Imidazole-Intercalated Cobalt Hydroxide Enabling the Li+ Desolvation/Diffusion Reaction and Flame Retardant Catalytic Dynamics for Lithium Ion Batteries.

Lithium-ion batteries have found extensive applications due to their high energy density and low self-discharge rates, spanning from compact consumer electronics to large-scale energy storage facilities. Despite their widespread use, challenges such as inherent capacity degradation and the potential for thermal runaway hinder sustainable development. In this study, we introduce a unique approach to synthesize anode materials for lithium-ion batteries, specifically imidazole-intercalated cobalt hydroxide. This innovative material significantly enhances the Li+ desolvation/diffusion reaction and flame-retardant dynamics through complexing and catalytic synergetic effects. The lithium-ion batteries incorporating these materials demonstrate exceptional performance, boasting an impressive capacity retention of 997.91 mAh g-1 after 500 cycles. This achievement can be attributed to the optimization of the solid electrolyte interphase (SEI) interface engineering, effectively mitigating anode degradation and minimizing electrolyte consumption. Experimental and theoretical calculations validate these improvements. Importantly, imidazole intercalated Co(OH)2 (MI-Co(OH)2) exhibits a remarkable catalytic effect on electrolyte carbonization and the conversion of CO to CO2. This dual action suppresses smoke and reduces toxicity significantly. The presented work introduces a novel approach to realizing high-performance and safe lithium-ion batteries, addressing key challenges in the pursuit of sustainable energy solutions.

Biomimetic Multifunctional Graphene-Based Coating for Thermal Management, Solar De-Icing, and Fire Safety: Inspired from the Antireflection Nanostructure of Compound Eyes.

Due to the ubiquitous and inexhaustible solar source, photothermal materials have gained considerable attention for their potential in heating and de-icing. Nevertheless, traditional photothermal materials, exemplified by graphene, frequently encounter challenges emanating from their elevated reflectance. Inspired by ocular structures, this study uses the Fresnel equation to enhance the photo-thermal conversion efficiency of graphene by introducing a polydimethylsiloxane (PDMS)/silicon dioxide (SiO2) coating, which reduces the light reflectance (≈20%) through destructive interference. The designed coating achieves an equilibrium temperature of ≈77 °C at one sun and a quick de-icing in ≈65 s, all with a thickness of 5 µm. Simulations demonstrate that applying this coating to high-rise buildings results in energy savings of ≈31% in winter heating. Furthermore, the combination of PDMS/SiO2 and graphene confers a notable enhancement in thermal stability through a synergistic flame-retardant mechanism, effectively safeguarding polyurethane against high temperatures and conflagrations, leading to marked reduction of 58% and 28% in heat release rate and total heat release. This innovative design enhances the photo-thermal conversion, de-icing function, and flame retardancy of graphene, thereby advancing its applications in outdoor equipment, high-rise buildings, and aerospace vessels.

Robust Ionics Reinforced Fiber As Implantable Sensor for Early Operando Monitoring Cell Thermal Safety of Commercial Lithium-Ion Batteries.

Commercial batteries have been largely applied in mobile electronics, electric vehicles, and scalable energy storage systems. However, thermal runaway of batteries still obstructs the reliability of electric equipment. Considering this, building upon recent investigations of energy thermal safety, commercially available organogel fiber-based implantable sensors have been developed through 3D printing technology for first operando implantable monitoring of cell temperature. The printed fibers present excellent reliability and superelasticity because of internal supramolecular cross-linking. High temperature sensitivity (-39.84% °C-1/-1.557% °C-1) within a wide range (-15 to 80 °C) is achieved, and the corresponding mechanism is clarified based on in situ temperature-dependent Raman technology. Furthermore, taking the pouch cell as an example, combined with finite element analysis, the real-time observation system of cell temperature is successfully demonstrated through an implanted sensor with wireless Bluetooth transmission. This enlightening approach paves the way for achieving safety monitoring and smart warnings for various electric equipment.

Built-in Electric Field in Quasi-2D CsPbI3 Perovskites Using High-Polarized Zwitterionic Spacer for Enhanced Charge Separation/Transport.

Two-dimensional (2D) halide perovskites are promising candidates for the fabrication of stable and high-efficiency solar cells. However, the low power conversion efficiency (PCE) of cell devices using 2D perovskites is attributed to reduced charge transport caused by poor organic barrier conductivity. In this study, we propose the use of a high-polarized organic zwitterionic spacer, p-aminobenzoic acid (PABA), to construct novel quasi-2D perovskite structures with enhanced self-driven charge separation and transfer. The NH3+ and COO- groups in PABA generate an aligned electric field, promoting carrier separation and aggregation on the opposite edges of the inorganic layer. This enables efficient in-plane transportation along the inorganic layer. Additionally, PABA intercalated quasi-2D perovskite exhibits improved stability compared with counterparts with diamine cation spacers due to the strong interaction between -COO- and inorganic layers. Our findings suggest that high-polarized organic zwitterionic spacers, with NH3+ and COO- functionality, hold promise for stable and efficient quasi-2D perovskite solar cells.

