Helmholtz-Institute Münster

This Review covers a sequence of key discoveries and technical achievements that eventually led to the birth of the lithium-ion battery. In doing so, it not only sheds light on the history with the advantage of contemporary hindsight but also provides insight and inspiration to aid in the ongoing quest for better batteries of the future. A detailed retrospective on ingenious designs, accidental discoveries, intentional breakthroughs, and deceiving misconceptions is given: from the discovery of the element lithium to its electrochemical synthesis; from intercalation host material development to the concept of dual-intercalation electrodes; and from the misunderstanding of intercalation behavior into graphite to the comprehension of interphases. The onerous demands of bringing all critical components (anode, cathode, electrolyte, solid-electrolyte interphases), each of which possess unique chemistries, into a sophisticated electrochemical device reveal that the challenge of interfacing these originally incongruent components often outweighs the individual merits and limits in their own properties. These important lessons are likely to remain true for the more aggressive battery chemistries of future generations, ranging from a revisited Li-metal anode, to conversion-reaction type chemistries such as Li/sulfur, Li/oxygen, and metal fluorides, and to bivalent cation intercalations.

When two is better than four Batteries based on the reaction of zinc and oxygen have been used for more than a century, but these have been primary (that is, nonrechargeable) cells. These batteries use an alkaline electrolyte and require a four-electron reduction of oxygen to water, which is a slow process. Sun et al. show that with the right choice of nonalkaline electrolyte, the battery can operate using a two-electron zinc-oxygen/zinc peroxide chemistry that is far more reversible. By making the electrolyte hydrophobic, water is excluded from the near surface of the cathode, thus preventing the four-electron reduction. These batteries also show higher energy density and better cycling stability. Science , this issue p. 46

Abstract Fast charging is considered to be a key requirement for widespread economic success of electric vehicles. Current lithium‐ion batteries (LIBs) offer high energy density enabling sufficient driving range, but take considerably longer to recharge than traditional vehicles. Multiple properties of the applied anode, cathode, and electrolyte materials influence the fast‐charging ability of a battery cell. In this review, the physicochemical basics of different material combinations are considered in detail, identifying the transport of lithium inside the electrodes as the crucial rate‐limiting steps for fast‐charging. Lithium diffusion within the active materials inherently slows down the charging process and causes high overpotentials. In addition, concentration polarization by slow lithium‐ion transport within the electrolyte phase in the porous electrodes also limits the charging rate. Both kinetic effects are responsible for lithium plating observed on graphite anodes. Conclusions drawn from potential and concentration profiles within LIB cells are complemented by extensive literature surveys on anode, cathode, and electrolyte materials—including solid‐state batteries. The advantages and disadvantages of typical LIB materials are analyzed, resulting in suggestions for optimum properties on the material and electrode level for fast‐charging applications. Finally, limitations on the cell level are discussed briefly as well.

Abstract Being successfully introduced into the market only 30 years ago, lithium‐ion batteries have become state‐of‐the‐art power sources for portable electronic devices and the most promising candidate for energy storage in stationary or electric vehicle applications. This widespread use in a multitude of industrial and private applications leads to the need for recycling and reutilization of their constituent components. Improving the “recycling technology” of lithium ion batteries is a continuous effort and recycling is far from maturity today. The complexity of lithium ion batteries with varying active and inactive material chemistries interferes with the desire to establish one robust recycling procedure for all kinds of lithium ion batteries. Therefore, the current state of the art needs to be analyzed, improved, and adapted for the coming cell chemistries and components. This paper provides an overview of regulations and new battery directive demands. It covers current practices in material collection, sorting, transportation, handling, and recycling. Future generations of batteries will further increase the diversity of cell chemistry and components. Therefore, this paper presents predictions related to the challenges of future battery recycling with regard to battery materials and chemical composition, and discusses future approaches to battery recycling.

Abstract Due to the rapidly increasing demand for electric vehicles, the need for battery cells is also increasing considerably. However, the production of battery cells requires enormous amounts of energy, which is expensive and produces greenhouse gas emissions. Here, by combining data from literature and from own research, we analyse how much energy lithium-ion battery (LIB) and post lithium-ion battery (PLIB) cell production requires on cell and macro-economic levels, currently and in the future (until 2040). On the cell level, we find that PLIB cells require less energy than LIB cells per produced cell energy. On the macro-economic level, we find that the energy consumption for the global production of LIB and PLIB cells will be 130,000 GWh if no measures are taken. Yet, it is possible to optimize future production and save up to 66% of this energy demand.

