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Organic electrode materials are capable candidates for next‐generation greener energy storage solutions. One advantage is that their electrochemical performance can be tuned by structural modification. We herein investigate anisyl‐substituted poly(vinyl‐) and poly(styrylphenothiazines) as positive electrode materials for dual‐ion batteries. π‐Interactions – characteristic to phenothiazine redox polymers – are facilitated in the poly(styrene) derivatives PSAPT and PSAPT‐X‐DVB due to the longer spacing between phenothiazine units and polymer backbone and lead to high cycling stabilities, but reduce their specific capacities. In the poly(vinylenes), the linear PVAPT shows high cycling stability but a dissolution/redeposition mechanism, diminishing its capacity, while the cross‐linked X‐PVAPT demonstrates high cycling stabilities at specific capacities up to 81 mAh g−1 paired with an excellent rate performance, where 10,000 cycles at 100 C rate proceed with 86 % capacity retention. [ABSTRACT FROM AUTHOR]

The electrochemical performance of lithium metal batteries is affected by many factors, among which the negative electrode is crucial. Although much of the research is focused on lithium metal electrodes from metallic foils, lithium metal powder can also provide several advantages. Herein, the synthesis of lithium metal powder (Lip) using a droplet emulsion technique is described in detail and the scientific background of the method is provided. Furthermore, the electrochemical performance of the composite Lip‐based electrodes prepared with conductive carbon additive (Super C65) via the electrode paste‐casting method is reported. The results indicate that under the same material loading, the composite Lip‐based electrodes can provide at least twice the practical electrode capacity of pure Lip electrodes and with lower overpotentials, as shown in symmetric Li||Li cells. Full cells assembled with an NMC622 cathode and a composite Lip‐based electrode are cycled at least for 100 cycles and show improved cycling performance as compared with the full cells assembled with pure Lip electrodes. In addition, the results also conclude that there are four different types of charge storage mechanisms in these composite Lip‐based electrodes. These occurring mechanisms should be considered when engineering lithium metal electrodes with various designs. [ABSTRACT FROM AUTHOR]

Dual‐ion batteries (DIBs) offer a great alternative to state‐of‐the‐art lithium‐ion batteries, based on their high promises due to the absence of transition metals and the use of low‐cost materials, which could make them economically favorable targeting stationary energy storage applications. In addition, they are not limited by certain metal cations, and DIBs with a broad variety of utilized ions could be demonstrated over the last years. Herein, a systematic study of different electrolyte approaches for Mg‐ion‐based DIBs was conducted. A side‐by‐side comparison of Li‐ and Mg‐ion‐based electrolytes using activated carbon as negative electrode revealed the opportunities but also limitations of Mg‐ion‐based DIBs. Ethylene sulfite was successfully introduced as electrolyte additive and increased the specific discharge capacity significantly up to 93±2 mAh g−1 with coulombic efficiencies over 99 % and an excellent capacity retention of 88 % after 400 cycles. In addition, and for the first time, highly concentrated carbonate‐based electrolytes were employed for Mg‐ion‐based DIBs, showing adequate discharge capacities and high coulombic efficiencies. [ABSTRACT FROM AUTHOR]

Organic redox polymers are attractive electrode materials for more sustainable rechargeable batteries. To obtain full‐organic cells with high operating voltages, redox polymers with low potentials (<2 V versus Li|Li+) are required for the negative electrode. Dibenzo[a,e]cyclooctatetraene (DBCOT) is a promising redox‐active group in this respect, since it can be reversibly reduced in a two‐electron process at potentials below 1 V versus Li|Li+. Upon reduction, its conformation changes from tub‐shaped to planar, rendering DBCOT‐based polymers also of interest to molecular actuators. Here, the syntheses of three aliphatic DBCOT‐polymers and their electrochemical properties are presented. For this, a viable three‐step synthetic route to 2‐bromo‐functionalized DBCOT as polymer precursor is developed. Cyclic voltammetry (CV) measurements in solution and of thin films of the DBCOT‐polymers demonstrate their potential as battery electrode materials. Half‐cell measurements in batteries show pseudo capacitive behavior with Faradaic contributions, which demonstrate that electrode composition and fabrication will play an important role in the future to release the full redox activity of the DBCOT polymers. [ABSTRACT FROM AUTHOR]

