Multilayer silica-methacrylate hybrid coatings prepared by sol–gel on stainless steel 316L: Electrochemical evaluation

AISI 316L stainless steel is a biocompatible alloy used in prosthetic devices for many years. However this alloy tends to suffer localized corrosion and needs external fixation to hard tissues. This work describes the development of a coating system of two layers with complementary properties. The inner layer is prepared using TEOS and MTES that has already shown good anticorrosion properties. The top layer is a new hybrid organic–inorganic coating prepared with TEOS, 3-methacryloxypropyl trimethoxysilane (MPS), and 2-hydroxyethyl methacrylate (HEMA). The properties of this sol let to produce a thick and porous coating formed by two interpenetrating (organic and inorganic) networks. This coating could be an excellent container for the later aggregate of bioactive particles as the following step in a future work based on its high thickness, plasticity and open structure to allow the electrolyte access to induce the formation of hydroxyapatite. The coating is electrochemically characterised in simulated body fluid at 37 °C after 1, 10 and 30 days of immersion by means of assays as electrochemical impedance spectroscopy (EIS) and polarization curves. The dual coating seems to join the best properties of the individual ones in time: their thickness restrict the passage of potentially toxic ions to the body fluid, the breakdown potential (Eb) remains high and far from the corrosion potential (Ecorr) and the film presents the open structure of the outer layer that allows the entrance of the electrolyte to react with the particles when added to the sol meanwhile the inner layer maintain its corrosion protective features.Peer reviewe

Observing and modeling the sequential pairwise reactions that drive solid-state ceramic synthesis

Solid-state synthesis from powder precursors is the primary processing route to advanced multicomponent ceramic materials. Designing ceramic synthesis routes is usually a laborious, trial-and-error process, as heterogeneous mixtures of powder precursors often evolve through a complicated series of reaction intermediates. Here, we show that phase evolution from multiple precursors can be modeled as a sequence of pairwise interfacial reactions, with thermodynamic driving forces that can be efficiently calculated using ab initio methods. Using the synthesis of the classic high-temperature superconductor YBa$_2$Cu$_3$O$_{6+x}$ (YBCO) as a representative system, we rationalize how replacing the common BaCO$_3$ precursor with BaO$_2$ redirects phase evolution through a kinetically-facile pathway. Our model is validated from in situ X-ray diffraction and in situ microscopy observations, which show rapid YBCO formation from BaO$_2$ in only 30 minutes. By combining thermodynamic modeling with in situ characterization, we introduce a new computable framework to interpret and ultimately design synthesis pathways to complex ceramic materials

Recubrimientos producidos por sol-gel con inhibidores de corrosión para la protección activa de aleaciones ligeras

Recubrimientos producidos por sol-gel con inhibidores de corrosión para la protección activa de aleaciones ligera

Composite cathode prepared by argyrodite precursor solution assisted by dispersant agents for bulk-type all-solid-state batteries

All-solid-state lithium batteries based on sulfide solid electrolytes are potential candidates for large-scale energy storage applications. Here, composite cathode with high content of an active material was prepared by a liquid phase process assisted by a dispersant agent to produce a better electrode and electrolyte interface. Li6PS5Cl sulfide electrolyte derived from a solution containing dispersant showed an argyrodite crystal phase with a better distribution of particle size and higher conductivity compared with those without dispersant. Regular distribution of Li6PS5Cl particles in nanometric scale with a spherical shape below 500 nm and conductivity of 0.6 x 10(-3 )S cm(-1) (rho = 1.40 g cm(-3)) at room temperature were obtained. Composite cathode was prepared by the dispersion of LiNi1/3Mn1/3Co1/3O2 particles and carbon additive in the Li6PS5Cl-solution containing dispersant agent and subsequent drying at 180 degrees C. Bulk-type all-solid-state battery fabricated with the composite cathode containing 89 wt% of the active material showed an initial discharge capacity of 110 mA h g(-1) at 25 degrees C and maintained 95% discharge capacity after 15 cycles

Influence of cerium concentration on the structure and properties of silica-methacrylate sol–gel coatings

The aim of this work was to study the effect of the incorporation of cerium nitrate in a silica-methacrylate sol–gel hybrid matrix reinforced with silica nanoparticles. Sols, coatings and powders have been studied, focusing specially in the determination of the redox ratio Ce3?/Ce4? and films structure. Sols have been characterised using viscosity measurements and FT-IR spectroscopy, and powders and coatings obtained with different Ce contents through UV–Vis and FT-IR spectroscopy, TGA, TEM, AFM and FE-SEM. The goal was to reach the best compromise between maximum cerium concentration and coating stability to better understand the mechanisms acting in active anti-corrosive processes.Peer reviewe

Instantaneous preparation of high lithium-ion conducting sulfide solid electrolyte Li7P3S11 by a liquid phase process

A solid electrolyte with a small particle size, good mechanical properties and high ionic conductivity is required to achieve high energy and power density in the all-solid-state battery. Here, we report an instantaneous preparation of high lithium-ion conducting sulfide solid electrolyte Li7P3S11 by a simple procedure involving a liquid phase process under ultrasonic irradiation and low thermal treatment at 220 degrees C. A short reaction time of 30 min was enough to produce the formation of PS43- units. Subsequent drying and heating processes led to the precipitation of the Li7P3S11 phase with a particle size below 500 nm, achieving high ionic conductivity of 1.0 x 10(-3) S cm(-1) at 22 degrees C and a low activation energy of 12.8 kJ mol(-1)

