Batteries, Volume 9, Issue 9 (September 2023) – 52 articles

An industrial submicron-sized Fe₂O₃ with no special shape was decorated by a multi-layer coating of oxygen-deficient TiO_2−x and conducting polymer PEDOT (poly 3,4-ethylenedioxythiophene). A facile sol–gel method followed by an EDOT polymerization process was adopted to synthesize the hierarchical coating composite. The microstructure and phase composition were characterized using an X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). In particular, the existence state of PEDOT was determined using Fourier transform infrared (FT-IR) and a thermogravimetric (TG) analysis. The characterization results indicated the dual phase was well-coated on the Fe₂O₃ and its thickness was nano scale. Electrochemical characterization indicated that the multi-layer coating was helpful for significantly enhancing the cycle stability of the Fe₂O₃, and its electrochemical performance was even better than that of the single-layer coating samples. The synergistic effects of the ceramic phase and conducting polymer were demonstrated to be useful for improving electrochemical properties. The obtained FTP-24 sample exhibited a specific discharge capacity of 588.9 mAh/g after 360 cycles at a current density of 100 mA/g, which effectively improved the intrinsic cycling performance of the Fe₂O₃, with a corresponding discharge capacity of 50 mAh/g after 30 cycles. Full article

Li₆PS₅Cl possesses high ionic conductivity and excellent interfacial stability to electrodes and is known as a promising solid-state electrolyte material for all-solid-state batteries (ASSBs). However, the optimal annealing process of Li₆PS₅Cl has not been studied systematically. Here, a Box–Behnken design is used to investigate the interactions of the heating rate, annealing temperature, and duration of annealing process for Li₆PS₅Cl to optimize the ionic conductivity. The response surface methodology with regression analysis is employed for simulating the data obtained, and the optimized parameters are verified in practice. As a consequence, Li₆PS₅Cl delivers a rather high conductivity of 4.45 mS/cm at 25 °C, and ASSB consisting of a LiNi_0.6Co_0.2Mn_0.2O₂ cathode and lithium anode shows a high initial discharge capacity of 151.7 mAh/g as well as excellent cycling performances for more than 350 cycles, highlighting the importance of the design of experiments. Full article

As a novel type of green energy storage device, supercapacitors exhibit several orders of magnitude higher capacities than the traditional dielectric capacitors and significantly higher power density than the traditional secondary batteries. Supercapacitors have been widely applied in energy storage fields. Electrode materials, as pivotal components of supercapacitors, play an important role in electrochemical performance. Molybdenum-based materials have attracted widespread attention for their high theoretical capacitance, abundant resources, and facile synthesis tactics. Therefore, it is necessary to systematically summarize the application of Mo-based electrode materials in high-performance supercapacitors and unveil their developmental direction and trends. In this paper, we provide a review of binary Mo-based materials, ternary Mo-based materials, nanocomposites of Mo-based materials, and Mo-based MOFs and derivative materials. In addition, we further point out the key issues on the development of Mo-based materials in supercapacitors. This review may inspire more insightful works and enlighten other electrochemical areas concerning Mo-based materials. Full article

Charge time has become one of the primary issues restricting the development of electric vehicles. To counter this problem, an adapted thermal management system needs to be designed in order to reduce the internal thermal gradient, by predicting the surface and internal temperature responses of the battery. In this work, a pseudo 3D model is developed to simulate battery cell performance and its internal states under various operational scenarios such as temperature and convection conditions as well as the applied current during charge and discharge. An original mesh of the JR is proposed where heat exchanges in the three directions (radial, orthoradial and axial) are considered. The model represents one of the solutions that enable increasing the lifespan of batteries while decreasing charging time. It offers the opportunity to optimize operating parameters to extend battery life. In this paper, attention was paid not only to the core and non-core components, but also to the experiments required to parametrize the thermal and electrochemical models (heat generation). Unlike existing approaches documented in the literature, the model developed in this work achieves an impressive balance between computational efficiency and result accuracy, making it a groundbreaking contribution in the field of electric vehicle technology. Full article

