in further markets, such as electromobility and large-scale grid storage. Although LIBs offer high energy density and have reached a high level of maturity, there are still many technological challenges to meet established user habits and increasing demands. [1] Among the remaining challenges of LIBs, one of the most crucial issues is the electrochemical instability of anodes toward electrolytes. When using anode materials with favorably low electrode potentials close to Li/Li + , common liquid electrolytes are decomposed. Ideally, this leads to the formation of a stable so-called solid-electrolyte interphase (SEI), preventing further electrolyte decomposition and leading to stable cycling performance. Furthermore, the SEI has decisive influence on the charge/discharge kinetics of the battery, as this is where the Li-ions overcome the interface between the electrolyte and the electrode. Accordingly, the SEI is a key component that determines the performance of LIBs. The "natural SEI" that forms at the anode/electrolyte interface during initial cycling represents a thin layer made of salts, oxides, polymers. [2] The conceptual model of SEI was introduced by Peled in 1979 [3] and further developed by other groups. [4][5][6][7][8][9][10][11][12] According to this model, natural SEIs possess only ionic conductivity, while serving as a barrier to electron transfer. In this regard, the thickness and conformity of SEI An intrinsic challenge of Li-ion batteries is the instability of electrolytes against anode materials. For anodes with a favorably low operating potential, a solid-electrolyte interphase (SEI) formed during initial cycles provides stability, traded off for capacity consumption. The SEI is mainly determined by the anode material, electrolyte composition, and formation conditions. Its properties are typically adjusted by changing the liquid electrolyte's composition. Artificial SEIs (Art-SEIs) offer much more freedom to address and tune specific properties, such as chemical composition, impedance, thickness, and elasticity. Art-SEIs for intercalation, alloying, conversion and Li metal anodes have to fulfil varying requirements. In all cases, sufficient transport properties for Li-ions and (electro-)chemical stability must be guaranteed. Several approaches for Art-SEIs preparation have been reported: from simple casting and coating techniques to elaborated Phys-Chem modifications and deposition processes. This review critically reports on the promising approaches for Art-SEIs formation on different type of anode materials, focusing on methodological aspects. The specific requirements for each approach and material class, as well as the most effective strategies for Art-SEI coating, are discussed and a roadmap for further developments towards next-generation stable anodes are provided.

We demonstrate localized electrodeposition of anisotropic metal nanoobjects, namely Au nanorods (GNR), on indium tin oxide (ITO) using scanning electrochemical microscopy (SECM). A gold microelectrode was the source of the gold ions whereby double pulse chronoamperometry was employed to generate initially Au seeds which were further grown under controlled conditions. The distance between the microelectrode and the ITO surface as well as the different experimental parameters (electrodeposition regime, solution composition and temperature) were optimized to produce faceted gold seeds with the required characteristics (size and distribution). Colloidal chemical synthesis was successfully exploited for better understanding the role of the surfactant and different additives in breaking the crystallographic symmetry and anisotropic growth of GNR. Experiments performed in a conventional three-electrode cell revealed the most appropriate electrochemical conditions allowing high yield synthesis of nanorods with well-defined shape as well as nanocubes and bipyramids.

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The localized electrodeposition of silver on gold coated with self-assembled monolayers (SAMs) by scanning electrochemical microscopy (SECM) is reported. The SAMs were ω-functionalized alkanethiols of the form X−(CH 2 ) 2 SH, X = OH, NH 2 , CO 2 H, SO 3 H, as well as 4-mercaptobenzoic acid. The SAMs were characterized by X-ray photoelectron spectroscopy (XPS) and cycling voltammetry (CV). The anodic dissolution of a Ag microelectrode, which was held within a few microns from the Au surface, formed a well-controlled flux of Ag + . Deposition of silver nanostructures was driven by the electrochemical reduction of the Ag + on the Au surface. The effect of the functional group on the Ag local deposition was studied and compared with bulk deposition on the same SAMs. For bulk deposition, we found that the interaction between Ag + ions and the functional group of the alkanethiols slowed the kinetics of Ag deposition, shifting the deposition to potential that is more negative and caused the formation of large, well-faceted Ag crystals. A clear correlation between the potential shift value and the morphology of deposited Ag was observed. The local deposition of Ag showed distinct difference compared to bulk deposition. We found that a continuous and homogeneous Ag film was formed locally below the Ag microelectrode in the presence of a 3-mercaptopropionic acid monolayer. This was observed when a 120 s delay between the electrogeneration of the silver ions and the application of a negative potential to the gold surface was applied. Moreover, the potential applied to the Au surface also affected deposition. The deposited silver was recollected by the Ag microelectrode by stripping the silver from the Au surface while holding the microelectrode in the same position. This enabled calculating the thickness of the Ag film deposited on the Au coated with 3-mercaptopropionic acid. Additional experiments clearly indicated that the mechanism of deposition involved complexation of silver ions by the SAM and their local reduction, which commenced prior to applying a negative potential to the Au surface.

The formation and local deposition of well-shaped Au nanostructures on a nonconducting surface are described. Specifically, the local electroless deposition of Au in aqueous solutions in the presence of various n-alkylpyridinium surfactants is driven by electrochemically generating a flux of AuCl4 – at a gold tip close to a 3-mercaptopropyltrimethoxysilane modified Si oxidized wafer. Two reducing agents, NaBH4 and ascorbic acid, were used for the reduction of the gold ions. We studied the effect of the solution temperature, the potential applied to the gold tip and its distance from the surface, the reductant, and the nature of the alkylpyridinium on the structure of the gold deposit. The chloride salts of methylpyridinium, butylpyridinium, cetylpyridinium, 4-carbamoyl-1-cetylpyridinium, and 4-methyl-1-cetylpyridinium were added separately and showed remarkable effect on the shape of the structures that were formed. We find that short chain n-alkylpyridinium salts do not adsorb preferentially on the gold facets, whereas the longer chain n-alkylpyridinium ions cause the formation of well-faceted Au structures, such as cubes, hexagons, and even multipods. Moreover, comparison between local and bulk deposition revealed a significant difference in Au structures that were formed, presumably due to the different concentration profile of the AuCl4 –.