Electrochemical performance of bulk-type all-solid-state batteries using small-sized Li7P3S11 solid electrolyte prepared by liquid phase as the ionic conductor in the composite cathode

A high lithium-ion conductive solid electrolyte with Li7P3S11 phase and small particle size was prepared by a liquid phase process, and the solid electrolyte was used as the ionic conductor in the composite cathode for bulk-type all-solid-state batteries. The electrochemical performance of the all-solid-state cell using Li7P3S11 solid electrolyte prepared by liquid phase was studied and compared to that using Li7P3S11 solid electrolyte prepared by ball milling. Solid electrolytes prepared by the liquid phase and ball milling processes consisted mainly of the Li7P3S11 crystal phase and the local structure was composed by PS43-, P2S74- and P2S64- units. Both solid electrolytes exhibited a comparable high ionic conductivity over 10(-3) Scm(-1). A particle size around 500 nm was obtained by the liquid phase process, while a particle size larger than 10 mu m was obtained by the ball milling process. The composite cathode using the solid electrolyte obtained by the liquid phase process displayed a better distribution of the solid electrolyte and the active material, verified by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The all-solid-state cell using LiNi1/3Co1/3Mn1/3O2 and the solid electrolyte prepared by the liquid phase exhibited a better electrochemical performance than that using the solid electrolyte prepared by ball milling. The all-solid-state cells exhibited a first discharge capacity of 154 mAh g(-1) and 46 mAh g(-1), respectively. Furthermore, the structure of the solid electrolyte prepared by the liquid phase process, after charge-discharge measurements with charge-end voltages of 4.6 V vs Li, was investigated by using ex-situ Raman spectroscopy. Significant structural changes were not observed, indicating that Li7P3S11 is stable against charge-discharge processes. (C) 2018 Elsevier Ltd. All rights reserved

Optimization of Al2O3 and Li3BO3 Content as Sintering Additives of Li7-xLa2.95Ca0.05ZrTaO12 at Low Temperature

Simultaneous effect of Al2O3 and Li3BO3 additions on sintering behavior and Li-ion conductivity of Li7-xLa2.95Ca0.05ZrTaO12 (LLCZT) garnet electrolyte sintered at 900 degrees C (10 h) is evaluated. The crystal phase and microstructure of the different composites were evaluated by x-ray diffraction and scanning electron microscopy (SEM), respectively. Electrical properties of the composites with high relative densities (95%) were examined by impedance spectroscopy. The cubic phase was formed for LLCZT sintered with 0-0.21 mol of Al2O3 and 0.70 mol-0.80 mol of Li3BO3. The excess of Al2O3 (0.22 mol) led to the formation of secondary phases. SEM observation revealed the good interconnection between LLCZT grains and the distribution of the glassy phase formed by Li3BO3 and Al2O3. Effective combination of 0.21 mol of Al2O3 and 0.80 mol of Li3BO3 produced denser material with high relative density of 95% and high Li-ion conduction of 1 x 10(-4) S/cm at 32 degrees C

Organic-Inorganic Hybrid Materials for Interface Design in All-Solid-State Batteries with a Garnet-Type Solid Electrolyte

The practical realization of all-solid-state lithiummetal batteries depends on the development of low interfacial resistance between the solid electrolyte and electrodes. Herein, an organic-inorganic hybrid solid electrolyte, formed by an organic network of poly(ethylene oxide) chains that is connected with an inorganic Si-O-Si backbone network containing lithium salt, is proposed as a new interfacial material between a garnet-type oxide solid electrolyte and high-potential cathodes. The properties of the hybrid solid electrolyte are evaluated to obtain a material that is chemically and electrochemically compatible with the solid electrolyte and active material. Thereafter, the different procedures to fabricate a low-resistance solid-solid interface between the solid electrolyte and LiCoO2 using the hybrid solid electrolyte are evaluated. The hybrid solid electrolyte provides an ionic/electronic percolation of active material particles and excellent adherence properties, thereby enabling the operation of the all-solid-state battery at room temperature to achieve a high initial discharge capacity of 125 mAh.g(-1)

Preparation of sulfide solid electrolytes in the Li2S-P2S5 system by a liquid phase process

Sulfide solid electrolytes in the Li2S-P2S5 system were synthesized by a liquid phase process under ultrasonic irradiation, and heat treatments at low temperatures. Crystal phase, structure, morphology and ionic conductivity of the sulfide electrolytes were examined after solvent removal at 180 degrees C and two different heat treatment temperatures, 220 degrees C and 250 degrees C. The study revealed that the ionic conductivities of the xLi(2)S center dot(100 - x)P2S5 sulfide electrolytes, in compositions with 70 <= x <= 75 mol%, are largely influenced by the local structure. The heat treatment at 220 degrees C was found to be an adequate temperature to promote crystallization of the high ionic conductive Li7P3S11 phase. Higher temperatures for heat treatment such as 250 degrees C lead to the formation of P2S64- (hypo-thiodiphosphate) units in the local structure of the sulfide electrolytes leading to a reduction of ionic conductivity. The formation and distribution of PS43- (orthothiophosphate), P2S74- (pyro-thiophosphate) and P2S64- units in the local structure were found to be key factors in achieving higher ionic conductivity (up to 10(-3)-10(-4) S cm(-1) at room temperature)