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The selection of an appropriate cathode active material is important for operation performance and production of high-performance lithium-ion batteries. Promising candidates are nickel-rich layered oxides like LiNi$_x$Co$_y$Mn$_z$O$_2$ (NCM, x+y+z=1) with nickel contents of ‘x’ ≥ 0.8, characterized by high electrode potential and specific capacity. However, these materials are associated with capacity fading due to their high sensitivity to moisture. Herein, two different polycrystalline NCM materials with nickel contents of 0.81 ≤ ‘x’ ≤ 0.83 and protective surface coatings are processed in dry-room atmosphere (dew point of supply air T$_D$ ≈ −65 °C) at lab scale including the slurry preparation and coating procedure. In comparison, cathodes are produced in ambient atmosphere and both variants are tested in coin cells. Moreover, processing at pilot scale in ambient atmosphere is realized successfully by continuous coating and drying of the cathodes. Relevant electrode properties such as adhesion strength, specific electrical resistance, and pore-size distribution for the individual process steps are determined, as well as the moisture uptake during calendering. Furthermore, rate capability and cycling stability are investigated in pouch cells, wherein initial specific discharge capacities of up to 190 mAh g$^{−1}$ (with regard to the cathode material mass) are achieved at 0.2C.

The specific energy/energy density of state-of-the-art (SOTA) Li ion batteries can be increased by raising the upper charge voltage. However, instability of SOTA cathodes, i.e. LiNiyCoxMnyO2 (x + y + z = 1; NCM) triggers electrode crosstalk via enhanced transition metal (TM) dissolution, and contributes to severe capacity fade, in worst case, to a sudden death ("roll-over failure"). Lithium difluorophosphate (LiDFP) as electrolyte additive is able to boost high voltage performance via scavenging of dissolved TMs. However, LiDFP is chemically unstable and rapidly decomposes to toxic (oligo-) organofluorophosphates (OFPs) at elevated temperature; a process which can be precisely analyzed by means of high-performance liquid chromatography - high resolution mass spectroscopy. The toxicity of LiDFP can be proven via the well-known acetylcholinesterase inhibition test. Interestingly, while fluoroethylene carbonate (FEC) is inappropriate for high voltage applications as single electrolyte additive due to rollover failure, it is able to suppress formation of toxic OFPs. Based on this, a synergistic LiDFP/FEC dual-additive approach is suggested in this work, showing characteristic benefits of both individual additives, i.e. good capacity retention at high voltage in the presence of LiDFP and decreased OFP formation/toxicity induced by FEC.

The electrochemical response of layered lithium transition metal oxides LiMO

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., Dual‐ion batteries: Different electrolyte approaches including ionic liquids, additives, and highly concentrated electrolytes for Mg‐ion‐based dual‐ion batteries with graphite as positive and activated carbon as negative electrodes are investigated. Combining the improved electrolyte formulation with an optimized cut‐off potential and specific current, specific discharge capacities of up to 93±2 mAh g−1 with a capacity retention of 88 % after 400 cycles are achieved.

N‐alkyl‐N‐alkyl pyrrolidinium‐based ionic liquids (ILs) are promising candidates as non‐flammable plasticizers for lowering the operation temperature of poly(ethylene oxide) (PEO)‐based solid polymer electrolytes (SPEs), but they present limitations in terms of lithium‐ion transport, such as a much lower lithium transference number. Thus, a pyrrolidinium cation was prepared with an oligo(ethylene oxide) substituent with seven repeating units. We show, by a combination of experimental characterizations and simulations, that the cation's solvating properties allow faster lithium‐ion transport than alkyl‐substituted analogues when incorporated in SPEs. This proceeds not only by accelerating the conduction modes of PEO, but also by enabling new conduction modes linked to the solvation of lithium by a single IL cation. This, combined with favorable interfacial properties versus lithium metal, leads to significantly improved performance on lithium‐metal polymer batteries., Ionic liquids (ILs) allow improvement of the ionic conductivity of ternary PEO‐based solid polymer electrolytes. However, the lack of Li‐ion coordination of these plasticizers and the addition of extra ions results in a low Li‐ion conductivity. An oligo(ethylene oxide)‐based IL was synthesized to overcome these limitations and enable additional transport modes, resulting in a high Li‐ion conductivity.

Electrically rechargeable zinc-air batteries attract extensive research interests due to their potentially high energy density and low cost but suffer from chemical instability and poor electrochemical reversibility caused by the corrosive nature of the conventional alkaline electrolyte. Here we demonstrate a non-alkaline zinc acetate electrolyte for electrically rechargeable zinc-air batteries with long-term operation stability (600 hours) in ambient air without any special cell engineering. The unique battery chemistry with reversible formation/decomposition of zinc hydroxyacetate dihydrate is systematically revealed using diversified electrochemical and analytical techniques. Furthermore, the carbon-based air cathode is modified towards a hydrophilic surface to increase the energy efficiency. This work provides new insight on effective electrolyte design to achieve long-term operation zinc-air batteries.

