Batteries

Lithium-ion battery health and remaining useful life (RUL) are essential indicators for reliable operation. Currently, most of the RUL prediction methods proposed for lithium-ion batteries use data-driven methods, but the length of training data limits data-driven strategies. To solve this problem and improve the safety and reliability of lithium-ion batteries, a Li-ion battery RUL prediction method based on iterative transfer learning (ITL) and Mogrifier long and short-term memory network (Mogrifier LSTM) is proposed. Firstly, the capacity degradation data in the source and target domain lithium battery historical lifetime experimental data are extracted, the sparrow search algorithm (SSA) optimizes the variational modal decomposition (VMD) parameters, and several intrinsic mode function (IMF) components are obtained by decomposing the historical capacity degradation data using the optimization-seeking parameters. The highly correlated IMF components are selected using the maximum information factor. Capacity sequence reconstruction is performed as the capacity degradation information of the characterized lithium battery, and the reconstructed capacity degradation information of the source domain battery is iteratively input into the Mogrifier LSTM to obtain the pre-training model; finally, the pre-training model is transferred to the target domain to construct the lithium battery RUL prediction model. The method’s effectiveness is verified using CALCE and NASA Li-ion battery datasets, and the results show that the ITL-Mogrifier LSTM model has higher accuracy and better robustness and stability than other prediction methods. Full article

Thermal propagation events of the traction batteries in electric vehicles are rare. However, their impact on the passengers in form of fire, smoke and heat can be severe. Current data on the dependencies and the reproducibility of thermal propagation is limited despite these major implications. Therefore, a thermal propagation test bench was developed for custom multi pouch experiments. This setup includes a multitude of temperature sensors throughout the module, voltage monitoring and a mass flow sensor. Two distinct experiments were initiated by nail penetration. These show a high degree of reproducibility thus allowing for future experiments regarding the dependencies of initial module temperatures and State of Charge (SoC) variations. Full article

Silicon is a desirable anode material for Li-ion batteries owing to its remarkable theoretical specific capacity of over 4000 mAh/g. Nevertheless, the poor cycling performance of pure Si electrodes caused by dramatic volume expansion has limited its practical application. To alleviate the adverse effects of Si expansion, we have synthesized anode materials of nano-Si particles trapped in a buffering space and outer carbon-based shells (Si@Void@C). The volume ratio of Si nanoparticle to void space could be adjusted accurately to approximately 1:3, which maintained the structural integrity of the as-designed nanoarchitecture during lithiation/delithiation and achieved a notable specific capacity of ~750 mAh/g for as-prepared half-cells. The yolk-shell nanostructure alleviates volumetric expansion on both material and electrode levels, which enhances the rate performance and cycling stability of the silicon-based anode. Full article

Germanium–cobalt–indium nanostructures were synthesized via cathodic electrodeposition from aqueous complex solutions of Ge (IV) and Co (II) with drop-like indium crystallization centers. This approach features simplicity, avoids heating and allows using cheaper GeO₂ instead of pure Ge as starting material. Further, in this case, target nanostructures grow directly upon the substrate. Various analytical methods (scanning electron microscopy, transmission electron microscope and X-ray diffraction) were used for characterization of the nanostructures under study. The samples obtained consist of an array of globular particles of 200 to 800 nm, with nanowires in between. The globules, in turn, contain primary particles of 5 to 10 nm consisting of cobalt, germanium and oxygen. Nanowires consist of germanium and indium. The electrochemical properties of the above-mentioned nanostructures were assessed with cyclic voltammetry and galvanostatic cycling. The germanium–cobalt–indium nanostructures are characterized by a high specific capacity upon lithium insertion, which is approximately 1350 mAh/g at C/8, and a high Coulomb cycling efficiency in the first cycle (approximately 0.76). Germanium–cobalt–indium nanostructures show the ability to operate at high rates up to 16 C at a wide temperature range from +20 to −35 °C. Full article

