Batteries, Volume 5, Issue 4 (December 2019) – 12 articles

The paper presents the market of portable lithium-ion batteries in the European Union (EU) with particular emphasis on the stream of used Li-ion cells in Poland by 2030. In addition, the article draws attention to the fact that, despite a decade of efforts in Poland, it has not been possible to create an effective management system for waste batteries and accumulators that would include waste management (collection and selective sorting), waste disposal (a properly selected mechanical method) and component recovery technology for reuse (pyrometallurgical and/or hydrometallurgical methods). This paper also brings attention to the fact that this EU country with 38 million people does not have in its area a recycling process for used cells of the first type of zinc-carbon, zinc-manganese or zinc-air, as well as the secondary type of nickel-hydride and lithium-ion, which in the stream of chemical waste energy sources will be growing from year to year. Full article

The lithium-ion capacitor (LIC) is a recent innovation in the area of electrochemical energy storage that hybridizes lithium-ion battery anode material and an electrochemical double layer capacitor cathode material as its electrodes. The high power compared to batteries and higher energy compared to capacitors has made it a promising energy-storage device for powering hand-held and portable electronic systems/consumer electronics, hybrid electric vehicles, and electric vehicles. The swelling and gassing of the LIC when subjected to abuse conditions is still a critical issue concerning the safe application in power electronics and commercial devices. However, it is imperative to carry out a thorough investigation that characterizes the safe operation of LICs. We investigated and studied the safety of LIC for commercial applications, by conducting a comprehensive abuse tests on LIC 200 F pouch cells with voltage range from 3.8 V to 2.2 V manufactured by General Capacitors LLC. The abuse tests include overcharge, external short circuit, crush (flat metal plate and blunt indentation), nail penetration test, and external heat test. Full article

Laser cutting is a promising technology for the singulation of conventional and advanced electrodes for lithium-ion batteries. Even though the continuous development of laser sources, beam guiding, and handling systems enable industrial relevant high cycle times, there are still uncertainties regarding the influence of, for this process, typical cutting edge characteristics on the electrochemical performance. To investigate this issue, conventional anodes and cathodes were cut by a pulsed fiber laser with a central emission wavelength of 1059–1065 nm and a pulse duration of 240 ns. Based on investigations considering the pulse repetition frequency, cutting speed, and line energy, a cell setup of anodes and cathodes with different cutting edge characteristics were selected. The experiments on 9 Ah pouch cells demonstrated that the cutting edge of the cathode had a greater impact on the electrochemical performance than the cutting edge of the anode. Furthermore, the results pointed out that on the cathode side, the contamination through metal spatters, generated by the laser current collector interaction, had the largest impact on the electrochemical performance. Full article

In this paper, we will describe in detail the setting up of a Design of Experiments (DoE) applied to the formulation of electrodes for Li-ion batteries. We will show that, with software guidance, Designs of Experiments are simple yet extremely useful statistical tools to set up and embrace. An Optimal Combined Design was used to identify influential factors and pinpoint the optimal formulation, according to the projected use. Our methodology follows an eight-step workflow adapted from the literature. Once the study objectives are clearly identified, it is necessary to consider the time, cost, and complexity of an experiment before choosing the responses that best describe the system, as well as the factors to vary. By strategically selecting the mixtures to be characterized, it is possible to minimize the number of experiments, and obtain a statistically relevant empirical equation which links responses and design factors. Full article

This paper presents a comprehensive study of the influences of lamination at both electrode-separator interfaces of lithium-ion batteries consisting of LiNi_1/3Mn_1/3Co_1/3O₂ cathodes and graphite anodes. Typically, electrode-separator lamination shows a reduced capacity fade at fast-charging cycles. To study this behavior in detail, the anode and cathode were laminated separately to the separator and compared to the fully laminated and non-laminated state in single-cell format. The impedance of the cells was measured at different states of charge and during the cycling test up to 1500 fast-charging cycles. Lamination on the cathode interface clearly shows an initial decrease in the surface resistance with no correlation to aging effects along cycling, while lamination on both electrode-separator interfaces reduces the growth of the surface resistance along cycling. Lamination only on the anode-separator interface shows up to be sufficient to maintain the enhanced fast-charging capability for 1500 cycles, what we prove to arise from a significant reduction in growth of the solid electrolyte interface. Full article

High manufacturing cost and thermal stability of Li-ion battery cells are currently the two main deterrents to prolific demand for electric vehicles. A plausible solution to this issue is a modular/scalable battery thermal management system (TMS). A modular TMS can ensure thermal reliability for battery cells of different capacities and size without needing major structural revision besides facilitating mass-production. However, understanding the relationship of heat generation rates with cell capacity and thickness is essential for developing a scalable TMS. The present paper discusses results derived from an experimental investigation undertaken with this purpose. Heat generation rates for LiFePO₄ pouch cells of different nominal capacities are measured at discharge rates of 0.33C, 1C and 3C in ambient temperatures ranging between −10 and 50 °C using a custom-designed calorimeter. It is observed that heat generation rates of the LiFePO₄ pouch cells become independent of their nominal capacity and thickness if the ambient temperature is regulated at 35 °C. In ambient temperatures lower than 35 °C though, the thin battery cells are found to be generating heat at rates greater than those of thick battery cells and vice-versa at temperatures over 35 °C for all discharge rates. Full article

