Batteries — Open Access Journal

The purpose of this work was to analyse and characterize the behavior of a 5 kW/5 kWh vanadium battery integrated in an experimental facility with all the auxiliary equipment and determine whether it would be possible to ascertain the most appropriate application for storage of electricity in photovoltaic (PV) grid applications. The battery has been in operation for 9–10 months. During this time the battery has achieve a full cycle efficiency of approximately 65%. A slight reduction in efficiency is the result of the constant auxiliary power consumption from pumps amounting to 8–9% of rated power, meanwhile the stack is quite efficient showing a cycle efficiency of 73%.The operation of the pumps has been adjusted to fix the current density applied together with the state of charge in order to reduce unnecessary consumption related to the energy required for pumping. According to the results obtained, the intended improvement in global efficiency for the system has not been achieved by this proposed strategy. However, the flow factor evolution selected at this stage needs further optimization in order to establish a trade-off between the concentration overpotential and a detrimental loss in energy due to pumping. Therefore, one should be able to improve system performance through a better configuration of flow factors in order to reach total system efficiencies of 70–75% required for achieving a commercially viable product. Full article

This study presents a review of how the end-of-life (EOL) stage is modelled in life cycle assessment (LCA) studies of lithium-ion batteries (LIBs). Twenty-five peer-reviewed journal and conference papers that consider the whole LIB life cycle and describe their EOL modelling approach sufficiently were analyzed. The studies were categorized based on two archetypal EOL modelling approaches in LCA: The cutoff (no material recovery, possibly secondary material input) and EOL recycling (material recovery, only primary material input) approaches. It was found that 19 of the studies followed the EOL recycling approach and 6 the cutoff approach. In addition, almost a third of the studies deviated from the expected setup of the two methods by including both material recovery and secondary material input. Such hybrid approaches may lead to double counting of recycling benefits by both including secondary input (as in the cutoff approach) and substituting primary materials (as in the EOL recycling approach). If the archetypal EOL modelling approaches are not followed, it is imperative that the modelling choices are well-documented and motivated to avoid double counting that leads to over- or underestimations of the environmental impacts of LIBs. Also, 21 studies model hydrometallurgical treatment, and 17 completely omit waste collection. Full article

The fluctuating nature of power produced by renewable energy sources results in a substantial supply and demand mismatch. To curb the imbalance, energy storage systems comprising batteries and supercapacitors are widely employed. However, due to the variety of operational conditions, the performance prediction of the energy storage systems entails a substantial complexity that leads to capacity utilization issues. The current article attempts to precisely predict the performance of a lithium-ion battery and capacitor/supercapacitor under dynamic conditions to utilize the storage capacity to a fuller extent. The grey box modeling approach involving the chemical and electrical energy transfers/interactions governed by ordinary differential equations was developed in MATLAB. The model parameters were extracted from experimental data employing regression techniques. The state-of-charge (SoC) of the battery was predicted by employing the extended Kalman (EK) estimator and the unscented Kalman (UK) estimator. The model was eventually validated via loading profile tests. As a performance indicator, the extended Kalman estimator indicated the strong competitiveness of the developed model with regard to tracking of the internal states (e.g., SoC) which have first-order nonlinearities. Full article

The second-life concept helps to reduce the cost for electric vehicles by adding monetary value to disused automotive batteries. However, the sudden-death effect, a change in ageing behaviour limits the total lifetime and might reduce the second-life timespan. In this paper, we utilize a common pseudo two-dimensional (P2D) cell model to investigate the influence of different porosity profiles in the graphite electrode on the battery’s ageing. Ageing is modeled by two irreversible side reactions at the anode, the formation of solid electrolyte interface (SEI) and lithium plating. We use parameters of a high-energy cell with thick electrodes. A constant initial anode porosity as a reference is compared with two optimized porosity profiles. Simulation results show that by using a layered anode, a two-stage porosity profile with higher porosity at the separator side, the cycle count until sudden-death and especially the cycles for second-life applications can both almost be doubled. Full article

