Batteries — Open Access Battery Technology & Materials Journal

A density functional theory (DFT) study has been carried out on transition metal phosphates with olivine structure and formula LiMPO4 (M = Fe, Mn, Co, Ni) to assess their potential as cathode materials in rechargeable Li-ion batteries based on their chemical and structural stability and high theoretical capacity. The investigation focuses on LiMnPO4, which could offer an improved cell potential (4.1 V) with respect to the reference LiFePO4 compound, but it is characterized by poor lithium intercalation/de-intercalation kinetics. Substitution of cations like Co and Ni in the olivine structure of LiMnPO4 was recently reported in an attempt to improve the electrochemical performances. Here the electronic structure and lithium intercalation potential of Ni- and Co-doped LiMnPO4 were calculated in the framework of the Hubbard U density functional theory (DFT+U) method for highly correlated materials. Moreover, the diffusion process of lithium in the host structures was simulated, and the activation barriers in the doped and pristine structures were compared. Our calculation predicted that doping increases Li insertion potential while activation barriers for Li diffusion remain similar to the pristine material. Moreover, Ni and Co doping induces the formation of impurity states near the Fermi level and significantly reduces the band gap of LiMnPO4. Full article

Batteries are used in the electricity grid to provide ancillary services. Area regulation seems to provide substantial revenues and profit, but Li-ion batteries are still too expensive to enter widely into this market. On the other hand, electric vehicle (EV) batteries are considered inappropriate for traction purposes when they reach a state of health (SoH) of 80%. The reuse of these batteries offers affordable batteries for second-life stationary applications. This study analyzes two possible scenarios where batteries may give power and energy support to a gas turbine cogeneration power plant, and how long these batteries may last under different loads. Full article

The prevailing standards and scientific literature offer a wide range of options for the construction of a battery thermal management system (BTMS). The design of an innovative yet well-functioning BTMS requires strict supervision, quality audit and continuous improvement of the whole process. It must address all the current quality and safety (Q&S) standards. In this review article, an effective battery thermal management is sought considering the existing battery Q&S standards and scientific literature. The article contains a broad overview of the current existing standards and literature on a generic compliant BTMS. The aim is to assist in the design of a novel compatible BTMS. Additionally, the article delivers a set of recommendations to make an effective BTMS. Full article

Open circuit voltage (OCV) of lithium batteries has been of interest since the battery management system (BMS) requires an accurate knowledge of the voltage characteristics of any Li-ion batteries. This article presents an OCV characteristic for lithium manganese oxide (LMO) batteries under several experimental operating conditions, and discusses factors for accurate OCV determination. A test system is developed for OCV characterization based on the OCV pulse test method. Various factors for the OCV behavior, such as resting period, step-size of the pulse test, testing current amplitude, hysteresis phenomena, and terminal voltage relationship, are investigated and evaluated. To this end, a general OCV model based on state of charge (SOC) tracking is developed and validated with satisfactory results. Full article

Three different methods were used to produce α-Ni(OH)₂ with higher discharge capacities than the conventional β-Ni(OH)₂, specifically a batch process of co-precipitation, a continuous process of co-precipitation with a phase transformation step (initial cycling), and an overcharge at low temperature. All three methods can produce α-Ni(OH)₂ or α/β mixed-Ni(OH)₂ with capacities higher than that of conventional β-Ni(OH)₂ and a stable cycle performance. The second method produces a special core–shell β-Ni(OH)₂/α-Ni(OH)₂ structure with an excellent cycle stability in the flooded half-cell configuration, is innovative and also already mass-production ready. The core–shell structure has been investigated by both scanning and transmission electron microscopies. The shell portion of the particle is composed of α-Ni(OH)₂ nano-crystals embedded in a β-Ni(OH)₂ matrix, which helps to reduce the stress originating from the lattice expansion in the β-α transformation. A review on the research regarding α-Ni(OH)₂ is also included in the paper. Full article

