable positive electrode|electrolyte interface, reducing the interface resistance to 31.6 Ω·cm2 at 25 °C, making a 700 times reduction compared to the LiCoO2 | LLZTO interface. Moreover, the conformal and tight HE-DRX | LLZTO solid-state interface avoids the transition metal migration issue observed with HE-DRX in liquid electrolytes. At 150 °C, HE-DRXs in ASSLBs (Li|LLZTO | HE-DRXs) exhibit an average specific capacity of 239.7 ± 2 mAh/g at 25 mA/g, with a capacity retention of 95% after 100 cycles relative to the initial cycle—a stark contrast to the 76% retention after 20 cycles at 25 °C in conventional liquid batteries. Our strategy, which considers the principles of thermodynamics and kinetics, may open avenues for tackling the positive electrode|electrolyte interface issue in ASSLBs based on garnet-type SSEs.

Characterization of pristine and aged NMC lithium-ion battery thermal runaway using ARC experiments coupled with optical techniques

Battery thermal runaway (TR) challenges battery applications due to safety considerations, potentially endangering consumers. Understanding the process is crucial to defining first alarm strategies that indicate the risk of TR and designing systems to mitigate this problem. For this reason, the present paper aims to characterise key variables of the venting and thermal runaway processes. Experimental tests were conducted in an accelerating rate calorimeter (ARC) using the heat wait seek (HWS) protocol, which tracks the battery temperature after detecting an exothermic reaction during the seek period. The maximum temperature rise rate and peak temperature that the calorimeter can achieve are 15 °C/min and 300 °C. Two optical accesses in the ARC were modified to use optical techniques such as Schlieren double pass and infrared. The results cover 3 different cell conditions: Pristine cells at state of charge (SOC) 100 %, pristine cells at SOC 50 %, and aged cells at SOC 100 %. For statical purposes, each cell condition was repeated 5 times. The aged battery was cycled to boost solid electrolyte interface growth. The images obtained were post-processed, with a specific methodology for each optical technique, and according to the parameters intended to be obtained. The main result shows that for higher SOC, the exothermic reaction is detected earlier than for SOC 50 %, which was only detected in an advanced TR stage (higher temperature rise rate). Therefore, the battery system capability to detect plays a crucial role in safety. Safety actuation time is reduced by ∼ 40 % for SOC 50 %. However, the energy to manage during this situation is lower (∼42 %), depending on the mass inside the battery, revealing the importance of a good venting cap design. Infrared images have shown higher particle temperatures for higher SOC, about 150 °C higher than the SOC 50 %. The particle velocity, in this case, achieved 30 m/s.

Simulation of lithium-ion battery thermal runaway considering active material volume fraction effect

The multi-physics solver BatteryFOAM couples with the side reaction model for thermal runaway (TR) simulations, including the electrolyte decomposition (E) and solid electrolyte interface layer decomposition (SEI), and the reaction of the electrolyte with graphite intercalated lithium (NE-E) and the reaction of positive electrode active material with the electrolyte (PE-E). This solver is used to study the lithium-ion battery (LIB) TR at different conditions. The published experimental results are used to validate the effectiveness and practicability of BatteryFOAM in predicting the temperature under constat high temperature. We also discuss the reactant concentration, reaction rate, and heat release rate during the LIB TR. The influences of the external factor of the equal equivalent heat transfer (h) on the battery TR is considered, and the sequence in which the battery reaches the critical temperature rising rate (RTR, 60 K/min) and the separator failure temperature (Tsep) is predicted. The results demonstrate that overall the exothermic reaction peaks arise sequentially from SEI decomposition, PE-E reaction, NE-E reaction, and electrolyte decomposition, and NE-E reaction has three exothermic peaks induced by other three side reactions. PE-E reaction contributes more heat for fuse energy to trigger TR, but the NE-E reaction and electrolyte decomposition mainly accounts for the runaway energy. In addition, increasing SEI and electrolyte decomposition intensity is found no effect on the TR temperature. Besides, the rapid reaching to RTR is caused by the high heat release rate of positive electrode active material with electrolyte. Results further show that reducing the fNE−E within 5.0 % will significantly reduce TR risk.