In light of the increasing penetration of electric vehicles (EVs) in the global vehicle market, understanding the environmental impacts of lithium-ion batteries (LIBs) that characterize the EVs is key to sustainable EV deployment. This study analyzes the cradle-to-gate total energy use, greenhouse gas emissions, SOx, NOx, PM10 emissions, and water consumption associated with current industrial production of lithium nickel manganese cobalt oxide (NMC) batteries, with the battery life cycle analysis (LCA) module in the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) model, which was recently updated with primary data collected from large-scale commercial battery material producers and automotive LIB manufacturers. The results show that active cathode material, aluminum, and energy use for cell production are the major contributors to the energy and environmental impacts of NMC batteries. However, this study also notes that the impacts could change significantly, depending on where in the world the battery is produced, and where the materials are sourced. In an effort to harmonize existing LCAs of automotive LIBs and guide future research, this study also lays out differences in life cycle inventories (LCIs) for key battery materials among existing LIB LCA studies, and identifies knowledge gaps. Full article

This paper presents a tradeoff analysis in terms of accuracy and computational cost between different architectures of artificial neural networks for the State of Charge (SOC) estimation of lithium batteries in hybrid and electric vehicles. The considered layouts are partly selected from the literature on SOC estimation, and partly are novel proposals that have been demonstrated to be effective in executing estimation tasks in other engineering fields. One of the architectures, the Nonlinear Autoregressive Neural Network with Exogenous Input (NARX), is presented with an unconventional layout that exploits a preliminary routine, which allows setting of the feedback initial value to avoid estimation divergence. The presented solutions are compared in terms of estimation accuracy, duration of the training process, robustness to the noise in the current measurement, and to the inaccuracy on the initial estimation. Moreover, the algorithms are implemented on an electronic control unit in serial communication with a computer, which emulates a real vehicle, so as to compare their computational costs. The proposed unconventional NARX architecture outperforms the other solutions. The battery pack that is used to design and test the networks is a 20 kW pack for a mild hybrid electric vehicle, whilst the adopted training, validation and test datasets are obtained from the driving cycles of a real car and from standard profiles. Full article

Ni-doped VO₂(B) samples (Ni_xVO₂(B)) were fabricated by a facile one-step hydrothermal method. When evaluated as a cathode material for lithium ion batteries (LIBs), these Ni-doped VO₂(B) exhibited improved lithium storage performance as compared to the pure VO₂(B). In particular, when the doping amount is 3%, Ni_xVO₂(B) showed the highest lithium storage capacity, best cycling stability, smallest electrochemical reaction resistance, and largest lithium diffusion coefficient. For example, after 100 cycles at a current density of 32.4 mA/g, Ni_xVO₂(B) delivered a high specific discharge capacity of 163.0 mAh/g, much higher than that of the pure VO₂(B) sample (95.5 mAh/g). Therefore, Ni doping is an effective strategy for enhancing the lithium storage performance of VO₂(B). Full article

Herein, the post-mortem study on 16 Ah graphite//LiFePO₄ pouch cells is reported. Aiming to understand their failure mechanism, taking place when cycling at low temperature, the analysis of the cell components taken from different portions of the stacks and from different positions in the electrodes, is performed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoemission spectroscopy (XPS). Also, the recovered electrodes are used to reassemble half-cells for further cycle tests. The combination of the several techniques detects an inhomogeneous ageing of the electrodes along the stack and from the center to the edge of the electrode, most probably due to differences in the pressure experienced by the electrodes. Interestingly, XPS reveals that more electrolyte decomposition took place at the edge of the electrodes and at the outer part of the cell stack independently of the ageing conditions. Finally, the use of high cycling currents buffers the low temperature detrimental effects, resulting in longer cycle life and less inhomogeneities. Full article

The aim of this paper was to propose and test a continuous cobalt recovery process from waste mobile phone batteries. The procedure started with dismantling, crushing, and classifying the materials. A study on leaching with sulfuric acid and hydrogen peroxide was carried out with subsequent selective separation of cobalt by means of liquid–liquid extraction. The best extraction conditions were determined based on a sequence of experiments that consisted of selecting the best extractant for cobalt, then assessing the impact of extractant concentration, pH, and contact time on the extraction yield. With these conditions, an extraction isotherm was obtained and correlated with a mathematical model to define the number of extraction stages for a countercurrent process using the McCabe–Thiele method. Then, a similar study was done for stripping conditions and, as a last step, cobalt electroplating was performed. The proposed process offers a solution for the treatment of these batteries, avoiding potential problems of contamination and risk for living beings, as well as offering an opportunity to recover valuable metal. Full article