The combination of Li-metal anode and high-voltage cathode is regarded as a solution for the next-generation high-energy-density secondary batteries. However, a traditional electrolyte is either incompatible with the Li-metal anode or vulnerable to high voltage. This work reports a 1 M dual-salts Localized-High-Concentration-Electrolyte with Fluoroethylene carbonate (FEC) additive. It enables stable cycling of Li||LiNi_0.8Co_0.1Mn_0.1O₂ (NMC811) battery, which shows 81.5% capacity retention after 300 cycles with a charge/discharge current density of 1 C and a voltage range of 2.7–4.4 V. Scanning electron microscopy (SEM) images show that this electrolyte not only largely reduced Li dendrites and ‘dead’ Li on anode surface but also well protected the microstructure of NMC811 cathode. Possible components of both solid-electrolyte interlayer (SEI) and cathode-electrolyte interlayer (CEI) were characterized by energy-dispersive X-ray spectroscopy (EDX). The result illustrates that FEC protected Li salts from decomposition on the anode side and suppressed the decomposition of solvents on the cathode side. Full article

The dynamic behavior and thermal performance of a high-power, high-energy-density lithium-ion battery for urban air mobility (UAM) applications were analyzed by using an electro-thermal model. To simulate the behavior of pouch-type nickel-cobalt-manganese (NCM) lithium–ion batteries, a battery equivalent circuit with a second order of resistance–capacitance (RC) elements was employed. The values of the RC models were determined by using curve fitting based on experimental data for the lithium-ion battery. A three–dimensional model of the lithium-ion battery was created, and a thermal analysis was performed while considering the external temperature and flight time under a 20 min load condition. At an external temperature of 20 °C, the heat generation increased proportionally to the square of the current as the C–rate increased. For 3C, the reaction heat source was 45.5 W, and the average internal temperature of the cell was 36 °C. Even at the same 3C, as the external temperature decreased to 0 °C, the increase in internal resistance led to a greater reaction heat source of 58.27 W, which was 36.9% higher than that at 20 °C. At 5C, the maximum operating time was 685.6 s. At this point, the average internal temperature of the cell was 59.8 °C, which allowed for normal operation. When the C–rate of the battery cell reached 8, which was the momentary maximum high-discharge condition, the temperature sharply rose before the state of charge ($SoC$) reached 0. With an average internal cell temperature of 80 °C, the maximum operating time became 111.9 s. This met the design requirements for urban air mobility (UAM) in this study. Full article

One of the major concerns in ensuring lithium-ion battery (LIB) safety in abuse scenarios is the structural integrity of the battery separator. This paper presents a coupled viscoelastic–viscoplastic model for predicting the thermomechanical response of polymeric battery separators in abuse scenarios under combined mechanical and thermal loadings. The viscoplastic model is developed based on a rheological framework that considers the mechanisms involved in the initial yielding, change in viscosity, strain softening and strain hardening of polymeric separators. The viscoplastic model is then coupled with a previously developed orthotropic nonlinear thermoviscoelastic model to predict the thermomechanical response of polymeric separators before the onset of failure. The model parameters are determined for Celgard^®2400, a polypropylene (PP) separator, and the model is implemented in the LS-DYNA^® finite element (FE) package as a user-defined subroutine. Punch test simulations are employed to verify the model predictions under biaxial stress states. Simulations of uniaxial tensile stress–strain responses at different strain rates and temperatures are compared with experimental data to validate the model predictions. The model predictions of the material anisotropy, rate and temperature dependence agree well with experimental observations. Full article

In this paper, an experimental and numerical study was conducted to analyze the performance of a hybrid thermal management concept for cylindrical lithium-ion battery modules at various discharge rates. The proposed concept consists of primary cooling through phase change material (PCM) and secondary cooling through vertical liquid channels between the PCM and airflow at the top of the cells. Two experimental studies were performed to obtain the temperature and heat flux profiles. In addition, the thermal performance of the battery module was obtained for 1 C, 2 C, 3 C, 5 C, and 7 C discharge rates using the numerical study. The results show that the maximum temperature was limited to ~30 °C. Additionally, the temperature uniformity in all the discharge rates was maintained below 5 °C. Finally, a meager amount of PCM was utilized during all the discharge cycles. At 1 C none of the PCM changed its phase, whereas at 2 C, 0.32%, 3 C, 0.14%, 5 C, 0.3%, and at 7 C, 0.12% of PCM changed its phase. The proposed hybrid concept can maintain the thermal environment required by the Li-ion cells for effective performance. Furthermore, this concept does not require excessive pumping fluid power and high air velocities, which reduces the energy required for the operation of the thermal management system, thereby increasing the available energy for propulsion. Full article

