Silicon/graphite (Si/Gr) composites, promising high-capacity anodes for next-generation lithium-ion batteries, suffer from instability due to silicon's large volume expansion and deleterious interfacial degradation. This work introduces a synergistic composite coating of poly(vinylidene fluoride) (PVDF) and magnesium oxide (MgO) nanoparticles, applied via facile immersion to Si/Gr electrodes, to stabilize the electrode structure and the critical electrode-electrolyte interface. Compared to pristine and PVDF-only controls, the PVDF-MgO coating significantly enhanced long-term cycling, achieving over 760 cycles with 77 % capacity retention, high Coulombic efficiencies (>99.9 %), and improved rate capability. Post-mortem analysis confirmed the PVDF-MgO coatings preserved electrode integrity, dramatically suppressing thickness expansion (from similar to 137 % for pristine to similar to 49 % for optimized PVDF-MgO) after hundreds of cycles. Significantly, the PVDF-MgO coating suppressed lithium dendrite formation under high-rate (5C) and capacity-driven (20 % over-lithiation) conditions, promoting uniform, non-dendritic Li deposition. This suppression is attributed primarily to MgO's beneficial lithiophilicity and Lewis acid-base characteristics guiding Li nucleation and homogenizing ion flux, enabled by the composite structure. Crucially, the processing sequence was found to be paramount; applying the coating before electrode calendering, rather than after, unlocks the material's full potential and yields optimal performance. This discovery of a non-obvious process-structure-property relationship, where process engineering dictates interfacial stability, establishes the synergistic PVDF-MgO composite coating as an effective, scalable strategy for enhancing the durability, efficiency, and safety of high-energy Si/Gr anodes.

Fumed alumina from the combustion of AlCl3 produced nano particles with specific areas from 30 to 220 m2 g-1 (BET) which were characterized by powder X-ray diffraction, 27Al solid-state NMR and transmission electron microscopy. During the short-lived synthesis, highly disordered gamma-alumina progressively transforms into a mixture of delta and theta-alumina. For the gamma-alumina particles, only for particles with the highest specific area a significant amount of five-coordinated Al can be found which is only partially located in the particle surface. Water can be bound reversibly and increases the coordination number of aluminium atoms in the particle surface. For the well-crystallized mixture of delta and theta-alumina, high resolution and high S/N powder XRD pattern features a large number of superstructure reflections along with the commonly observed diffuse reflections. 27Al MQMAS NMR provides a total of 8 crystallographic sites with an unusually high resolution in the tetrahedral region, with 4 distinct AlO4 sites pertaining to the delta phase alone. The results suggest that the delta-alumina phase produced in this process can be described as an ordered structure. Fumed alumina from the combustion of AlCl3 produced nano particles with specific areas from 30 to 220 m2 g-1 (BET) which were characterized by powder X-ray diffraction, 27Al solid-state NMR and transmission electron microscopy.

Powder X-ray diffraction, 27Al solid-state NMR and TEM were used to study the structure and phase transformations in a series of transition alumina materials with BET surface areas ranging from 220 to 30 m2/g produced by gas-to-particle flame method. During the short-lived synthesis, highly disordered γ-alumina progressively transforms into a mixture of δ and θ-alumina. For the well-crystallized mixture of δ and θ-alumina, high resolution and high S/N powder XRD pattern features a large number of superstructure reflections along with the commonly observed diffuse reflections. 27Al MQMAS NMR provides a total of 8 crystallographic sites with an unusually high resolution in the tetrahedral region, with 4 distinct AlO 4 sites pertaining to the δ phase alone. We propose here based on data acquired on high-quality δ and θ-alumina that the bulk structures of both phases must be ordered.

