Katrin Hoeppner

Bio: Katrin Hoeppner is an academic researcher from Technical University of Berlin. The author has contributed to research in topics: Battery (electricity) & Electrode. The author has an hindex of 5, co-authored 12 publications receiving 551 citations.

An Overview and Future Perspectives of Aluminum Batteries

Abstract: A critical overview of the latest developments in the aluminum battery technologies is reported. The substitution of lithium with alternative metal anodes characterized by lower cost and higher abundance is nowadays one of the most widely explored paths to reduce the cost of electrochemical storage systems and enable long-term sustainability. Aluminum based secondary batteries could be a viable alternative to the present Li-ion technology because of their high volumetric capacity (8040 mAh cm(-3) for Al vs 2046 mAh cm(-3) for Li). Additionally, the low cost aluminum makes these batteries appealing for large-scale electrical energy storage. Here, we describe the evolution of the various aluminum systems, starting from those based on aqueous electrolytes to, in more details, those based on non-aqueous electrolytes. Particular attention has been dedicated to the latest development of electrolytic media characterized by low reactivity towards other cell components. The attention is then focused on electrode materials enabling the reversible aluminum intercalation-deintercalation process. Finally, we touch on the topic of high-capacity aluminum-sulfur batteries, attempting to forecast their chances to reach the status of practical energy storage systems.

Insights into the reversibility of aluminum graphite batteries

Abstract: Herein we report a novel study on the reaction mechanism of non-aqueous aluminum/graphite cell chemistry employing 1-ethyl-3-methylimidazolium chloride:aluminum trichloride (EMIMCl:AlCl3) as the electrolyte. This work highlights new insights into the reversibility of the anion intercalation chemistry besides confirming its outstanding cycle life exceeding 2000 cycles, corresponding to more than 5 months of cycling test. The reaction mechanism, involving the intercalation of AlCl4− in graphite, has been fully characterized by means of ex situ X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure spectroscopy (XANES) and small-angle X-ray scattering (SAXS), evidencing the accumulation of anionic species into the cathode as the main factor responsible for the slight initial irreversibility of the electrochemical process.

High-throughput battery materials testing based on test cell arrays and dispense/jet printed electrodes

Abstract: A cost effective and reliable technology for the fabrication of electrochemical test-cell arrays for battery materials research, based on batch-fabricated glass micro packages was developed and tested. Jet dispensing was investigated for the first time as a process for fabricating battery electrode arrays and separators and compared to micro dispense printing. The process shows the reproducibility over the whole range of investigated materials and battery cell structures that is required for battery materials research. Such setup gives rise to a significantly improved reliability and reproducibility of electrochemical experiments. Cost-effective fabrication of our test chips by batch processing allows for their single-use in electrochemical experiments, thereby preventing contamination issues due to repeated use as in conventional laboratory test cells. In addition, the integration of micro pseudo reference electrodes is demonstrated. Thus, the test cell array together with the developed electrode/electrolyte deposition technology provide a highly efficient tool for speedy combinatorial and high throughput testing of battery materials on a system level (full cell tests). Experimental results are shown for the microfabrication of lithium-ion test cells with help of several electrode and binder materials. The influence of jetting parameters on electrode lateral dimensions and thickness, reproducibility of the electrode mass as well as the use of integrated micro-reference electrodes for impedance spectroscopy and cyclic voltammetry measurements in micro cells are presented in detail.

An Overview and Future Perspectives of Aluminum Batteries

Abstract: A critical overview of the latest developments in the aluminum battery technologies is reported. The substitution of lithium with alternative metal anodes characterized by lower cost and higher abundance is nowadays one of the most widely explored paths to reduce the cost of electrochemical storage systems and enable long-term sustainability. Aluminum based secondary batteries could be a viable alternative to the present Li-ion technology because of their high volumetric capacity (8040 mAh cm(-3) for Al vs 2046 mAh cm(-3) for Li). Additionally, the low cost aluminum makes these batteries appealing for large-scale electrical energy storage. Here, we describe the evolution of the various aluminum systems, starting from those based on aqueous electrolytes to, in more details, those based on non-aqueous electrolytes. Particular attention has been dedicated to the latest development of electrolytic media characterized by low reactivity towards other cell components. The attention is then focused on electrode materials enabling the reversible aluminum intercalation-deintercalation process. Finally, we touch on the topic of high-capacity aluminum-sulfur batteries, attempting to forecast their chances to reach the status of practical energy storage systems.

Design, Fabrication and Testing of Silicon-integrated Li-ion Secondary Micro Batteries with Side-by-Side Electrodes

Abstract: This paper reports the design, fabrication, and testing of silicon-integrated lithium ion secondary micro batteries with a side-by-side electrode setup. Two cavities separated by a narrow silicon spacer served as a containment for the electrodes and were etched into -Si by wet chemical etching using aqueous KOH solution. The etched silicon battery containment was passivated by a stress-compensated layer of SiO2/Si3N4. Ti/Pt-current collectors were applied by E-beam evaporation and lift-off structuring. A volumetric dispenser served to fill the cavities with slurries of the active materials – lithium cobalt oxide (LiCoO2) as the anode and graphite as the cathode material. Encapsulation, electrolyte filling, and electrochemical characterisation of the finished cells took place in an Ar-filled glove box. The fabricated batteries have shown a rate capability of up to 5C and a linear capacity loss rate of <1 % per cycle over 30 full-cycles. Battery containments with different cavity and spacer widths have been fabricated.

