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Based on the LiNi0.6Co0.2Mn0.2O2 cathode (NCM622), this work confirmed the occurrence of H+ intercalation upon charging in hybrid electrolyte, which is dramatically severe at high de-lithiated states.

The direct correlation between the surface area of the current collector (CC) and the ‘dead Li’ is evaluated in this study.

Energy technology (2022). doi:10.1002/ente.202201239, Published by Wiley-VCH, Weinheim [u.a.]

Aqueous processing of Ni rich layered oxide cathode materials is a promising approach to simultaneously decrease electrode manufacturing costs, while bringing environmental benefits by substituting the state of the art often toxic and costly organic processing solvents. However, an aqueous environment remains challenging due to the high reactivity of Ni rich layered oxides towards moisture, leading to lithium leaching and Al current collector corrosion because of the resulting high pH value of the aqueous electrode paste. Herein, a facile method was developed to enable aqueous processing of LiNi0.8Co0.1Mn0.1O2 NCM811 by the addition of lithium sulfate Li2SO4 during electrode paste dispersion. The aqueously processed electrodes retained 80 amp; 8201; of their initial capacity after 400 cycles in NCM811 graphite full cells, while electrodes processed without the addition of Li2SO4 reached 80 amp; 8201; of their capacity after only 200 cycles. Furthermore, with regard to electrochemical performance, aqueously processed electrodes using carbon coated Al current collector outperformed reference electrodes based on state of the art production processes involving N methyl 2 pyrrolidone as processing solvent and fluorinated binders. The positive impact on cycle life by the addition of Li2SO4 stemmed from a formed sulfate coating as well as different surface species, protecting the NCM811 surface against degradation. Results reported herein open a new avenue for the processing of Ni rich NCM electrodes using more sustainable aqueous routes

Low cost and environmentally friendly production of graphite anodes from naturally available biomass resources is of great importance to satisfy the increasing material demand for lithium ion batteries. Herein, graphitization of coffee ground was performed using four different iron-based activating additives, including iron (III) chloride, iron (III) nitrate, iron (III) oxide and pure iron, following either a wet or a dry mixing approach. The structural development regarding the type of activator used and the impact on the corresponding electrochemical performance are systematically investigated. A maximum degree of graphitization between 55 and 74 % (as determined by Raman spectroscopy) is attained using iron (III) chloride and iron powder, respectively. The graphitic anode material synthesized using iron powder reached a maximum reversible capacity of ≈320 mAh g−1 at a rate of 0.1 C. This study provides significant insights into the impact of activators on the design of synthetic graphite from renewable sources. Ministry of Economic Affairs, Innovation, Digitalization and Energy of the State of North Rhine-Westphalia 313-W044A Junta de Andalucía P20-01186, US-1380856 Ministerio de Ciencia e Innovación PID2019-107019RB-I00

Lithium alloying materials are promising candidates to replace the current intercalation-type graphite negative electrode materials in lithium-ion batteries (LIBs) due to their high specific capacity and relatively low cost. Here, we investigate the electrochemical performance of TiSnSb regarding its charge/discharge cycling stability as a negative electrode material in LIB cells. To assess a more practical performance with respect to a limited active lithium content in LIB full-cells, we evaluate the impact of pre-lithiation for TiSnSb with respect to the cycling stability in a NCM111||TiSnSb cell setup. The observation of the individual electrode potentials reveals comprehensive insights into the ongoing cell chemistry, showing that clear performance improvements can be achieved via pre-lithiation. Furthermore, the lithiation mechanism of TiSnSb is systematically studied via ex situ7Li magic-angle spinning (MAS) nuclear magnetic resonance (NMR), ex situ X-ray diffraction, and static ex situ119Sn wideband uniform rate smooth truncation Carr–Purcell Meiboom–Gill (CPMG) WCPMG NMR experiments. For comprehensive references regarding the isotropic 7Li shift of the Li–Sb intermetallic phases, all thermodynamically stable Li–Sb intermetallics of the binary Li–Sb systems have been synthesized and subsequently characterized by 7Li MAS NMR. Combined, our measurements for lithiated TiSnSb do not give any evidence for the formation of Li–Sn and Li–Sb intermetallics related to crystalline bulk phases (Li7Sn3, Li7Sn2, Li3Sb, and Li2Sb) as has been previously reported. In contrast, unique insights obtained from static ex situ119Sn WCPMG NMR and ex situ XRD measurements reveal the formation of ternary Li–Sb–Sn species during lithiation, which can be assigned to the intermetallic phase Li2.8SbSn0.2. Additionally, the 7Li MAS NMR measurements combined with the observed discharge capacity reveal a second Li species, which we assign to an amorphous Li–Sn phase.

