The vertically aligned 3D structure is a promising host for dendrite-free sodium metal anodes. The distribution of electric field at the Helmholtz layer of anode surface plays a critical role in determining Na plating behavior. However, the said electric field is poorly understood, and its control remains highly challenging. Herein, we demonstrate the fabrication of vertically aligned Cu micro-cone arrays with tuned tip radii using a high precision femtosecond laser beam shaping method. Computational results confirm the advantageous effect of increasing the tip radius in promoting a widely distributed and uniform electric field. Investigations into the kinetic mechanism reveal that the uniform electric field accelerates Na ion diffusion and diminishes energy barrier, facilitating compact Na plating with suppressed dendrite growth. The Cu host having micro-cones with a large tip radius delivers excellent plating performance with exceptional high-rate capabilities. The symmetric cell presents a low overpotential of 39 mV with a negligible voltage fluctuation after 1100 h of cycle, while the full cell retains 92.1 % and 83.9 % of its specific capacities at 5C and 10C, respectively, compared to its capacity at 1C. The rational design of the micro-cone arrays with proven advantages shed new insights into the development of Na hosts for high energy density, dendrite-free Na metal batteries.

High interfacial thermal resistance (ITR) between thermally conductive nanofillers and polymer matrix, and lack of good orientation of nanofillers are primary limiting factors in harnessing their inherent thermal conductivity in polymer nanocomposites. Thus, exploiting ultrahigh thermal conductivities of nanofillers involves developing methods or mechanisms that can minimize the ITR. In this work, boron nitride nanosheets (BNNS)/polyvinyl alcohol (PVA) nanocomposite films with segregation-induced interconnection among BNNS are fabricated by a sequential unidirection freeze-casting (UFC) technique. A PVA aerogel is first made by UFC followed by infiltrating functionalized BNNS into its pores and microchannels which is subjected to a second UFC process. The composite aerogel is subsequently hot pressed to compact the available pore channels for reduced ITR arising from better contact between the segregated BNNS cell walls. The resulting segregated BNNS/PVA (SBP) nanocomposite film with 40 wt% BNNS exhibits high thermal conductivity of 5.2 W/mK, which is about 267 % higher than the nanocomposite film containing dispersed BNNS made by conventional UFC. The SBP film also possessed high electrical insulation characteristics and a very low dielectric loss of 10- 2 at a frequency of 1 kHz, properties arising directly from the segregated BNNS. The sequential UFC provides an effective method to incorporate aligned and interconnected BNNS through segregation for enhanced thermal conductivity and electrical resistivity for thermal management in microelectronics and integrated circuits.

The urgency of addressing the environmental and resource challenges posed by spent lithium-ion batteries (LIBs) has led to significant advancements in recycling and upcycling methodologies. This work aims to provide a comprehensive understanding of the progress made for LIB recycling and upcycling, offering perspectives for achieving a circular economy in battery technology. The review examines the latest innovations in LIB material recovery, focusing on both conventional recycling techniques and emerging upcycling strategies. It explores the motivation and importance of recycling spent LIBs, showing the critical need for sustainable solutions. A comprehensive overview of LIB recycling methodologies is provided, including pretreatment, preprocessing, pyrometallurgical, hydrometallurgical, bioleaching, direct recovery processes, electrochemical processes, and deep eutectic solvents. Emphasis is placed on the advanced upcycling of the cathode, anode, and separator materials, exploring composition/crystallisation engineering and structural modifications, including doping and surface coating. Furthermore, upcycling spent LIB materials into high-value products like catalysts and graphene is explored. The environmental impact, legislative landscape, and socioeconomic implications of battery recycling are critically analysed, with life cycle assessments underscoring the ecological benefits of these processes. Global perspectives on battery recycling practices are also examined, considering the varied approaches across different regions. Additionally, integrating artificial intelligence and the internet of things in optimising battery recycling is explored, demonstrating their potential to enhance efficiency and sustainability. The review concludes by identifying current challenges and proposing recommendations for future research and policy development.

