For battery architectures that need a solid ion conductor with good contacting performance and high stability against electrochemical oxidation, polymerized ionic liquids (PIL) pose a valuable class of materials. The low conductivity of the binary PIL/ lithium salt system can be increased using a ternary ionic liquid acting as plasticiser. The conductive mechanism of the ternary system is however not fully understood. This work shows the shift in conduction mechanism for the ternary Li−/[1,3]PYR-/PDADMA-FSI system by increasing the lithium salt concentration and comparing the transfer mechanism to binary ionic liquid (IL) electrolyte analogues using pulsed field gradient (PFG) nuclear magnetic resonance (NMR), NMR relaxometry, Raman spectroscopy and electrochemical techniques. Two conducting regimes were found which show a strong trade-off between conductivity and transference number. In the low lithium salt regime (≤35 wt% LiFSI), cluster diffusion of aggregated lithium is the dominating mechanism leading to low transference numbers (0.04–0.15 at room temperature (RT)). The high salt regime (≥50 wt% LiFSI) shows diffusion through free lithium ion hopping transfer, which has a stronger dependence on temperature and yields higher transference numbers (0.31 at RT). Increasing lithium salt concentration shows an inverse linear correlation with conductivity. The electrochemical characteristics of ternary IL/PIL/lithium salt are shown to be highly tuneable by varying the lithium salt fraction, while it maintains excellent characteristics like processability, stability and mechanical function.

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Energy storage technologies are critical to the global energy transition, given the need to reduce carbon emissions and the ever-increasing demand for energy. The need for energy storage is particularly crucial in the automotive and electricity generation sectors, where a shift from fossil fuels to renewable sources is imperative. Lithium-ion batteries are central contributors to this transition, powering electric vehicles (EVs) and supporting renewable energy integration into electricity grids. Historically, lithium-ion batteries evolved from using Li metal as a negative electrode to safer alternatives like graphite, and positive electrode materials such as LiNi0.8Mn0.1Co0.1O2 (NMC811) and LiFePO4 (LFP). However, despite these advancements, several challenges still need to be addressed.
First, increasing the energy density of lithium-ion batteries is a priority, particularly for EVs, where higher energy densities can extend the driving range and improve market adoption. Feasible solutions in this regard could be increasing the thickness of electrodes and switching to higher energy density materials such as Li metal. Second, safety remains a key concern, as current batteries use liquid electrolytes that are prone to thermal runaway, leading to fires or explosions. Solid-state electrolytes offer a safer alternative with higher thermal stability. However, they also present their own challenges at the electrode/electrolyte interfaces. Third, there is a growing emphasis on developing environmentally friendly batteries, as many of the materials and manufacturing processes for current lithium-ion batteries are not sustainable. Efforts are being made to eliminate fluorinated compounds and other toxic components from batteries, but this needs to be done without compromising performance. The optimization of the electrode-electrolyte interfaces in batteries holds the key to enabling batteries of the future. Optimizing Li morphology during plating/stripping, improving interfacial stability, and ensuring sufficient ion and electron percolation in cathode composites are key to improving battery capacity, lifetime, safety, and efficiency. @en

Sulfide-based solid-state batteries (SSBs) are emerging as a top contender for next-generation rechargeable batteries with improved safety and higher energy densities. However, SSBs with Ni-rich cathode materials such as LiNi0.82Mn0.07Co0.11O2 (NMC82) exhibit several chemomechanical challenges at the cathode–electrolyte interface, such as contact loss and solid-electrolyte decomposition, resulting in poor interfacial Li+ ion transport. To overcome these challenges, we used polymerized ionic liquids (PIL) as coatings at the NMC82 cathode surface, with and without incorporating a lithium salt. The thin Li+ ion-conductive Li–PIL nanocoating shows excellent compatibility with sulfide solid electrolytes and enables efficient Li+ transfer over the cathode–solid electrolyte interface, as demonstrated by 2D solid-state exchange NMR. It also improves contact retention between the cathode–solid electrolyte particles and mitigates electrolyte oxidation-induced degradation. This is reflected in the electrochemical performance of coated NMC82 in sulfide SSBs, where both a higher rate performance (190 mA h g−1 vs. 163 mA h g−1 for uncoated at 0.1C) and a remarkable capacity retention of 82.7% after 500 cycles at 0.2C and ambient conditions (20 °C) are observed. These results emphasize the effectiveness of PILs with Li salts as multifunctional coatings that enable high-performance sulfide-based SSBs with Ni-rich cathode materials at ambient temperature.@en