Coal tar pitch (CTP) is a high-quality raw material for producing functional carbon materials owing to its high carbon yield and high degree of condensation. The rational structure regulation of CTP-derived carbon materials is paramount for their special application. Herein, a green template strategy is proposed to fabricate hierarchically porous carbon (HPC) and employ it as the anode material for lithium-ion batteries. It can be demonstrated that the mass ratio of the template (KHCO₃) and carbon source (CTP) significantly influences the microstructure and electrochemical performances of HPC. HPC-3 synthesized by a mass ratio of 3:1 shows a coral-like lamellar nanostructure with high specific surface area, developed nanopores, and ample defects, enabling fast and high-flux lithium storage. Thus, the HPC-3 electrode achieves an excellent rate capacity of 219 mAh g⁻¹ at 10 A g⁻¹ and maintains a high discharge capacity of 660 mAh g⁻¹ after 1400 cycles at 1 A g⁻¹. This work takes a step towards the high-value-added and green utilization of CTP and offers a promising solution for the sustainable production of advanced carbon electrode materials. Full article

In all-solid-state battery (ASSB) research, the importance of sulfide electrolytes is steadily increasing. However, several challenges arise concerning the future mass production of this class of electrolytes. Among others, the high reactivity with atmospheric moisture forming toxic and corrosive hydrogen sulfide (H₂S) is a major issue. On a production scale, excessive exposure to H₂S leads to serious damage of production workers’ health, so additional occupational health and safety measures are required. This paper investigates the environmental conditions for the commercial fabrication of slurry-based sulfide solid electrolyte layers made of Li₃PS₄ (LPS) and Li₁₀GeP₂S₁₂ (LGPS) for ASSBs. First, the identification of sequential production steps and processing stages in electrolyte layer production is carried out. An experimental setup is used to determine the H₂S release of intermediates under different atmospheric conditions in the production chain, representative for the production steps. The H₂S release rates obtained on a laboratory scale are then scaled up to mass production dimensions and compared to occupational health and safety limits for protection against H₂S. It is shown that, under the assumptions made for the production of a slurry-based electrolyte layer with LPS or LGPS, a dry room with a dew point of $\mathsf{\tau }=-40{}^{\circ }\mathrm{C}$ and an air exchange rate of $\mathrm{AER}=30\frac{1}{\mathrm{h}}$ is sufficient to protect production workers from health hazards caused by H₂S. However, the synthesis of electrolytes requires an inert gas atmosphere, as the H₂S release rates are much higher compared to layer production. Full article

To optimize the preparation process of polymer electrolytes by in situ UV curing and improve the performance of polymer electrolytes, we investigated the effect of carrier film phase conversion time on the properties of polymer electrolyte properties in all-solid-state LIBs. We compared several carrier films with phase conversion times of 24 h, 32 h, 40 h, and 48 h. Then, the physical properties of the polymer electrolytes were characterized and the properties of the polymer electrolytes were further explored. It was concluded that the carrier membrane with a phase transition time of 40 h and the prepared electrolyte had the best performance. The ionic conductivity of the sample was 1.02 × 10⁻³ S/cm at 25 °C and 3.42 × 10⁻³ S/cm at 60 °C. At its best cycle performance, it had the highest discharge-specific capacity of 155.6 mAh/g, and after 70 cycles, the discharge-specific capacity was 152.4 mAh/g, with a capacity retention rate of 98% and a discharge efficiency close to 100%. At the same time, the thermogravimetric curves showed that the samples prepared by this process had good thermal stability which can meet the various requirements of lithium-ion batteries. Full article

This paper presents a comparative analysis of different battery charging strategies for off-grid solar PV systems. The strategies evaluated include constant voltage charging, constant current charging, PWM charging, and hybrid charging. The performance of each strategy is evaluated based on factors such as battery capacity, cycle life, DOD, and charging efficiency, as well as the impact of environmental conditions such as temperature and sunlight. The results show that each charging strategy has its advantages and limitations, and the optimal approach will depend on the specific requirements and limitations of the off-grid solar PV system. This study provides valuable insights into the performance and effectiveness of different battery charging strategies, which can be used to inform the design and operation of off-grid solar PV systems. This paper concludes that the choice of charging strategy depends on the specific requirements and limitations of the off-grid solar PV system and that a careful analysis of the factors that affect performance is necessary to identify the most appropriate approach. The main needs for off-grid solar photovoltaic systems include efficient energy storage, reliable battery charging strategies, environmental adaptability, cost-effectiveness, and user-friendly operation, while the primary limitations affecting these systems encompass intermittent energy supply, battery degradation, environmental variability, initial investment costs, fluctuations in energy demand, and maintenance challenges, emphasizing the importance of careful strategy selection and system design to address these factors. It also provides valuable insights for designing and optimizing off-grid solar PV systems, which can help to improve the efficiency, reliability, and cost-effectiveness of these systems. Full article