Lithium–sulfur batteries (LSBs) have received great attention as promising candidates for next-generation energy-storage systems due to their high theoretical energy density. However, their practical energy density is limited by a large electrolyte-to-sulfur (E/S) ratio (>10 µL _electrolyte/mg _s), and their cycle performance encounters challenges from electrode passivation and Li dendrite formation. In this work, a dual-functional electrolyte additive of tetraethylammonium nitrate (TEAN) is presented to address these issues. NO₃⁻ as a high-donor-number (DN) salt anion can promote polysulfide dissolution, increase sulfur utilization, and alleviate electrode passivation. The tetraethylammonium cation can adsorb around Li protrusions to form a lithiophobic protective layer to inhibit the formation of Li dendrites. TEAN LSBs show improving capacity, cycling stability, and higher coulombic efficiency under lean electrolyte (5 μL _electrolyte/mg _s) conditions. Full article

This study presents a method to analyze the electrical resistance of planar contacts. The method can determine whether the contact resistance of the joint exhibits linear or non-linear behavior. By analyzing the current distribution over a planar contact, it can be determined whether an area-based contact resistance is justified or if other parameters define the contact resistance. Additionally, a quantitative evaluation of the factors that affect the measurement accuracy, including the positioning, the measurement equipment used, and the influence of the current injection on the sense pin was conducted. Based on these findings, the electrical contact resistance and the mechanical ultimate tensile force of a silver-filled epoxy-based adhesive are analyzed and discussed. The layer thickness and the lap joint length were varied. Overall, the investigated adhesive shows a low contact resistance and high mechanical strength of the same magnitude as that of well-established joining techniques, such as welding, press connections, and soldering. In addition to evaluating the mechanical and electrical properties, the electric conductive adhesive underwent an economic assessment. This analysis revealed that the material costs of the adhesive significantly contribute to the overall connection costs. Consequently, the effective costs in mass production are higher than those associated with laser beam welding. Full article

State of charge (SOC) estimation is an important part of a battery management system (BMS). As for small portable devices powered by lithium-ion batteries, no current sensor will be configured in BMS, which presents a challenge to traditional current-based SOC estimation algorithms. In this work, an electrochemical model is developed for lithium batteries, and three methods, including the incremental seeking method, dichotomous method, and extended Kalman filter algorithm (EKF), are separately developed to establish the framework of current and SOC estimation simultaneously. The results show that the EKF algorithm performs better than the other two methods in terms of estimation accuracy and convergence speed. In addition, the estimation error of the EKF algorithm is within ±2%, which demonstrates its feasibility. Full article

Remaining useful life (RUL) prediction has become one of the key technologies for reducing costs and improving safety of lithium-ion batteries. To our knowledge, it is difficult for existing nonlinear degradation models of the Wiener process to describe the complex degradation process of lithium-ion batteries, and there is a problem with low precision in parameter estimation. Therefore, this paper proposes a method for predicting the RUL of lithium-ion batteries based on a cubic polynomial degradation model and envelope extraction. Firstly, based on the degradation characteristics of lithium-ion batteries, a cubic polynomial function is used to fit the degradation trajectory and compared with other nonlinear degradation models for verification. Secondly, a subjective parameter estimation method based on envelope extraction is proposed that estimates the actual degradation trajectory by using the average of the upper and lower envelope curves of the degradation data of lithium-ion batteries and uses the maximum likelihood estimation (MLE) method to estimate the unknown model parameters in two steps. Finally, for comparison with several typical nonlinear models, experiments are carried out based on the practical degradation data of lithium-ion batteries. The effectiveness of the proposed method to improve the accuracy of RUL prediction for lithium-ion batteries was demonstrated in terms of the mean square error (MSE) of the model and MSE of RUL prediction. Full article

Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) have drawn widespread attention for application in large-scale accumulation energy because of their plentiful resources and lower cost. However, the lack of anodes with high energy density and long cycle lifetimes has hampered the progress of SIBs and PIBs. Bismuth (Bi), an alloying-type anode, on account of its high volumetric capacity and cost advantage, has become the most potential candidate for SIBs and PIBs. Nevertheless, Bi anodes undergo significant volume strain during the insertion and extraction of ions, resulting in the crushing of structures and a volatile solid electrolyte interface (SEI). As a result, the tactics to boost the electrochemical properties of Bi metal anodes in recent years are summarized in this study. Recent advances in designing nanostructure Bi-based materials are reviewed, and the reasonable effects of architectural design and compound strategy on the combination property are discussed. Some reasonable strategies and potential challenges for the design of Bi-based materials are also summarized. This review aims to provide practical guidance for the development of alloying-type anode materials for next-generation SIBs and KIBs. Full article