The distribution of relaxation times (DRT) analysis offers a model-free approach for a detailed investigation of electrochemical impedance spectra. Typically, the calculation of the distribution function is an ill-posed problem requiring regularization methods which are strongly parameter-dependent. Before statements on measurement data can be made, a process parameter study is crucial for analyzing the impact of the individual parameters on the distribution function. The optimal regularization parameter is determined together with the number of discrete time constants. Furthermore, the regularization term is investigated with respect to its mathematical background. It is revealed that the algorithm and its handling of constraints and the optimization function significantly determine the result of the DRT calculation. With optimized parameters, detailed information on the investigated system can be obtained. As an example of a complex impedance spectrum, a commercial Nickel–Manganese–Cobalt–Oxide (NMC) lithium-ion pouch cell is investigated. The DRT allows the investigation of the SOC dependency of the charge transfer reactions, solid electrolyte interphase (SEI) and the solid state diffusion of both anode and cathode. For the quantification of the single polarization contributions, a peak analysis algorithm based on Gaussian distribution curves is presented and applied. Full article

Automobile dependency and the inexorable proliferation of electric vehicles (EVs) compels accurate predictions of cycle life across multiple usage conditions and for multiple lithium-ion battery systems. Synthetic driving cycles have been essential in accumulating data on EV battery lifetimes. However, since battery deterioration is path-dependent, the representability of synthetic cycles must be questioned. Hence, this work compared three different synthetic driving cycles to real driving data in terms of mimicking actual EV battery degradation. It was found that the average current and charge capacity during discharge were important parameters in determining the appropriate synthetic profile, and traffic conditions have a significant impact on cell lifetimes. In addition, a stage of accelerated capacity fade was observed and shown to be induced by an increased loss of lithium inventory (LLI) resulting from irreversible Li plating. New metrics, the ratio of the loss of active material at the negative electrode (LAM_NE) to the LLI and the plating threshold, were proposed as possible predictors for a stage of accelerated degradation. The results presented here demonstrated tracking properties, such as capacity loss and resistance increase, were insufficient in predicting cell lifetimes, supporting the adoption of metrics based on the analysis of degradation modes. Full article

The principle of the circular economy is to reintroduce end-of-life materials back into the economic cycle. While reintroduction processes, for example, recycling or refurbishing, undoubtedly support this objective, they inevitably present material losses or generation of undesired by-products. Balancing losses and recoveries into a single and logical assessment has now become a major concern. The present work broadens the use of relative statistical entropy and material flow analysis to assess the recycling processes of two lithium-ion batteries previously published in the literature. Process simulation software, that is, HSC Sim^®, was employed to evaluate with a high level of accuracy the performance of such recycling processes. Hereby, this methodology introduces an entropic association between the quality of final recoveries and the pre-processing stages, that is, shredding, grinding, and separation, by a parameter based on information theory. The results demonstrate that the pre-processing stages have a significant impact on the entropy value obtained at the final stages, reflecting the losses of materials into waste and side streams. In this manner, it is demonstrated how a pre-processing system capable of separating a wider number of components is advantageous, even when the final quality of refined products in two different processes is comparable. Additionally, it is possible to observe where the process becomes redundant, that is, where processing of material does not result in a significant concentration in order to take corrective actions on the process. The present work demonstrates how material flow analysis combined with statistical entropy can be used as a parameter upon which the performance of multiple recycling processes can be objectively compared from a material-centric perspective. Full article

The electric vehicle market is expected to grow substantially in the coming years, which puts new requirements on the end-of-life phase and on the recycling systems. To a larger extent, the environmental footprint from these vehicles is related to raw material extraction and production, and, consequently, a material- and energy-efficient 3R system (reuse, remanufacturing, recycling) is urgently needed. The ability to understand and model the design and development of such a system therefore becomes important. This study contributes to this by identifying factors that affect 3R system design and performance, relating these factors to the various actors and processes of the system and categorising them according to time from implementation to impact. The above is achieved by applying a PEST analysis (political, economic, social and technological factors), differentiating between political, economic, social and technological factors. Data were gathered from literature, by interviews and by a number of workshops in the automotive industry and the 3R system and observations at meetings, etc. The study confirms some previous results on how vehicle battery 3R systems work and adds knowledge about the influencing factors, especially the timeframes and dynamics of the system, necessary for modelling the system and the influencing factors. For practitioners, the results indicate how to use appropriate models and which factors are most relevant to them. Full article

The mixed sodium-iron ortho-pyrophosphate Na₄Fe₃(PO₄)₂P₂O₇ (NFPP) is a promising Na-containing cathode material with the highest operating voltage among sodium framework structured materials. It operates both in Na and Li electrochemical cells. When cycled in a hybrid Li/Na cell, a competitive co-intercalation of the Li⁺ and Na⁺ ions occurs at the cathode side. The present study shows that this process can be tuned by changing the concentration of the Na⁺ ions in the mixed Li⁺/Na⁺-ion electrolyte and current density. It is shown that if the Na concentration in the electrolyte increases, the specific capacity of NFPP also increases and its high-rate capability is significantly improved. Full article

