Since the resurgence of interest in lithium–sulfur (Li–S) batteries at the end of the 2000s, research in the field has grown rapidly. Li–S batteries hold great promise as the upcoming post-lithium-ion batteries owing to their notably high theoretical specific energy density of 2600 W h kg⁻¹, nearly five-fold larger than that of current lithium-ion batteries. However, one of their major technical problems is found in the shuttling of soluble polysulfides between the electrodes, resulting in rapid capacity fading and poor cycling stability. This review spotlights the foremost findings and the recent progress in enhancing the electrochemical performance of Li–S batteries by using nanoscaled metal compounds and metals. Based on an overview of reported functional metal-based materials and their specific employment in certain parts of Li–S batteries, the underlying mechanisms of enhanced adsorption and improved reaction kinetics are critically discussed involving both experimental and computational research findings. Thus, material design principles and possible interdisciplinary research approaches providing the chance to jointly advance with related fields such as electrocatalysis are identified. Particularly, we elucidate additives, sulfur hosts, current collectors and functional interlayers/hybrid separators containing metal oxides, hydroxides and sulfides as well as metal–organic frameworks, bare metal and further metal nitrides, metal carbides and MXenes. Throughout this review article, we emphasize the close relationship between the intrinsic properties of metal-based nanostructured materials, the (electro)chemical interaction with lithium (poly)sulfides and the subsequent effect on the battery performance. Concluding the review, prospects for the future development of practical Li–S batteries with metal-based nanomaterials are discussed.

The aim to produce highly active, selective, and long-lived electrocatalysts by design drives major research efforts toward gaining fundamental understanding of the relationship between material properties and their catalytic performance. Surface characterization tools enable to assess atomic scale information on the complexity of electrocatalyst materials. Advancing electrochemical methodologies to adequately characterize such systems was less of a research focus point. In this Review, we shed light on the ability to gain fundamental insights into electrocatalysis from a complementary perspective and establish corresponding design strategies. These may rely on adopting the perceptions and models of other subareas of electrochemistry, such as corrosion, battery research, or electrodeposition. Concepts on how to account for and improve mass transport, manage gas bubble release, or exploit magnetic fields are highlighted in this respect. Particular attention is paid to deriving design strategies for nanoelectrocatalysts, which is often impeded, as structural and physical material properties are buried in electrochemical data of whole electrodes or even devices. Thus, a second major approach focuses on overcoming this difference in the considered level of complexity by methods of single-entity electrochemistry. The gained understanding of intrinsic catalyst performance may allow to rationally advance design concepts with increased complexity, such as three-dimensional electrode architectures. Many materials undergo structural changes upon formation of the working catalyst. Accordingly, developing “precatalysts” with low hindrance of the electrochemical transformation to the active catalyst is suggested as a final design strategy.

The three-dimensional (3D) distribution of individual atoms on the surface of catalyst nanoparticles plays a vital role in their activity and stability. Optimising the performance of electrocatalysts requires atomic-scale information, but it is difficult to obtain. Here, we use atom probe tomography to elucidate the 3D structure of 10 nm sized Co₂FeO₄and CoFe₂O₄nanoparticles during oxygen evolution reaction (OER). We reveal nanoscale spinodal decomposition in pristine Co₂FeO₄. The interfaces of Co-rich and Fe-rich nanodomains of Co₂FeO₄become trapping sites for hydroxyl groups, contributing to a higher OER activity compared to that of CoFe₂O₄. However, the activity of Co₂FeO₄drops considerably due to concurrent irreversible transformation towards Co^IVO₂and pronounced Fe dissolution. In contrast, there is negligible elemental redistribution for CoFe₂O₄after OER, except for surface structural transformation towards (Fe^III, Co^III)₂O₃. Overall, our study provides a unique 3D compositional distribution of mixed Co-Fe spinel oxides, which gives atomic-scale insights into active sites and the deactivation of electrocatalysts during OER.

Single-entity electrochemistry allows for assessing electrocatalytic activities of individual material entities such as nanoparticles (NPs). Thus, it becomes possible to consider intrinsic electrochemical properties of nanocatalysts when researching how activity relates to physical and structural material properties. Conversely, conventional electrochemical techniques provide a normalized sum current referring to a huge ensemble of NPs constituting, along with additives (e.g., binders), a complete catalyst-coated electrode. Accordingly, recording electrocatalytic responses of single NPs avoids interferences of ensemble effects and reduces the complexity of electrocatalytic processes, thus enabling detailed description and modelling. Herein, we present insights into the oxygen evolution catalysis at individual cubic Co₃O₄ NPs impacting microelectrodes of different support materials. Simulating diffusion at supported nanocubes, measured step current signals can be analyzed, providing edge lengths, corresponding size distributions, and interference-free turnover frequencies. The provided nano-impact investigation of (electro-)catalyst-support effects contradicts assumptions on a low number of highly active sites.

The thermolysis of electrodeposited metal–organic framework (MOF) films represents a novel approach to build supercapacitor electrodes of already electrically contacted MOF-derived high-performance metal oxide/carbon materials which are also highly interesting for other applications. MOFs are widely utilised as precursors to synthesise functional materials by thermal decomposition (pyrolysis, carbonisation). Using electrochemically coated MOF precursor films instead of powder greatly simplifies the processing of such materials and potentially enhances the resulting active materials' performance. In the case of electrochemical energy storage electrodes, the coated substrate later functions as current collector which is well-attached to the active material without the need for any additives. This close connection decreases electron transfer resistances and saves multiple steps of powder formulation and coating. Films of a metal–organic framework based on 1,3,5-benzene-tricarboxylate (BTC) and cobalt^(II) cations were electrochemically coated on cobalt foils which act as the Co²⁺ cation source. Manganese films were electrodeposited and subsequently partly redissolved in a linker-containing electrolyte to achieve Mn/Mn–BTC bilayered films on stainless steel. This procedure extends the method for any kind of current collector material. The films were thermolysed to gain nanostructured metal oxide spinel (Me₃O₄)/carbon hybrid electrodes. Investigations of the electrochemical properties in regard to supercapacitor applications show that Co₃O₄/C films exhibit pseudocapacitance and that Mn₃O₄/C films are suitable for redox electrodes with high-rate capability operating in a wide potential range in aqueous electrolytes. Co–BTC powder was also thermally treated yielding cobalt particles embedded in a graphitic carbon matrix. The pseudocapacitive properties of conventionally coated films of this powder material are limited.