Energy Level Matching and Band Edge Reconfiguration for Enhanced Charge Transport in Dion-Jacobson 3D/2D Perovskite Heterojunctions.

Generally, the 2D CsPbI3 layer capping on 3D counterparts has been considered as an effective strategy for both enhancing photovoltaic efficiency and stability. However, the intrinsically poor out-of-plane charge transport through the 2D layer remarkably hinders the overall performance of solar devices. To overcome such a challenge, we report the rationally designed 3D-CsPbI3/2D-(PYn)PbI4 (n = 1-4) heterojunctions with desirable energy level matching. It is evidenced that the valence band (VB) edge reconfiguration would occur with the increase of n, accompanied by the VB maximum (VBM) of the 2D component moving down from the higher level above that of the 3D component to the underneath. Consequently, the as-constructed 3D/2D-(PYn)PbI4 (n = 1, 2) heterojunctions exhibit optimal energy level matching, with accelerated transport of holes from 3D to 2D component and limited backflow of electrons. These findings might provide some meaningful insights on the energy level matching in 3D/2D perovskite heterojunctions.

Heterojunction Engineering Enhanced Self-Polarization of PVDF/CsPbBr3 /Ti3 C2 Tx Composite Fiber for Ultra-High Voltage Piezoelectric Nanogenerator.

Piezoelectric nanogenerator (PENG) for practical application is constrained by low output and difficult polarization. In this work, a kind of flexible PENG with high output and self-polarization is fabricated by constructing CsPbBr3 -Ti3 C2 Tx heterojunctions in PVDF fiber. The polarized charges rapidly migrate to the electrodes from the Ti3 C2 Tx nanosheets by forming heterojunctions, achieving the maximum utilization of polarized charges and leading to enhanced piezoelectric output macroscopically. Optimally, PVDF/4wt%CsPbBr3 /0.6wt%Ti3 C2 Tx -PENG exhibits an excellent voltage output of 160 V under self-polarization conditions, which is higher than other self-polarized PENG previously. Further, the working principle and self-polarization mechanism are uncovered by calculating the interfacial charge and electric field using first-principles calculation. In addition, PVDF/4wt%CsPbBr3 /0.6wt%Ti3 C2 Tx -PENG exhibits better water and thermal stability attributed to the protection of PVDF. It is also evaluated in practice by harvesting the energy from human palm taps and successfully lighting up 150 LEDs and an electronic watch. This work presents a new idea of design for high-performance self-polarization PENG.

Are formation and adsorption energies enough to evaluate the stability of surface-passivated tin-based halide perovskites?

Surface passivation is one of the effective and widely-used strategies to enhance the stability of halide perovskites with reduced surface defects and suppressed hysteresis. Among all existing reports, the formation and adsorption energies are popularly used as the decisive descriptors for screening passivators. Here, we propose that the often-ignored local surface structure should be another critically important factor governing the stability of tin-based perovskites after surface passivation, but has no detrimental effect on the stability of lead-based perovskites. It is verified that poor surface structure stability and deformation of the chemical bonding framework of Sn-I caused by surface passivation are ascribed to the weakened Sn-I bond strength and facilitated formation of surface iodine vacancy (VI). Therefore, the surface structure stability represented by the formation energy of VI and Sn-I bond strength should be used to accurately screen preferred surface passivators of tin-based perovskites.

Improving Out-of-Plane Charge Mobility and Phase Stability of Dion-Jacobson Lead-Free Perovskites via Intercalating π-Conjugated Aromatic Spacers.

The layered quasi-2D perovskites are recognized as one of the effective strategies to resolve the big problem of intrinsic phase instability of the perovskites. However, in such configurations, their performance is fundamentally limited due to the correspondingly weakened out-of-plane charge mobility. Herein, the π-conjugated p-phenylenediamine (PPDA) is introduced as organic ligand ions for rationally designing lead-free and tin-based 2D perovskites with the aid of theoretical computation. It is evidenced that both out-of-plane charge transport capacity and stability can be significantly enhanced within as-established quasi-2D Dion-Jacobson (DJ) (PPDA)Csn -1 Snn I3 n +1 perovskites. The obviously increased electrical conductivity and reduced carrier effective masses are attributed to the enhanced interlayer interactions, limited structural distortions of diamine cations, as well as improved orbital coupling between Sn2+ and I- ions of (PPDA)Csn -1 Snn I3 n +1 perovskites. Accordingly, by dimension engineering of the inorganic layer (n), the bandgap (Eg ) of quasi-2D perovskites can be linearly tailored toward the suitable Eg (1.387 eV) with optimal photoelectric conversion efficiency (PCE) of 18.52%, representing their great potential toward promising applications in advanced solar cells.