Daily temperature variations induce phase transitions and lattice strains in halide perovskites, challenging their stability in solar cells. We stabilized the perovskite black phase and improved solar cell performance using the ordered dipolar structure of β-poly(1,1-difluoroethylene) to control perovskite film crystallization and energy alignment. We demonstrated p-i-n perovskite solar cells with a record power conversion efficiency of 24.6% over 18 square millimeters and 23.1% over 1 square centimeter, which retained 96 and 88% of the efficiency after 1000 hours of 1-sun maximum power point tracking at 25° and 75°C, respectively. Devices under rapid thermal cycling between -60° and +80°C showed no sign of fatigue, demonstrating the impact of the ordered dipolar structure on the operational stability of perovskite solar cells.

This review analyzes 53 publications that forecast battery cost and provides transparency on methodological and technological details.

Rechargeable Li-based battery technologies utilising silicon, silicon-based, and Si-derivative anodes coupled with high-capacity/high-voltage insertion-type cathodes have reaped significant interest from both academic and industrial sectors. This stems from their practically achievable energy density, offering a new avenue towards the mass-market adoption of electric vehicles and renewable energy sources. Nevertheless, such high-energy systems are limited by their complex chemistry and intrinsic drawbacks. From this perspective, we present the progress, current status, prevailing challenges and mitigating strategies of Li-based battery systems comprising silicon-containing anodes and insertion-type cathodes. This is accompanied by an assessment of their potential to meet the targets for evolving volume- and weight-sensitive applications such as electro-mobility.

Further enhancement in the energy densities of rechargeable lithium batteries calls for novel cell chemistry with advanced electrode materials that are compatible with suitable electrolytes without compromising the overall performance and safety, especially when considering high-voltage applications. Significant advancements in cell chemistry based on traditional organic carbonate-based electrolytes may be successfully achieved by introducing fluorine into the salt, solvent/cosolvent, or functional additive structure. The combination of the benefits from different constituents enables optimization of the electrolyte and battery chemistry toward specific, targeted applications. This Review aims to highlight key research activities and technical developments of fluorine-based materials for aprotic non-aqueous solvent-based electrolytes and their components along with the related ongoing scientific challenges and limitations. Ionic liquid-based electrolytes containing fluorine will not be considered in this Review.

This review summarizes the history and critical working mechanisms of Li-rich oxides with a special focus on anionic redox reactions.

Abstract Research and development of advanced rechargeable battery technologies is dominated by application‐specific targets, which predominantly focus on cost and performance targets, including high gravimetric energy, volumetric energy, and related power densities, while ensuring a high safety and long lifetime. The need for high‐performance and low‐cost batteries is driven by the growing market of electromobility, in order to fulfill key requirements, such as a sufficient driving range and fast charging ability, for achieving broad consumer acceptance. Currently, the lithium ion battery (LIB) is one of the state‐of‐the‐art technologies able to meet most of these key requirements at a reasonable cost. In addition to performance and costs, the environmental impact, i.e., the sustainability of the battery and in particular of the battery cell over the whole life cycle—i.e., from raw material extraction and battery material production, to cell and battery pack production, battery utilization, and to possibilities for second life usage and recycling—does receive continuously increasing attention. Within this review, different approaches for the development of “greener” batteries are introduced with a view on the complete battery life cycle, while focusing on the LIB technology. Moreover, alternative battery technologies are critically evaluated regarding their sustainability aspects and competitiveness.

Abstract Electrochemical energy storage at a large scale poses one of the main technological challenges of this century. The scientific community in academia and industry worldwide intensively is exploring various alternative rechargeable battery concepts beside state‐of‐the‐art lithium ion batteries (LIBs), for example, all‐solid‐state batteries, lithium/sulfur batteries, magnesium/sulfur batteries or dual‐ion batteries that could outperform LIBs in different aspects. Often, these concepts also promise very high theoretical energies per mass or volume. However, as theoretical values exclude numerous relevant parameters, they do not translate directly into practically achievable energy values: The gaps between practical capacities and voltages compared to the theoretical values differ for each system. In order to provide high transparency and to illustrate which cell components are most important in the limitation of the practical energy values, in this study, the specific energies and energy densities are calculated in six subsequent steps—from the theoretical energy values of the active materials alone to the practical energy values in an 18650 cylindrical cell. By providing a tool to calculate the energy values of six different battery technologies with different assumptions made evident, this study aims for more transparency and reliability in the comparison of different cell chemistries.

