Presodiation Architected Robust Surface Enables Packaging Optimal Performance of Sodium-Ion Batteries.

Presodiation has shown great promise in compensating sodium storage losses. In the absence of a mechanistic understanding of how presodiation affects the surface of an electrode material, packaging optimization is restricted. Focusing on interfaces, we illustrate the working principle of presodiation in virtue of short-circuiting internal circuits. The presodiated carbon nanotubes (PS-CNTs) provide a thin, denser, and more robust solid electrolyte interfacial layer, enabling a high initial Coulombic efficiency (ICE), high power density, and cycling stability with the merits of uniformly distributed NaF. As a result, our assembled sodium-ion battery (SIB) full cell with PS-CNT has an ICE of 91.6% and an energy density of 226 Wh kg-1, which was superior to the pristine CNT control electrode (ICE of 42.9% and energy density of 163 Wh kg-1). The gained insights can be practically applied to directly promote the commercial uses of carbon-based materials in sodium-ion batteries.

Significantly Increased Specific Discharge Capacitance at Carbon Fibers Created via Architected Ultramicropores.

Carbon is commonly used as an electrode material for supercapacitors operating on an electrical double-layer energy storage mechanism. However, the low specific capacitance limits its application. Increasing the specific surface area is by far the most common expansion method, and surprisingly, they are not always positively correlated. The overmuch specific surface will show the characteristics of nanoconfinement, and the potential synergistic enhancement mechanism of various key parameters is still controversial. In this work, carbon fiber electrodes with different ultramicropore structures were designed in order to improve the utilization rate and the discharge capacitance. It has been found that when the ultramicropore entrance's surface is too small, it will lead to the decrease of the external charge of the pore transport channel, and then, the selectivity of the opposite ions will decrease. The numerical simulation based on Poisson and Nernst-Planck equations also indicates that ions have difficulty diffusing into the micropores when their entrance surface decreases. Surface properties within the nanocontainment space become critical factors influencing ion transport and adsorption. The specific discharge capacitance of carbon fiber is increased from 3 to 1430 mF cm-2.

Ultrafast Nucleation Reverses Dissolution of Transition Metal Ions for Robust Aqueous Batteries.

The dissolution of transition metal ions causes the notorious peeling of active substances and attenuates electrochemical capacity. Frustrated by the ceaseless task of pushing a boulder up a mountain, Sisyphus of the Greek myth yearned for a treasure to be unearthed that could bolster his efforts. Inspirationally, by using ferricyanide ions (Fe(CN)63-) in an electrolyte as a driving force and taking advantage of the fast nucleation rate of copper hexacyanoferrate (CuHCF), we successfully reversed the dissolution of Fe and Cu ions that typically occurs during cycling. The capacity retention increased from 5.7% to 99.4% at 0.5 A g-1 after 10,000 cycles, and extreme stability of 99.8% at 1 A g-1 after 40,000 cycles was achieved. Fe(CN)63- enables atom-by-atom substitution during the electrochemical process, enhancing conductivity and reducing volume change. Moreover, we demonstrate that this approach is applicable to various aqueous batteries (i.e., NH4+, Li+, Na+, K+, Mg2+, Ca2+, and Al3+).

Oxygen Vacancies Boosted Hydronium Intercalation: A Paradigm Shift in Aluminum-Based Batteries.

In aqueous aluminum-ion batteries (AAIBs), the insertion/extraction chemistry of Al3+ often leads to poor kinetics, whereas the rapid diffusion kinetics of hydronium ions (H3O+) may offer the solution. However, the presence of considerable Al3+ in the electrolyte hinders the insertion reaction of H3O+. Herein, we report how oxygen-deficient α-MoO3 nanosheets unlock selective H3O+ insertion in a mild aluminum-ion electrolyte. The abundant oxygen defects impede the insertion of Al3+ due to excessively strong adsorption, while allowing H3O+ to be inserted/diffused through the Grotthuss proton conduction mechanism. This research advances our understanding of the mechanism behind selective H3O+ insertion in mild electrolytes.

Ostwald-Ripening Induced Interfacial Protection Layer Boosts 1,000,000-Cycled Hydronium-Ion Battery.

Collapsing and degradation of active materials caused by the electrode/electrolyte interface instability in aqueous batteries are one of the main obstacles that mitigate the capacity. Herein by reversing the notorious side reactions include the loss and dissolution of electrode materials: as we applied Ostwald ripening (OR) in the electrochemical cycling of a copper hexacyanoferrate electrode in a hydronium-ion batteries, the dissolved Cu and Fe ions undergo a crystallization process that creates a stable interface layer of cross-linked cubes on the electrode surface. The layer exposed the low-index crystal planes (100) and (110) through OR-induced electrode particle growth, supplemented by vacancy-ordered (100) superlattices that facilitated ion migration. Our design stabilized the electrode-electrolyte interface considerably, achieving a cycle life of one million cycles with capacity retention of 91.6%, and a capacity retention of 91.7% after 3000 cycles for a full battery.