Boosted photocatalytic hydrogen production over two-dimensional/two-dimensional Ta3N5/ReS2 van der Waals heterojunctions.

Currently, two-dimensional/two-dimensional (2D/2D) van der Waals heterojunctions, as novel and excellent candidates for photocatalysts, have attracted significant attention because of their fundamentally improved interfacial charge separation/transfer and massive reactive centers. Herein, novel 2D/2D Ta3N5-nanosheet/ReS2-nanosheet van der Waals heterojunction photocatalysts are rationally designed through a method combining template-assisted and solution-adsorption processes. The resultant heterojunctions exhibit enhanced interfacial charge transfer, boosted light absorption and significantly increased reaction sites for hydrogen evolution. Correspondingly, they deliver a high photocatalytic hydrogen production activity of 615 µmol g-1 h-1, which is ∼3 and ∼12 times greater than that of bare Ta3N5 nanosheets and ReS2 nanosheets, respectively, and superior to those in the most recent reports about photocatalytic water splitting on Ta3N5 material, implying their potential applications as advanced catalysts for hydrogen evolution.

Ethanol inducing self-assembly of poly-(thioctic acid)/graphene supramolecular ionomers for healable, flame-retardant, shape-memory electronic devices.

In recent years, flexible electronic devices have great application potential in the fields of healthcare, VR virtual reality, electronic skin and intelligent robots. However, electronic devices fail during operation due to fatigue, corrosion or damage, making it difficult and expensive to maintain highly integrated portable/wearable electronic devices. In this study, highly healable, flame retardant, shape memorized supramolecular PTAZ/GO was fabricated by restricting the crosslinking of zinc ions, carboxyl graphene and poly-(thioctic acid) via self-polymerization in ethanol inducing self-assembly. The rich carboxyl groups associated with hydroxyl and disulfide groups in the system provide excellent self-healing efficiency and shape memory properties for supramolecular ionomers. The results of a microscale combustion calorimeter (MCC) test in this study showed a 65.3 % reduction in the peak heat release rate (pHRR) for ionomers compared to pure polymer, thus implying that ionic coordination cross-linking and GO nanosheets are beneficial for improving the fire safety of the materials. For the shape-memory device, the supramolecular elastomers can switch LED lights on and off by changing the shape, and the conductivity can be restored after reconnection of two damaged parts. Thus, the proposed materials have wide applications in electronic engineering.

FeNi LDH/V2CTx/NF as Self-Supported Bifunctional Electrocatalyst for Highly Effective Overall Water Splitting.

The development of bifunctional electrocatalysts with efficient oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is still a key challenge at the current stage. Herein, FeNi LDH/V2CTx/nickel foam (NF) self-supported bifunctional electrode was prepared via deposition of FeNi LDH on V2CTx/NF substrate by hydrothermal method. Strong interfacial interaction between V2CTx/NF and FeNi LDH effectively prevented the aggregation of FeNi LDH, thus exposing more catalytic active sites, which improved electrical conductivity of the nanohybrids and structural stability. The results indicated that the prepared FeNi LDH/V2CTx/NF required 222 mV and 151 mV overpotential for OER and HER in 1 M KOH to provide 10 mA cm-2, respectively. Besides, the FeNi LDH/V2CTx/NF electrocatalysts were applied to overall water splitting, which achieved a current density of 10 mA cm-2 at 1.74 V. This work provides ideas for improving the electrocatalytic performance of electrocatalysts through simple synthesis strategies, structural adjustment, use of conductive substrates and formation of hierarchical structures.

High-performance K-ion half/full batteries with superb rate capability and cycle stability.

SignificanceThe present work might be significant for exploring advanced K-ion batteries with superb rate capability and cycle stability toward practical applications. The as-assembled K-ion half cell exhibits an excellent rate capability of 428 mA h g-1 at 100 mA g-1 and a high reversible specific capacity of 330 mA h g-1 with 120% specific capacity retention after 2,000 cycles at 2,000 mA g-1, which is the best among those based on carbon materials. The as-constructed full cell delivers 98% specific capacity retention over 750 cycles at 500 mA g-1, superior to most of those based on carbon materials that have been reported thus far.

Ti3C2Tx (MXene)/Pt nanoparticle electrode for the accurate detection of DA coexisting with AA and UA.