One of the most important parameters for the design of redox flow batteries is a uniform distribution of the electrolyte solution over the complete electrode area. The performance of redox flow batteries is usually investigated by general measurements of the cell in systematic experimental studies such as galvanostatic charge-discharge cycling. Local inhomogeneity within the electrode cannot be locally-resolved. In this study a printed circuit board (PCB) with a segmented current collector was integrated into a 40 cm² all-vanadium redox flow battery to analyze the locally-resolved current density distribution of the graphite felt electrode. Current density distribution during charging and discharging of the redox flow battery indicated different limiting influences. The local current density in redox flow batteries mainly depends on the transport of the electrolyte solution. Due to this correlation, the electrolyte flow in the porous electrode can be visualized. A PCB electrode can easily be integrated into the flow battery and can be scaled to nearly any size of the electrode area. The carbon coating of the PCB enables direct contact to the corrosive electrolyte, whereby the sensitivity of the measurement method is increased compared to state-of-the-art methods. Full article

This paper presents a fully embedded state of health (SoH) estimator for widely used C/LiFePO₄ batteries. The SoH estimation study was intended for applications in electric vehicles (EV). C/LiFePO₄ cells were aged using pure electric vehicle cycles and were monitored with an automotive battery management system (BMS). An online capacity estimator based on incremental capacity analysis (ICA) is developed. The proposed estimator is robust to depth of discharge (DoD), charging current and temperature variations to satisfy real vehicle requirements. Finally, the SoH estimator tuned on C/LiFePO₄ cells from one manufacturer was tested on C/LiFePO₄ cells from another LFP (lithium iron phosphate) manufacturer. Full article

Reliable development of LIBs requires that they be correlated with accurate aging studies. The present project focuses on the implementation of a weighted ampere-hour throughput model, taking into account the operating parameters, and modulating the impact of an exchanged ampere-hour by the well-established three major stress factors: temperature, current intensity (rated), and state of charge (SoC). This model can drift with time due to repeated solicitation, so its parameters need to be updated by on-field measurements, in order to remain accurate. These on-field measurements are submitted to the so-called Incremental Capacity Analysis method (ICA), consisting in the analysis of dQ/dV as a function of V. It is a direct indicator of the state of health of the cell, as the experimental peaks are related to the active material chemical/structural evolution, such as phase transitions and recorded potential plateaus during charging/discharging. It is here applied to NMC/graphite based commercial cells. These peaks’ evolution can be correlated with the here-defined Ah-kinetic and $\sqrt{t}$-kinetic aging, which are chemistry-dependent, and therefore, has to be adjusted to the different types of cells. Full article

Primary battery recycling has important environmental and economic benefits. According to battery sales worldwide, the most used battery type is alkaline batteries with 75% of market share due to having a higher performance than other primary batteries such as Zn–MnO₂. In this study, carbothermal reduction for zinc oxide from battery waste was completed for both vacuum and Ar atmospheres. Thermodynamic data are evaluated for vacuum and Ar atmosphere reduction reactions and results for Zn reduction/evaporation are compared via the FactSage program. Zn vapor and manganese oxide were obtained as products. Zn vapor was re-oxidized in end products; manganese monoxide and steel container of batteries are evaluated as ferromanganese raw material. Effects of carbon source, vacuum, temperature and time were studied. The results show a recovery of 95.1% Zn by implementing a product at 1150 °C for 1 h without using the vacuum. The residues were characterized by Atomic Absorption Spectrometer (AAS) and X-ray Diffraction (XRD) methods. Full article

To ensure sufficient thermal performance within electric vehicle (EV) batteries, thermal interface materials (TIMs), such as pastes or adhesives, are widely used to fill thermally insulating voids between cells and cooling components. However, TIMs are composite materials that are subject to degradation over the battery’s lifetime. Using TIMs for battery applications is a new and emerging topic, creating the need to rapidly acquire knowledge about appropriate lifetime testing and evaluation methods, in close collaboration with the battery manufacturers. This paper reviews suitable methods for durability testing as well as basic modeling approaches which allow for the transfer of laboratory results to the longtime behavior of interface materials during a vehicle’s lifetime. Full article