Superb Energy Storage Capability for NaNbO3 -Based Ceramics Featuring Labyrinthine Submicro-Domains with Clustered Lattice Distortions.

Designing superb dielectric capacitors is valuable but challenging since achieving simultaneously large energy-storage (ES) density and high efficiency is difficult. Herein, the synergistic effect of grain refining, bandgap widening, and domain engineering is proposed to boost comprehensive ES properties by incorporating CaTiO3 into 0.92NaNbO3 -0.08BiNi0.67 Ta0.33 O3 matrix (as abbreviated NN-BNT-xCT). Apart from grain refining and bandgap widening, multiple local distortions embedded in labyrinthine submicro-domains, as indicated by diffraction-freckle splitting and ½-type superlattices, produce slush-like polar clusters for the NN-BNT-0.2CT ceramic, which should be ascribed to the coexisting P4bm, P21 ma, and Pnma2 phases. Consequently, a high recoverable ES density Wrec of ≈ 7.1 J cm-3 and a high efficiency η of ≈ 90% at 646 kV cm-1 is achieved for the NN-BNT-0.2CT ceramic. Such hierarchically polar structure is favorable to superb comprehensive ES properties, which provide a strategy for developing high-performance dielectric capacitors.

Highly Sensitive, Flexible MEMS Based Pressure Sensor with Photoresist Insulation Layer.

Pressure sensing is a crucial function for flexible and wearable electronics, such as artificial skin and health monitoring. Recent progress in material and device structure of pressure sensors has brought breakthroughs in flexibility, self-healing, and sensitivity. However, the fabrication process of many pressure sensors is too complicated and difficult to integrate with traditional silicon-based Micro-Electro-Mechanical System(MEMS). Here, this study demonstrates a scalable and integratable contact resistance-based pressure sensor based on a carbon nanotube conductive network and a photoresist insulation layer. The pressure sensors have high sensitivity (95.5 kPa-1 ), low sensing threshold (16 Pa), fast response speed (<16 ms), and zero power consumption when without loading pressure. The sensitivity, sensing threshold, and dynamic range are all tunable by conveniently modifying the hole diameter and thickness of insulation layer.

Improving the performance of perovskite solar cells using a dual-hole transport layer.

The energy loss (Eloss) caused by inefficient charge transfer and large energy level offset at the buried interface can easily restrict the performance of p-i-n perovskite solar cells (PVSCs). In this study, the utilization of poly-TPD and P3CT-N as a dual-hole transporting layer (HTLs) was implemented in a sequential manner. This approach aimed to improve the charge transfer efficiency of the HTL and mitigate charge recombination at the interface between the HTL and PVK. The results showed that this strategy also could achieve more suitable energy levels, improve the quality of the perovskite film layer, and ultimately enhance the device's stability. IPVSCs employing the dual-HTLs approach exhibited the highest power conversion efficiency of 19.85%, and the open-circuit voltage increased to 1.09 V from 1.00 V. This study offers a straightforward and efficient approach to boost the device performance by minimizing Eloss and reducing the buried interfacial defects. The findings underscore the potential of employing a dual-HTL strategy as a promising pathway for further advancements in PVSCs.

Potassium Ammonium Vanadate with Rich Oxygen Vacancies for Fast and Highly Stable Zn-Ion Storage.

Vanadium-based materials have been extensively studied as promising cathode materials for zinc-ion batteries because of their multiple valences and adjustable ion-diffusion channels. However, the sluggish kinetics of Zn-ion intercalation and less stable layered structure remain bottlenecks that limit their further development. The present work introduces potassium ions to partially substitute ammonium ions in ammonium vanadate, leading to a subtle shrinkage of lattice distance and the increased oxygen vacancies. The resulting potassium ammonium vanadate exhibits a high discharge capacity (464 mAh g-1 at 0.1 A g-1) and excellent cycling stability (90% retention over 3000 cycles at 5 A g-1). The excellent electrochemical properties and battery performances are attributed to the rich oxygen vacancies. The introduction of K+ to partially replace NH4+ appears to alleviate the irreversible deammoniation to prevent structural collapse during ion insertion/extraction. Density functional theory calculations show that potassium ammonium vanadate has a modulated electron structure and a better zinc-ion diffusion path with a lower migration barrier.

In situ sulfur loading in graphene-like nano-cell by template-free method for Li-S batteries.

Carbon nanomaterials with 3D structures as sulfur hosts have been widely developed in lithium-sulfur batteries because of their high specific surface area, high conductivity and structural stability. However, sulfur, loaded by melting-diffusion method, is usually attached to the outside surface of carbon host, resulting in weak adsorption to expose polysulfide. Herein, we report a template-free method for synthesizing graphene-like nano-cell (GLC) with high in situ sulfur loading (S@GLC). The GLC is expected to provide physical adsorption by enclosed graphene cell architecture and chemical adsorption by pyridinic N-doping and oxygen functional group. With these merits, the S@GLC cathode owned high sulfur content (72%) and also, it exhibited a reversible specific capacity of 1253 mA h g-1 at 0.2C, excellent rate performance, and long cycling stability (502 mA h g-1 after 400 cycles at 1C).