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.

The energy density of lithium-ion batteries (LIBs) can be meaningfully increased by utilizing Si-on-graphite composites (Si@Gr) as anode materials, because of several advantages, including higher specific capacity and low cost. However, long cycling stability is a key challenge for commercializing these composites. In this study, to solve this issue, we have developed a multifunctional polymeric artificial solid-electrolyte interphase (A-SEI) protective layer on carbon-coated Si@Gr anode particles (making Si@Gr/C-SCS) to prolong the cycling stability in LIBs. The coating is made of sulfonated chitosan (SCS) that is crosslinked with glutaraldehyde promoting good ionic conduction together with sufficient mechanical strength of the A-SEI. The focused ion beam-scanning electron microscopy and high-resolution transmission electron microscopy images show that the SCS is uniformly coated on the composite particles with thickness in nanometer. The anodes are investigated in Li metal cells Si@Gr/C-SCS||Li metal) and lithium-ion full-cells (LiNi

We report the performance of a conversion-type magnetite-decorated partially reduced graphene oxide (Fe

MXenes, as an emerging class of 2D materials, display distinctive physical and chemical properties, which are highly suitable for high-power battery applications, such as lithium ion batteries (LIBs). Ti3C2Tx (Tx = O, OH, F, Cl) is one of the most investigated MXenes to this day; however, most scientific research studies only focus on the design of multilayered or monolayer MXenes. Here, we present a comprehensive study on the synthesis of few-layered Ti3C2Tx materials and their use in LIB cells, in particular for high-rate applications. The synthesized Ti3C2Tx MXenes are characterized via complementary XRD, Raman spectroscopy, XPS, EDX, SEM, TGA, and nitrogen adsorption techniques to clarify the structural and chemical changes, especially regarding the surface groups and intercalated cations/water molecules. The structural changes are correlated with respect to the acidic and basic post-treatment of Ti3C2Tx. Furthermore, the detected alterations are put into an electrochemical perspective via galvanostatic and potentiostatic investigations to study the pseudocapacitive behavior of few-layered Ti3C2Tx, exhibiting a stable capacity of 155 mAh g–1 for 1000 cycles at 5 A g–1. The acidic treatment of Ti3C2Tx synthesized via the in situ formation of HF through LiF/HCl is able to increase the initial capacity in comparison to the pristine or basic treatment. To gain further insights into the structural changes occurring during (de)lithiation, in situ XRD is applied for LIB cells in a voltage range from 0.01 to 3 V to give fundamental mechanistic insights into the structural changes occurring during the first cycles. Thereby, the increased initial capacity observed for acidic-treated MXenes can be explained by the reduced co-intercalation of solvent molecules.

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.

Because of their high specific capacity and rather low operating potential, silicon-based negative electrode materials for lithium-ion batteries have been the subject of extensive research over the past 2 decades. Although the understanding of the (de)lithiation behavior of silicon has significantly increased, several major challenges have not been solved yet, hindering its broad commercial application. One major issue is the low initial Coulombic efficiency and the ever-present self-discharge of silicon electrodes. Self-discharge itself affects the long-term stability of electrochemical storage systems and, additionally, must be taken into consideration for inevitable prelithiation approaches. The impact of the crystalline Li15Si4 phase is of great interest as the phase transformation between crystalline (c) and amorphous (a) phases not only increases the specific surface area but also causes huge polarization. Moreover, there is the possibility for electrochemical over-lithiation toward the Li15+aSi4 phase because of the electron-deficient Li15Si4 phase, which can be highly reactive toward the electrolyte. This poses the question about the impact of the c-Li15Si4 phase on the self-discharge behavior in comparison to its amorphous counterpart. Here, silicon thin films used as model electrodes are lithiated to cut-off potentials of 10 mV and 50 mV versus Li|Li+ (U10mV and U50mV) in order to systematically investigate their self-discharge mechanism via open-circuit potential (UOCP) measurements and to visualize the solid electrolyte interphase (SEI) growth by means of scanning electrochemical microscopy. We show that the c-Li15Si4 phase is formed for the U10mV electrode, while it is not found for the U50mV electrode. In turn, the U50mV electrode displays an almost linear self-discharge behavior, whereas the U10mV electrode reaches a UOCP plateau at ca. 380 mV versus Li|Li+, which is due to the phase transition from c-Li15Si4 to the a-LixSi phase. At this plateau potential, the phase transformation at the Si|electrolyte interface results in an electronically more insulating and more uniform SEI (U10mV electrode), while the U50mV electrode displays a less uniform SEI layer. In summary, the self-discharge mechanism of silicon electrodes and, hence, the irreversible decomposition of the electrolyte and the corresponding SEI formation process heavily depend on the structural nature of the underlying lithium-silicon phase.

