The present study describes a novel strategy for preparing thin Silicon 2D and 3D electrodes for lithium ion batteries by a spin coating method. A homogeneous and stable suspension of Si nanoparticles (SiNPs) was prepared by dispersing the nanoparticles in 1-methyl-2-pyrrolidone (NMP) or in the room temperature ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (Pyr14TFSI). This proposed methodology was successfully employed to prepare 2D and 3D with different aspect ratios electrodes. Both 2D and 3D materials were then used as anode materials. The 2D SiNPs anodes exhibit a high reversible capacity, which is close to 3500 mAh·g⁻¹ at C/10. For a higher discharge rate, the capacity of the 2D anode is considerably improved by dispersing the nanoparticles in Pyr14TFSI instead of NMP solvent. In order to further improve the anode performances, graphene particles were added to the SiNPs suspension. The anodes prepared using this suspension method exhibit relatively low columbic efficiency during the first few cycles (less than 30%) and low reversible capacity (2800 mAh·g⁻¹ at C/10). The 3D SiNPs (NMP) electrode shows a higher intensity during cyclic voltammograms and a better stability under galvanostatic cycling than the 2D SiNPs (NMP) electrode.

This study reports a sustainable approach for developing electrodes for microsupercapacitors. This approach includes the synthesis of TiO₂ nanoparticles via a green sol–gel method and the deposition of thin films of that electrochemically active material on three-dimensional (3D) Si substrates with a high area enlargement factor (AEF) via a simple, fast, and inexpensive spin-coating pathway. The thickness of the film was first optimized via its deposition over two-dimensional (2D) substrates to achieve high capacitances to provide high energy density but also to deliver a good rate capability to ensure the power density required for a supercapacitor device. A film thickness of ~120 nm realizes the best compromise between the electronic/ionic conductivity and capacitance in a supercapacitor device. Such layers of TiO₂ were successfully coated onto 3D microstructured substrates with different architectures, such as trenches and pillars, and different aspect ratios. The spin-coating-based route developed here has been established to be superior as, on the one hand, a conformal deposition can be achieved over high AEF subtracts, and on the other hand, the 3D electrodes present higher surface capacitances than those obtained using other deposition techniques. The rate capability and appreciable cyclability ensure a reliable supercapacitor behavior.

While it is known that strongly correlated transition metal oxides described by a multi-band Hubbard model show microscopic multiscale phase separation, little is known about the possibility to manipulate them with vacuum ultraviolet (VUV), 27 eV lighting. We have investigated the photo-induced effects of VUV light illumination of a super-oxygenated La₂NiO_4+y single crystal by means of scanning photoelectron microscopy. VUV light exposure induces the increase of the density of states (DOS) in the binding energy range around E_b = 1.4 eV below E_F. The photo-induced states in this energy region have been predicted due to clustering of oxygen interstitials by band structure calculations for large supercell of La₂CuO_4.125. We finally show that it is possible to generate and manipulate oxygen rich domains by VUV illumination as it was reported for X-ray illumination of La₂CuO_4+y. This phenomenology is assigned to oxygen-interstitials ordering and clustering by photo-illumination forming segregated domains in the La₂NiO_4+y surface.