The Li ion transfer between a solid and a liquid Li electrolyte has been investigated by DC polarisation techniques. The current density i is measured as a function of the electrochemical potential drop Δ[small mu, Greek, tilde] at the interface, using a liquid electrolyte with different Li concentrations. The subject of this experimental study is the interface between the solid electrolyte Ta-substituted lithium lanthanum zirconate (LiLaZrTaO) and a liquid electrolyte consisting of LiPF dissolved in ethylene carbonate/dimethyl carbonate (1 : 1). The functional course of i vs. Δ[small mu, Greek, tilde] can be described by a serial connection between a constant ohmic resistance R and a current dependent thermally activated ion transfer process. For the present solid-liquid electrolyte interface the areal resistance R of the surface layer is independent of the Li concentration in the liquid electrolyte. At room temperature a value of about 300 Ω cm is found. The constant ohmic resistance R can be attributed to a surface layer on the solid electrolyte with a (relatively) low conductivity (solid-liquid electrolyte interphase). The low conducting surface layer is formed by degradation reactions with the liquid electrolyte. R is considerably increased if a small amount (ppm) of water is added to the liquid electrolyte. The thermally activated ionic transfer process obeys a Butler-Volmer like behaviour, resulting in an exchange current density i depending on the Li concentration in the liquid electrolyte by a power-law. At a Li concentration of 1 mol l a value of 53.1 μA cm is found. A charge transfer coefficient α of ∼0.44 is measured. The finding of a superposed constant ohmic resistance due to a solid-liquid electrolyte interphase and a current dependent thermally activated ion transfer process is confirmed by the results of two former experimental studies from the literature, performing AC measurements/EIS.

The properties of porous materials benefit from hierarchical porosity. A less noted element of hierarchy is the occurrence of directionality in functional gradient materials. A sharp boundary is replaced by a transition from one feature to the next. The number of cases known for porous materials with either structural or chemical gradients is small. A method capable of generating combinations of structural and chemical gradients in one material does not exist. Such a method is presented with a focus on silver and nitrogen containing carbon materials because of the potential of this system for electrocatalytic CO2 reduction. A structural gradient results from controlled separation using ultracentrifugation of a binary mixture of template particles in a resorcinol–formaldehyde (RF) sol as carbon precursor. A new level of complexity can be reached, if the surfaces of the template particles are chemically modified. Although the template is removed during carbonization, the modification (Ag, N) becomes integrated into the material. Understanding how modified and unmodified large and small particles sediment in the RF sol enables almost infinite variability of combinations: chemically graded but structurally homogeneous materials and vice versa. Ultimately, a material containing one structural gradient and two chemical gradients with opposing directions is introduced.

Porosity is of high importance for functional materials, as it allows for high surface areas and the accessibility of materials. While the fundamental interplay between different pore sizes and functionalities is quite well understood, few studies on gradually changing properties in a material exist. To date, only a few examples of such materials have been synthesized successfully. Herein, we present a facile method for synthesizing macroscopic carbon aerogels with locally changing pore sizes and functionalities. We used ultracentrifugation to fractionate differently functionalized and sized polystyrene nanoparticles. The assembly into gradient templates was conducted in a resorcinol–formaldehyde (RF) sol, which acted as a liquid phase and carbon precursor. We show that the modification of nanoparticles and a sol–gel precursor is a powerful tool for introducing dopants (sulfur and phosphorous) and metal nanoparticles (e.g., Ni) into gradient porous carbons formed during the carbonization of the RF sol. Understanding the underlying interactions between particles and precursors will lead to a plethora of possibilities in the material design of complex functionally graded materials. We showed this by exchanging parts of the template with magnetite–polystyrene composites as templating nanoparticles. This led to the incorporation of magnetite nanoparticles in the formed gradient porous carbon aerogels. Finally, gradually increasing concentrations of magnetite were obtained, ultimately leading to macroscopic carbon aerogels with locally changing magnetic properties, while the graded porosity was maintained.

Learning which parameters influence order is important for the generation of future particle‐based materials. Aspect ratio and polydispersity could be influenced independently from each other for ZnO nanorods. Sebastian Polarz and co‐workers deduce the impact on order parameters and structural defects from a quantitative evaluation of electron microscopy data in article number 1600215.

The supreme aim of nanoparticle‐based materials is to achieve new properties extending over the features of individual constituents. The emergence of cooperativity necessitates precise positioning and orientation of nanoparticle ensembles. Thus, it is important to understand and learn how to control self‐assembly processes of nanoparticles. Besides shape, the structural uniformity plays a key role for ordering in superstructures. Therefore, it is challenging to synthesize nanorods with narrow polydispersity. An analysis of the systematic variation of aspect ratio and polydispersity is missing. A series of zinc oxide nanorods is presented and it is shown that their formation resembles step‐polymerization with an amorphous precursor state as a monomer and polar ZnO particles as entities capable of growing. The width of nanorods is kept constant (15 nm) and the length is varied between 20 and 100 nm, as well as improving the polydispersity of the nanorod length from 36% to 10%. Best samples have been achieved by post‐preparative treatment using gradient centrifugation. A method has been developed for semiquantitative evaluation of orientational order. Ordering in structures formed by quasispherical particles is always low despite low polydispersity. For rod‐like nanoparticles with increasing aspect ratio, superstructure order depends on the occurrence of different defects, which correlate differently to nanoparticle polydispersity.