O3-NaCoO${}_2$ is a promising cathode material for sodium ion secondary batteries (SIBs). Na${}_x$CoO${}_2$ shows phase separation (PS) into the O3 and O${}^{\prime }$3 phases in the Na concentration range of 0.89 $⩽x⩽$ 0.99. In order to estimate the domain size (r) in the two-phase region, we performed X-ray microdiffraction (XRMD) of thin films of Na${}_x$CoO${}_2$ at x = 0.97 and ∼1. We found that r (≈400 nm) of the O${}^{\prime }$3 domain is comparable to the particle size d (=331 ± 87 nm) in the as-grown O3-NaCoO${}_2$ film. This observation suggests that individual particles of Na${}_x$CoO${}_2$ are single phase to minimize the strain at the O3–O${}^{\prime }$3 phase boundary. Full article

The voltage of an alkaline electrolyte-based battery is often limited by the narrow electrochemical stability window of water (1.23 V). As an alternative to water, ionic liquid (IL)-based electrolyte has been shown to exhibit excellent proton conducting properties and a wide electrochemical stability window, and can be used in proton conducting batteries. In this study, we used IL/acid mixtures to replace the 30 wt % KOH aqueous electrolyte in nickel/metal hydride (Ni/MH) batteries, and verified the proton conducting character of these mixtures through electrochemical charge/discharge experiments. Dilution of ILs with acetic acid was found to effectively increase proton conductivity. By using 2 M acetic acid in 1-ethyl-3-methylimidazolium acetate, stable charge/discharge characteristics were obtained, including low charge/discharge overpotentials, a discharge voltage plateau at ~1.2 V, a specific capacity of 161.9 mAh·g⁻¹, and a stable cycling performance for an AB₅ metal hydride anode with a (Ni,Co,Zn)(OH)₂ cathode. Full article

Temperature gradients, thermal cycling and temperatures outside the optimal operation range can have a significant influence on the reliability and lifetime of Li-ion battery cells. Therefore, it is essential for the developer of large-scale battery systems to know the thermal characteristics, such as heat source location, heat capacity and thermal conductivity, of a single cell in order to design appropriate cooling measures. This paper describes an advanced test facility, which allows not only an estimation of the thermal properties of a battery cell, but also the verification of proposed cooling strategies in operation. To do this, an active measuring unit consisting of a temperature and heat flux density sensor and a Peltier element was developed. These temperature/heat flux sensing (THFS) units are uniformly arranged around a battery cell with a spatial resolution of 25 mm. Consequently, the temperature or heat flux density can be controlled individually, thus forming regions with constant temperature (cooling) or zero heat flux (insulation). This test setup covers the whole development loop from thermal characterization to the design and verification of the proposed cooling strategy. Full article

Overcurrent abuse has been performed on commercial 48 Ah primary prismatic zinc (Zn)–Air battery cells with full air supply as well as with shut-off air supply. Compared to other battery technologies, e.g., lithium-ion batteries, metal–air batteries offer the possibility to physically stop the battery operation by stopping its air supply, thus offering an additional protection against severe battery damage in the case of, e.g., an accidental short circuit. This method may also reduce the electrical hazard in a larger battery system since, by stopping the air supply, the voltage can be brought to zero while maintaining the energy capacity of the battery. Measurements of overdischarge currents and current cut-off by suffocation have been performed to assess the safety of this type of Zn–air battery. The time to get to zero battery voltage is shown to mainly be determined by the volume of air trapped in the cell. Full article

Lithium-ion (Li-ion) batteries are complex energy storage devices with their performance behavior highly dependent on the operating conditions (i.e., temperature, load current, and state-of-charge (SOC)). Thus, in order to evaluate their techno-economic viability for a certain application, detailed information about Li-ion battery performance behavior becomes necessary. This paper proposes a comprehensive seven-step methodology for laboratory characterization of Li-ion batteries, in which the battery’s performance parameters (i.e., capacity, open-circuit voltage (OCV), and impedance) are determined and their dependence on the operating conditions are obtained. Furthermore, this paper proposes a novel hybrid procedure for parameterizing the batteries’ equivalent electrical circuit (EEC), which is used to emulate the batteries’ dynamic behavior. Based on this novel parameterization procedure, the performance model of the studied Li-ion battery is developed and its accuracy is successfully verified (maximum error lower than 5% and a mean error below 8.5 mV) for various load profiles (including a real application profile), thus validating the proposed seven-step characterization methodology. Full article