Lithium-ion batteries (LIBs) have been widely applied in our daily life due to their high energy density, long cycle life, and lack of memory effect. However, the current commercialized LIBs still face the threat of flammable electrolytes and lithium dendrites. Solid-state electrolytes emerge as an answer to suppress the growth of lithium dendrites and avoid the problem of electrolyte leakage. Among them, polymer electrolytes with excellent flexibility, light weight, easy processing, and good interfacial compatibility with electrodes are the most promising for practical applications. Nevertheless, most of the polymer electrolytes are flammable. It is urgent to develop flame-retardant solid polymer electrolytes. This review introduces the latest advances in emerging flame-retardant solid polymer electrolytes, including Polyethylene oxide (PEO), polyacrylonitrile (PAN), Poly (ethylene glycol) diacrylate (PEGDA), polyvinylidene fluoride (PVDF), and so on. The electrochemical properties, flame retardancy, and flame-retardant mechanisms of these polymer electrolytes with different flame retardants are systematically discussed. Finally, the future development of flame-retardant solid polymer electrolytes is pointed out. It is anticipated that this review will guide the development of flame-retardant polymer electrolytes for solid-state LIBs. Full article

Gas production analysis during the thermal runaway (TR) process plays a crucial role in early fire accident detection in electric vehicles. To assess the TR behavior of lithium-ion batteries and perform early warning and risk estimation, gas production and analysis were conducted on LiNi_xCoyMn_1-x-yO₂/graphite and LiFePO₄/graphite cells under various trigger conditions. The findings indicate that the unique gas signals can provide TR warnings earlier than temperature, voltage, and pressure signals, with an advanced warning time ranging from 16 to 26 min. A new parameter called the thermal runaway degree (TRD) is introduced, which is the product of the molar quantity of gas production and the square root of the maximum temperature during the TR process. TRD is proposed to evaluate the severity of TR. The research reveals that TRD is influenced by the energy density of cells and the trigger conditions of TR. This parameter allows for a quantitative assessment of the safety risk associated with different battery types and the level of harm caused by various abuse conditions. Despite the uncertainties in the TR process, TRD demonstrates good repeatability (maximum relative deviation < 5%) and can be utilized as a characteristic parameter for risk estimation in lithium-ion batteries. Full article

As lithium-ion battery (LIB) cells degrade over time and usage, it is crucial to understand their remaining capacity, also known as State of Health (SoH), and inconsistencies between cells in a pack, also known as cell-to-cell variation (CtCV), to appropriately operate and maintain LIB packs. This study outlines efforts to model pack SoH and SoH CtCV of nickel-cobalt-aluminum (NCA) and lithium-iron-phosphate (LFP) battery packs consisting of four cells in series using pack-level voltage data. Using small training data sets and rapid testing procedures, partial least squares regression (PLS) models were built and achieved a mean absolute error of 0.38% and 1.43% pack SoH for the NCA and LFP packs, respectively. PLS models were also built that correctly categorized the packs as having low, medium, and high-ranked SoH CtCV 72.5% and 65% of the time for the NCA and LFP packs, respectively. This study further investigates the relationships between pack SoH, SoH CtCV, and the voltage response of the NCA and LFP packs. The slope of the discharge voltage response of the NCA packs was shown to have a strong correlation with pack dynamics and pack SoH, and the lowest SoH cell within the NCA packs was shown to dominate the dynamic response of the entire pack. Full article