Carbon allotropes are widely used as anodes and conductive additives for lithium-ion batteries (LIBs) owing to their large surface area, high electrical conductivity, and stability. By far, as only graphite has been commercialized, with limited capacity and stability, it is important to explore other carbon allotropes as anodes. Our review provides a comprehensive study of theoretical insights and electrochemical comparison of various carbon allotropes, mostly as anodes in LIBs. The theoretical insights mainly express the interaction of Li-ions with each carbon allotrope and guide about Li-ion diffusivity and adsorption that varies with geometry, edges, doping, vacancies, etc. Electrochemical battery performance discusses the structural limits of each carbon structure and emphasizes adopting methods such as doping, hybridization, and derivatization to improve LIB anode performance. To the above framework of theoretical and electrochemical investigation of carbon allotropes, a third layer of recyclability is purposely included to offer sustainable approaches in selecting the most appropriate carbon allotrope as anode for LIBs. The recycling process of each carbon with the most relevant purification method is highlighted, encouraging the use of greener and more sustainable approaches. In the landscape of carbon-based anode materials, this review directs through theoretical, experimental, and sustainable aspects to optimize carbon allotropes as potential LIB anodes.

Mixed-dimensional heterostructures provide additional freedom to construct diverse functional electronic and optoelectronic devices, gaining significant interest. Herein, highly-aligned pseudo-1D tellurium is epitaxially grown on 2D monolayer transition metal dichalcogenides (TMDs), including MoSe2, MoS2, and WS2. A one-pot chemical vapor deposition (CVD) technique eliminates the normally required transfer steps, thereby producing mixed-dimensional heterostructures with an ultraclean interface. The controllable epitaxial growth of Te/TMD heterostructures are verified by Raman, scanning probe microscopy (SPM), and transmission electron microscopy (TEM) observation. The photoluminescence results indicate that the emission from TMDs is quenched in the heterostructure, confirming the efficient transfer of photogenerated carriers from TMDs to Te. Additionally, the mixed-dimensional p-n Te/MoSe2 heterojunction photodetector presents self-driven behavior with high responsivity (328 mA W-1), external quantum efficiency (79%), and specific detectivity (8.2 x 10(9) Jones). The modified facile synthesis strategy and proposed growth mechanism in this study shed light on synthesizing mixed-dimensional heterojunctions. This opens avenues for fabricating functional devices with reduced sizes and high densities, further enabling miniaturization and integration opportunities.

With the commercialization of first-generation flexible mobiles and displays in the late 2010s, humanity has stepped into the age of flexible electronics. Inevitably, soft multifunctional sensors, as essential components of next-generation flexible electronics, have attracted tremendous research interest like never before. This review is dedicated to offering an overview of the latest emerging trends in soft multifunctional sensors and their accordant future research and development (R&D) directions for the coming decade. First, key characteristics and the predominant target stimuli for soft multifunctional sensors are highlighted. Second, important selection criteria for soft multifunctional sensors are introduced. Next, emerging materials/structures and trends for soft multifunctional sensors are identified. Specifically, the future R&D directions of these sensors are envisaged based on their emerging trends, namely i) decoupling of multiple stimuli, ii) data processing, iii) skin conformability, and iv) energy sources. Finally, the challenges and potential opportunities for these sensors in future are discussed, offering new insights into prospects in the fast-emerging technology.

Catalytic conversion is a new strategy to mitigate the shuttle effects of lithium-sulfur batteries, but the catalyst must play an effective role in both oxidation and reduction processes. In this paper, a lotus root-like ZnO@MnO2 PCNFs with a built-in electric field are proposed as cathodes for lithium-sulfur batteries. Due to the synergistic effect of both components, ZnO@MnO2 PCNFs demonstrated outstanding bidirectional catalytic performance, with ZnO primarily enhancing catalysis and MnO2 regulating adsorption. The ZnO@MnO2 PCNFs exhibit higher initial capacity (1582 mAh g- 1 at 0.1 C), and longer cycle life (2000 cycles with 0.023 % decay per period at 2 C). Even under high S loading of 8.32 mg cm- 2 and a low electrolyte to sulfur ratio is about 4.8 mu L mg- 1 , the cell with ZnO@MnO2 PCNFs shows a discharge capacity of 688.6 mAh g- 1 at 0.2 C, and maintained at 420.9 mAh g- 1 after 100 cycles. This approach has shown promise in improving the efficiency and cycling stability of Li-S batteries, making them more viable for practical applications.