In order to increase the energy content of lithium ion batteries (LIBs), researchers worldwide focus on high specific energy (Wh/kg) and energy density (Wh/L) anode and cathode materials. However, most of the attention is primarily paid to the specific gravimetric and/or volumetric capacities of these materials, while other key parameters are often neglected. For practical applications, in particular for large size battery cells, the Coulombic efficiency (CE), voltage efficiency (VE), and energy efficiency (EE) have to be considered, which we point out in this work by comparing numerous LIB active materials. For all presented active materials, energy inefficiency is mainly caused by a voltage inefficiency, which in turn is affected by the voltage hysteresis between the charge and discharge curves. Hence, this study could show that materials with larger voltage hysteresis such as the ZnFe2O4 (ZFO) anode or the Li-rich cathode material exhibit also a lower VE and EE than for instance graphite and LiNi0.5Mn1.5O4. Furthermore, from the accumulated EE losses the resulting “extra energy costs” are calculated based on industry and domestic electricity costs in Germany, in Japan and in the U.S.A. In particular, in countries with higher electricity costs such as Germany, the accumulated extra energy, which is necessary to compensate the energy inefficiency while retaining a certain energy level in the electrode material, has a stronger impact on the extra energy costs and thus on the total cost of ownership of the battery cell system.

There is an increasing demand for modern diagnostic systems for batteries under real-world operation, specifically for the estimation of their state of health, for example, via their remaining capacity. The online estimation of the capacity of a cell is challenging due to the dynamic nature of cell aging and the limited variety of inputs available from a cell under operation. The scope of this work is the development of a data-driven capacity estimation model for cells under real-world working conditions with recurrent neural networks having long short-term memory capability. Voltage-time sensor data from the partial constant current phase charging curve is used as input, reflecting input availability in the real world. The network achieves a best-case mean absolute percentage error of 0.76% and is extremely robust while handling input noise. It also has the ability to handle variations in the length of the input time series and can generate a viable estimation even with an incomplete collection of input due to sensor errors. The model validation with several scenarios is done in a local embedded device, highlighting the use case of such models in future battery management systems.

In order to meet the sophisticated demands for large-scale applications such as electro-mobility, next generation energy storage technologies require advanced electrode active materials with enhanced gravimetric and volumetric capacities to achieve increased gravimetric energy and volumetric energy densities. However, most of these materials suffer from high 1st cycle active lithium losses, e.g., caused by solid electrolyte interphase (SEI) formation, which in turn hinder their broad commercial use so far. In general, the loss of active lithium permanently decreases the available energy by the consumption of lithium from the positive electrode material. Pre-lithiation is considered as a highly appealing technique to compensate for active lithium losses and, therefore, to increase the practical energy density. Various pre-lithiation techniques have been evaluated so far, including electrochemical and chemical pre-lithiation, pre-lithiation with the help of additives or the pre-lithiation by direct contact to lithium metal. In this review article, we will give a comprehensive overview about the various concepts for pre lithiation and controversially discuss their advantages and challenges. Furthermore, we will critically discuss possible effects on the cell performance and stability and assess the techniques with regard to their possible commercial exploration.

A comprehensive review article addressing the prospects of the<italic>in situ</italic>polymerization strategy as a tool for surpassing the challenges of electrode|electrolyte interfaces &amp; interphases in lithium polymer batteries.

ConspectusAs the world transitions away from fossil energy to green and renewable energy, electrochemical energy storage increasingly becomes a vital component of the mix to conduct this transition. The central goal in developing next-generation batteries is to maximize the gravimetric and volumetric energy density and battery cycle life and improve safety. All solid-state batteries using a solid electrolyte and a lithium metal anode represent one of the most promising technologies that can achieve this goal. Highly conductive solid electrolytes (>10 mS·cm–1) are the key component to remove the safety concerns inherent with flammable organic liquid electrolytes and achieve high energy density by enabling high active material loading. Considering a range of inorganic solid electrolytes that have been developed to date, sulfide solid electrolytes exhibit the highest ionic conductivities, which even surpass those of conventional organic liquid electrolytes. Argyrodite-structured sulfide solid electrolytes are among the most promising materials in this class and are currently the dominantly used solid electrolytes for all-solid-state battery fabrication. Argyrodite solid electrolytes are particularly appealing because of their ultrahigh Li-ion conductivity, quasi-stable solid–electrolyte interphase (SEI) formed with Li metal, and ability to be prepared via scalable solution-assisted synthesis approaches. These factors are all vital for commercial applications.In this Account, we afford an overview of our recent development of several argyrodite superionic conductors, including Li6.6Si0.6Sb0.5S5I (24 mS·cm–1), Li6.6Ge0.6P0.4S5I (18 mS·cm–1), and Li5.5PS4.5Cl1.5 (12 mS·cm–1), and a comprehensive understanding of the origin of the underlying high conductivity, namely, sulfide/halide anion site disorder and Li cation site disorder. A high degree of sulfide/halide anion site disorder (changes in anion distribution) modifies the anionic charge, which in turn strongly influences the lithium distribution. A more inhomogeneous charge distribution in anion-disordered systems generates a spatially diffuse and delocalized lithium density, resulting in faster ionic transport. Lithium cation site disorder generated by increasing Li carrier concentration through aliovalent substitution creates high-energy interstitial sites for Li ion diffusion, which activate concerted ion migration and flatten the energy landscape for Li ion diffusion. This enables high conductivity in Li-rich argyrodite superionic conductors. These concepts are also expected to promote the design of rational new solid electrolytes and fundamental understanding of the structure–ion transport relationships in inorganic ionic conductors.Collectively, a comprehensive and deep understanding of the interphase formation between argyrodite solid electrolytes and cathode active materials/Li metal and the failure mechanism of all-solid-state batteries with argyrodite solid electrolytes will lead to the bottom-up engineering of the cathode/anode-solid electrolyte interfaces, which will accelerate the development of safe, high-energy-density all-solid-state lithium batteries.