Covalent organic frameworks (COFs) have emerged as a promising platform of materials for solid-state battery electrolytes due to their porous and robust structures, and their special spaces such as 1D and 3D, as well as their ability to be modified with functional groups. This review focuses on the use of COF materials in solid-state batteries and explores the various types of bonds between building blocks and the impact on key properties such as conductivity, transfer number, and electrochemical stability. The aim is to provide an overview of the current state of COF-based electrolytes for solid-state batteries and to highlight the prospects for future development in this field. The use of COF materials in solid-state batteries has the potential to overcome limitations such as low theoretical energy density, limited temperature stability, and the risk of fire and explosion associated with traditional liquid electrolyte batteries. By providing a more in-depth understanding of the potential applications of COF-based electrolytes in solid-state batteries, this review seeks to pave the way for further advancements and innovations in this field. Full article

The analysis aims to determine the most efficient and cost-effective way of providing power to a remote site. The two primary sources of power being considered are photovoltaics and small wind turbines, while the two potential storage media are a battery bank and a hydrogen storage fuel cell system. Subsequently, the hydrogen is stored within a reservoir and employed as required by the fuel cell. This strategy offers a solution for retaining surplus power generated during peak production phases, subsequently utilizing it during periods when the renewable power sources are generating less power. To evaluate the performance of the hydrogen storage system, the analysis included a sensitivity analysis of the wind speed and the cost of the hydrogen subsystem. In this analysis, the capital and replacement costs of the electrolyzer and hydrogen storage tank were linked to the fuel cell capital cost. As the fuel cell cost decreases, the cost of the electrolyzer and hydrogen tank also decreases. The optimal system type graph showed that the hydrogen subsystem must significantly decrease in price to become competitive with the battery bank. Full article

Sodium-ion batteries (SIBs) are expected to replace lithium-ion batteries (LIBs) as a new generation of energy storage devices due to their abundant sodium reserves and low cost. Among the anode materials of SIBs, transition metal chalcogenides (TMXs) have attracted much attention because of their large layer spacing, narrow band gap, and high theoretical capacity. However, in practical applications, TMXs face problems, such as structural instability and poor electrical conductivity. In this review, the research progress and challenges of TMXs in SIBs in recent years are summarized, the application of nanostructure design, defect engineering, cladding engineering, and heterogeneous construction techniques and strategies in improving the electrochemical performance of TMXs anode are emphatically introduced, and the storage mechanism of sodium is briefly summarized. Finally, the application and development prospects of TMX anodes in electrochemical energy storage are discussed and prospected. Full article

In this work, dimethoxyethane (DME) and 1,3-dioxolane (DOL) are studied as the co-solvent of an advanced electrolyte for fast charging of Li-ion batteries by using lithium bis(fluorosulfonyl)imide (LiFSI) as a salt and fluorinated ethylene carbonate (FEC) as an additive. It is shown that even when used with LiFSI and FEC, neither DME nor DOL constitute a suitable electrolyte for Li-ion batteries, either because of their inability to form a robust solid-electrolyte interphase (SEI) with graphite (Gr) anodes or because of their oxidative instability against oxygen released from the delithiated LiNi_0.80Co_0.10Mn_0.10O₂ (NCM811) and LiNi_0.80Co_0.15Al_0.05O₂ (NCA), respectively. However, using 30% FEC as the co-solvent can make 1:1 DME/DOL mixture compatible with high-voltage Li-ion batteries and combining it with conventional ethylene carbonate (EC) and ethyl methyl carbonate (EMC) significantly enhances the fast charging capability of Li-ion batteries. As a result, an advanced electrolyte composed of 1.2 m (molality) LiFSI 1:1:1:2 DME/DOL/EC/EMC + 10% FEC (all by wt.) offers much improved fast-charging performances in terms of capacity and capacity retention for a 200 mAh Gr/NCA pouch cell, compared with a 1.2 m LiFSI 3:7 EC/EMC baseline electrolyte. AC impedance analysis reveals that the significant improvement is attributed to a much reduced charge transfer resistance, while the advanced electrolyte has little effect on the bulk and SEI resistances. Full article