Almost all implantable electronic medical devices (IEMDs) are powered by bulky Li-ion batteries (LIBs), limiting their miniaturization and lifespan advancements. In addition, LIBs contain toxic materials and flammable electrolytes that are dangerous if they leak into human organs. In this context, there is an urgent need to explore new approaches and concepts that can address the critical challenges of designing novel electrochemical energy storage systems and gain a mechanistic understanding of the phenomena taking place in diverse scenarios. This review summarizes recent advancements in biocompatible supercapacitors (B-SCs) as a power source for various IEMDs, offering a potential solution to these challenges. Different types of IEMDs and their power requirements are briefly discussed, along with challenges arising from energy storage systems and their applications in IEMDs. Given the importance of electrode materials in determining the electrochemical performance of B-SCs in terms of energy and power densities, different electrode materials and their developments are systematically reviewed. Finally, new insights are offered into potential opportunities and future prospects for the rational design of next-generation B-SCs. The search for biocompatible power systems is central to the miniaturization and lifespan improvements of implantable electronic medical devices (IEMDs). This review presents an overview of the recent advancements in developing biocompatible supercapacitors (B-SCs) from the perspective of electrode materials, electrolytes, their design, and possible challenges for advanced IEMDs. image

Smart windows, capable of tailoring light transmission, can significantly reduce energy consumption in building services. While mechano-responsive windows activated by strains are promising candidates, they face long-lasting challenges in which the space for the light scatterer's operation has to be enlarged along with the window size, undermining the practicality. Recent attempts to tackle this challenge inevitably generate side effects with compromised performance in light modulation. Here, we introduce a cuttlefish-inspired design to enable the closing and opening of pores within the 3D porous structure by through-thickness compression, offering opacity and transparency upon release and compression. By changing the activation mode from the conventional in-plane to through-thickness direction, the space requirement is intrinsically decoupled from the lateral size of the scatterer. Central to our design is the asymmetry of pore orientation in the 3D porous structure. These inclined pores against the normal direction increase the opaqueness upon release and improve light modulation sensitivity to compression, enabling transmittance regulation upon compression by an infinitesimal displacement of 50 μm. This work establishes a milestone for smart window technologies and will drive advancements in the development of opto-electric devices.

A Zn anode can offset the low energy density of a flow battery for a balanced approach toward electricity storage. Yet, when targeting inexpensive, long-duration storage, the battery demands a thick Zn deposit in a porous framework, whose heterogeneity triggers frequent dendrite formation and jeopardizes the stability of the battery. Here, Cu foam is transferred into a hierarchical nanoporous electrode to homogenize the deposition. It begins with alloying the foam with Zn to form Cu5 Zn8 , whose depth is controlled to retain the large pores for a hydraulic permeability ≈10-11  m2 . Dealloying follows to create nanoscale pores and abundant fine pits below 10 nm, where Zn can nucleate preferentially due to the Gibbs-Thomson effect, as supported by a density functional theory simulation. Morphological evolution monitored by in situ microscopy confirms uniform Zn deposition. The electrode delivers 200 h of stable cycles in a Zn-I2 flow battery at 60 mAh cm-2 and 60 mA cm-2 , performance that meets practical demands.

Sn has been considered one of the most promising metallic anode materials for lithium-ion batteries (LIBs) because of its high specific capacity. Herein, we report a novel amorphous tin-titanium-ethylene glycol (Sn-Ti-EG) bimetal organic compound as an anode for LIBs. The Sn-Ti-EG electrode exhibits exceptional cyclic stability with high Li-ion storage capacity. Even after 700 cycles at a current density of 1.0 A g−1, the anode maintains a capacity of 345 mAh g−1. The unique bimetal organic structure of the Sn-Ti-EG anode and the strong coordination interaction between Sn/Ti and O within the framework effectively suppress the aggregation of Sn atoms, eliminating the usual pulverization of bulk Sn through volume expansion. Furthermore, the Sn M-edge of the X-ray absorption near-edge structure spectra obtained using soft X-ray absorption spectroscopy signifies the conversion of Sn2+ ions into Sn0 during the initial lithiation process, which is reversible upon delithiation. These findings reveal that Sn is one of the most active components that account for the excellent electrochemical performance of the Sn-Ti-EG electrode, whereas Ti has no practical contribution to the capacity of the electrode. The reversible formation of organic functional groups on the solid electrolyte interphase is also partly responsible for its cyclic stability.

