Lithium-ion batteries, which power portable electronics, electric vehicles, and stationary storage, have been recognized with the 2019 Nobel Prize in chemistry. The development of nanomaterials and their related processing into electrodes and devices can improve the performance and/or development of the existing energy storage systems. We provide a perspective on recent progress in the application of nanomaterials in energy storage devices, such as supercapacitors and batteries. The versatility of nanomaterials can lead to power sources for portable, flexible, foldable, and distributable electronics; electric transportation; and grid-scale storage, as well as integration in living environments and biomedical systems. To overcome limitations of nanomaterials related to high reactivity and chemical instability caused by their high surface area, nanoparticles with different functionalities should be combined in smart architectures on nano- and microscales. The integration of nanomaterials into functional architectures and devices requires the development of advanced manufacturing approaches. We discuss successful strategies and outline a roadmap for the exploitation of nanomaterials for enabling future energy storage applications, such as powering distributed sensor networks and flexible and wearable electronics.

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The lithium–O2 ‘semi-fuel’ cell based on the reversible reaction of Li and O2 to form Li2O2 can theoretically provide energy densities that exceed those of Li-ion cells by up to a factor of five. A key limitation that differentiates it from other lithium batteries is that it requires effective catalysts (or ‘promoters’) to enable oxygen reduction and evolution. Here, we report the synthesis of a novel metallic mesoporous oxide using surfactant templating that shows promising catalytic activity and results in a cathode with a high reversible capacity of 10,000 mAh g(−1) (∼1,000 mAh g(−1) with respect to the total electrode weight including the peroxide product). This oxide also has a lower charge potential for oxygen evolution from Li2O2 than pure carbon. The properties are explained by the high fraction of surface defect active sites in the metallic oxide, and its unique morphology and variable oxygen stoichiometry. This strategy for creating porous metallic oxides may pave the way to new cathode architectures for the Li–O2 cell.

Na 0.44 MnO 2 nanowires were acid leached in nitric acid, and dehydrated by heat treatment to induce controllable defect formation as monitored by high resolution TEM studies. The charge-discharge tests using these materials as catalysts (or ''promoters'') in rechargeable lithium-oxygen batteries (in noncarbonate electrolytes) showed that a high defect concentration results in a doubling of the reversible energy storage capacity up to 11 000 mA h g À1 , and lowered overpotentials for oxygen evolution. The role of the defects/vacancies in determining oxygen reduction behavior is highlighted.

The realization of next-generation portable electronics and integrated microsystems is directly linked with the development of robust batteries with high energy and power density. Three-dimensional micro- and nanostructured electrodes enhance energy and power through higher surface area and thinner active materials, respectively. Here, we present a novel approach for the fabrication of hierarchical electrodes that combine benefits of both length scales. The electrodes consist of self-assembled, virus-templated nanostructures conformally coating three-dimensional micropillars. Active battery material (V(2)O(5)) is deposited using atomic layer deposition on the hierarchical micro/nanonetwork. Electrochemical characterization of these electrodes indicates a 3-fold increase in energy density compared to nanostructures alone, in agreement with the surface area increase, while maintaining the high power characteristics of nanomaterials. Investigation of capacity scaling for varying active material thickness reveals underlying limitations in nanostructured electrodes and highlights the importance of our method in controlling both energy and power density with structural hierarchy.

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A series of 11 oxovanadium(V) complexes mimicking the active site of vanadium haloperoxidases have been investigated by (51)V magic angle spinning NMR spectroscopy and density functional theory (DFT). The MAS spectra are dominated by the anisotropic quadrupolar and chemical shielding interactions; for these compounds, C(Q) ranges from 3 to 8 MHz, and delta(sigma) is in the range 340-730 ppm. The quadrupolar coupling and chemical shielding tensors as well as their relative orientations have been determined by numerical simulations of the spectra. The spectroscopic NMR observables appear to be very sensitive to the details of the electronic and geometric environment of the vanadium center in these complexes. For the four crystallographically characterized compounds from the series, the quadrupolar and chemical shielding anisotropies were computed at the DFT level using two different basis sets, and the calculated tensors were in general agreement with the experimental solid-state NMR data. A combination of (51)V solid-state NMR and computational methods is thus beneficial for investigation of the electrostatic and geometric environment in diamagnetic vanadium systems with moderate quadrupolar anisotropies.