Due to their high theoretical energy densities and superior safety, thiophosphate‐based all‐solid‐state batteries (ASSBs) are considered as promising power source for electric vehicles. However, for large‐scale industrial applications, interfacial degradation between high‐voltage cathode active materials (CAMs) and solid‐state electrolytes (SSEs) needs to be overcome with a simple, cost‐effective solution. Surface coatings, which prevent the direct physical contact between CAM and SSE and in turn stabilize the interface, are considered as promising approach to solve this issue. In this work, an Al 2 O 3 /LiAlO 2 coating for Li(Ni 0.70 Co 0.15 Mn 0.15 )O 2 (NCM) is tested for ASSBs. The coating is obtained from a recently developed dry coating process followed by post‐annealing at 600 °C. Structural characterization reveals that the heat treatment results in the formation of a dense Al 2 O 3 /LiAlO 2 coating layer. Electrochemical evaluations confirm that the annealing‐induced structural changes are beneficial for ASSB. Cells containing Al 2 O 3 /LiAlO 2 ‐coated NCM show a significant improvement of the rate capability and long‐term cycling performance compared to those assembled from Al 2 O 3 ‐coated and uncoated cathodes. Moreover, electrochemical impedance spectroscopy analysis shows a decreased cell impedance after cycling indicating a reduced interfacial degradation for the Al 2 O 3 /LiAlO 2 ‐coated electrode. The results highlight a promising low‐cost and scalable CAM coating process, enabling large‐scale cathode coating for next‐generation ASSBs.

Al2O3/LiAlO2 Coating for Thiophosphate-Based All-Solid-State Batteries In article number 2101428, Rajendra S. Negi, Ruijun Pan, Anja Henss, Matthias T. Elm, and co-workers demonstrate the beneficial effect of a high-temperature treatment on several structural properties of dry-processed Al2O3 cathode coatings, such as reduced porosity and improved interfacial contact between cathode active material and solid electrolyte, which improves the electrochemical performance of thiophosphate-based all-solid-state batteries. Cover design by Elisa Monte.

Applying a thin film coating is a vital strategy to enhance long term and interface stability of Ni-rich layered oxide cathode materials (NRLOs), especially when they are matched with sulfidic solid electrolytes (SSEs) in solid-state batteries (SSBs). The coating prevents direct contact between the cathode active material (CAM) and the SSE, shielding against parasitic side reactions at the cathode electrolyte interface (CEI). Conventional coatings are based on wet-chemical methods and therefore harmful to the environment and require long-lasting processing and high costs. In this study, we present a versatile, facile and highly-scalable dry-coating method (with suitable equipment up to 500 kg per batch) successfully employed for both multi- and single-crystalline LiNi0.70Mn0.15Co0.15O2 (NCM70) particles by fumed Li2ZrO3 nanostructured particles (LZONPs) via high intensity mixing process. The resulting porous coating layer stays firmly attached at the CAM particle surface without a need of post-calcination step at elevated temperatures. The electrochemical testing results signify enhanced rate capability up to 1.5 mA cm(-2) for both particle types and cyclic stability up to 650 cycles with a capacity retention of 86.1 % for single-crystalline NCM70. We attribute the enhanced performance to the reduced CEI reactions as cathodic charge transfer resistance depressed significantly after dry-coating by LZONPs, being an important step towards sulfidic solid-state batteries.

Considering the high theoretical energy density and improved safety, thiophosphate-based all-solid-state batteries (ASSBs) have become one of the most promising candidates for next-generation energy storage systems. However, the intrinsic electrochemical instability of thiophosphate-based solid electrolytes in contact with oxide-based cathodes results in rapid capacity fading and has driven the need of protective cathode coatings. In this work, for the first time, a fumed lithium titanate (LTO) powder-based coating has been applied to Ni-rich oxide-based cathode active material (CAM) using a newly developed dry-coating process. The LTO cathode coating has been tested in thiophosphate-based ASSBs. It exhibits a significantly improved C-rate performance along with superior long-term cycling stability. The improved electrochemical performance is attributed to a reduced interfacial resistance between coated cathode and solid electrolyte as deduced from in-depth electrochemical impedance spectroscopy analysis. These results open up a new, facile dry-coating route to fabricate effective protective CAM coatings to enable long-life ASSBs. This nondestructive coating process with no post-heat-treatment approach is expected to simplify the coating process for a wide range of coatings and cathode materials, resulting in much improved cathode/electrolyte interfacial stability and electrochemical performance of ASSBs.