This paper presents a method to assess the effect of electrolyte additives on the energy capacity of Pb-acid batteries. The method applies to additives of various kinds, including suspensions and gels. The approach is based on thermodynamics and leads to the definition of a region of admissible concentrations—the battery’s admissible range—where the battery can operate without suffering irreversible changes. An experimental procedure to determine this range is presented. The obtained results provide a way to assess the potential of electrolyte additives to improve the energy capacity of Pb-acid batteries. They also provide a means to determine the additive concentration that produces the maximum energy capacity increase of the battery. The paper closes with an example of the application of the proposed approach to a practical case. Full article

A series of 250–350 $\mathsf{\mu }$m-thick single-sided lithium ion cell graphite anodes and lithium nickel manganese cobalt oxide (NMC) cathodes with constant area weight, but varying porosity were prepared. Over this wide thickness range, micron-sized carbon fibers were used to stabilize the electrode structure and to improve electrode kinetics. By choosing the proper porosities for the anode and cathode, kinetic limitations and aging losses during cell cycling could be minimized and energy density improved. The cell (C38%-A48%) exhibits the highest energy density, 441 Wh/L at the C/10 rate, upon cycling at elevated temperature and different C-rates. The cell (C38%-A48%) showed 9% higher gravimetric energy density at C/10 in comparison to the cell with as-coated electrodes. Full article

The effects of Fe partially replacing Ni in a misch metal-based superlattice hydrogen absorbing alloy (HAA) were studied. Addition of Fe increases the lattice constants and abundance of the main Ce₂Ni₇ phase, decreases the NdNi₃ phase abundance, and increases the CaCu₅ phase when the Fe content is above 2.3 at%. For the gaseous phase hydrogen storage (H-storage), Fe incorporation does not change the storage capacity or equilibrium pressure, but it does decrease the change in both entropy and enthalpy. With regard to electrochemistry, >2.3 at% Fe decreases both the full and high-rate discharge capacities due to the deterioration in both bulk transport (caused by decreased secondary phase abundance and consequent lower synergetic effect) and surface electrochemical reaction (caused by the lower volume of the surface metallic Ni inclusions). In a low-temperature environment (−40 °C), although Fe increases the reactive surface area, it also severely hinders the ability of the surface catalytic, leading to a net increase in surface charge-transfer resistance. Even though Fe increases the abundance of the beneficial Ce₂Ni₇ phase with a trade-off for the relatively unfavorable NdNi₃ phase, it also deteriorates the electrochemical performance due to a less active surface. Therefore, further surface treatment methods that are able to increase the surface catalytic ability in Fe-containing superlattice alloys and potentially reveal the positive contributions that Fe provides structurally are worth investigating in the future. Full article

The effects of climate change are just beginning to be felt, and as such, society must work towards strategies of reducing humanity’s impact on the environment. Due to the fact that energy production is one of the primary contributors to greenhouse gas emissions, it is obvious that more environmentally friendly sources of power are required. Technologies such as solar and wind power are constantly being improved through research; however, as these technologies are often sporadic in their power generation, efforts must be made to establish ways to store this sustainable energy when conditions for generation are not ideal. Battery storage is one possible supplement to these renewable energy technologies; however, as current Li-ion technology is reaching its theoretical capacity, new battery technology must be investigated. Lithium–sulphur (Li–S) batteries are receiving much attention as a potential replacement for Li-ion batteries due to their superior capacity, and also their abundant and environmentally benign active materials. In the spirit of environmental harm minimization, efforts have been made to use sustainable carbonaceous materials for applications as carbon–sulphur (C–S) composite cathodes, carbon interlayers, and carbon-modified separators. This work reports on the various applications of carbonaceous materials applied to Li–S batteries, and provides perspectives for the future development of Li–S batteries with the aim of preparing a high energy density, environmentally friendly, and sustainable sulphur-based cathode with long cycle life. Full article

