Fokko M. Mulder

Electrochemical ammonia oxidation to nitrite using a homogeneous nickel copper hydroxide catalyst with H ₂ recovery at high current density.

Hydrogen evolution is more than a competing reaction in direct toluene hydrogenation. The cathode catalyst layer enables the utilization of electrochemically generated H ₂ for thermochemical hydrogenation.

Fluorination of electrolytes has been a widely used strategy to enable stable cycling in lithium metal batteries. However, a move toward fluorine-free electrolytes is desirable given the safety and environmental concerns surrounding fluorinated materials. Designing these electrolytes requires a comprehensive understanding of bulk electrolyte and interfacial properties in the absence of fluorine, particularly the solvation structures surrounding Li⁺ and the solid electrolyte interface (SEI) composition. Among fluorine-free Li salts, lithium nitrate (LiNO₃) is often used to obtain highly ion-conductive SEI components. However, its poor ion dissociation and rapid consumption upon freshly plated lithium currently hinder its use as the main electrolyte salt. Herein, we show that the modification of Li⁺ inner solvation structures by employing lithium bis(oxalato)borate (LiBOB) as the secondary salt in LiNO₃/diglyme electrolytes synergistically improves both bulk Li⁺ transport and SEI properties. It significantly enhances ion dissociation, which increases the ionic conductivity of the electrolyte despite an increase in its viscosity. Furthermore, the presence of LiBOB-derived outer SEI components over the LiNO₃-derived ion-conductive inner SEI layer results in low-surface-area Li deposits and lower Li⁺/anion consumption during cycling. The dual-salt fluorine-free electrolyte enables stable, long-term cycling in Li/Cu cells for >700 cycles and shows promising capacity retention in Li/LFP full cells at ambient temperature. Our work highlights the importance of tuning the Li⁺ solvation structures for optimizing bulk and interface properties in fluorine-free electrolytes and presents a viable pathway toward the development of greener electrolytes for lithium metal batteries.

The emerging area and challenges of electrochemical nitrogen oxide formation from dinitrogen and ammonia are reviewed.

The Li-mediated nitrogen reduction reaction (Li-NRR) has been proposed as one of the most promising ambient production routes for green ammonia. However, the effect of the applied potential ( E _we ) on the reaction performance and the properties of the solid electrolyte interphase (SEI) remain poorly understood. Herein, we combine potential controlled experiments using a reliable Li _x FePO ₄ based reference electrode with post-mortem SEI characterization techniques, wherein we observe both an increase in the LiF concentration in the SEI, originating from LiTFSI decomposition, and the Faradaic efficiency (FE _NH3 ) with an increasing E _we . The transition from a predominantly organic SEI at low E _we (−3.2 V _SHE ) to a LiF-enriched layer at higher E _we indicates the existence of kinetic barriers for the SEI formation reactions. Moreover, thicker and denser SEI structures observed at a higher E _we enhance the Li-NRR by improving the mass transport regulation between reactant species. However, these thicker and denser SEI morphologies lead to current instabilities due to dynamic SEI thickening and breakdown.

A physics-based network model of primary particles, informed by tomography, predicts LiFePO ₄ electrode behavior across conditions without empirical tuning, bridging particle-scale physics to cell performance.

Current commercial battery designs contain fluorinated materials as binders and electrolyte salts to ensure high electrochemical and thermal stability. Upcoming regulations in Europe and the US restrict the manufacturing of such materials, as their persistence in drinking water and soil can cause long‐term ecological harm. In this perspective, a completely fluorine‐free battery design that has similar performance compared to commercial standards, while using aqueously processed LiNi _0.8 Mn _0.1 Co _0.1 O ₂ (NMC811) and graphite as cathode and anode active materials, respectively, is showcased. The cell shows 98% retained capacity after 600 cycles at room temperature, indicating good stability of active material with nonfluorinated binders. The charge rate performance (69% retained capacity at 1C, 1.5 mAh cm ⁻² ) can be improved by combining two fluorine‐free salts (67% retained capacity at 1C with 2.5 times the loading, 3.3 mAh cm ⁻² ). This work illustrates that fluorine‐free cell designs show good battery performance over a wide potential window.

Predicting lithium-ion battery behavior is critical for advancing next-generation energy storage. Conventional Doyle–Fuller–Newman models can simulate many materials, but they fail in phase-separating single-crystal systems, such as lithium iron phosphate (LiFePO4), where the electrical connectivity of primary particles limits charge transport. We redefine the electrode as a network of reactive primary particles, each governed by validated electrochemical kinetics and interconnected through tomographic-informed contact resistances. Without empirical tuning, the model predicts voltage responses of LiFePO4 electrodes across temperatures, rates, loadings, and dynamic load conditions using a single fitted physical parameter. It also captures and explains charge-discharge asymmetries and hysteresis. By bridging particle-scale physics up to cell-level performance, while retaining computational efficiency, this physics-based framework provides a foundation for the design, and control of single-crystal electrode systems.