Porous carbon electrode materials are utilized in supercapacitors with very fast charge/discharge and high stability upon cycling thanks to their electrostatic charge storage mechanism. Further enhancement of the performance of such materials can be achieved by doping them with heteroatoms which alter the kinetics of charge/discharge of the adsorbed species and result in pseudocapacitance phenomena. Here, microporous N-doped activated carbons were synthesized by thermochemical activation process. The structure and composition of the final material were adjusted by tuning the synthesis conditions and the choice of precursor molecules. In particular, N-doped activated carbons with a controlled specific surface area in the range of 270–1380 m²/g have been prepared by KOH-activation of sucrose/ammonium citrate mixture. By adjusting the composition of precursors, N-doping was varied from ca. 1.5 to 7.3 at%. The role of the components and synthesis conditions on the composition and structure of final products has been evaluated. The N-doped activated carbon with optimized structure and composition has demonstrated an outstanding performance as electrode material for aqueous electrolyte supercapacitors. The specific capacitance measured in a 3-electrode cell with 0.75 mg/cm² loading of optimized activated carbon in 1M H₂SO₄ changed from 359 F/g at 0.5 A/g charging rate to 243 F/g at 20 A/g. Less than 0.01% of capacitance loss has been detected after 1000 charging/discharging cycles. Full article

In our initial study on the high-voltage 5 V cobalt-free spinel LiNi_0.5Mn_1.5O₄ (LNMO) cathode, we discovered a severe delamination issue in the laminates when cycled at a high upper cut-off voltage (UCV) of 4.95 V, especially when a large cell format was used. This delamination problem prompted us to investigate further by studying the transition metal (TM) dissolution mechanism of cobalt-free LNMO cathodes, and as a comparison, some cobalt-containing lithium nickel manganese cobalt oxides (NMC) cathodes, as the leachates from the soaking experiment might be the culprit for the delamination. Unlike other previous reports, we are interested in the intrinsic stability of the cathode in the presence of a baseline Gen2 electrolyte consisting of 1.2 M of LiPF₆ in ethylene carbonate/ethyl methyl carbonate (EC/EMC), similar to a storage condition. The electrode laminates (transition metal oxides, transition metal oxides, TMOs, coated on an Al current collector with a loading level of around 2.5 mAh/cm²) or the TMO powders (pure commercial quality spinel LNMO, NMC, etc.) were stored in the baseline solution, and the transition metal dissolution was studied through nuclear magnetic resonance, such as ¹H NMR, ¹⁹F NMR, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma mass spectrometry (ICP-MS). Significant electrolyte decomposition was observed and could be the cause that leads to the TM dissolution of LNMO. To address this TM dissolution, additives were introduced into the baseline electrolyte, effectively alleviating the issue of TM dissolution. The results suggest that the observed delamination is caused by electrolyte decompositions that lead to etching, and additives such as lithium difluorooxalato borate and p-toluenesulfonyl isocyanate can alleviate this issue by forming a firm cathode electrolyte interface. This study provides a new perspective on cell degradation induced by electrode/electrolyte interactions under storage conditions. Full article

Lithium-ion batteries (LIBs) are leading the energy storage market. Significant efforts are being made to widely adopt LIBs due to their inherent performance benefits and reduced environmental impact for transportation electrification. However, achieving this widespread adoption still requires overcoming critical technological constraints impacting battery aging and safety. Battery aging, an inevitable consequence of battery function, might lead to premature performance losses and exacerbated safety concerns if effective thermo-electrical battery management strategies are not implemented. Battery aging effects must be better understood and mitigated, leveraging the predictive power of aging modelling methods. This review paper presents a comprehensive overview of the most recent aging modelling methods. Furthermore, a multiscale approach is adopted, reviewing these methods at the particle, cell, and battery pack scales, along with corresponding opportunities for future research in LIB aging modelling across these scales. Battery testing strategies are also reviewed to illustrate how current numerical aging models are validated, thereby providing a holistic aging modelling strategy. Finally, this paper proposes a combined multiphysics- and data-based modelling framework to achieve accurate and computationally efficient LIB aging simulations. Full article

NaCrO₂ is a promising cathode for Na-ion batteries. However, further studies of the mechanisms controlling its specific capacities and cycle stability are needed for real-world applications in the future. This study reveals, for the first time, that the typical specific capacity of ~110 mAh/g reported by many researchers when the charge/discharge voltage window is set between 2.0 and 3.6 V vs. Na/Na⁺ is actually controlled by the low electronic conductivity at the electrode/electrolyte interface. Through wet solution mixing of NaCrO₂ particles with carbon precursors, uniform carbon coating can be formed on the surface of NaCrO₂ particles, leading to unprecedented specific capacities at 140 mAh/g, which is the highest specific capacity ever reported in the literature with the lower and upper cutoff voltages at the aforementioned values. However, such carbon-coated NaCrO₂ with ultrahigh specific capacity does not improve cycle stability because with the specific capacity at 140 mAh/g the Na deintercalation during charge is more than 50% Na ions per formula unit of NaCrO₂ which leads to irreversible redox reactions. The insights from this study provide a future direction to enhance the long-term cycle stability of NaCrO₂ through integrating carbon coating and doping. Full article