As possible electrolyte materials for all-solid-state Na-ion batteries (NIBs), scandium-substituted Na3Zr2(SiO4)2(PO4) in the structure of NASICONs (Na superionic conductors) has received hardly any attention so far, although among all the trivalent cations, Sc3+ might be the most suitable substitution ion for Na3Zr2(SiO4)2(PO4) because the ionic radius of Sc3+ (74.5 pm) is the closest to that of Zr4+ (72.0 pm). In this study, a solution-assisted solid-state reaction (SASSR) method is described, and a series of scandium-substituted Na3Zr2(SiO4)2(PO4) with the formula of Na3+xScxZr2-x(SiO4)2(PO4) (NSZSPx, 0 ≤ x ≤ 0.6) have been prepared. This synthesis route can be applied for powder preparation on a large scale and at low cost. With increasing degrees of scandium substitution, the total conductivity of the samples also increases. An optimum total Na-ion conductivity of 4.0 × 10–3 S cm–1 at 25 °C is achieved by Na3.4Sc0.4Zr1.6(SiO4)2(PO4) (NSZSP0.4), which is the best value of all reported polycrystalline Na-ion conductors. The possible reasons for such high conductivity are discussed.

Dual-graphite cells have been proposed as electrochemical energy storage systems using graphite as both, the anode and cathode, whereas the electrolyte cations intercalate into the negative electrode and the electrolyte anions intercalate into the positive electrode during charge. On discharge, cations and anions are released back into the electrolyte. In this contribution, we present highly promising results for "dual-ion cells" based on intercalation of bis(trifluoromethanesulfonyl)imide anions into a graphite cathode from an ionic liquid-based electrolyte, namely N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI). As the compatibility of this ionic liquid with graphitic anodes is relatively poor, metallic lithium and lithium titanate (Li4Ti5O12) are used as anode. As both cations and anions participate in the charge/discharge reaction and other anode materials than graphite are possible, we propose the name "dual-ion cells" for these systems. The cell performance was studied in terms of cut-off voltage, temperature, cycling stability, self-discharge and rate performance. Depending on the cut-off voltage and temperature, coulombic efficiencies of more than 99 % and specific discharge capacities exceeding 100 mAh g−1 (based on graphite cathode weight) were achieved. Furthermore, this system provides an excellent cycling stability and capacity retention above 99 % after 500 cycles, outperforming reported organic solvent-based dual-graphite or dual-ion cells.

Layered lithium‐ and manganese‐rich oxides (LMROs), described as xLi 2 MnO 3 ·(1–x)LiMO 2 or Li 1+y M 1–y O 2 (M = Mn, Ni, Co, etc., 0 &lt; x &lt;1, 0 &lt; y ≤ 0.33), have attracted much attention as cathode materials for lithium ion batteries in recent years. They exhibit very promising capacities, up to above 300 mA h g −1 , due to transition metal redox reactions and unconventional oxygen anion redox reaction. However, they suffer from structural degradation and severe voltage fade (i.e., decreasing energy storage) upon cycling, which are plaguing their practical application. Thus, this review will aim to describe the pristine structure, high‐capacity mechanisms and structure evolutions of LMROs. Also, recent progress associated with understanding and mitigating the voltage decay of LMROs will be discussed. Several approaches to solve this problem, such as adjusting cycling voltage window and chemical composition, optimizing synthesis strategy, controlling morphology, doping, surface modification, constructing core‐shell and layered‐spinel hetero structures, are described in detail.