Electrolytes with sparingly polysulfide solubility such as 1.5 M LiTFSI in tetramethylene sulfone (TMS) and 1,1,2,2-tetrafluoroethyl- 2,2,3,3-tetrafluoropropyl ether (TTE) are beneficial for the cycle stability of Li-S pouch cells. In this work, this specific electrolyte system and the role of dissolved polysulfides (PS) in symmetrical Li/Li cells is investigated. By studying varying TMS/TTE volume ratios and polysulfide addition aided by both ex situ and operando spectroscopic as well as microscopic techniques, the positive impact of PS on the lithium plating/ stripping behavior is evaluated. The composition of the solid-electrolyte interphase (SEI) as well as the microscopic morphology differs for electrolytes with PS from those without PS addition. These findings are crucial for the development of electrolytes for cycle-stable Li-S prototype cells.

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., Solid‐state lithium metal batteries (LMBs) are an emerging field of energy storage. The inherent benefits of solid electrolytes, however, are offset by difficulties at the lithium|electrolyte interface. In this study, the often‐overlooked wetting phenomena of widely used polymeric electrolytes (PEs) are discussed and the strong influence of the topography of the lithium metal (Li) surface and the viscoelastic properties of the PEs on the Li|PEs interface are presented.

A novel capillary electrophoresis (CE) method with ultraviolet-visible spectroscopy (UV-Vis) detection for the investigation of dissolved Cu+ and Cu2+ in lithium ion battery (LIB) electrolytes was developed. This method is of relevance, as the current collector at the anode of LIBs may dissolve under certain operation conditions. In order to preserve the actual oxidation states of dissolved copper in the electrolytes and to prevent any precipitation during sample preparation and CE measurements, neocuproine (NC) and ethylenediamine tetraacetic (EDTA) were effectively applied as complexing agents for both ionic copper species. However, precipitation and loss of the Cu+ -NC-complex for quantification occurred in presence of the commonly applied conducting salt lithium hexafluorophosphate (LiPF6 ). Therefore, acetonitrile (ACN) was added to the sample in order to suppress this precipitation. Dissolution experiments with copper-based negative electrode current collectors in a LIB electrolyte were conducted at 60°C under non-oxidizing atmosphere. First findings regarding the copper species via CE revealed dissolved Cu+ and mainly Cu2+ . However, primarily Cu+ dissolved from the passivating oxide layer (Cu2 O and CuO) of the current collector due to the formation of acidic electrolyte decomposition products. Due to the instability of Cu+ in the electrolyte a further disproportionation reaction to Cu0 and Cu2+ occurred. The results show the high potential of this CE method for prospective investigations regarding the current collector stability in new battery electrode formulations and correlations of dissolution events with dissolution mechanisms and battery cell operation conditions.

A capillary electrophoresis (CE) method with ultraviolet/visible (UV-Vis) spectroscopy for iron speciation in lithium ion battery (LIB) electrolytes was developed. The complexation of Fe2+ with 1,10-phenantroline (o-phen) and of Fe3+ with ethylenediamine tetraacetic acid (EDTA) revealed effective stabilization of both iron species during sample preparation and CE measurements. For the investigation of small electrolyte volumes from LIB cells, a sample buffer with optimal sample pH was developed to inhibit precipitation of Fe3+ during complexation of Fe2+ with o-phen. However, the presence of the conducting salt lithium hexafluorophosphate (LiPF6 ) in the electrolyte led to the precipitation of the complex [Fe(o-phen)3 ](PF6 )2 . Addition of acetonitrile (ACN) to the sample successfully re-dissolved this Fe2+ -complex to retain the quantification of both species. Further optimization of the method successfully prevented the oxidation of dissolved Fe2+ with ambient oxygen during sample preparation, by previously stabilizing the sample with HCl or by working under counterflow of argon. Following dissolution experiments with the positive electrode material LiFePO4 (LFP) in LIB electrolytes under dry room conditions at 20°C and 60°C mainly revealed iron dissolution at elevated temperatures due to the formation of acidic electrolyte decomposition products. Despite the primary oxidation state of iron in LFP of +2, both iron species were detected in the electrolytes that derive from oxidation of dissolved Fe2+ by remaining molecular oxygen in the sample vials during the dissolution experiments.

