Publications by authors named "Ce-Wen Nan"

The safety and cycle stability of lithium metal batteries (LMBs) under conditions of high cut-off voltage and fast charging put forward higher requirements for electrolytes. Here, a sulfonate-based deep eutectic electrolyte (DEE) resulting from the eutectic effect between solid sultone and lithium bis(trifluoromethanesulfonyl)imide without any other additives is reported. The intermolecular coordination effect triggers this eutectic phenomenon, as evidenced with nuclear magnetic resonance, and thus the electrochemical behavior of the DEE can be controlled by jointly regulating the coordination effects of F···H and Li···O intermolecular interactions.

View Article and Find Full Text PDF

Symmetry engineering is explicitly effective to manipulate and even create phases and orderings in strongly correlated materials. Flexural stress is universally practical to break the space-inversion or time-reversal symmetry. Here, by introducing strain gradient in a centrosymmetric antiferromagnet Sr_{2}IrO_{4}, the space-inversion symmetry is broken accompanying a nonequivalent O p-Ir d orbital hybridization along the z axis.

View Article and Find Full Text PDF

HfO-based ferroelectric materials are emerging as key components for next-generation nanoscale devices, owing to their exceptional nanoscale properties and compatibility with established silicon-based electronics infrastructure. Despite the considerable attention garnered by the ferroelectric orthorhombic phase, the polar rhombohedral phase has remained relatively unexplored due to the inherent challenges in its stabilization. In this study, the successful synthesis of a distinct ferroelectric rhombohedral phase is reported, i.

View Article and Find Full Text PDF

Thermoelectrics converting heat and electricity directly attract broad attentions. To enhance the thermoelectric figure of merit, zT, one of the key points is to decouple the carrier-phonon transport. Here, we propose an entropy engineering strategy to realize the carrier-phonon decoupling in the typical SrTiO-based perovskite thermoelectrics.

View Article and Find Full Text PDF
Article Synopsis
  • Relaxor ferroelectrics are essential for pulse-power dielectric capacitors, but improving energy density often reduces energy efficiency in high fields.
  • This study introduces a new high-entropy ceramic made from a mix of ferroelectric cations, which creates a unique dipole structure that enhances energy density and efficiency.
  • The resulting materials achieved impressive recoverable energy densities (up to ~26.3 J/cm³) with high efficiency and stability for use in multilayer ceramic capacitors.
View Article and Find Full Text PDF
Article Synopsis
  • The Jahn-Teller effect (JTE) influences the physical properties of transition-metal compounds, making it essential for material functionality.
  • A new strategy has been proposed that focuses on controlling JTE by analyzing the occupancy of electron orbitals and the symmetry of oxygen atoms in manganese oxides.
  • The effectiveness of this approach has been shown in creating different types of NaLiMnO oxides and holds potential for other transition-metal compounds, offering a way to design materials with specific desired properties.
View Article and Find Full Text PDF

Manipulating optical chirality via electric fields has garnered considerable attention in the realm of both fundamental physics and practical applications. Chiral ferroelectrics, characterized by their inherent optical chirality and switchable spontaneous polarization, are emerging as a promising platform for electronic-photonic integrated circuits applications. Unlike organics with chiral carbon centers, integrating chirality into technologically mature inorganic ferroelectrics has posed a long-standing challenge.

View Article and Find Full Text PDF
Article Synopsis
  • Polymeric dielectric materials are promising for energy storage in capacitors, but their thermal resistance issues at high temperatures limit their use in tough environments.
  • This study introduces a flexible laminated polymer nanocomposite with nanoscale-confined polyetherimide (PEI) between solid AlO layers, which improves its thermal, mechanical, and electrical stability.
  • The nanolaminate achieves high energy density (18.9 J/cm) and efficiency (around 91%) at 200°C, with optimized performance due to increased glass-transition temperature and better electrical breakdown strength, enabling innovative applications like compact metal-wired capacitors.
View Article and Find Full Text PDF

Printing technology enables the integration of chemically exfoliated perovskite nanosheets into high-performance microcapacitors. Theoretically, the capacitance value can be further enhanced by designing and constructing multilayer structures without increasing the device size. Yet, issues such as interlayer penetration in multilayer heterojunctions constructed using inkjet printing technology further limit the realization of this potential.

View Article and Find Full Text PDF

Hybrid halide perovskites are good candidates for a range of functional materials such as optical electronic and photovoltaic devices due to their tunable band gaps, long carrier diffusion lengths, and solution processability. However, the instability in moisture/air, the toxicity of lead, and rigorous reaction setup or complex postprocessing have long been the bottlenecks for practical application. Herein, we present a simultaneous configurational entropy design at A-sites, B-sites, and X-sites in the typical (CHA)PbBr two-dimensional (2D) hybrid perovskite.

View Article and Find Full Text PDF

Flexible polymer-based dielectrics with high energy storage characteristics over a wide temperature range are crucial for advanced electrical and electronic systems. However, the intrinsic low dielectric constant and drastically degraded breakdown strength hinder the development of polymer-based dielectrics at elevated temperatures. Here, we propose a magnetic-assisted approach for fabricating a polyethyleneimine (PEI)-based nanocomposite with precisely aligned nanofibers within the polymer matrix, and with AlO deposition layers applied on the surface.

View Article and Find Full Text PDF

Dielectric capacitors offer great potential for advanced electronics due to their high power densities, but their energy density still needs to be further improved. High-entropy strategy has emerged as an effective method for improving energy storage performance, however, discovering new high-entropy systems within a high-dimensional composition space is a daunting challenge for traditional trial-and-error experiments. Here, based on phase-field simulations and limited experimental data, we propose a generative learning approach to accelerate the discovery of high-entropy dielectrics in a practically infinite exploration space of over 10 combinations.