Recent Advances in Aqueous Zinc-Ion Batteries

Abstract: Although current high-energy-density lithium-ion batteries (LIBs) have taken over the commercial rechargeable battery market, increasing concerns about limited lithium resources, high cost, and insecurity of organic electrolyte scale-up limit their further development. Rechargeable aqueous zinc-ion batteries (ZIBs), an alternative battery chemistry, have paved the way not only for realizing environmentally benign and safe energy storage devices but also for reducing the manufacturing costs of next-generation batteries. This Review underscores recent advances in aqueous ZIBs; these include the design of a highly reversible Zn anode, optimization of the electrolyte, and a wide range of cathode materials and their energy storage mechanisms. We also present recent advanced techniques that aim at overcoming the current issues in aqueous ZIB systems. This Review on the future perspectives and research directions will provide a guide for future aqueous ZIB study.

Advances and issues in developing salt-concentrated battery electrolytes

Abstract: With a worldwide trend towards the efficient use of renewable energies and the rapid expansion of the electric vehicle market, the importance of rechargeable battery technologies, particularly lithium-ion batteries, has steadily increased. In the past few years, a major breakthrough in electrolyte materials was achieved by simply increasing the salt concentration in suitable salt–solvent combinations, offering technical superiority in numerous figures of merit over alternative materials. This long-awaited, extremely simple yet effective strategy can overcome most of the remaining hurdles limiting the present lithium-ion batteries without sacrificing manufacturing efficiency, and hence its impact is now widely felt in the scientific community, with serious potential for industrial development. This Review aims to provide timely and objective information that will be valuable for designing better realistic batteries, including a multi-angle analysis of their advantages and disadvantages together with future perspectives. Emphasis is placed on the pathways to address the remaining technical and scientific issues rather than re-highlighting the many technical advantages. New electrolyte materials can offer breakthroughs in the development of next-generation batteries. Here Atsuo Yamada and colleagues review the progress made and the road ahead for salt-concentrated electrolytes, an emerging and promising electrolyte candidate.

Voltage issue of aqueous rechargeable metal-ion batteries

Abstract: Over the past two decades, a series of aqueous rechargeable metal-ion batteries (ARMBs) have been developed, aiming at improving safety, environmental friendliness and cost-efficiency in fields of consumer electronics, electric vehicles and grid-scale energy storage. However, the notable gap between ARMBs and their organic counterparts in energy density directly hinders their practical applications, making it difficult to replace current widely-used organic lithium-ion batteries. Basically, this huge gap in energy density originates from cell voltage, as the narrow electrochemical stability window of aqueous electrolytes substantially confines the choice of electrode materials. This review highlights various ARMBs with focuses on their voltage characteristics and strategies that can effectively raise battery voltage. It begins with the discussion on the fundamental factor that limits the voltage of ARMBs, i.e., electrochemical stability window of aqueous electrolytes, which decides the maximum-allowed potential difference between cathode and anode. The following section introduces various ARMB systems and compares their voltage characteristics in midpoint voltage and plateau voltage, in relation to respective electrode materials. Subsequently, various strategies paving the way to high-voltage ARMBs are summarized, with corresponding advancements highlighted. The final section presents potential directions for further improvements and future perspectives of this thriving field.

Intercalation chemistry of graphite: alkali metal ions and beyond.

Abstract: Reversibly intercalating ions into host materials for electrochemical energy storage is the essence of the working principle of rocking-chair type batteries. The most relevant example is the graphite anode for rechargeable Li-ion batteries which has been commercialized in 1991 and still represents the benchmark anode in Li-ion batteries 30 years later. Learning from past lessons on alkali metal intercalation in graphite, recent breakthroughs in sodium and potassium intercalation in graphite have been demonstrated for Na-ion batteries and K-ion batteries. Interestingly, some significant differences proved to exist for the intercalation of Na+ and K+ into graphite compared with the Li+ case. Such different host-guest interactions are unique depending on the host materials and electrolytes, which greatly contribute to a deeper understanding of intercalation-type electrode materials for next generation alkali metal ion batteries. This review summarizes significant advances from both experimental and theoretical calculations with a focus on comparing the intercalation of three alkali metal ions (Li+, Na+, K+) into graphite and aims to clarify the intimate host-guest relationships and the underlying mechanisms. New approaches developed to achieve favorable intercalation coupled with the challenges in this field are also discussed. We also extrapolate alkali metal ion intercalation in graphite to mono-/multi-valent ions in layered electrode materials, which will deepen the understanding of intercalation chemistry and provide guidance to explore new guests and hosts.

Current Status and Future Prospects of Metal–Sulfur Batteries

Abstract: Lithium-sulfur batteries are a major focus of academic and industrial energy-storage research due to their high theoretical energy density and the use of low-cost materials. The high energy density results from the conversion mechanism that lithium-sulfur cells utilize. The sulfur cathode, being naturally abundant and environmentally friendly, makes lithium-sulfur batteries a potential next-generation energy-storage technology. The current state of the research indicates that lithium-sulfur cells are now at the point of transitioning from laboratory-scale devices to a more practical energy-storage application. Based on similar electrochemical conversion reactions, the low-cost sulfur cathode can be coupled with a wide range of metallic anodes, such as sodium, potassium, magnesium, calcium, and aluminum. These new "metal-sulfur" systems exhibit great potential in either lowering the production cost or producing high energy density. Inspired by the rapid development of lithium-sulfur batteries and the prospect of metal-sulfur cells, here, over 450 research articles are summarized to analyze the research progress and explore the electrochemical characteristics, cell-assembly parameters, cell-testing conditions, and materials design. In addition to highlighting the current research progress, the possible future areas of research which are needed to bring conversion-type lithium-sulfur and other metal-sulfur batteries into the market are also discussed.