3D printing of flexible strain sensor based on MWCNTs/flexible resin composite.

The flexible strain sensor is an indispensable part in flexible integrated electronic systems and an important intermediate in external mechanical signal acquisition. The 3D printing technology provides a fast and cheap way to manufacture flexible strain sensors. In this paper, a MWCNTs/flexible resin composite for photocuring 3D printing was prepared using mechanical mixing method. The composite has a low percolation threshold (1.2%ωt). Based on the composite material, a flexible strain sensor with high performance was fabricated using digital light processing technology. The sensor has a GF of 8.98 under strain conditions ranging between 0% and 40% and a high elongation at break (48%). The sensor presents mechanical hysteresis under cyclic loading. With the increase of the strain amplitude, the mechanical hysteresis becomes more obvious. At the same time, the resistance response signal of the sensor shows double peaks during the unloading process, which is caused by the competition of disconnection and reconstruction of conductive network in the composite material. The test results show that the sensor has different response signals to different types of loads. Finally, its practicability is verified by applying it to balloon pressure detection.

Additive Manufacturing of Stretchable Multi-Walled Carbon Nanotubes/Thermoplastic Polyurethanes Conducting Polymers for Strain Sensing.

With the development of science and technology, flexible sensors play an indispensable role in body monitoring. Rapid prototyping of high-performance flexible sensors has become an important method to develop flexible sensors. The purpose of this study was to develop a flexible resin with multi-walled carbon nanotubes (MWCNTs) for the rapid fabrication of flexible sensors using digital light processing additive manufacturing. In this study, MWCNTs were mixed in thermoplastic polyurethane (TPU) photosensitive resin to prepare polymer-matrix composites, and a flexible strain sensor was prepared using self-developed additive equipment. The results showed that the 1.2 wt% MWCNTs/TPU composite flexible sensor had high gauge factor of 9.988 with a linearity up to 45% strain and high mechanical durability (1000 cycles). Furthermore, the sensor could be used for gesture recognition and monitoring and has good performance. This method is expected to provide a new idea for the rapid personalized forming of flexible sensors.

Cobalt substitution-induced π-donation in NiMoO4 for enhanced electrochemical charge storage.

NiMoO4 (NM) has garnered significant attention due to its rich d-orbital electronic structure and multivalent electroactive cations. However, the inherently low electrical conductivity of NM limits its reaction kinetics. Herein, cobalt-substituted NM (Co-NM) nanorods were prepared via a hydrothermal reaction followed by subsequent thermal treatment. The incorporation of Ni-O-Co configurations stimulates an enhanced π-donation effect of the Co-O bond, facilitating the hybridization between the O 2p and Co 3d orbitals and thereby boosting charge transfer kinetics during electrochemical processes. The optimized 10 %Co-NM nanorods demonstrated a remarkable specific capacity of 557.8 C·g-1 at 1 A·g-1. Furthermore, an asymmetric supercapacitor constructed with 10 %Co-NM as the positive electrode and FeOOH as the negative electrode, achieved a significant energy density of 63.58 Wh·kg-1 at a power density of 805.38 W·kg-1. Thus, our work provides new insights into the rational design of stable bridging configurations to significantly improve electrochemical reaction kinetics.

Impact of housing policies on the real estate market - Systematic literature review.

Real estate majorly contributes to the national gross domestic product (GDP) growth, occupying an important position in the national economy. It is the largest fixed asset for households. The real estate market is associated with a wide range of economic aspects with more upstream and downstream enterprises. Simultaneously, the factors affecting the real estate market are complex and variable. Fluctuations in the real estate market affect the entire economic system. This requires the government to formulate relevant housing policies to stabilize the operation of the real estate market. Therefore, it is meaningful to study the impact of housing policies on the real estate market and provide reasonable opinions for the housing sector in formulating policies. This study adopts a systematic quantitative literature review to examine the impact of housing policies on the real estate market. This study finds that housing policies affecting the real estate market can be divided into the following three categories: monetary, tax, and macro-prudential policies. Changes in supply and demand in the real estate market primarily reflect the effectiveness of policies, with housing price factors as the transmission mechanism. Furthermore, the influence of housing policies from different countries and regions on real estate market factors is compared to provide a reference for scholars to pursue further study.