Herein we report on an analytical approach for targeted identification of hazardous 1,3-propane sultone (PS) in spent lithium ion battery material. PS decomposition is investigated with chromatographic techniques coupled to high-resolution accurate mass spectrometry. Speciation of sulfur-containing decomposition products is performed and aging marker molecules are defined. The observed PS decomposition results in characteristic 1-propanesulfonate via electrochemical ring-opening. Based on this, 1-propanesulfonate is defined as an ionic marker molecule for electrochemical PS decomposition. Further, volatile methyl and ethyl esters of 1-propanesulfonate are identified. Their formation is observed mainly caused by elevated temperatures after preceding PS ring-opening during cell formation. Both, ionic and volatile decomposition markers can be applied for targeted identification of hazardous PS-containing lithium ion battery material, despite possible consumption of the initial additive molecule.

Ni-rich layered oxide cathodes are promising candidates to satisfy the increasing energy demand of lithium ion batteries for automotive applications. Aqueous processing of such materials, although being desirable to reduce costs and improve sustainability, remains challenging due to the Li + /H + -exchange upon contact with water, resulting in a pH increase and corrosion of the aluminum current collector. Herein, an example for tuning the properties of aqueous LiNi 0.83 Co 0.12 Mn 0.05 O 2 electrode pastes using a lithium polyacrylate-based binder to find the “sweet spot” for processing parameters and electrochemical performance is given. Polyacrylic acid is partially neutralized to balance high initial capacity, good cycling stability and the prevention of aluminum corrosion. Optimized LiOH/polyacrylic acid ratios in water are identified, showing comparable cycling performance to electrodes processed with polyvinylidene difluoride requiring toxic N-methyl-2-pyrrolidone as solvent. This work gives an exemplary study for tuning aqueous electrode pastes properties aiming towards a more environmentally friendly processing of Ni-rich cathodes.

Rechargeable aqueous zinc batteries (AZBs) have been recognized as attractive energy storage devices because of their intrinsic superiorities, e.g., high safety, low material cost and environmental benignity. However, challenges such as dendrite formation on the surface of Zn anode, poor reversibility of Zn plating/stripping and short circuit of the cell, having detrimental impact on cycle life and safety, hinder their further development. Herein, we design an artificial solid electrolyte interphase (SEI) layer for the Zn anode by coating it with a zinc phytate (ZP) layer via a facile acid-etching approach. Since the ZP layer can guide uniform Zn deposition under the layer without dendrite formation and maintain a smooth interface between separator and electrode, the symmetric cell with a modified Zn electrode exhibits excellent cycling stability and low polarization voltage. Moreover, compared to the full cell employing a bare Zn anode (MnO 2 /carbon nanofibers (CNFs) || Zn), the one with modified Zn anode (MnO 2 /CNFs || ZP-Zn) delivers much better long-term cycling stability with a capacity retention of 80.2% after 1000 cycles a 0.5 A g -1 . The coating via acid etching method offers a practical technique for further development of AZBs.

Herein we report on an analytical study of dry-shredded lithium-ion battery (LIB) materials with unknown composition. Samples from an industrial recycling process were analyzed concerning the elemental composition and (organic) compound speciation. Deep understanding of the base material for LIB recycling was obtained by identification and analysis of transition metal stoichiometry, current collector metals, base electrolyte and electrolyte additive residues, aging marker molecules and polymer binder fingerprints. For reversed engineering purposes, the main electrode and electrolyte chemistries were traced back to pristine materials. Furthermore, possible lifetime application and accompanied aging was evaluated based on target analysis on characteristic molecules described in literature. With this, the reported analytics provided precious information for value estimation of the undefined spent batteries and enabled tailored recycling process deliberations. The comprehensive feedstock characterization shown in this work paves the way for targeted process control in LIB recycling processes.

International audience; This roadmap presents the transformational research ideas proposed by "BATTERY 2030+", the European large-scale research initiative for future battery chemistries. In this paper we outline a "chemistry-neutral" roadmap to advance battery research, particularly at low TRL, with a time horizon of about ten years. The roadmap is centered around six themes: 1) accelerated materials discovery platform, 2) battery interface genome, with the integration of smart functionalities such as 3) sensoring and 4) self-healing processes. Beyond chemistry related aspects we also include crosscutting research regarding 5) manufacturability and 6) recyclability. This roadmap should be seen as an important enabling complement to the many global battery roadmaps which focus on expected ultrahigh battery performance, especially for the future of transports. Batteries are used in many other applications and are considered to be one of Europe's key technologies necessary to reach the climate goals. Currently the market is dominated by lithium-ion batteries, which performs well in most applications, but despite new generations coming in near time, soon will approach their performance limits. Without major breakthroughs, battery performance and production requirements will not be sufficient to enable the building of a climate-neutral society. Through our "chemistry neutral" approach we aim to create a generic toolbox transforming the way we develop and design batteries, which later benefit into the development of specific battery chemistries and technologies. The goal is to integrate modeling and high-through-put experimental results in a closed integrated loop and manage the large amounts of data we generate to learn more about complex processes on different levels affecting the function of a battery cell or a battery system. Based on this we suggest concrete actions with the ambition to be part of and support the implementation of the European Green Deal, the UN Sustainable Development Goals, as well as the European Strategic Action plan on Batteries and the Strategic Energy Technology Plan.