To fulfill the high requirement for high-energy-density storage, Zn ions batteries (ZIBs) has been garnering great scientific attention and considered the promising candidate due to the moderate redox potential, high safety and reasonable cost. However, the problem of the inferior reversibility and limited-service period owing to the issues of side reactions and Zn dendrites hinder its application. In our study, the hexagonal 1T VSe 2 , owns metallic appearance, was used as the zincophilic film to replace the conventional metal and graphene-based matrix for hexagonal closest packed (HCP) typed Zn metal electrodeposition in ZIBs. Our experimental results discovers that 1T VSe 2 /Zn anode is beneficial to regulating Zn crystal morphology from randomly oriented to horizontally (002)-oriented plate-like. Combining with computational modelling, the early stage of Zn nucleation and morphological evolution is investigated from atomistic to meso scale. VSe 2 substrate exhibits higher adsorption energy (-0.54 eV) with Zn, contrasting with graphene (-0.38 eV) and pure Zn (-0.48 eV) based on the density functional theory (DFT) calculations. And classical molecular dynamic (MD) simulations reveal the plate-like Zn electrodeposits undergo a reorientation transition with a higher fraction of the (002) facet due to the rapid adatom diffusion coefficient, which effectively prohibits the dendrite formation. The symmetric cell with modified electrodes shows an ultra-stable cyclic life with 50 mV overpotential up to 2500 cycles in the condition of 1 mA cm -2 and 1 mAh cm -2 .

Thermally conductive polymer nanocomposites are enticing candidates for not only thermal managements in electronics but also functional components in emerging thermal energy storage and conversion systems and intelligent devices. A high thermal conductivity (k) depends largely on the ordered assembly of high-k fillers in the composites. In the past decades, various templating assembly techniques have been developed to rationally construct nanoscale fillers into three-dimensional (3D) interconnected structures, further improving the k of composites compared to conventional methods. Herein, recent advances are summarized in developing thermally conductive polymer composites based on self-templating, sacrificial templating, foam-templating, ice-templating and template-directed chemical vapor deposition techniques. These unique templating methods to fabricate 3D interconnected fillers in the form of segregated, cellular, lamellar, and radially aligned structures are reviewed, and their correlations to the k of composites are thoroughly probed. Moreover, multiscale structural design strategies combined with different templating methods to further improve the k of composites are highlighted. This review offers a constructive guidance to fabricate next-generation thermally conductive polymer composites for diverse thermal energy applications.

Following earlier research efforts dedicated to the realization of multifunctional sensing, recent developments of artificial skins endeavor to go beyond human sensory functions by integrating interactive visualization of strain and pressure stimuli. Inspired by the microcracked structure of spider slit organs and the mechanochromic mechanism of chameleons, this work aims to design a flexible optical/electrical skin (OE-skin) capable of responding to complex stimuli with interactive feedback of human-readable structural colors. The OE-skin consists of an ionic electrode combined with an elastomer dielectric layer, a chromotropic layer containing photonic crystals and a conductive carbon nanotube/MXene layer. The electrode/dielectric layers function as a capacitive pressure sensor. The mechanochromic photonic crystals of ferroferric oxide-carbon magnetic arrays embedded in the gelatin/polyacrylamide stretchable hydrogel film perceive strain and pressure stimuli with bright color switching outputs in the full visible spectrum. The underlying microcracked conductive layer is devoted to ultrasensitive strain sensing with a gauge factor of 191.8. The multilayered OE-skin delivers an ultrafast, accurate response for capacitive pressure sensing with a detection limit of 75 Pa and long-term stability of 5000 cycles, while visualizing complex deformations in the form of high-resolution spatial colors. These findings offer deep insights into the rational design of OE-skins as multifunctional sensing devices.

