Joaquín Ramírez Rico

In situ TEM and synchrotron SAXS/WAXS show that FeCl₃ as a catalyst precursor results in considerably faster graphitization of cellulose than Fe(NO₃)₃.

Graphene and its composites have attracted much attention for applications in energy storage systems. However, the toxic solvents required for the exfoliation process have hampered the exploitation of its properties. In this work, graphene dispersions are obtained via liquid phase exfoliation (LPE) of graphite in cyrene, an environmentally friendly solvent with solubility parameters like those of N-methyl-2-pirrolidone. The obtained dispersions with a concentration of 0.2 mg ml⁻¹ comprised multilayered graphene sheets with lateral sizes in the hundreds of nanometers, as confirmed by scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. Mixing the obtained dispersions with ethanol made it possible to collect the graphene, which was redispersed in 2-Propanol. This active material was used to fabricate supercapacitor electrodes using a scalable spray deposition method on carbon nanotube (CNT) current collectors with the aid of vinyl masks. The device, tested with a PVA/LiCl gel electrolyte, achieved a specific capacitance of 3.4 mF cm⁻² (0.015 mA cm⁻²). In addition, the devices show excellent cycling stability (>10 000 cycles at 0.5 mA cm⁻²) and good mechanical properties, losing less than 10% of initial capacitance after 1000 bending cycles. This work demonstrates the adaptability of liquid-phase exfoliation to produce graphene sustainably, providing the proof-of-concept for further 2D materials processing and green microsupercapacitor (MSC) fabrication.

New zirconia/20 vol% tantalum (3Y-TZP/Ta) biocermets exhibit exceptional capabilities due to a combination of properties that make them highly suitable for biomedical applications in orthopedics, dentistry and other areas of hard tissue replacement.

To achieve a broader public acceptance for electric vehicles based on lithium-ion battery (LIB) technology, long driving ranges, low cost, and high safety are needed. A promising pathway to address these key parameters lies in the further improvement of Ni-rich cathode materials for LIB cells. Despite the higher achieved capacities and thus energy densities, there are major drawbacks in terms of capacity retention and thermal stability (of the charged cathode) which are crucial for customer acceptance and can be mitigated by protecting cathode particles. We studied the impact of surface modifications on cycle life and thermal stability of LiNi_0.90Co_0.05Mn_0.05O₂ layered oxide cathodes with WO₃ by a simple sol–gel coating process. Several advanced analytical techniques such as low-energy ion scattering, differential scanning calorimetry, and high-temperature synchrotron X-ray powder diffraction of delithiated cathode materials, as well as charge/discharge cycling give significant insights into the impact of surface coverage of the coatings on mitigating degradation mechanisms. The results show that successful surface modifications of WO₃ with a surface coverage of only 20% can prolong the cycle life of an LIB cell and play a crucial role in improving the thermal stability and, hence, the safety of LIBs.

Invited for this issue's Front Cover is the group of Prof. Dr. Martin Winter from the MEET Battery Research Center (University of Münster, Germany). The cover picture shows two battery‐shaped coffee cups filled with coffee. In addition, the scientists (represented by gloved hands) have added both pure iron and an iron solution to the cups. The left cup filled with iron is highly energetic and strikes sparks, indicating better electrochemical performance and crystallinity than the right cup filled with the iron solution. The impact of activator addition prior to ‘catalytic’ graphitization and its effect on material and electrochemical properties is systematically investigated. Read the full text of the Research Article at 10.1002/celc.202201073.

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.