The cell case temperature versus time profiles of a multistage fast charging technique (4C-1C-constant voltage (CV))/fast discharge (4C) in a 2.3 Ah cylindrical lithium-ion cell are analyzed using a thermal model. Heat generation is dominated by the irreversible component associated with cell overpotential, although evidence of the reversible component is also observed, associated with the heat related to entropy from the electrode reactions. The final charging stages (i.e., 1C-CV) significantly reduce heat generation and cell temperature during charge, resulting in a thermally safe charging protocol. Cell heat capacity was determined from cell-specific heats and the cell materials’ thickness. The model adjustment of the experimental data during the 2 min resting period between discharge and charge allowed us to calculate both the time constant of the relaxation process and the cell thermal resistance. The obtained values of these thermal parameters used in the proposed model are almost equal to those found in the literature for the same cell model, which suggests that the proposed model is suitable for its implementation in thermal management systems. Full article

Nineteen papers focusing on recent research investigations in the field of nickel/metal hydride (Ni/MH) batteries have been selected for this Special Issue of Batteries. These papers summarize the joint efforts in Ni/MH battery research from BASF, Wayne State University, the National Institute of Standards and Technology, Michigan State University, and FDK during 2015–2016 through reviews of basic operational concepts, previous academic publications, issued US Patent and filed Japan Patent Applications, descriptions of current research results in advanced components and cell constructions, and projections of future works. Full article

Charge-discharge properties of the surface-modified ZrNi negative electrodes with different degrees of boiling alkaline treatment were investigated. The boiling alkaline treatment was performed by immersing the ZrNi electrode in a boiling 6 M KOH aqueous solution for 2 h or 4 h. The initial discharge capacity for the untreated ZrNi negative electrode was 21 mAh·g⁻¹, but it was increased to 114 mAh·g⁻¹ and 308 mAh·g⁻¹ after the boiling alkaline treatments for 2 h and 4 h, respectively. The discharge capacity for the ZrNi negative electrode after the treatment for 2 h steadily increased with repeating charge-discharge cycles as well as that of the untreated electrode, whereas that for the ZrNi negative electrode after the 4 h treatment greatly decreased. The high rate of dischargeability was improved with an increase in the treatment period of time, and the charge-transfer resistance was drastically decreased. Scanning electron microscopy (SEM) and electron dispersive X-ray spectroscopy demonstrated the ZrO₂ passive layer on the ZrNi alloy surface was removed by the boiling alkaline treatment to form a porous morphology containing Ni(OH)₂, which can be reduced to Ni during charging, leading to the reduction of a barrier for the charge-discharge reactions. Full article

The application of stationary battery storage systems to German electrical grids can help with various storage services. This application requires controlling the charge and discharge power of such a system. For example, photovoltaic (PV) home storage, uninterruptible power supply, and storage systems for providing ancillary services such as primary control reserves (PCRs) represent battery applications with positive profitability. Because PCRs are essential for stabilizing grid frequency and maintaining a robust electrical grid, German transmission system operators (TSOs) released strict regulations in August 2015 for providing PCRs with battery storage systems as part of regulating the International Grid Control Cooperation (IGCC) region in Europe. These regulations focused on the permissible state of charge (SoC) of the battery during nominal and extreme conditions. The concomitant increased capacity demand oversizing may result in a significant profitability reduction, which can be attenuated only by using an optimal parameterization of the control algorithm for energy management of the storage systems. In this paper, the sizing optimization is achieved and a recommendation for a control algorithm that includes the appropriate parameters for the requirements in the German market is given. Furthermore, the storage cost is estimated, including battery aging simulations for different aging parameter sets to allow for a realistic profitability calculation. Full article