Solid-state batteries with lithium metal anodes are considered the next major technology leap with respect to today’s lithium-ion batteries, as they promise a significant increase in energy density. Expectations for solid-state batteries from the automotive and aviation sectors are high, but their implementation in industrial production remains challenging. Here, we report a solid-state lithium–metal battery enabled by a polymer electrolyte consisting of a poly(DMADAFSI) cationic polymer and LiFSI in Pyr13FSI as plasticizer. The polymer electrolyte is infiltrated and solidified in the pores of a commercial LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode with up to 2.8 mAh cm–2 nominal areal capacity and in the pores of a 25 μm thin commercial polypropylene separator. Cathode and separator are finally laminated into a cell in combination with a commercial 20 μm thin lithium metal anode. Our demonstration of a solid-state polymer battery cycling at full nominal capacity employing exclusively commercially available components available at industrial scale represents a critical step forward toward the commercialization of a competitive all-solid-state battery technology.@en

Increasing the electrode thickness, thereby reducing the proportion of inactive cell components, is one way to achieve higher-energy-density lithium-ion batteries. This, however, results in higher electronic and ionic overpotentials and/or mechanical failure induced by binder migration. Here, we report ethanol-induced phase inversion as an effective method for making high-mass-loading nickel-rich, layered oxide (LiNi0.8Mn0.1Co0.1O2 [NMC811]) electrodes. The ethanol-induced phase inversion electrodes significantly outperform their conventionally processed counterparts with similar loading (35 mg/cm2) and porosity (30%) in Li/NMC half-cells (131.7 mAh/g vs. 56.7 mAh/g) at 1C (7 mA/cm2) discharge. The binder structure induced by the nonsolvent improves the pore connectivity and results in lower tortuosity factors. The rapid solvent removal reduces the binder migration during drying, enabling ultrahigh active mass loadings up to 60 mg/cm2 (12 mAh/cm2). Further, the compatibility of the phase inversion process with current roll-to-roll coating setups makes this a processing technique with high industrial feasibility.@en

High energy density electrochemical systems such as metal batteries suffer from uncontrollable dendrite growth on cycling, which can severely compromise battery safety and longevity. This originates from the thermodynamic preference of metal nucleation on electrode surfaces, where obtaining the crucial information on metal deposits in terms of crystal orientation, plated volume, and growth rate is very challenging. In situ liquid phase transmission electron microscopy (LPTEM) is a promising technique to visualize and understand electrodeposition processes, however a detailed quantification of which presents significant difficulties. Here by performing Zn electroplating and analyzing the data via basic image processing, this work not only sheds new light on the dendrite growth mechanism but also demonstrates a workflow showcasing how dendritic deposition can be visualized with volumetric and growth rate information. These results along with additionally corroborated 4D STEM analysis take steps to access information on the crystallographic orientation of the grown Zn nucleates and toward live quantification of in situ electrodeposition processes.

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Hydrogen permeable electrodes can be utilized for electrolytic ammonia synthesis from dinitrogen, water, and renewable electricity under ambient conditions, providing a promising route toward sustainable ammonia. The understanding of the interactions of adsorbing N and permeating H at the catalytic interface is a critical step toward the optimization of this NH3 synthesis process. In this study, we conducted a unique in situ near ambient pressure X-ray photoelectron spectroscopy experiment to investigate the solid-gas interface of a Ni hydrogen permeable electrode under conditions relevant for ammonia synthesis. Here, we show that the formation of a Ni oxide surface layer blocks the chemisorption of gaseous dinitrogen. However, the Ni 2p and O 1s XPS spectra reveal that electrochemically driven permeating atomic hydrogen effectively reduces the Ni surface at ambient temperature, while H2 does not. Nitrogen gas chemisorbs on the generated metallic sites, followed by hydrogenation via permeating H, as adsorbed N and NH3 are found on the Ni surface. Our findings suggest that the first hydrogenation step to NH and the NH3 desorption might be limiting under the operating conditions. The study was then extended to Fe and Ru surfaces. The formation of surface oxide and nitride species on iron blocks the H permeation and prevents the reaction to advance; while on ruthenium, the stronger Ru-N bond might favor the recombination of permeating hydrogen to H2 over the hydrogenation of adsorbed nitrogen. This work provides insightful results to aid the rational design of efficient electrolytic NH3 synthesis processes based on but not limited to hydrogen permeable electrodes.

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Nanostructured solid composite electrolyte or nano-SCE, which is composed of an ionic liquid, nanoporous silica, and residuals of immobilized precursor components, shows promising synergistic properties. The ionic conductivity of nano-SCE is in the range of 2–5 mS cm⁻¹, which exceeds the bulk ionic liquid conductivity at ambient temperature, while maintaining characteristics of a solid electrolyte such as having no leakage issues as the ionic liquid is confined, and lower flammability compared to conventional liquid electrolytes. In this study, the underlying mechanism of enhanced conductivity is investigated by using magic angle spinning NMR and NMR relaxometry analysis. Water, one of the volatile precursor molecules has shown to play a key role in the final conductivity and stability at the solid-electrolyte interface, as it enhances the temperature range in which the ionic liquid remains mobile. In line with previous studies, water with lowered mobility is found in the silicon matrix. The activation energies of lithium ion transfer probed by NMR relaxometry, however, do not change as function of water content. The increase in bulk mobility of lithium ions under ambient conditions compared to water-less nano-SCE is found to be the origin of the altered conductivity of this material.

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