The breakthroughs in rechargeable lithium metal‐anode‐based batteries is still challenged by safety and performance limitations. Ionic liquid (IL)‐based electrolytes are in consideration for increased safety but their moderate electrolyte performance and high costs still suppress their usefulness in Li metal‐batteries. In an effort to deepen the understanding of the limited performance, galvanic corrosion as an electrochemical degradation process is herein identified as a contributing factor toward battery cell deterioration. Four different ILs, based on bis(trifluoromethylsulfonyl)imide in combination with the quaternary ammonium cations N‐butyl‐N‐methylpyrrolidinium, N‐methyl‐N‐propyl‐pyrrolidinium, N‐butyl‐N‐methylpiperidinium, and N‐butyltrimethylammonium, respectively, are systematically investigated for such corrosive side reactions. The reaction pathways of this commonly neglected phenomenon are found to be both Hofmann‐type and reductive eliminations. Supported by headspace‐gas chromatography‐mass spectrometry, the evolving gaseous reaction products are characterized. With zero resistance ammetry and Li electrochemical dissolution and deposition experiments, the dependency of galvanic corrosion on the presence of the galvanically coupled materials is elucidated. Variation of the lithium bis(trifluoromethylsulfonyl)imide concentration in the electrolytes is shown to influence the extent of detectable degradation products. Based on these findings, the necessity for more sophisticated electrode designs and electrolyte formulations is emphasized. [ABSTRACT FROM AUTHOR]

We report on the reversible (de)intercalation of TFSI− anions from a Mg‐based ionic liquid electrolyte, Mg(TFSI)2 in Pyr14TFSI, in graphite ∥ activated carbon hybrid dual‐ion capacitor (DIC) cells. The role of different pseudo reference electrodes (PREs) including Ag‐wire and Li metal is discussed regarding the comparability of different battery cells. We show that an Ag‐wire PRE is not suitable for the designated purpose, while the use of a Li metal PRE results in high reproducibility. Mg‐based DIC cells are compared with cells based on pure Pyr14TFSI and LiTFSI‐Pyr14TFSI electrolytes, and with graphite ∥ Li metal dual‐ion cells employing LiTFSI‐Pyr14TFSI. At 5.2 V vs. Li|Li+, Mg‐containing DIC cells reveal an improved performance compared to Li‐based cells, i. e. higher capacity (87 vs. 85 mAh g−1) and higher Coulombic efficiency (98 vs. 96 %). These results may pave the way to further studies and performance improvements of Mg‐based batteries and to hybrid DIC chemistries with other cations, especially multi‐valent ones. [ABSTRACT FROM AUTHOR]

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Li metal batteries (LMBs) containing cross‐linked polymer electrolytes (PEs) are auspicious candidates for next‐generation batteries. However, the wetting behavior of PEs on uneven Li metal surfaces has been neglected in most studies. Herein, it is shown that microscale defect sites with curved edges play an important role in a wettability‐dependent electrodeposition. The wettability and the viscoelastic properties of PEs are correlated, and the impact of wettability on the nucleation and diffusion near the Li|PE interface is distinguished. It is found that the curvature of the edges is a key factor for the investigation of wetting phenomena. The appearance of microscale defects and phase separation are identified as main causes for erratic nucleation. It is emphasized that the implementation of stable and consistent long‐term cycling performance of LMBs using PEs requires a deeper understanding of the "soft‐solid"–solid contact between PEs and inherently rough Li metal surfaces. [ABSTRACT FROM AUTHOR]

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 FROM AUTHOR]

In recent years, the electrochemical power sources community has launched massive research programs, conferences, and workshops on the "post Li battery era." However, in this report it is shown that the quest for post Li‐ion and Li battery technologies is incorrect in its essence. This is the outcome of a three day discussion on the future technologies that could provide an answer to a question that many ask these days: Which are the technologies that can be regarded as alternative to Li‐ion batteries? The answer to this question is a rather surprising one: Li‐ion battery technology will be here for many years to come, and therefore the use of "post Li‐ion" battery technologies would be misleading. However, there are applications with needs for which Li‐ion batteries will not be able to provide complete technological solutions, as well as lower cost and sustainability. In these specific cases, other battery technologies will play a key role. Here, the term "side‐by‐side technologies" is coined alongside a discussion of its meaning. The progress report does not cover the topic of Li‐metal battery technologies, but covers the technologies of sodium‐ion, multivalent, metal–air, and flow batteries. [ABSTRACT FROM AUTHOR]