The rapid growth of renewable energy sources and the expanding market for electric vehicles (EVs) have escalated the demand for safe lithium-ion batteries (LIBs) with excellent performance. But the limitations of safety issues and energy density for LIBs continue to be obstacles to their future use. Recently, single-ion covalent-organic-framework-based (COF-based) solid electrolytes have emerged as a promising avenue to address the limitations of traditional liquid electrolytes and enhance the performance of LIBs. COFs have a porous structure and abundant electron-donating groups, enabling the construction of an available ionic conductive network. So, COFs are the subject of extensive and in-depth investigation, especially in terms of the impacts their adjustable porous structure and tunable chemistry on the research of ionic transport thermodynamics and transport kinetics. In this perspective, we present a comprehensive and significant overview of the recent development progress of single-ion COF-based solid electrolytes, highlighting their rare performance and potential applications in solid lithium batteries. This review illustrates the merits of single-ion conducting solid electrolytes and single-ion COF conductor-based solid electrolytes. Furthermore, the properties of anionic, cationic, and hybrid single-ion COF-based conducting electrolytes are discussed, and their electrochemical performance is also compared when applied in Li-ion batteries. Finally, to solve challenges in COF-based Li-ion batteries, strategies are provided to obtain a high lifespan, rate performance, and stable and safe batteries. This work is promising to offer valuable insights for researchers and the energy storage industry. Full article

Tailored partially methylated and methacrylated hyperbranched polyglycerols (hbPG-MA_x/OMe_y) combined with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as conducting salt were investigated after crosslinking with respect to their application as solid polymer electrolytes (SPE) in lithium metal batteries. For sample preparation and coating, a straightforward solvent-free photopolymerization method was applied. With the aim of finding the right balance between mechanical and electrochemical properties, electrolytes with different crosslinking densities were studied. High crosslink density increases mechanical integrity but reduces local chain motion and thus ionic conductivity at the same time. Differential scanning calorimetry (DSC), chronoamperometric and impedance measurements show that the hyperbranched polyether structure interacts strongly with lithium cations. Finally, the SPE with the lowest crosslinking density was selected and investigated in cycling tests due to the parameters of highest absolute values in conductivity (2.1 × 10⁻⁶ S cm⁻¹ at 30 °C; 2.0 × 10⁻⁵ S cm⁻¹ at 60 °C), lowest T_g (from DSC: −39 °C), electrochemical stability window (4.3 V vs. Li/Li⁺) and mechanical strength (1.6 ± 0.4 MPa at 25 °C). At low C-rates and elevated temperatures (60 °C), cells were cycled with high Coulombic efficiency. At high C-rates, a distinct decrease in specific capacity was observed due to insufficient ionic conductivity. Full article

All-solid-state batteries (ASSBs) are the important attributes of the forthcoming technologies for electrochemical energy storage. A key element of ASSBs is the solid electrolyte materials. Garnets are considered promising candidates for solid electrolytes of ASSBs due to their chemical stability with Li metal anodes, reasonable kinetic characteristics ($\sigma$${}_{Li}$∼ 10${}^{-3}$–10${}^{-4}$ S · cm${}^{-1}$) and a wide electrochemical window. This study is aimed at the analysis of the experimental data available for garnet thin films, examining the ionic conductivity through the film/substrate lattice mismatch, the elastic properties and the difference in the thermal expansion characteristics of the film and the substrate, the deposition temperature of the film, and the melting point and the dielectric constant of the substrate. Based on the results of this analysis and by introducing the corresponding characteristics involved as the descriptors, the quantitative models for predicting the ionic conductivity values were developed. Some important characteristic features for ion transport in garnet films, which are primarily concerned with the film/substrate misfit, elastic properties, deposition temperature, cation segregation and the space charge effects, are discussed. Full article