View Article and Find Full Text PDF

The compromise of contradictive parameters, polarization, and breakdown strength, is necessary to achieve a high energy storage performance. The two can be tuned, regardless of material types, by controlling microstructures: amorphous states possess higher breakdown strength, while crystalline states have larger polarization. However, how to achieve a balance of amorphous and crystalline phases requires systematic and quantitative investigations.

View Article and Find Full Text PDF

Ferroelectric materials have important applications in transduction, data storage, and nonlinear optics. Inorganic ferroelectrics such as lead zirconate titanate possess large polarization, though they are rigid and brittle. Ferroelectric polymers are light weight and flexible, yet their polarization is low, bottlenecked at 10 μC cm.

View Article and Find Full Text PDF

MXene inks offer a promising avenue for the scalable production and customization of printing electronics. However, simultaneously achieving a low solid content and printability of MXene inks, as well as mechanical flexibility and environmental stability of printed objects, remains a challenge. In this study, we overcame these challenges by employing high-viscosity aramid nanofibers (ANFs) to optimize the rheology of low-concentration MXene inks.

View Article and Find Full Text PDF

Lithium-sulfur (Li-S) batteries offer high theoretical capacity but are hindered by poor rate capability and cycling stability due to sluggish LiS precipitation kinetics. Here a sulfonate-group-rich liquid crystal polymer (poly-2,2'-disulfonyl-4,4'-benzidine terephthalamide, PBDT) is designed and fabricated to accelerate LiS precipitation by promoting the desolvation of Li from electrolyte. PBDT-modified separators are employed to assemble Li-S batteries, which deliver a remarkable rate capacity (761 mAh g at 4 C) and cycling stability (500 cycles with an average decay rate of 0.

View Article and Find Full Text PDF

Polar metals have recently garnered increasing interest because of their promising functionalities. Here we report the experimental realization of an intrinsic coexisting ferromagnetism, polar distortion and metallicity in quasi-two-dimensional CaCoO. This material crystallizes with alternating stacking of oxygen tetrahedral CoO monolayers and octahedral CoO bilayers.

View Article and Find Full Text PDF

Ultrahigh-power-density multilayer ceramic capacitors (MLCCs) are critical components in electrical and electronic systems. However, the realization of a high energy density combined with a high efficiency is a major challenge for practical applications. We propose a high-entropy design in barium titanate (BaTiO)-based lead-free MLCCs with polymorphic relaxor phase.

View Article and Find Full Text PDF

BiCuSeO is a promising oxygen-containing thermoelectric material due to its intrinsically low lattice thermal conductivity and excellent service stability. However, the low electrical conductivity limits its thermoelectric performance. Aliovalent element doping can significantly improve their carrier concentration, but it may also impact carrier mobility and thermal transport properties.

View Article and Find Full Text PDF

Electric field-induced second harmonic generation allows electrically controlling nonlinear light-matter interactions crucial for emerging integrated photonics applications. Despite its wide presence in materials, the figures-of-merit of electric field-induced second harmonic generation are yet to be elevated to enable novel device functionalities. Here, we show that the polar skyrmions, a topological phase spontaneously formed in PbTiO/SrTiO ferroelectric superlattices, exhibit a high comprehensive electric field-induced second harmonic generation performance.

View Article and Find Full Text PDF

Ferroelectricity, especially the Si-compatible type recently observed in hafnia-based materials, is technologically useful for modern memory and logic applications, but it is challenging to differentiate intrinsic ferroelectric polarization from the polar phase and oxygen vacancy. Here, we report electrically controllable ferroelectricity in a HfZrO-based heterostructure with Sr-doped LaMnO, a mixed ionic-electronic conductor, as an electrode. Electrically reversible extraction and insertion of an oxygen vacancy into HfZrO are macroscopically characterized and atomically imaged .

View Article and Find Full Text PDF

Dielectric capacitors, characterized by ultra-high power densities, are considered as fundamental energy storage components in electronic and electrical systems. However, synergistically improving energy densities and efficiencies remains a daunting challenge. Understanding the role of polarity heterogeneity at the nanoscale in determining polarization response is crucial to the domain engineering of high-performance dielectrics.

View Article and Find Full Text PDF

Topology created by quasi-continuous spatial variations of a local polarization direction represents an exotic state of matter, but field-driven manipulation has been hitherto limited to creation and destruction. Here we report that relatively small electric or mechanical fields can drive the non-volatile rotation of polar spirals in discretized microregions of the relaxor ferroelectric polymer poly(vinylidene fluoride-ran-trifluoroethylene). These polar spirals arise from the asymmetric Coulomb interaction between vertically aligned helical polymer chains, and can be rotated in-plane through various angles with robust retention.

View Article and Find Full Text PDF

Electrical control of magnetism is highly desirable for energy-efficient spintronic applications. Realizing electric-field-driven perpendicular magnetization switching has been a long-standing goal, which, however, remains a major challenge. Here, electric-field control of perpendicularly magnetized ferrimagnetic order via strain-mediated magnetoelectric coupling is reported.

View Article and Find Full Text PDF

Owing to their excellent discharged energy density over a broad temperature range, polymer nanocomposites offer immense potential as dielectric materials in advanced electrical and electronic systems, such as intelligent electric vehicles, smart grids and renewable energy generation. In recent years, various nanoscale approaches have been developed to induce appreciable enhancement in discharged energy density. In this Review, we discuss the state-of-the-art polymer nanocomposites with improved energy density from three key aspects: dipole activity, breakdown resistance and heat tolerance.

View Article and Find Full Text PDF