Organic cathode materials are handled as promising candidates for new energy‐storage solutions based on their transition‐metal‐free composition. Phenothiazine‐based polymers are attractive owing to their redox potential of 3.5 V vs. Li/Li+ and high cycling stabilities. Herein, three types of poly(norbornene)s were investigated, functionalized with phenothiazine units through either a direct connection or ester linkages, as well as their crosslinked derivatives. The directly linked poly(3‐norbornylphenothiazine)s demonstrated excellent rate capability and cycling stability with a capacity retention of 73 % after 10 000 cycles at a C‐rate of 100 C for the crosslinked polymer. The polymer network structure of the crosslinked poly(3‐norbornylphenothiazine) was beneficial for its rate performance. [ABSTRACT FROM AUTHOR]

Lithium metal is considered to be the most promising anode for the next generation of batteries if the issues related to safety and low coulombic efficiency can be overcome. It is known that the initial morphology of the lithium metal anode has a great influence on the cycling characteristics of a lithium metal battery (LMB). Lithium‐powder‐based electrodes (Lip‐electrodes) are reported to diminish the occurrence of high surface area lithium deposits. Usually, ultra‐thin lithium foils (<50 µm) and Lip‐electrodes are prepared on a copper substrate, thus a metal–metal contact area is generated. The combination of these two metals in the presence of an electrolyte, however, can lead to galvanic corrosion. Herein, the corrosion behavior of Lip‐electrodes is studied. The porosity of such electrodes leads to a high amount of accessible Cu surface in contact with electrolyte. As a consequence, Lip‐electrodes aged for 1 week in the electrolyte show spontaneous lithium dissolution near the junction to copper and void formation on the lithium‐powder particles. This corrosion process affects the delivered capacity of Lip‐electrodes and increases the overvoltage of the lithium electrodissolution process. The occurrence of corrosion at the Cu|Lip interface raises concerns about the practicality of multi‐metallic component systems for LMBs. [ABSTRACT FROM AUTHOR]

Solid‐state lithium–sulfur battery (SSLSB) is attractive due to its potential for providing high energy density. However, the cell chemistry of SSLSB still faces challenges such as sluggish electrochemical kinetics and prominent "chemomechanical" failure. Herein, a high‐performance SSLSB is demonstrated by using the thio‐LiSICON/polymer composite electrolyte in combination with sulfurized polyacrylonitrile (S/PAN) cathode. Thio‐LiSICON/polymer composite electrolyte, which processes high ionic conductivity and wettability, is fabricated to enhance the interfacial contact and the performance of lithium metal anodes. S/PAN is utilized due to its unique electrochemical characteristics: electrochemical and structural studies combined with nuclear magnetic resonance spectroscopy and electron paramagnetic resonance characterizations reveal the charge/discharge mechanism of S/PAN, which is the radical‐mediated redox reaction within the sulfur grafted conjugated polymer framework. This characteristic of S/PAN can support alleviating the volume change in the cathode and maintaining fast redox kinetics. The assembled SSLSB full cell exhibits excellent rate performance with 1183 mAh g−1 at 0.2 C and 719 mAh g−1 at 0.5 C, respectively, and can accomplish 50 cycles at 0.1 C with the capacity retention of 588 mAh g−1. The superior performance of the SSLSB cell rationalizes the construction concept and leads to considerations for the innovative design of SSLSB. [ABSTRACT FROM AUTHOR]

Lithium metal as an electrode material possesses a native surface film, which leads to a rough surface and this has a negative impact on the cycling behavior. A simple, fast, and reproducible technique is shown, which makes it possible to flatten and thin the native surface film of the lithium-metal anode. Atomic force microscopy and scanning electron microscopy images are presented to verify the success of the method and X-ray photoelectron spectroscopy measurements reveal that the chemical composition of the lithium surface is also changed. Furthermore, galvanostatic measurements indicate superior cycling behavior of the surface modified electrodes compared to the as-received ones. These results demonstrate that the native surface film plays a key role in the application of lithium metal as an anode material for lithium-metal batteries and that the shown surface modification method is an excellent tool to obtain better performing Li metal electrodes. [ABSTRACT FROM AUTHOR]

