Antonio Gutiérrez-Pardo

Solid polymer electrolytes offer a safer alternative to organic liquid electrolytes in high‐voltage lithium metal batteries, yet challenges remain in achieving adequate cyclability, energy density, scalability, and safety. This study presents the cycling performance of 1 Ah high‐voltage lithium polymer batteries featuring a hybrid ceramic polymer electrolyte (HCPE), a lithium metal anode, and a LiNi _0.8 Mn _0.1 Co _0.1 O ₂ (NMC‐811)‐based positive electrode. The HCPE stands out for its remarkable mechanical properties, with a Young's modulus exceeding 200 MPa at room temperature, providing robust resistance against dendrite formation. The Li||Li symmetric cells exhibited outstanding performance, cycling for over 1000 hours at a capacity of 2 mAh cm ⁻² , highlighting the exceptional attributes of HCPE. Full cell testing is conducted under practical conditions, utilizing various cell configurations, from coin cells to large pouch cells with a 1 Ah capacity, achieving an energy density of nearly 250 Wh kg ⁻¹ and promising cyclability with 80% capacity retention after 110 cycles. The study also investigated thermal runaway characteristics, showing comparability with commercial lithium‐ion batteries. This research underscores the scalability and performance of high‐voltage lithium metal polymer batteries, advancing their potential for commercial viability.

The industrial development of Li metal solid state batteries will be boosted not only by providing highly Li⁺ conductive electrolyte materials, but also by demonstrating their technical viability in the actual device.

A simple, low-cost and environmentally friendly method has been used to obtain highly porous biomorphic carbon monoliths with a good combination of interconnected macro-, mesoand microporosity, and good electrical conductivity and mechanical strength, making these biocarbon materials interesting for electrochemical applications as binder-free electrodes. Highly porous monolithic biocarbons were obtained from beech wood precursors through pyrolysis and subsequent surface modification in a steam heated to 970°C with different activation times. The obtained biocarbons demonstrated good electrical conductivity and mechanical strength. They were studied as electrodes for supercapacitors in half cell experiments, demonstrating maximum gravimetric capacitance of 200 F g-1 in a basic media at scan rate 1 mV s-1. Galvanostatic charge-discharge experiments showed maximum capacitance of 185 F g-1 at current density of 0.15 A g-1 and ~100 F g-1 at current density of 0.75 A g-1. It has been shown that in addition to the developed porous surface, the micropores with diameters exceeding 1 nm play a key role for the enhanced electrochemical capacity. Long-cycling experiments demonstrated excellent stability of the monolithic biocarbon electrodes with no reduction of the initial capacitance values after 600 cycles in voltammetry.

The effect of partial graphitization on electrical and galvanomagnetic properties of BE-C(Fe) biomorphic carbons produced by beech wood carbonization at temperatures of 850–1600°C in the presence of an iron-containing catalyst is studied. The use of an Fe catalyst at Т_carb ≥ 1000°C leads to the formation of nanoscale graphite-phase inclusions; its total volume and nanocrystallite sizes increase with Т_carb. The data on the carrier concentration and mobility are obtained. It was shown that partially graphitized BE-C(Fe) carbons with Т_carb ≥ 1000°C in the conductivity type and magnetoresistance features relate to highly disordered metal systems whose conductivity can be described taking into account the contribution of quantum corrections, mainly the correction caused by the electron–electron interaction. It is shown that nonmonotonic dependences of the Hall constant R on the magnetic field are characteristic of BE-C(Fe) samples with 1000 ≤ Т_carb < 1600°C, which is most probably caused by the contribution of various carrier groups, i.e., electrons and holes. In BE-C(Fe) samples with Т_carb = 1600°C, the Hall coefficient corresponds to the metal state, which is associated with conducting medium homogenization resulting from the formation of a significant graphite phase volume.

A facile and low-cost method has been employed to fabricate MnO₂/C hybrid materials for use as binder-free electrodes for supercapacitor applications. Biocarbon monoliths were obtained through pyrolysis of beech wood, replicating the microstructure of the cellulosic precursor, and serve as 3D porous and conductive scaffolds for the direct growth of MnO₂ nanosheets by a solution method. Evaluation of the experimental results indicates that a homogeneous and uniform composite material made of a carbon matrix exhibiting ordered hierarchical porosity and MnO₂ nanosheets with a layered nanocrystalline structure is obtained. The tuning of the MnO₂ content and crystallite size via the concentration of KMnO₄ used as impregnation solution allows to obtain composites that exhibit enhanced electrochemical behavior, achieving a capacitance of 592 F g^–1 in electrodes containing 3 wt % MnO₂ with an excellent cyclic stability. The electrode materials were characterized before and after electrochemical testing.

We report here on controlled synthesis, characterization and electrochemical properties of different polymorphs of niobium pentoxides grown by CVD of new single-source precursors. Nb2O5 films deposited at different temperatures showed systematic phase evolution from low-temperature tetragonal (TT-Nb2O5, T-Nb2O5) to high temperature monoclinic modifications (H-Nb2O5). Optimization of the precursor flux and substrate temperature enabled phase-selective growth of Nb2O5 nanorods and films on conductive mesoporous biomorphic carbon matrices (Bio-C). Nb2O5 thin films deposited on monolithic mesoporous biomorphic carbon (Bio-C) scaffolds produced composite materials integrating the high surface area and conductivity of carbonaceous matrix with the intrinsically high capacitance of nanostructured niobium oxide. Hetero-junctions in Nb2O5/BioC composites were found to be beneficial in electrochemical capacitance. Electrochemical characterization of Nb2O5/BioC composites showed that small amounts of Nb2O5 (as low as 5%) in conjunction with Bio-C resulted in a seven-fold increase in the electrode capacitance, from 15 to 104 F g-1, making these materials ideally suited for electrochemical energy storage applications.

Catalytic hydrogen combustion was studied with H₂/air mixtures in conditions that simulate the H₂ concentration of the exhaust gases from fuel cells (3–4% v/v H₂ in air). Pt-impregnated monoliths based on porous biomorphic SiC (bio-SiC) substrates were employed for the first time for this reaction. Capillary forces were exploited for the incipient impregnation of supports with H₂PtCl₆ solutions. Freeze drying permitted us to obtain a homogeneous distribution of the active phase reducing accumulation at the monolith's outer shell. The supports and catalysts were characterized from a structural and thermal point of view. Catalytic tests were performed in a homemade reactor fed with up to 1000 ml min⁻¹ H₂/air mixtures and a diffusional regime (non-isothermal) was achieved in the selected conditions. Catalyst loading was tested in the range of 0.25–1.5 wt% Pt and 100% conversion was achieved in all cases. Temperatures were recorded at different points of the monoliths during the reaction showing anisotropic thermal behavior for selected bio-SiC substrates. These effects are of interest for heat management applications and were explained in correlation with thermal conductivity measurements performed on the supports. Pt-impregnated monoliths were also tested in less than 100% conversion conditions (1% v/v H₂ in air) and in powder form in kinetic conditions for comparative purposes.