Lithium-rich layered oxide cathode materials of Li_1.2Mn_0.5100Ni_0.2175Co_0.0725O₂ have been synthesized using metal salts with acetate and nitrate anions as precursors in glycerol solvent. The effects of the precursor metal salts on particle size, morphology, cationic ordering, and ultimately, the electrode performance of the cathode powders have been studied. It was demonstrated that the use of cornstarch as a gelling agent with nitrate-based metal salts results in a reduction of particle size, leading to higher surface area and initial discharge capacity. However, the cornstarch gelling effect was minimized when acetate salts were used. As observed in the Fourier-transform infrared spectroscopy analysis, cornstarch can react with acetates to form acetyl groups during the synthesis, effectively preventing the cornstarch gel from capping the particles, thus leading to larger particles. A tradeoff was found when nitrate and acetate salts were mixed in the synthesis. It was shown that the new cathode powder has the best cationic ordering and capacity retention, promising a much stable Li-rich cathode material for lithium-ion batteries. Full article

Lithium-ion batteries (LIBs) are currently one of the most important electrochemical energy storage devices, powering electronic mobile devices and electric vehicles alike. However, there is a remarkable difference between their rate of production and rate of recycling. At the end of their lifecycle, only a limited number of LIBs undergo any recycling treatment, with the majority go to landfills or being hoarded in households. Further losses of LIB components occur because the the state-of-the-art LIB recycling processes are limited to components with high economic value, e.g., Co, Cu, Fe, and Al. With the increasing popularity of concepts such as “circular economy” (CE), new LIB recycling systems have been proposed that target a wider spectrum of compounds, thus reducing the environmental impact associated with LIB production. This review work presents a discussion of the current practices and some of the most promising emerging technologies for recycling LIBs. While other authoritative reviews have focused on the description of recycling processes, the aim of the present was is to offer an analysis of recycling technologies from a CE perspective. Consequently, the discussion is based on the ability of each technology to recover every component in LIBs. The gathered data depicted a direct relationship between process complexity and the variety and usability of the recovered fractions. Indeed, only processes employing a combination of mechanical processing, and hydro- and pyrometallurgical steps seemed able to obtain materials suitable for LIB (re)manufacture. On the other hand, processes relying on pyrometallurgical steps are robust, but only capable of recovering metallic components. Full article

Information derived from microscopic images of Li-ion cells is the base for research on the function, the safety, and the degradation of Li-ion batteries. This research was carried out to acquire information required to understand the mechanical properties of Li-ion cells. Parameters such as layer thicknesses, material compositions, and surface properties play important roles in the analysis and the further development of Li-ion batteries. In this work, relevant parameters were derived using microscopic imaging and analysis techniques. The quality and the usability of the measured data, however, are tightly connected to the sample generation, the preparation methods used, and the measurement device selected. Differences in specimen post-processing methods and measurement setups contribute to variability in the measured results. In this paper, the complete sample preparation procedure and analytical methodology are described, variations in the measured dataset are highlighted, and the study findings are discussed in detail. The presented results were obtained from an analysis conducted on a state-of-the-art Li-ion pouch cell applied in an electric vehicle that is currently commercially available. Full article

We present the manufacturing and utilization of an all-polymer arrayed waveguide grating (AWG) interacting with a fiber Bragg grating (FBG) for battery status monitoring on the example of a 40 Ah lithium-ion battery. The AWG is the main component of a novel low-cost approach for an optical interrogation unit to track the FBG peak wavelength by means of intensity changes monitored by a CMOS linear image sensor, read out by a Teensy 3.2 microcontroller. The AWG was manufactured using laser direct lithography as an all-polymer-system, whereas the FBG was produced by point-by-point femtosecond laser writing. Using this system, we continuously monitored the strain variation of a battery cell during low rate charge and discharge cycles over one month under constant climate conditions and compared the results to parallel readings of an optical spectrum analyzer with special attention to the influence of the relative air humidity. We found our low-cost interrogation unit is capable of precisely and reliably capturing the typical strain variation of a high energy pouch cell during cycling with a resolution of 1 pm and shows a humidity sensitivity of −12.8 pm per %RH. Full article

Hybrid capacitors have been developed to bridge the gap between batteries and ultracapacitors. These devices combine a capacitive electrode and a battery-like material to achieve high energy-density high power-density devices with good cycling stability. In the quest of improved electrochemical responses, several hybrid devices have been proposed. However, they are usually limited to bench-scale prototypes that would likely face severe challenges during a scaling up process. The present case study reports the production of a hybrid prototype consisting of commercial activated carbon and nickel-cobalt hydroxide, obtained by chemical co-precipitation, separated by means of polyolefin-based paper. Developed to power a 12 W LED light, these materials were assembled and characterized in a coin-cell configuration and stacked to increase device voltage. All the processes have been adapted and constrained to scalable conditions to ensure reliable production of a pre-commercial device. Important challenges and limitations of this process, from geometrical constraints to increased resistance, are reported alongside their impact and optimization on the final performance, stability, and metrics of the assembled prototype. Full article

Commercial lithium ion cells are now optimised for either high energy density or high power density. There is a trade off in cell design between the power and energy requirements. A tear down protocol has been developed, to investigate the internal components and cell engineering of nine cylindrical cells, with different power–energy ratios. The cells designed for high power applications used smaller particles of the active material in both the anodes and the cathodes. The cathodes for high power cells had higher porosities, but a similar trend was not observed for the anodes. In terms of cell design, the coat weights and areal capacities were lower for high power cells. The tag arrangements were the same in eight out of nine cells, with tags at each end of the anode, and one tag on the cathode. The thicknesses of the current collectors and separators were based on the best (thinnest) materials available when the cells were designed, rather than materials optimised for power or energy. To obtain high power, the resistance of each component is reduced as low as possible, and the lithium ion diffusion path lengths are minimised. This information illustrates the significant evolution of materials and components in lithium ion cells in recent years, and gives insight into designing higher power cells in the future. Full article