Lithium Metal Batteries: Galvanic Corrosion of Lithium-Powder-Based Electrodes (Adv. Keywords: electrodeposition; electrodissolution; galvanic corrosion; lithium metal batteries; lithium-powder-based electrodes EN electrodeposition electrodissolution galvanic corrosion lithium metal batteries lithium-powder-based electrodes 1 1 1 04/23/20 20200421 NES 200421 In article number 2000017, Martin Winter, Marian Cristian Stan and co-workers demonstrate that Cu|Li interfaces create favorable pre-conditions for galvanic corrosion. Electrodeposition, electrodissolution, galvanic corrosion, lithium metal batteries, lithium-powder-based electrodes. [Extracted from the article]

The combination of mechanically modified lithium electrodes and solid polymer electrolytes (SPEs) is investigated. So far, modified lithium electrodes, e.g., via structuring, are successfully used in combination with liquid electrolytes like ionic liquid‐based and organic solvent‐based ones. Specific SPEs have proven to be well compatible with lithium metal, even better than with liquid electrolytes. Nevertheless, the interface between lithium and SPEs is a complex issue. In this work, the challenge of the adequate wetting of the lithium electrode surface, especially a structured lithium surface, with a solid polymer is faced to successfully improve the interfacial properties and thus the performance, by a new method for the coating of such electrodes. The wetting of the micropatterned lithium surface by the SPE and the directed lithium electrodeposition in the patterns are verified by scanning electron microscopy analysis. The electrochemical properties of Li|SPE assemblies are investigated on the basis of constant current cycling and impedance experiments. [ABSTRACT FROM AUTHOR]

Lithium metal batteries (LMBs) combining a Li metal anode with a transition metal (TM) cathode can achieve higher practical energy densities (Wh L−1) than Li/S or Li/O2 cells. Research for improving the electrochemical behavior of the Li metal anode by, for example, modifying the liquid electrolyte is often conducted in symmetrical Li/Li or Li/Cu cells. This study now demonstrates the influence of the TM cathode on the Li metal anode, thus full cell behavior is analyzed in a way not considered so far in research with LMBs. Therefore, the deposition/dissolution behavior of Li metal and the resulting morphology is investigated with three different cathode materials (LiNi0.5Mn1.5O4, LiNi0.6Mn0.2Co0.2O2, and LiFePO4) by post mortem analysis with a scanning electron microscope. The observed large differences of the Li metal morphology are ascribed to the dissolution and crossover of TMs found deposited on Li metal and in the electrolyte by X‐ray photoelectron spectroscopy, energy‐dispersive X‐ray spectroscopy, and total reflection X‐ray fluorescence analysis. To support this correlation, the TM dissolution is simulated by adding Mn salt to the electrolyte. This study offers new insights into the cross talk between the Li metal anodes and TM cathodes, which is essential, when investigating Li metal electrodes for LMB full cells. [ABSTRACT FROM AUTHOR]

Organic cathode materials are a sustainable alternative to transition metal oxide‐based compounds in high voltage rechargeable batteries due to their low toxicity and availability from less‐limited resources. Important criteria in their design are a high specific capacity, cycling stability, and rate capability. Furthermore, the cathode should contain a high mass loading of active material and be compatible with different anode materials, allowing for its use in a variety of cell designs. Here, cross‐linked poly(3‐vinyl‐N‐methylphenothiazine) as cathode‐active material is presented, which shows a remarkable rate capability (up to 10C) and cycling stability at a high and stable potential of 3.55 V versus Li/Li+ and a specific capacity of 112 mAh g−1. Its use in full cells with a high mass loading of 70 wt% is demonstrated against lithium titanate as intercalation material as well as lithium metal, which both show excellent performance. Through comparison with poly(3‐vinyl‐N‐methylphenothiazine) the study shows that changing the structure of the redox‐active polymer through cross‐linking can lead to a change in charge/discharge mechanism and cycling behavior of the composite electrode. Poly(3‐vinyl‐N‐methylphenothiazine) in its cross‐ and non‐cross‐linked form both show excellent results as cathode‐active materials with variable specifications regarding specific capacity, cycling stability, and rate capability. The full discharge capacity of poly(vinylphenothiazine) as battery cathode material is unlocked by cross‐linking. This leads to a reduction in polymer mobility and prevention of rearrangement processes. The cross‐linked polymer shows a high cycling stability and rate capability and excellent performance in full cells with a high mass loading of 70 wt% versus lithium and lithium titanate. [ABSTRACT FROM AUTHOR]