Dopamine (DA), uric acid (UA) and ascorbic acid (AA) are biomolecules widely distributed in the human body and play an important role in many physiological processes. An abnormal concentration of them is associated with various diseases. Thus, the accurate and fast detection of them has been one of the major demands in the healthcare industry. In this study, we demonstrate that Ti3C2Tx/PtNP modified glassy carbon electrodes (GCEs) show a good electrochemical performance in the detection of DA and UA. However, there is no response signal to AA for either the CV or DPV curve due to the electrostatic repulsion between the negatively charged electrode surface and the negatively charged AA. Ti3C2Tx(MXene)/Pt nanoparticles (PtNPs) are prepared by etching Ti3AlC2(MAX) with HF and reducing H2PtCl6 with a NaBH4 aqueous solution. The morphology of Ti3C2Tx/PtNPs is multilayered accordion-like Ti3C2Tx decorated with PtNPs with a diameter of 10-20 nm. Furthermore, it is found that the electrochemical detection of DA will be enhanced by AA. The electrochemical detection rule of AA enhanced DA can be expressed as follows: I(DA+AA) = 0.011216CAA + 0.039950CDA + 1.1175(I(DA+AA) is the peak current of DA coexisting with AA. CAA is the concentration of AA. CDA is the concentration of DA). This can be used as a calibration to correct the concentration of DA when AA and DA coexist. Notably, AA promotes the stability of the electrode because it cleans the oxidation products from the electrode surface in time. In addition, the sensor exhibits good reproducibility and satisfactory recovery results in a real sample.

High energy density and extremely stable supercapacitors based on carbon aerogels with 100% capacitance retention up to 65,000 cycles.

In terms of ideal future energy storage systems, besides the always-pursued energy/power characteristics, long-term stability is crucial for their practical application. Here, we report a facile and sustainable strategy for the scalable fabrication of carbon aerogels with three-dimensional interconnected nanofiber networks and rationally designed hierarchical porous structures, which are based on the carbonization of bacterial cellulose assisted by the soft template of Zn-1,3,5-benzenetricarboxylic acid. As binder-free electrodes, they deliver a fundamentally enhanced specific capacitance of 352 F ⋅ g-1 at 1 A ⋅ g-1 in a wide potential window (1.2 V, 6 M KOH) in comparison with those of bacterial cellulose-derived carbons (178 F ⋅ g-1) and most activated carbons (usually lower than 250 F ⋅ g-1). The as-assembled supercapacitors exhibit an ultrahigh capacitance of 297 F ⋅ g-1 at 1 A ⋅ g-1, remarkable energy density (14.83 Wh ⋅ kg-1 at 0.60 kW ⋅ kg-1), and extremely high stability, with 100% capacitance retention for up to 65,000 cycles at 6 A ⋅ g-1, representing their superior energy storage performance when compared with that of state-of-the-art supercapacitors of commercial activated carbons and biomass-derived analogs.

Enhancing the Stability of Orthorhombic CsSnI3 Perovskite via Oriented π-Conjugated Ligand Passivation.

Lead-free orthorhombic CsSnI3 (Bγ-CsSnI3) perovskite has been emerging as one of the potential candidates of photovoltaic materials with superior performance. However, the instability induced by rapid reconstructive phase transition and the oxidation of Sn2+ greatly limits their future application. We thus reported a strategy, oriented π-conjugated ligand passivation, for enhancing the stability of Bγ-CsSnI3, simulated using a Bγ-CsSnI3 slab model based on the first-principles computation. The phase stability was found to be strongly dependent on the orientations of phenylethylammonium (PEA+) ligands. The passivated Bγ-CsSnI3 slab with the ligand molecule axis along [414] was demonstrated as the most stable with the lowest adsorption energy (Eads). Based on this configuration, the calculated formation energies (Eform) of half- and full-monolayer coverage were even more negative than that of yellow phase (Y-) CsSnI3 passivated by PEA+ ligands, verifying the enhanced phase stability. Furthermore, the surface states could be effectively suppressed and the downshifted conduction band minimum (CBM) resulted in a reduced band gap for the completely capped Bγ-CsSnI3. Moreover, the CBM and the valence band maximum (VBM) of the system with complete coverage were respectively donated by the surface and bulky components of the slab, which might benefit the separation and transfer of photogenerated carriers.

Superior Photodetectors Based on All-Inorganic Perovskite CsPbI3 Nanorods with Ultrafast Response and High Stability.

Currently, one-dimensional all-inorganic CsPbX3 (X = Br, Cl, and I) perovskites have attracted great attention, owning to their promising and exciting applications in optoelectronic devices. Herein, we reported the exploration of superior photodetectors (PDs) based on a single CsPbI3 nanorod. The as-constructed PDs had a totally excellent performance with a responsivity of 2.92 × 103 A·W-1 and an ultrafast response time of 0.05 ms, respectively, which were both comparable to the best ones ever reported for all-inorganic perovskite PDs. Furthermore, the detectivity of the PDs approached up to 5.17 × 1013 Jones, which was more than 5 times the best one ever reported. More importantly, the as-constructed PDs showed a high stability when maintained under ambient conditions.