New anode materials beyond graphite are needed to improve the performance of lithium ion batteries (LIBs). Chemical doping with nitrogen has emerged as a simple strategy for enhancing lithium storage in carbon-based anodes. While specific capacity and rate capability are improved by doping, little is known about other key electrochemical properties relevant to practical applications. This work presents a systematic evaluation of electrochemical characteristics of nitrogen-doped carbons derived from a biomass source and urea powder as anodes in LIB half- and full-cells. Results show that doped carbons suffer from a continuous loss in capacity upon cycling that is more severe for higher nitrogen contents. Nitrogen negatively impacts the voltage and energy efficiencies at low charge/discharge current densities. However, as the charge/discharge rate increases, the voltage and energy efficiencies of the doped carbons outperform the non-doped ones. We provide insights towards a fundamental understanding of the requirements needed for practical applications and reveal drawbacks to be overcome by novel doped carbon-based anode materials in LIB applications. With this work, we also want to encourage other researchers to evaluate electrochemical characteristics besides capacity and cycling stability which are mandatory to assess the practicality of novel materials. Ministerio de Economía y Competitividad MAT2016-76526-R Ministerium fur Wirtschaft, Innovation, Digitalisierung und Energie des Landes Nordrhein-Westfalen 313-W044A

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.

High-voltage Li ion batteries are compromised by lower cycle life due to enhanced degradation of cathode material, e.g. NCM523. Crucial part is the initiated electrode crosstalk, i.e. transition metal (TM) dissolution from the cathode and subsequent deposition on the anode, as it forces formation of high surface area lithium, capacity losses and risk of Li dendrite penetration, finally leading to an abrupt end-of-life (= rollover failure). Hence, suppression of this failure cascade is the pivotal strategy to prolong cycle life. A pragmatic approach is the electrolyte manipulation towards formation/presence of fluorophosphates, as they effectively suppress electrode crosstalk via TM scavenging. Either, they can be intrinsically formed, e.g. via elimination of ethylene carbonate (EC) solvent (= EC-free electrolyte), or simply externally added, e.g. via (good-soluble) lithium difluorophosphate electrolyte additive. Their effectiveness is demonstrated for conventional EC-based and EC-free electrolytes at limiting conditions (4.5 and 4.6 V, respectively). In parallel to supportive approach combinations ( e.g. coating), also destructive combinations are highlighted, i.e. approaches, which even decrease the fluorophosphate content, e.g. vinylene carbonate additive in EC-free electrolytes. Finally, by demonstrating the value of (concentration-optimized) fluorophosphates, appropriate benchmark electrolyte formulations for high-voltage LIBs are discussed.

In this work, a cell concept comprising of an anion intercalating graphite-based positive electrode (cathode) and an elemental sulfur-based negative electrode (anode) is presented as a transition metal- and in a specific concept even Li-free cell setup using a Li-ion containing electrolyte or a Mg-ion containing electrolyte. The cell achieves discharge capacities of up to 37 mAh g−1 and average discharge cell voltages of up to 1.9 V. With this setup, more than 100 cycles with a high capacity retention (> 90% of the highest achieved value) and Coulombic efficiencies up to 95% could be achieved, which opens a broad new field for energy storage approaches.