The solid polymer electrolyte is a promising candidate for solid-state lithium battery because of favorable interfacial contact, good processability and economic availability. However, its application is limited because of low ionic conductivity and insufficient mechanical strength. In this study, the delicate molecular structural design was realized via controlled / “living” radical polymerization in order to decouple the trade-off between ionic conductivity and mechanical strength. The random and triblock copolymer electrolytes were designed and synthesized to investigate the influence of molecular structure on ionic conduction, while a chemical cross-linking network was constructed via a semi-spontaneous post-crosslinking reaction. Compared with a random counterpart, the triblock copolymer electrolyte presented stronger chain segment motion and a liquid-like mechanical response due to the independent ion-conducting block, resulting in significantly improved ionic conductivity (from 6.29 ± 1.11 × 10⁻⁵ to 9.57 ± 2.82 × 10⁻⁵ S cm⁻¹ at 60 °C) and cell performance. When assembled with LiFePO₄ and lithium metal electrodes, the cell with triblock copolymer electrolyte showed significantly improved rate performance (150 mAh g⁻¹ at 1 C) and cycling life (200 cycles with 92.8% capacity retention at 1 C). This study demonstrates the advantages of molecular structure regulation on ionic conduction and mechanical support, which may provide new insights for the future design of solid polymer electrolytes. Full article

Vanadium redox flow batteries are gaining great popularity in the world due to their long service life, simple (from a technological point of view) capacity increase and overload resistance, which hardly affects the service life. However, these batteries have technical problems, namely in balancing stacks with each other in terms of volumetric flow rate of electrolyte. Stack power depends on the speed of the electrolyte flow through the stack. Stacks are connected in parallel by electrolytes to increase battery power. If one of the stacks has a lower hydrodynamic resistance, the volume of electrolytes passing through it increases, which leads to a decrease in the efficiency of the remaining stacks in the system. This experimental study was conducted on a 10 kW uninterruptible power supply system based on two 5 kW stacks of all-vanadium redox flow batteries. It was demonstrated that forced flow attenuation in a circuit with low hydrodynamic resistance leads to an overall improvement in the system operation. Full article

The Li intercalation reaction exhibits non-uniform behavior along the thickness direction of the electrode in a Li-ion battery. This non-uniformity, or intra-layer inhomogeneity (ILIH), becomes more serious as the charging and discharging speed increases. Substantial ILIH can lead to Li plating and the emergence of inhomogeneous inner stress, resulting in a decrease in battery service life and an increase in battery safety risks. In this study, an operando optical observation was conducted based on the color change reaction during Li intercalation in the anode. Subsequently, we introduce a novel quantitative method to assess ILIH in commercial Li-ion batteries. A specific ILIH value ($K_{ILIH}$) is first used in this article for ILIH characterization. An analysis of $K_{ILIH}$ at different charging and discharging rates was conducted, alongside the exploration of $K_{ILIH}$-SOC trends and their underlying mechanisms. The proposed method exhibits favorable mathematical convergence and physical interpretability, as supported by the results and mechanism analysis. By enabling the assessment of ILIH evolution in response to SOC and (dis)charging rate variations, the proposed method holds significant potential for optimizing fast charging protocols in commercial batteries and contributing to the development of refined electrochemical battery models in future research. Full article

Aqueous zinc-ion batteries (AZIBs) are considered hopeful large-scale electrochemical energy storage devices because of their simple production process, high specific capacity, intrinsic safety and low cost. However, the dendritic growth of Zn and side reactions cause rapid battery performance degradation, which limits the application of AZIBs for large-scale energy storage. In this work, following the addition of tetraethylene glycol dimethyl ether (TEGDME) to 1 mol L⁻¹ (M) Zn(CF₃SO₃)₂ aqueous electrolyte as a cosolvent, the 1 M Zn(CF₃SO₃)₂/TEGDME-H₂O (1:1 by volume) hybrid electrolyte showed enhanced battery performance resulting from the expanding electrochemical window, inhibiting the growth of zinc dendrites and the parasitic reactions on the negative Zn electrode. The experimental results show that this hybrid electrolyte enabled a high coulombic efficiency (CE) of >99% for 200 cycles in the Zn||Cu battery and a steady discharge/charge property for 1000 h with a low overpotential of 100 mV at 1 mA cm⁻² (the capacity: 1.13 mAh) in the Zn||Zn battery. Remarkably, Zn||V₂O₅ batteries with the hybrid electrolyte also performed much better in terms of cycling stability than a device with a 1 M Zn(CF₃SO₃)₂ aqueous electrolyte. Zn||V₂O₅ batteries delivered a high specific capacity of 200 mAh g⁻¹ with an average CE of >99.9% after 1500 cycles at 0.5 A g⁻¹. This study provides a promising strategy for the development of high-performance electrolyte solutions for practical rechargeable AZIBs. Full article

