Transition metal tungstate-based nanomaterials have become one of the research hotspots in electrochemistry due to their abundant natural resources, low costs, and environmental friendliness. Extensive studies have demonstrated their significant potentials for electrochemical applications, such as supercapacitors, Li-ion batteries, Na-ion batteries, electrochemical sensing, and electrocatalysis. Considering the rapidly growing research enthusiasm for this topic over the last several years, herein, a critical review of recent progress on the application of transition metal tungstates and their composites for electrochemical applications is summarized. The relationships between synthetic methods, nano/micro structures and electrochemical properties are systematically discussed. Finally, their promising prospects for future development are also proposed. It is anticipated that this review will inspire ongoing interest in rational designing and fabricating novel transition metal tungstate-based nanomaterials for high-performance electrochemical devices.

The fundamental understanding of the mechanism underlying the early stages of crystallization of hexagonal-close-packed (hcp) nanocrystals is crucial for their synthesis with desired properties, but it remains a significant challenge. Here, we report using in situ liquid cell transmission electron microscopy (TEM) to directly capture the dynamic nucleation process and track the real-time growth pathway of hcp Ni nanocrystals at the atomic scale. It is demonstrated that the growth of amorphous-phase-mediated hcp Ni nanocrystals is from the metal-rich liquid phases. In addition, the reshaped preatomic facet development of a single nanocrystal is also imaged. Theoretical calculations further identify the non-classical features of hcp Ni crystallization. These discoveries could enrich the nucleation and growth model theory and provide useful information for the rational design of synthesis pathways of hcp nanocrystals.

Dielectric composites boost the family of energy storage and conversion materials as they can take full advantage of both the matrix and filler. This review aims at summarizing the recent progress in developing high-performance polymer- and ceramic-based dielectric composites, and emphases are placed on capacitive energy storage and harvesting, solid-state cooling, temperature stability, electromechanical energy interconversion, and high-power applications. Emerging fabrication techniques of dielectric composites such as 3D printing, electrospinning, and cold sintering are addressed, following by highlighted challenges and future research opportunities. The advantages and limitations of the typical theoretical calculation methods, such as finite-element, phase-field model, and machine learning methods, for designing high-performance dielectric composites are discussed. This review is concluded by providing a brief perspective on the future development of composite dielectrics toward energy and electronic devices.

Lithium (Li) metal with high theoretical capacity and low electrochemical potential is the most ideal anode for next-generation high-energy batteries. However, the practical implementation of Li anode has been hindered by dendritic growth and volume expansion during cycling, which results in low Coulombic efficiency (CE), short lifespan, and safety hazards. Here, we report a highly stable and dendrite-free Li metal anode by utilizing N-doped hollow porous bowl-like hard carbon/reduced graphene nanosheets (CB@rGO) hybrids as three-dimensional (3D) conductive and lithiophilic scaffold host. The lithiophilic carbon bowl (CB) mainly works as excellent guides during the Li plating process, whereas the rGO layer with high conductivity and mechanical stability maintains the integrity of the composite by confining the volume change in long-range order during cycling. Moreover, the local current density can be reduced due to the 3D conductive framework. Therefore, CB@rGO presents a low lithium metal nucleation overpotential of 18 mV, high CE of 98%, and stable cycling without obvious voltage fluctuation for over 600 cycles at a current density of 1 mA·cm^–2. Our study not only provides a good CB@rGO host and pre-Lithiated CB@rGO composite anode electrode, but also brings a new strategy of designing 3D electrodes for those active materials suffering from severe volume expansion.