Lithium-rich disordered rocksalts (DRX) are a promising class of cathode materials for high-energy lithium ion batteries (LIBs) and lithium metal batteries (LMBs) due to the high initial specific capacities (>200 mAh g−1) as well as flexible chemical composition. However, challenges concerning severe capacity fade and voltage decay upon cycling at high cut-off voltages are still to be overcome. Moreover, state-of-the-art carbonate-based electrolytes can be decomposed by reactive oxygen species released by DRX materials during cycling. In this work, the electrochemical performance of Li1.25Fe0.5Nb0.25O2 (LFNO) || Li LMB and LFNO || graphite LIB cells is compared for a conventional, carbonate-based electrolyte and the solvate ionic liquid (SIL) [Li(G3)][TFSI] (G3: triethyleneglycoldimethylether). Cycle life is notably improved by the chemically more stable ionic liquid electrolyte, as the anionic redox activity of LFNO is prolonged compared to the carbonate-based cells. This work represents an important step toward an improved cycle life of DRX cathodes.

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.

Silicon (Si) is one of the most promising anode candidates to further push the energy density of lithium ion batteries. However, its practical usage is still hindered by parasitic side reactions including electrolyte decomposition and continuous breakage and (re-)formation of the solid electrolyte interphase (SEI), leading to consumption of active lithium. Pre-lithiation is considered a highly appealing technique to compensate for active lithium losses. A critical parameter for a successful pre-lithiation strategy by means of Li metal is to achieve lithiation of the active material/composite anode at the most uniform lateral and in-depth distribution possible. Despite extensive exploration of various pre-lithiation techniques, controlling the lithium amount precisely while keeping a homogeneous lithium distribution remains challenging. Here, the thermal evaporation of Li metal as a novel pre-lithiation technique for pure Si anodes that allows both, that is, precise control of the degree of pre-lithiation and a homogeneous Li deposition at the surface is reported. Li nucleation, mechanical cracking, and the ongoing phase changes are thoroughly evaluated. The terms dry-state and wet-state pre-lithiation (without/with electrolyte) are revisited. Finally, a series of electrochemical methods are performed to allow a direct correlation of pre-SEI formation with the electrochemical performance of pre-lithiated Si.

Dual-graphite batteries (DGBs), which are based on anion intercalation into graphite positive electrodes, exhibit great potential for stationary energy storage due to use of more sustainable and low-cost electrode materials and processing routes. Binary-mixed highly concentrated electrolytes (HCEs) appeal highly suitable for the high operating voltages of DGBs, although the lack of sufficient insights into the formation of graphite intercalation compounds (GICs) limits the cell performance in terms of specific capacity and lifetime so far. Herein, anion intercalation from single-salt HCEs (LiPF6 and LiBF4) and an equimolar binary mixture of LiPF6/LiBF4 are studied in graphite || Li metal cells, revealing an improved performance in terms of specific capacity and Coulombic efficiency in the order LiPF6 > LiPF6/LiBF4 > LiBF4. LiBF4-based cells exhibit an increased onset potential for anion intercalation and higher area specific impedance, suggesting an ineffective interphase formation at graphite. X-ray diffraction reveals GIC formation, while a lower stage number is achieved for the LiBF4-based HCE. 19F MAS NMR spectroscopy analysis at various states-of-charge confirms no significant charge transfer between the intercalated anions and the graphite host and suggest preferred intercalation of PF6- compared to BF4- as well as a high translational and/or rotational mobility of the intercalated anions.

Ni-rich layered oxide cathodes are promising candidates to satisfy the increasing energy demand of lithium-ion batteries for automotive applications. Thermal and cycling stability issues originating from increasing Ni contents are addressed by mitigation strategies such as elemental bulk substitution ("doping") and surface coating. Although both approaches separately benefit the cycling stability, there are only few reports investigating the combination of two of such approaches. Herein, the combination of Zr as common dopant in commercial materials with effective Li2 WO4 and WO3 coatings was investigated with special focus on the impact of different material processing conditions on structural parameters and electrochemical performance in nickel-cobalt-manganese (NCM) || graphite cells. Results indicated that the Zr4+ dopant diffusing to the surface during annealing improved the electrochemical performance compared to samples without additional coatings. This work emphasizes the importance to not only investigate the effect of individual dopants or coatings but also the influences between both.

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