In the quest for ever higher energy and power densities of lithium‐based batteries, numerous functional materials are being utilized, however in many cases their highly reactive nature is likely to increase the risk of danger in case of battery failures. This especially affects the aprotic non‐aqueous organic carbonate‐based electrolyte, still considered as the state‐of‐the‐art (SOTA) and its volatile and highly flammable components. Efforts to identify different forms of flame‐retardants or nonflammable electrolyte solvents/co‐solvents to reduce the risk of fire or explosion are inevitably followed by a trade‐off between the improved safety and deteriorated overall cycling performance of a battery. Here, we report on a smartly tailored, multifunctional nonflammable electrolyte formulation comprising 15.0 wt.% 2‐(2,2,3,3,3‐pentafluoro‐propoxy)‐4‐(trifluormethyl)‐1,3,2‐dioxaphospholane (PFPOEPi‐1CF3), significantly advancing the cycling performance of the NMC111||graphite cells by formation of an effective interphase on/at both anode and cathode and correlate its performance to the 2‐(2,2,3,3,3‐pentafluoropropoxy)‐1,3,2‐dioxaphospholane (PFPOEPi) containing electrolyte counterpart by establishing a strong structure‐reactivity‐performance‐relationship.

A new CE method with ultraviolet-visible detection was developed in this study to investigate manganese dissolution in lithium ion battery electrolytes. The aqueous running buffer based on diphosphate showed excellent stabilization of labile Mn3+ , even under electrophoretic conditions. The method was optimized regarding the concentration of diphosphate and modifier to obtain suitable signals for quantification. Additionally, the finally obtained method was applied on carbonate-based electrolytes samples. Dissolution experiments of the cathode material LiNi0.5 Mn1.5 O4 (lithium nickel manganese oxide [LNMO]) in aqueous diphosphate buffer at defined pH were performed to investigate the effect of a transition metal-ion-scavenger on the oxidation state of dissolved manganese. Quantification of both Mn species revealed the formation of mainly Mn3+ , which can be attributed to a comproportionation reaction of dissolved and complexed Mn2+ with Mn4+ at the surface of the LNMO structure. It was also shown that the formation of Mn3+ increased with lower pH. In contrast, dissolution experiments of LNMO in carbonate-based electrolytes containing LIPF6 showed only dissolution of Mn2+ .

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., Fast charging: Poly(norbornene)s, functionalized with phenothiazine units through either a direct connection or ester linkages, are tested as cathode‐active battery materials. Directly linked poly(3‐norbornylphenothiazine) demonstrates excellent rate capability and cycling stability with a capacity retention of 73 % after 10 000 cycles at a C‐rate of 100 C.

Pre lithiation via electrolysis, herein defined as electrolytic pre lithiation, using cost efficient electrolytes based on lithium chloride LiCl , is successfully demonstrated as a proof of concept for enabling lithium ion battery full cells with high silicon content negative electrodes. An electrolyte for pre lithiation based on amp; 947; butyrolactone and LiCl is optimized using boron containing additives lithium bis oxalato borate, lithium difluoro oxalate borate and CO2 with respect to the formation of a protective solid electrolyte interphase SEI on silicon thin films as model electrodes. Reversible lithiation in Si Li metal cells is demonstrated with Coulombic efficiencies CEff of 95 96 for optimized electrolytes comparable to 1 m LiPF6 EC EMC 3 7. Formation of an effective SEI is shown by cyclic voltammetry and X ray photoelectron spectroscopy XPS . electrolytic pre lithiation experiments show that notable amounts of the gaseous product Cl2 dissolve in the electrolyte leading to a self discharge Cl2 Cl amp; 8722; shuttle mechanism between the electrodes lowering pre lithiation efficiency and causing current collector corrosion. However, no significant degradation of the Si active material and the SEI due to contact with elemental chlorine is found by SEM, impedance, and XPS. In NCM111 Si full cells, the capacity retention in the 100th cycle can be significantly increased from 54 to 78 by electrolytic pre lithiation, compared to reference cells without pre lithiation of Si