Given the abundance of potassium resources, potassium-ion batteries are considered a low-cost alternative to lithium-ion types. However, their electrochemical performance remains rather unsatisfactory because potassium ions have sluggish kinetics and large ionic radius. In this study, NiCo2Se4 nanotube spheres are synthesized as efficient potassium storage hosts via a facile two-step hydrothermal process. The rationally designed electrode has various ameliorating morphological and functional features, including the following: (i) A hollow structure allows for relief of the volume expansion while offering an excellent electrochemical reactivity to accelerate the conversion kinetics; (ii) a high electrical conductivity for enhanced electron transfer; and (iii) myriad vacancies to supply active sites for electrochemical reactions. As such, the electrode delivers an initial reversible capacity of 458.1 mAh g−1 and retains 346.6 mAh g−1 after 300 cycles at 0.03 A g−1. The electrode sustains a high capacity of 101.4 mAh g−1 even at a high current density of 5 A g−1 and outperforms the majority of state-of-the-art anodes in terms of both cyclic capacity and rate capability, especially at above 1.0 A g−1. This study not only proves bimetallic selenides are promising candidates for potassium storage devices but also offers new insight into the rational design of electrode materials for high-rate potassium-ion batteries.

A highly anisotropic boron nitride composite aerogel is obtained at a low freezing temperature, exhibiting excellent thermal insulation and solar reflectance for energy efficient cooling.

The practical application of naturally abundant sodium (Na) metal anodes with high energy densities is hindered by large volume expansion and dendrite formation during battery operation. This work reports the synthesis of tin selenide nanoparticles uniformly grown on highly conductive, porous 3D graphene foam (SnSe@GF) as a stable host for Na metal anodes and the underlying conversion reactions as their energy storage mechanism. The SnSe@GF electrode prepared via hydrogel coating and phase transformation sustains remarkable reversibility after 1500 cycles in asymmetric cells and delivers extraordinary cyclic stability and low overpotentials for 2000 h at 1 mA cm-2 and 1 mAh cm-2 in symmetric cells. The conversion of crystalline SnSe into low-crystallinity Na15Sn4 and Na2Se dual nucleation sites after pre-sodiation is responsible for the outstanding performance according to the in-situ microscopy and density functional theory calculations. The conversion enables the in-situ formation of a unique interface that possesses high Na affinity featured by abundant active sites, contributing to uniform Na nucleation/plating and dendrite suppression, thus give rising to superior stability and electrochemical performance of the SnSe@GF electrode. The rational design of the current 3D architecture can shed new insights into the development of Na hosts for next-generation rechargeable batteries.

Hydrogel electrolytes are widely explored in Zn metal batteries for application in wearable electronics. While extensive studies have been conducted on optimizing the chemical structure and boosting the tensile elasticity, the mechanical stability of the hydrogel under repeated deformation is largely overlooked, leading to unsatisfactory performance at large cycling capacity. This work systematically analyzes the compressive fatigue‐resistance properties of the hydrogel electrolyte, revealing the critical roles of the salt and copolymer matrix on crack initiation and propagation. It shows that, on the premise of homogeneous Zn deposition, an improved anti‐fatigue property is essential to achieve high‐capacity Zn metal anodes. The optimal Zn(ClO 4 ) 2 ‐polyacrylamide/chitosan hydrogel electrolyte (C‐PAMCS) exhibits an unprecedented lifespan of 1500 h for Zn//Zn cells at a current density of 10 mA cm −2 and a high areal capacity of 10 mAh cm −2 . The potential application of C‐PAMCS is exemplified in all‐flexible Zn‐ion batteries enabled by a flexible current collector consisting of a Ag nanowires embedded elastomer. This study provides the rationale under hydrogel electrolyte engineering toward advanced Zn‐ion battereis and the application in flexible devices.

Thermally insulating materials are commonly used to reduce energy consumption in buildings. Most commercial products possess only low thermal conductivities but poor insulating capabilities in the daytime with little sunlight reflectance and thermal emittance. It is challenging to achieve all traits in the same material. Herein, anisotropic boron nitride nanosheet (BNNS)/polyvinyl alcohol composite aerogels are developed using the unidirectional freeze-casting technique. Benefitting from the aligned porous structure, the composite aerogel with an optimal BNNS content exhibits a combination of an ultralow TC of 20.3 mW/mK in the through-thickness direction, a high solar-weighted reflectance of 95.0 % over the whole sunlight wavelength and a high emittance of above 93 % within the atmospheric transparency window. These exceptional thermo-optical properties enable the composite aerogel to maintain the interior temperature much cooler than commercially available foams, making them promising candidates as superinsulating envelopes for energy saving in buildings towards carbon neutrality.