RESUMEN
Ionic and electronic transport in electrodes is crucial for electrochemical energy storage technology. To optimize the transport pathway of ions and electrons, electrode materials are minimized to nanometer-sized dimensions, leading to problems of volumetric performance, stability, cost, and pollution. Here we find that a bulk hexagonal molybdenum oxide with unconventional ion channels can store large amounts of protons at a high rate even if its particle size is tens of micrometers. The diffusion-free proton transport kinetics based on hydrogen bonding topochemistry is demonstrated in hexagonal molybdenum oxide whose proton conductivity is several orders of magnitude higher than traditional orthorhombic molybdenum oxide. In situ X-ray diffraction and theoretical calculation reveal that the structural self-optimization in the first discharge effectively promotes the reversible intercalation/de-intercalation of subsequent protons. The open crystal structure, suitable proton channels, and negligible volume strain enable rapid and stable proton transport and storage, resulting in extremely high volumetric capacitance (~1750 F cm-3), excellent rate performance, and ultralong cycle life (>10,000 cycles). The discovery of unconventional materials and mechanisms that enable proton storage of micrometer-sized particles in seconds boosts the development of fast-charging energy storage systems and high-power practical applications.
RESUMEN
Achieving all-solid-state lithium-based batteries with high energy densities requires lightweight and ultrathin solid-state electrolytes (SSEs) with high Li+ conductivity, but this still poses significant challenges. Herein, we designed a robust and mechanically flexible SSE (denoted BC-PEO/LiTFSI) by using an environmentally friendly and low-cost approach that involves bacterial cellulose (BC) as a three-dimensional (3D) rigid backbone. In this design, BC-PEO/LiTFSI is tightly integrated and polymerized through intermolecular hydrogen bonding, and the rich oxygen-containing functional groups from the BC filler also provide the active site for Li+ hopping transport. Therefore, the all-solid-state Li-Li symmetric cell with BC-PEO/LiTFSI (containing 3% BC) showed excellent electrochemical cycling properties over 1000 h at a current density of 0.5 mA cm-2. Furthermore, the Li-LiFePO4 full cell showed steady cycling performance under 3 mg cm-2 areal loading at a current of 0.1 C, and the resultant Li-S full cell maintained over 610 mAh g-1 for upward of 300 cycles at 0.2 C and 60 °C.
RESUMEN
The sluggish ionic transport in thick electrodes and freezing electrolytes has limited electrochemical energy storage devices in lots of harsh environments for practical applications. Here, a 3D-printed proton pseudocapacitor based on high-mass-loading 3D-printed WO3 anodes, Prussian blue analog cathodes, and anti-freezing electrolytes is developed, which can achieve state-of-the-art electrochemical performance at low temperatures. Benefiting from the cross-scale 3D electrode structure using a 3D printing direct ink writing technique, the 3D-printed cathode realizes an ultrahigh areal capacitance of 7.39 F cm-2 at a high areal mass loading of 23.51 mg cm-2 . Moreover, the 3D-printed pseudocapacitor delivers an areal capacitance of 3.44 F cm-2 and excellent areal energy density (1.08 mWh cm-2 ). Owing to the fast ion kinetics in 3D electrodes and the high ionic conductivity of the hybrid electrolyte, the 3D-printed supercapacitor delivers 61.3% of the room-temperature capacitance even at -60 °C. This work provides an effective strategy for the practical applications of energy storage devices with complex physical structure at extreme temperatures.
RESUMEN
Simultaneously improving the energy density and power density of electrochemical energy storage systems is the ultimate goal of electrochemical energy storage technology. An effective strategy to achieve this goal is to take advantage of the high capacity and rapid kinetics of electrochemical proton storage to break through the power limit of batteries and the energy limit of capacitors. This article aims to review the research progress on the physicochemical properties, electrochemical performance, and reaction mechanisms of electrode materials for electrochemical proton storage. According to the different charge storage mechanisms, the surface redox, intercalation, and conversion materials are classified and introduced in detail, where the influence of crystal water and other nanostructures on the migration kinetics of protons is clarified. Several reported advanced full cell devices are summarized to promote the commercialization of electrochemical proton storage. Finally, this review provides a framework for research directions of charge storage mechanism, basic principles of material structure design, construction strategies of full cell device, and goals of practical application for electrochemical proton storage.
RESUMEN
External photo-stimuli on heterojunctions commonly induce an electric potential gradient across the interface therein, such as photovoltaic effect, giving rise to various present-day technical devices. In contrast, in-plane potential gradient along the interface has been rarely observed. Here we show that scanning a light beam can induce a persistent in-plane photoelectric voltage along, instead of across, silicon-water interfaces. It is attributed to the following movement of a charge packet in the vicinity of the silicon surface, whose formation is driven by the light-induced potential change across the capacitive interface and a high permittivity of water with large polarity. Other polar liquids and hydrogel on silicon also allow the generation of the in-plane photovoltage, which is, however, negligible for nonpolar liquids. Based on the finding, a portable silicon-hydrogel array has been constructed for detecting the shadow path of a moving Cubaris. Our study opens a window for silicon-based photoelectronics through introducing semiconductor-water interfaces.