Despite substantial research efforts in developing high-voltage sodium-ion batteries (SIBs) as high-energy-density alternatives to complement lithium-ion-based energy storage technologies, the lifetime of high-voltage SIBs is still associated with many fundamental scientific questions. In particular, the structure phase transition, oxygen loss, and cathode–electrolyte interphase (CEI) decay are intensely discussed in the field. Synchrotron X-ray and neutron scattering characterization techniques offer unique capabilities for investigating the complex structure and dynamics of high-voltage cathode behavior. In this review, to accelerate the development of stable high-voltage SIBs, we provide a comprehensive and thorough overview of the use of synchrotron X-ray and neutron scattering in studying SIB cathode materials with an emphasis on high-voltage layered transition metal oxide cathodes. We then discuss these characterizations in relation to polyanion-type cathodes, Prussian blue analogues, and organic cathode materials. Finally, future directions of these techniques in high-voltage SIB research are proposed, including CEI studies for polyanion-type cathodes and the extension of neutron scattering techniques, as well as the integration of morphology and phase characterizations. Full article

Silicon as an electrode material in the lithium-ion battery application scenario has been hindered by its significant volumetric expansion and intricate synthesis processes. In this research, we have successfully synthesized Si@C/carbon nanotubes/carbon sheets (Si@C-CNTs/CS) composites by employing a simple one-pot method along with modified magnesium thermal reaction, which involves melamine to prevent high temperature. The resulting multifunctional Si@C-CNTs/CS composites demonstrate enhanced stability during volume change in silicon, resulting in both higher capacity compared to conventional carbon coating layer and improved conductivity of the materials. The results indicate that the Si@C-CNTs/CS composites exhibit a high discharge-specific capacity of up to 2981.64 mAh g⁻¹ at 0.5 A g⁻¹ current density and retain a discharge-specific capacity of 1487.71 mAh g⁻¹ even after 300 cycles. Therefore, the double-layer carbon network structure of carbon nanotubes/carbon nanosheets can provide an efficient and simple preparation method for high-performance Si-base anode materials in practical applications. Full article

Batteries are becoming highly important in automotive and power system applications. The lithium-ion battery, as the fastest growing energy storage technology today, has its specificities, and requires a good understanding of the operating characteristics in order to use it in full capacity. One such specificity is the dependence of the one-way charging/discharging efficiency on the charging/discharging current. This paper proposes a novel method for the determination of battery capacity based on experimental testing. The proposed method defines battery energy capacity as the energy actually stored in the battery, while accounting for both the charging and discharging losses. The experiments include one-way efficiency determination based on multiple cycles conducted under different operational and ambient conditions, the goal of which is to acquire the charging/discharging energies. The measured energies are corrected for one-way efficiencies to obtain values actually stored in a battery during charging or actually extracted from the battery during discharging. The proposed method is tested in a laboratory and compared against two existing baseline methods at different ambient temperatures. The results indicate that the proposed method significantly outperforms the baseline methods in terms of the accuracy of the determined battery energy capacity and state-of-energy. The prime reason for the good performance of the proposed method is that it accounts for both the operational (efficiency) and the ambient (temperature) conditions. Full article

Lithium-ion cells are widely used in various applications. For optimal performance and safety, it is crucial to have accurate knowledge of the temperature of each cell. However, determining the temperature for individual cells is challenging as the core temperature may significantly differ from the surface temperature, leading to the need for further research in this field. This study presents the first sensorless temperature estimation method for determining the core temperature of each cell within a battery module. The accuracy of temperature estimation is in the range of $\Delta T\approx 1$ K. The cell temperature is determined using an artificial neural network (ANN) based on electrochemical impedance spectroscopy (EIS) data. Additionally, by optimizing the frequency range, the number of measurement points, input neurons, measurement time, and computational effort are significantly reduced, while maintaining or even improving the accuracy of temperature estimation. The required time for the EIS measurement can be reduced to 0.5 s, and the temperature calculation takes place within a few milliseconds. The setup consists of cylindrical 18,650 lithium-ion cells assembled into modules with a 3s2p configuration. The core temperature of the cells was measured using sensors placed inside each cell. For the EIS measurement, alternating current excitation was applied across the entire module, and voltage was measured individually for each cell. Various State of Charge (SoC), ambient temperatures, and DC loads were investigated. Compared to other methods for temperature determination, the advantages of the presented study lie in the simplicity of the approach. Only one impedance chip per module is required as additional hardware to apply the AC current. The ANN consists of a simple feedforward network with only one layer in the hidden layer, resulting in minimal computational effort, making this approach attractive for real-world applications. Full article

Bidirectional pulsed current (BPC) heating has proven to be an effective method for internal heating. However, current research has primarily focused on the impact of symmetrical BPC on battery heat generation, while neglecting the influence of different BPC parameters. To address this gap, this paper investigates the effects of various BPC parameters on battery heat generation. Initially, an electro-thermal coupled model of the battery is constructed based on the results of electrochemical impedance spectroscopy (EIS) tests conducted at different temperatures and amplitudes at 20% state of charge (SOC). The validation results of the model demonstrate that the absolute errors of voltage and temperature are generally less than 50 mV and 1.2 °C. Subsequently, the influence of BPC parameters on battery heat generation is examined under different terminal voltage constraints, temperatures, and frequencies. The findings at 20% SOC reveal that symmetrical BPC does not consistently correspond to the maximum heating power. The proportion of charge time and discharge time in one cycle, corresponding to the maximum heating power, varies depending on the charge and discharge cut-off voltages. Moreover, these variations differ across frequencies and temperatures. When the terminal voltage is constrained between 3 V and 4.2 V, the maximum heat power corresponds to a discharge time share of 0.55 in one cycle. In conclusion, the results underscore the complex relationship between BPC parameters and battery heat generation, which can further enhance our understanding of effective heating strategies for batteries. Full article

A thermal management system for lithium-ion batteries is an essential requirement for electric vehicle operation due to the large amount of heat generated by these cylindrical batteries during fast charging/discharging. Previously, researchers have focused mostly on pouch and prismatic cells with heat pipes arranged in the horizontal direction. The current study introduces a novel vertically-oriented heat-pipe-based hybrid cooling battery thermal management system (BTMS) that numerically evaluates the thermal performance of the cylindrical batteries and the flow pattern within the cooling channel at C rates as high as 8C. The model was experimentally validated using five round heat pipes in a vertical orientation utilizing the effect of gravity to assist condensate flow through the heat pipe. The heat pipes were arranged in a staggered pattern to improve the overall heat transfer performance by means of forced convective cooling. This design allowed for maximizing the heat transfer process despite the lack of contact between the cylindrical-shaped batteries and round-shaped heat pipes. During this study, the temperatures of the evaporator end and the condenser end of the heat pipes and battery surfaces were monitored, and the thermal performances of the system were determined at varying inlet cooling liquid temperatures (15, 20, 25 °C) and high rates of 4C and 8C. Representatively, the proposed hybrid BTMS could maintain a maximum battery surface temperature of around 64 °C and a temperature difference between cells under 2.5 °C when the inlet velocity was 0.33 L/min and the cooling liquid temperature was 25 °C. The high temperatures reached the fourth and fifth heat pipes because they are part of the backflow design and are affected by backflow temperature. Nevertheless, the current design shows that the proposed system can maintain battery surface temperatures well within 5 °C. Full article

In the drying process of electrodes for lithium-ion batteries, the layer structure is defined and can only be influenced slightly in the subsequent process steps. An essential point in the drying process is the fixation of the binder, ensuring both the adhesive and cohesive strength of the electrode. It is known that high drying rates lead to the segregation of the binder in the direction of the coating surface, which results in reduced mechanical stability of the electrode. In a previous publication, an experimental approach was used to investigate the underlying processes that influence binder migration. These results are now used in a model-based approach to describe the binder migration using the convection–diffusion equation. The convective term originates from the shrinkage behavior of the layer during drying due to the relative movement between the active material particles and the solvent in which the binder is dissolved or dispersed; it is expected to be the cause of the binder migration. The diffusive term, representing the binder movement in the solvent, counteracts segregation. The interaction of these forces is simulated at different drying temperatures and the associated drying rates. Full article

Battery aging of electrified vehicles is a key parameter to be controlled in order to ensure sufficient energy efficiency and driving range across the whole vehicle lifespan. The United Nations Economic Commission for Europe has recently adopted a new regulatory framework, the Global Technical Regulation No. 22, prescribing minimum performance requirements for in-vehicle battery durability. With the implementation of this new GTR, monitors of the battery state of certified energy and range will be available in every production vehicle, the accuracy of which will be tested statistically by applying an in-use verification procedure (Part A). Once the monitors’ correctness is checked, the battery durability performances are controlled in Part B against the defined limit values by a fleet monitoring procedure. This work presents the results of a testing campaign executed at the Joint Research Centre testing facilities on an aged pure electric vehicle to measure its capacity and range fade. The aim is to explore the applicability of GTR No. 22, assessing the in-vehicle battery performance fade of an aged electric vehicle, illustrating the several steps of the developed regulation and experimental methodology. Full article

Given the rising upscaling trend in lithium-ion battery (LiB) production, there is a growing emphasis on the environmental and economic impacts alongside the high energy density demands. The cost and environmental impact of battery production primarily arise from the critical elements Ni, Co, and F. This drives the exploration of Ni-free and Co-free cathode alternatives such as LiMn₂O₄ (LMO) and LiFePO₄ (LFP). However, the absence of Ni and Co results in reduced capacity and insufficient cyclic stability, particularly in the case of LMO due to Mn dissolution. To compensate for both low cathode capacitance and low cycle stability, we propose the GREENcell, a lithium cell combining a F-free polyisobutene (PIB) binder-based LMO cathode with a stabilized in -situ LiAL alloy anode. A LiAl alloy anode with the chemical composition of LiAl already shows a theoretical capacity of 993 Ah·kg⁻¹. Therefore, it promises extraordinarily higher energy densities compared to a commercial graphite anode with a capacity of 372 Ah·kg⁻¹. Following an iterative development process, different optimization strategies, especially those targeting the stability of the Al-based anode, were evaluated. During Al foil selection, foil purity and thickness could be identified as two of the dominant influencing parameters. A pressed-in stainless steel mesh provides both mechanical stability to the anode and facilitates alloy formation by breaking up the Al oxide layer beforehand. Additionally, a binder-stabilized Al oxide or silicate layer is pre-coated on the Al surface, posing as a SEI-precursor and ensuring a uniform liquid electrolyte distribution at the phase boundary. Employing a commercially available Si-containing Al alloy mitigated the mechanical degradation of the anode, yielding a favorable impact on long-term stability. The applicability of the novel optimized GREENcell is demonstrated using laboratory coin cells with LMO and LFP as the cathode. As a result, the functionality of the GREENcell was demonstrated for the first time, and thanks to the anode stabilization strategies, a capacity retention of >70% after 200 was achieved, representing an increase of 32.6% compared to the initial Al foil. Full article

Ionic gel electrolyte retains the characteristics of non-volatilization, non-flammability and outstanding electrochemical stability of ionic liquid, and shows good electrochemical performance combined with the excellent characteristics of different matrix materials, which is considered to be the best choice to achieve high energy density and safety at the same time. In this paper, a flexible and self-healing ionic gel electrolyte was prepared using a solvent-assisted method based on a zteric ion (ZI) copolymer. Abundant hydrogen bonds and synergistic interaction of ions in the electrolyte system endowed it with remarkable self-healing ability. An ionic conductivity of 9.06 × 10⁻⁴ S cm⁻¹ at room temperature was achieved. Moreover, the lithium-ion transference number was increased to 0.312. The ionic gel electrolyte has a self-healing function which guarantees long-term tolerance during charging and discharging. The capacity retention rate of the Li//LiFePO₄ battery was 96% after 155 cycles at 0.1 C at 60 °C. This polymer electrolyte is expected to solve the problem of increasing polarization, which is caused by the low lithium ions migration number in ionic liquid electrolyte. And ultimately, it gave rise to a good rate performance. Full article